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Chronic inflammatory demyelination polyradiculoneuropathy (CIDP) is a rare autoimmune neuropathy generated by cellular and humoral immune responses. Its course can be chronic, progressive, monophasic, or relapsing-remitting. Misdiagnosis and inappropriate therapy are common in CIDP. Given the scarcity of integrative information, we aimed to briefly summarize the epidemiology, pathophysiology, clinical phenotypes, diagnostic tools, and diagnostic criteria and provide a systematic diagnostic approach. We reviewed articles on Medline (PubMed) from 2018 to 2023, using Google Scholar to summarize the topics. The results are presented as a narrative review, in accordance with recommendations of the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines. The included evidence showed that CIDP is a challenging neuropathy to diagnose and treat. Pathologic factors initiating typical CIDP and atypical CIDP are still clearly unknown. CIDP is diagnosed using the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria, which combine clinical features with electrophysiological evidence of demyelination. However, some patients need to fulfill the requirements. Another challenge is monitoring the disease progression and recognizing patients who do not respond to evidence-based first-line therapy to individualize their treatment. Based on the evidence, we conclude that 2021 EFNS/PNS guidelines allow for a more accurate diagnosis and treatment of CIDP and its variants. New diagnostic tools and molecular approaches are helpful in the diagnosis process but cannot replace clinical and electrodiagnostic criteria., Competing Interests: Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2025, Roman-Guzman et al.)

Background: Atypical aging in Down syndrome (DS) is associated with neuropathological characteristics consistent with Alzheimer disease. Gait abnormalities have been shown to be associated with an increased risk of dementia for the general population. The aim of this study was to determine whether gait disorders are associated with worse cognitive performance and dementia in adults with DS., Methods: We evaluated 66 individuals with DS (≥20 y of age), divided into 3 groups: stable cognition, prodromal dementia, and dementia (presumed Alzheimer disease). Each individual was evaluated with the Performance-Oriented Mobility Assessment (POMA), Timed Up and Go test, and Cambridge Examination for Mental Disorders of Older People with Down's Syndrome and Others with Intellectual Disabilities (CAMDEX-DS), in addition to a comprehensive clinical protocol to ascertain the occurrence of medical or psychiatric comorbidities., Results: The score on the POMA-Gait subscale score and body mass index were found to be independent predictors of prodromal dementia and dementia ( P <0.001 for both). With the exception of perception, all cognitive domains correlated with the POMA-Total score ( P <0.05)., Conclusion: A lower POMA-Gait score increases the chance of prodromal dementia and dementia in adults with DS. Unlike other research, in this study higher body mass index was also found to increase the chance of prodromal dementia and dementia. In those individuals, applying the POMA could facilitate the early diagnosis of dementia, help identify fall risks, and promote the adoption of geriatric interventions focused on improving functional mobility., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: This study aimed to provide insight into health disparities among Veterans by (a) documenting the prevalence of physical and mental health problems in a racially diverse sample of Veterans, (b) comparing Veterans' willingness to seek treatment for various physical and mental health conditions, and (c) examining the impact of discrimination and coping on willingness to seek treatment., Method: Veterans reported on current physical and mental health symptoms and the importance of treatment for various health conditions. Patterns were examined in the full sample ( N = 334, 32% female) and the subsample who reported hazardous alcohol use in the past year ( n = 116, 33% female). Linear regression was used to test alternative coping as a moderator of the association between experiences with discrimination and willingness to seek treatment among Veterans of color ( n = 242, 37% female)., Results: Participants reported greater willingness to seek treatment for physical than mental health conditions. Sleep problems (75%) and substance use (74%) were the most prevalent health behaviors, but they were rated lowest in treatment importance. Among Veterans of color, everyday experiences with discrimination were generally associated with less willingness to seek physical or mental health treatment, but often only among those who denied use of coping strategies., Conclusions: Veterans are least willing to seek treatment for the health conditions that are most prevalent in their communities. Coping strategies may mitigate the negative association between discriminatory experiences and willingness to seek treatment among Veterans of color. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Introduction: Veterans in general-and especially those who identify as Veterans of color-are underrepresented in health-related treatment research. This contributes to health inequity by hindering the development of evidence-based treatment recommendations for people of color. This project utilized culturally centered research procedures to identify health-related research priorities and examine motives for and barriers to research participation in a diverse sample of Veterans., Materials and Methods: Veterans (N = 330, 32% female; 36% Black, 28% White, 15% Latinx, 12% Asian, 4% Multiracial) reported their experiences with and perspectives on health-related research online from remote locations. Linear regression was used to test associations between discrimination and motives/barriers for research. All procedures were approved by the Institutional Review Board (#2033562)., Results: Participants identified psychological concerns, particularly PTSD, as research priorities for Veterans in their communities, but also prioritized physical problems (e.g., brain injury) and social concerns (e.g., homelessness, access to care). Perceptions of, motives for, and barriers to research were similar across racial/ethnic groups. The most common motive was contributing to research that seems important, and the most common barrier was not knowing about research opportunities. Every-day experiences with discrimination (e.g., people acting as if they are afraid of you because of your race/ethnicity) were associated with more barriers to research among Black participants., Conclusions: Experiences of racial/ethnic discrimination are associated with different research-related outcomes across racial/ethnic groups. Efforts to engage diverse populations should prioritize access to (not willingness to participate in) health-related research., (© The Association of Military Surgeons of the United States 2022. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Study Objectives: Empirical evidence linking individual sleep hygiene practices to subsequent sleep parameters is limited, particularly at the daily level. This study compared the strength of daily, within-person associations between these modifiable sleep behaviors and nighttime sleep in young adult drinkers with insomnia., Methods: Young adults (ages 18-30 years; n = 56) who met diagnostic criteria for insomnia and reported past-month binge drinking wore wrist actigraphy and completed online sleep diaries for 8.5 days (standard deviation = 2.3; 477 reports). Diaries assessed engagement in 11 sleep hygiene recommendations. Multilevel models tested daily associations between sleep behaviors and 3 outcomes: sleep quality, self-reported sleep efficiency, and actigraphy-measured sleep efficiency., Results: Participants self-reported better sleep quality/efficiency on days that they slept in a comfortable environment, limited naps to 30 minutes, and maintained a consistent wake time. They self-reported worse sleep quality and efficiency on nights that they avoided alcohol use before bedtime. No sleep behaviors were significantly associated with actigraphy-measured sleep efficiency after correcting for inflation in type I error., Conclusions: The sleep hygiene recommendations most strongly associated with sleep at the daily level were consistent with stimulus control. Creating a comfortable sleep environment also emerged as an important correlate of daily sleep. Heavy drinkers with insomnia may perceive better sleep if they drink before bedtime; however, this finding may be unique to this population., Citation: Miller MB, Curtis AF, Hall NA, et al. Daily associations between modifiable sleep behaviors and nighttime sleep among young adult drinkers with insomnia. J Clin Sleep Med. 2022;18(3):703-712., (© 2022 American Academy of Sleep Medicine.)

The mycotoxin Ochratoxin A (OTA) is responsible for producing many effects on human and animal health. In this work, the evaluation of the presence of OTA in tea beverage samples consisted of extraction and preconcentration through the solidification of a floating organic drop (DLLME-SFO) combined with an additional octadecyl silane clean-up step. The obtained extract was analyzed by UHPLC-MS/MS. Interferences from the matrix were effectively reduced and, consequently, recovery increased from 43.18% ± 4.1%-96.02% ± 2.54%. The validation assays were carried out by external calibration and spiked samples, with satisfactory recoveries. An adequate dynamic calibration range was obtained over a concentration interval between 0.5 and 70 μg mL -1 OTA. Capabilities of detection and quantification were 0.5 and 1.4 μg mL -1 . The obtained Green Certificate was compared with other techniques to establish the greenness profile of the procedure. Quantification of ochratoxin A levels in tea samples was performed., Competing Interests: The authors declare no conflict of interest., (© 2021 The Authors.)

Background: Cesarean delivery reduces the risk of infant and maternal morbidity and mortality when medically indicated, however, the cesarean delivery rate is estimated to be two to three times higher than medically necessary. The World Health Organization and American College of Obstetricians and Gynecologists have expressed concern over the high rates of cesarean delivery, citing evidence that cesarean delivery has negative short- and long-term consequences for the health of the infant, mother, and for future pregnancies. Infants delivered by cesarean are at an increased risk of metabolic disease and immune dysfunction throughout the lifespan. Preliminary research suggests that the hypothalamic pituitary adrenal (HPA) axis is a plausible pathway linking cesarean delivery to poor health later in life. The present study examines the relation between mode of delivery and HPA axis function in six-month-old infants. We also examine whether the cesarean delivery was elective or indicated altered to the relation between mode of delivery and infant cortisol profiles., Methods: The sample included 136 mother/infant pairs. Thirty-nine women delivered by cesarean and 97 delivered vaginally. Maternal and infant medical records were reviewed for prenatal medical history and birth outcomes. Infant saliva was collected for cortisol analysis at a 6-month well-baby checkup. Samples were collected upon arrival to the appointment (baseline) and 20 min after exposure to a painful stressor, the inoculation procedure (response). A mixed model ANCOVA was conducted to determine whether salivary cortisol concentrations differed between the two delivery groups. To examine whether complications related to having an indicated cesarean delivery contributed to any association between mode of delivery and cortisol production, cortisol concentrations were compared between the subgroup of infants whose cesarean deliveries were elective (e.g. maternal request or previous cesarean delivery) to infants delivered vaginally., Results: Infants delivered by cesarean had lower cortisol concentrations at baseline and after the inoculation procedure compared to those delivered vaginally. Further, the relation between mode of delivery and cortisol levels persisted even when the analyses were restricted to compare only the elective cesarean deliveries (e.g. maternal request or previous cesarean delivery) to those delivered vaginally., Discussion: This study provides evidence for an association between cesarean delivery and infant HPA axis function in infancy. Findings are consistent with the hypothesis that the HPA axis is a plausible pathway that links cesarean delivery with long-term health outcomes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, a novel, simple, and highly sensitive analytical procedure for the quantitative evaluation of oxygenated and nitrated polycyclic aromatic hydrocarbons in volcanic ash samples based on dispersive solid-liquid microextraction (DSLME) coupled to ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed. Diverse chemometric tools were applied to optimize DSLME working conditions. Thus, a linear calibration curve for all the target analytes in the concentration range from 0.01 to 100 μg g -1 (r 2  > 0.994) was obtained. The limits of detection for all the compounds were between 14.6 and 56.0 pg g -1 , with high reproducibility (relative standard deviation (RSD) was below 8.1% for all the analytes). Additionally, recoveries ranged from 94.2 to 100%. The applicability of the method was evaluated and the feasibility of the existence of nitrated and oxygenated-PAHs in volcanic ashes at ultra-trace levels was demonstrated, which reveals an unknown source of distribution of these pollutants to the environment. Graphical Abstract.

Levels of essential metals in human breast milk (HBM) have been determined by different analytical techniques, but there is few woks about human whey milk fractions. However, the current trend lies in metalloproteomic and identification of different metalloproteins. In this sense, native separative techniques (N-PAGE and SEC) coupled to ICP-MS provide us with valuable information. Besides it is necessary the development of new methodologies in order to determine with accuracy and precision the profile of such metals and metalloproteins in the different whey protein fractions of HBM. Thus, the aim of this work was to develop a new method for metals and metalloproteins determination by SEC-ICP-MS in whey protein fractions of HBM. Human whey fractions were obtained of HBM samples by ultracentrifugation. Then, protein fractions of whey milk were separated by SEC coupled to ICP-MS for metalloproteins and Mn, Co, Cu and Se quantification. Besides, protein profile of whey milk was determined by N-PAGE and computer assisted image analysis. SEC-ICP-MS results indicated that first and second protein fractions showed detectable levels of the Mn, Co, Cu, and Se. Protein profile determined by N-PAGE and image analysis showed that molecular weight of protein fractions ranged between 68,878-1,228.277 Da. In this work, metalloproteins were analyzed by SEC coupled to ICP-MS, with adequate sensitivity and accuracy. Our study has shown the presence of Mn, Co, Cu and Se bound to two protein fractions in whey milk of HBM. Metals levels analyzed were within the ranges reported in the literature., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00μg As L(-1). The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A single-step procedure for trace elements analysis of milk samples is presented. Solubilization with small amounts of dymethylformamide (DMF) was assayed prior to inductively coupled plasma mass spectrometry (ICPMS) detection with a high efficiency sample introduction system. All main instrumental conditions were optimized in order to readily introduce the samples without matrix elimination. In order to assess and mitigate matrix effects in the determination of As, Cd, Co, Cu, Eu, Ga, Gd, Ge, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sm, S, Sr, Ta, Tb, V, Zn, and Zr, matrix matching calibration with (103)Rh as internal standard (IS) was performed. The obtained limits of detection were between 0.68 (Tb) and 30 (Zn) μg L(-1). For accuracy verification, certified Skim milk powder reference material (BCR 063R) was employed. The developed method was applied to trace elements analysis of commercially available milks. Principal components analysis was used to correlate the content of trace metals with the kind of milk, obtaining a classification according to adults, baby or baby fortified milks. The outcomes highlight a simple and fast approach that could be trustworthy for routine analysis, quality control and traceability of milks., (Copyright © 2015 Elsevier B.V. All rights reserved.)

We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid-liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A high performance liquid chromatography coupled with atomic fluorescence spectrometry method for the determination of thimerosal (sodium ethylmercury thiosalicylate, C9H9HgNaO2S), ethylmercury, and inorganic mercury is proposed. Mercury vapor is generated by the post-column reduction of mercury species in formic acid media using UV-radiation. Thimerosal is quantitatively converted to Hg(II) followed by the reduction of Hg(II) to Hg(0). This method is applied to the determination of thimerosal (THM), ethylmercury (EtHg) and inorganic Hg in samples of a pharmaceutical industry effluent, and in waters of the San Luis River situated in the west side of San Luis city (Middle West, Argentine) where the effluents are dumped. The limit of detections, calculated on the basis of the 3σ criterion, where 0.09, 0.09 and 0.07 μg L(-1) for THM, EtHg(II) and for Hg(II), respectively. Linearity was attained from levels close to the detection limit up to at least 100 μg L(-1)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Trace metals have negative effects on the oxidative stability of edible oils and they are important because of possibility for oils characterisation. A single-step procedure for trace elemental analysis of edible oils is presented. To this aim, a solubilisation with tetramethylammonium hydroxide (TMAH) was assayed prior to inductively coupled plasma mass spectrometry detection. Small amounts of TMAH were used, resulting in high elemental concentrations. This method was applied to edible oils commercially available in Argentine. Elements present in small amounts (Cu, Ge, Mn, Mo, Ni, Sb, Sr, Ti, and V) were determined in olive, corn, almond and sunflower oils. The limits of detection were between 0.004 μg g(-1) for Mn and Sr, and 0.32 μg g(-1) for Sb. Principal components analysis was used to correlate the content of trace metals with the type of oils. The two first principal components retained 91.6% of the variability of the system. This is a relatively simple and safe procedure, and could be an attractive alternative for quality control, traceability and routine analysis of edible oils., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

An approach to understand vines (Vitis vinifera) defense mechanism against heavy metal stress by isolation and determination of Hg-phytochelatins (PCs) complexes was performed. PCs are important molecules involved in the control of metal concentration in plants. PCs complex toxic metals through -SH groups and stores them inside cells vacuole avoiding any toxic effect of free metals in the cytosol. The Hg-PCs identification was achieved by determination of Hg and S as hetero-tagged atoms. A method involving two-dimensional chromatographic analysis coupled to atomic spectrometry and confirmation by tandem mass spectrometry is proposed. An approach involving size exclusion chromatography coupled to inductively coupled plasma mass spectrometry on roots, stems, and leaves extracts describing Hg distribution according to molecular weight and sulfur associations is proposed for the first time. Medium-low molecular weight Hg-S associations of 29-100 kDa were found, suggesting PCs presence. A second approach employing reversed-phase chromatography coupled to atomic fluorescence spectrometry analysis allowed the determination of Hg-PCs complexes within the mentioned fractions. Chromatograms showed Hg-PC2, Hg-PC3 and Hg-PC4 presence only in roots. Hg-PCs presence in roots was confirmed by ESI-MS/MS analysis.

An on-line scandium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry associated with flow injection was studied. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with oxidized multiwalled carbon nanotubes, at pH 1.5. The retained analyte was removed from the minicolumn with 30% (v/v) nitric acid. A total enrichment factor of 225-fold was obtained within a preconcentration time of 300 s (for a 25 mL sample volume). The overall time required for preconcentration and elution of 25 mL of sample was about 6 min; the throughput was about 10 samples per hour. The value of the detection limit was 4 ng L(-1) and the precision for 10 replicate determinations at 100 ng L(-1) Sc level was 5% relative standard deviation, calculated from the peak heights obtained. The calibration graph using the preconcentration system was linear with a correlation coefficient of 0.9996 at levels near the detection limits up to at least 10 mg L(-1). After optimization, the method was successfully applied to the determination of Sc in an acid drainage from an abandoned mine located in the province of San Luis, Argentina., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Monitoring carnitine and acetylcarnitine levels in biological fluids is a powerful tool for diagnostic studies. Research has recently shown that the analysis of carnitine and related compounds in clinical samples can be accomplished by different analytical approaches. Because of the polar and ionic nature of the analytes and matrix complexity, accurate quantitation is a highly challenging task. Thus, sample processing factors, preparation/cleanup procedures, and chromatographic/ionization/detection parameters were evaluated. On the basis of the results obtained, a rapid, selective, sensitive method based on hydrophilic interaction liquid chromatography-tandem mass spectrometry for the analysis of carnitine and acetylcarnitine in serum and urine samples is proposed. The matrix effect was assessed. The proposed approach was validated, the limits of detection were in the nanomolar range, and carnitine and acetylcarnitine levels were found within the micromolar range in both types of sample.

Concerns regard watering crops with Hg contaminated waters have arisen worldwide recently. In these sense Hg uptake by Vitis vinifera L. cv. Malbec was evaluated under greenhouse conditions by the administration of Hg(2+) for 4 days through irrigation water (short-term administration). Vines uptake Hg translocating it from roots through stems to leaves. Roots accumulated the higher Hg concentration. Hg in stems and leaves was accumulated mostly as organic Hg, bind to different moieties. Size exclusion chromatography (SEC) and ion pair chromatography (IPC) were employed to reach insights into these ligands. Hg is distributed mainly in high molecular weight fractions of 669 kDa in vine plants. In stems and leaves, Hg-S associations were found in 669 and 66 kDa fractions. Hg-S association at 66 kDa suggests a possible protein or peptide binding affecting vines normal physiology. Since Hg contamination through organomercurials is more harmful than Hg(2+) itself, methyl mercury, dimethyl mercury, and phenyl mercury, more toxic Hg species were evaluated with negative results.

Melatonin (MT) presence in higher plants was recently discovered and the knowledge of its function in vivo is limited. Several studies have recently shown the occurrence of MT and related compounds in grapes and wines. The analysis of MT in plants and foods represents a highly challenging task due to its wide concentration range, the difficulty in the selection of the extraction solvents because of its amphipathic nature, and the fact that it reacts quickly with other matrix components. Thus, sample processing factors; preparation/cleanup procedures; and chromatographic/detection parameters, such as HILIC and reverse phase (C(8) and C(18)) chromatographic modes, ESI, and atmospheric pressure chemical ionization (APCI) in both negative and positive modes were evaluated. Taken together, we have demonstrated that optimal conditions were quite different for each of the matrices under study. A sonication-mediated extraction step was necessary for grape skin (100% v/v methanol) and plant tissues (50% v/v methanol), while wine and must required a SPE preconcentration step. HILIC-(+) APCI ionization was better for MT standards, while C(8) -(+) APCI was the best choice for grape skin and C(18) -(+ESI) was suitable for wine. On the other hand, C(8) -(+)ESI was the most appropriate for vegetal tissues of Arabidopsis thaliana. Proposed methods were validated and the LODs were in the low picogram levels range. The optimized approaches were applied to the determination of MT and its isomer in different vegetal/food samples; levels found within the range: 4.9-440 ng/g., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel method for analysis of biodiesel by electrothermal atomic absorption spectrometry is described. This analytical strategy involves sample preparation as emulsions for routine and reliable determination of Cd and Hg. Several experimental conditions were investigated, including emulsion stability and composition, furnace temperature program and matrix modification. Different calibration strategies were also evaluated, being the analyte addition method preferred both for Cd and Hg. The accuracy was verified through comparison with an acid digestion in a microwave closed system. The injection repeatability was evaluated as the average relative standard deviation (R.S.D %) for five successive firings and was better than 4.4% for Cd and 5.4% Hg respectively. The detection limits, evaluated by the 3σ concept of calculation (n=10), were of 10.2 μg kg(-1) (0.9 μg L(-1)) for Hg and 0.3 μg kg(-1) (0.04 μg L(-1)) for Cd. This method was successfully applied to the determination of Cd and Hg in biodiesel samples obtained from local vendors., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The present paper evaluates the applicability of a new FIA system for COD determination. The new system, flow injection microwave solid phase extraction by means of activated carbon (FI-MW-SPE), consists of a digestion circuit, placed in a home MW oven, coupled to an ICP-OES spectrophotometer. Doehlert experimental design was used to speed up the optimization of different experimental variables studied for assisted digestion methods. The method provided a high throughput of about 18 samples h(-1). To assess the accuracy of analytical methods linear regression, elliptic joint confidence region (EJCR) was used. A large linear range of 2.78-850 mg O(2) L(-1) with an excellent detection limit of 0.94 mg O(2) L(-1) was obtained. The interference by high chloride concentration was studied, and values below 3000 mg Cl(-) ions L(-1), allowed the estimation of COD load without any masking agents. COD values for various types of wastewater samples were correlated with those obtained by standard manual methods. Moreover, interferences due to matrix nature are absent; since matrix is washed out of the column before Cr (III) is eluted. This method reduces the time, reagent volume, hazardous emission, external contamination, with a good reproducibility and accuracy., (Copyright © 2012. Published by Elsevier B.V.)

A method to obtain robust information on short term leaching behaviour of volcanic ashes has been developed independently on the sample age. A mixed factorial design (MFD) was employed as a multivariate strategy for the evaluation of the effects of selected control factors and their interactions (amount of sample (A), contact time (B), and liquid to solid ratio or L/S (C)) on the leaching process of selected metals (Na, K, Mg, Ca, Si, Al, V, Mn, Fe, and Co) and anions (Cl(-) and SO(4)(2-)). Box plots of the data acquired were used to evaluate the reproducibility achieved at different experimental conditions. Both the amount of sample (A) and leaching time (B) had a significant effect on the element stripping whereas the L/S ratio influenced only few elements. The lowest dispersion values have been observed when 1.0 g was leached with an L/S ratio equal to 10, shaking during 4 h. The entire method is completed within few hours, and it is simple, feasible and reliable in laboratory conditions., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Common snook (Centropomus undecimalis) is one of the most important marine species under commercial exploitation in the Gulf of Mexico; for this reason, interest in developing its culture is a priority. However, larviculture remains as the main bottleneck for massive production. In this sense, our objective was to determine the changes of digestive enzymes activities using biochemical and electrophoretic techniques during 36 days of Common snook larviculture fed with live preys (microalgae, rotifers, and Artemia). During larviculture, all digestive enzymatic activities were detected with low values since yolk absorption, 2 days after hatching (dah) onwards. However, the maximum values for alkaline protease (6,500 U mg protein(-1)), trypsin (0.053 mU × 10(-3) mg protein(-1)), and Leucine aminopeptidase (1.4 × 10(-3) mU mg protein(-1)) were detected at 12 dah; for chymotrypsin at 25 dah (3.8 × 10(-3) mU mg protein(-1)), for carboxypeptidase A (280 mU mg protein(-1)) and lipase at 36 dah (480 U mg protein(-1)), for α-amylase at 7 dah (1.5 U mg protein(-1)), for acid phosphatases at 34 dah (5.5 U mg protein(-1)), and finally for alkaline phosphatase at 25 dah (70 U mg protein(-1)). The alkaline protease zymogram showed two active bands, the first (26.3 kDa) at 25 dah onwards, and the second (51.6 kDa) at 36 dah. The acid protease zymogram showed two bands (RF = 0.32 and 0.51, respectively) at 34 dah. The digestive enzymatic ontogeny of C. undecimalis is very similar to other strictly marine carnivorous fish, and we suggest that weaning process should be started at 34 dah.

A fast method for the determination of As, Co, Cu, Fe, Mn, Ni, Se and V in biological samples by ETV-ICP-MS, after a simple sample treatment with formic acid, is proposed. Approximately 75 mg of each sample is mixed with 5 mL of formic acid, kept at 90°C for 1 h and then diluted with nitric acid aqueous solution to a 5% (v/v) formic acid and 1% (v/v) nitric acid final concentrations. A palladium solution was used as a chemical modifier. The instrumental conditions, such as carrier gas flow rate, RF power, pyrolysis and vaporization temperatures and argon internal flow rate during vaporization were optimized. The formic acid causes a slight decrease of the analytes signal intensities, but does not increase the signal of the mainly polyatomic ions ((14)N(35)Cl(+), (14)N(12)C(+), (40)Ar(12)C(+), (13)C(37)Cl(+), (40)Ar(36)Ar(+), (40)Ar(35)Cl(+), (35)Cl(16)O(+), (40)Ar(18)O(+)) that affect the analytes signals. The effect of charge transfer reactions, that could increase the ionization efficiency of some elements with high ionization potentials was not observed due to the elimination of most of the organic compounds during the pyrolysis step. External calibration with aqueous standard solutions containing 5% (v/v) formic acid allows the simultaneous determination of all analytes with high accuracy. The detection limits in the samples were between 0.01 (Co) and 850 μg kg(-1) (Fe and Se) and the precision expressed by the relative standard deviations (RSD) were between 0.1% (Mn) and 10% (Ni). Accuracy was validated by the analysis of four certified reference biological materials of animal tissues (lobster hepatopancreas, dogfish muscle, oyster tissue and bovine liver). The recommended procedure avoids plasma instability, carbon deposit on the cones and does not require sample digestion., (Copyright © 2011 Elsevier B.V. All rights reserved.)

In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)mim][PF(6)] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L(-1), while the relative standard deviation (RSD) was 4.7% (at 0.5 μg L(-1) Co level and n=10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A novel, simple, and rapid reversed-phase liquid chromatography-tandem mass spectrometric methodology was developed for the analysis of natamycin in wine samples. Natamycin was protonated to form singly charged ions in an electrospray positive ion mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of three fragment ion transitions (666.3 → 648.2, 666.3 → 503.3, and 666.3 → 485.2) to provide a high degree of sensitivity and specificity. Chromatographic separation was performed on a rapid resolution column using a mobile phase consisting of an acetonitrile/water mixture with a total run time of 5.0 min. After only filtration as pretreatment, the sample was injected into the chromatographic system. The proposed method was validated in terms of selectivity, trueness, precision, decision limit (CCα), and detection capability (CCβ) according to 2002/657/EC Commission decision. The values for trueness, reported as bias (%), agreed with those established by the aforementioned document. Repeatability (intraday variability) values were 12.37% at a concentration of 1.0 μg L(-1) and 8.99-4.19% at concentrations between 2.5 and 10 μg L(-1). The overall within-laboratory (interday variability) reproducibility was 15.47% at a concentration of 1.0 μg L(-1), which was significantly lower than the indicative value reported in the EU decision. The results indicated that the proposed approach is a sensitive, fast, reproducible, and robust methodology suitable for the analysis of natamycin levels in wine samples.

In this study we developed an interesting alternative to HPLC-mass spectrometry for the quantification of seven important drugs of abuse in racehorses. The procedure proposed in this work is a combination of single-drop microextraction (SDME) and an open tubular capillary electrochromatography (OT-CEC) using multi-wall carbon nanotubes (MWCTs) immobilized into a fused-silica capillary as a stationary phase. The SDME showed to be a powerful tool for extraction/preconcentration of the seven drugs analyzed in the study, showing an enrichment factor between 38- and 102-fold depending on the drug. We have investigated the electrophoretic features of MWCTs immobilized fused-silica capillary by covalent modification of the inner surface of the capillary. The results show a good run-to-run, day-to-day and capillary-to-capillary reproducibility of the method. Compared with the capillary zone electrophoresis (CZE), the coating of the capillary allowed the separation of the analytes with high resolution, with less band-broadening and without distortion of the baseline. The interactions between the analytes and the MWCTs resulted in an increased migration time and probably this was the reason of the front tailing effect. The results showed a good capillary efficiencies and an improved of the electrophoretic separation., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Biosorption is a term that usually describes the removal of heavy metals from an aqueous solution through their passive binding to a biomass. Bacteria, yeast, algae and fungi are microorganisms that have been immobilized and employed as sorbents in biosorption processes. The binding characteristics of microorganisms are attributed to functional groups on the surface providing some features to the biosorption process like selectivity, specificity and easy release. These characteristics turn the biosorption into an ideal process to be introduced in solid phase extraction systems for analytical approaches. This review encompasses the research carried out since 2000, focused on the employment of biosorption processes as an analytical tool to improve instrumental analysis. Since aminoacids and peptides as synthetic analogues of natural metallothioneins, proteins present in the cell wall of microorganisms, have been also immobilized on solid supports (controlled pore glass, carbon nanotubes, silica gel polyurethane foam, etc.) and introduced into solid phase extraction systems; a survey attending this issue will be developed as well in this review., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A study about the capabilities of three kinds of nanomaterials namely, carbon nanotubes (CNT), oxidized carbon nanotubes (ox-CNT) and l-alanine immobilized on carbon nanotubes (ala-CNT) to serve as sorbents for preconcentrating Ni and Pb using an on-line system coupled to electrothermal atomic absorption spectroscopy (ETAAS) technique, was accomplished. The solid phase extraction was performed in a conical minicolumn used as sorbent holder. After loading a fixed volume of the analytes, they were eluted with a discrete volume (50 μL) of nitric acid, placed directly into the platform of a L'Vov tube. After that, each analyte was determined individually. Ni and Pb retention was strongly influenced by pH but exhibiting different behaviors. The study demonstrated that the sorbent based on ox-CNTs was the one that exhibited the highest capacity and linearity for both analytes when compared with CNT or ala-CNT. The analytical performance was evaluated for the three sorbents to establish the best conditions regarding sensitivity, reproducibility and accuracy. The precision expressed as relative standard deviations (n=6) were 3.9 and 0.5% for Ni(2+) and Pb(2+), respectively The limit of detection (LOD), calculated as the concentration required to yield a net peak equal to three times the standard deviation of the background signal (3σ) was 30 and 10 ng L(-1) for Ni(2+) and Pb(2+) respectively. Alternatively, the limit of quantification (10σ) was calculated and resulted to be 0.79 and 0.07 μg L(-1) for Ni(2+) and Pb(2+) respectively. After optimization, the method that involved the use of ox-CNT associated to an on-line preconcentration was tested in samples of relevant environmental importance. Accuracy was evaluated analyzing a certified reference material namely, Municipal Sludge (QC MUNICIPAL SLUDGE A) and a reference sample of Lake Sediment (TRAP-LRM from IJS)., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Dispersive solid-phase extraction (DSPE) is proposed for the first time as a simplified, fast and low cost clean-up technique of biological sample extracts for polybrominated diphenyl ethers (PBDEs) determination. The combination of a traditional extraction technique, such as ultrasound-assisted leaching (USAL) with DSPE was successfully applied for sample preparation prior to gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The analytes were first extracted from 1g homogenized sample in n-hexane:dichloromethane (8:2) by applying USAL technique and further cleaned-up using DSPE with 0.20 g C(18)-silica as sorbent material. Different solvent mixtures, sorbent type and amount, and lipid digestion procedures were evaluated in terms of clean-up and extraction efficiency. Under optimum conditions, the method detection limits (MDLs) for PBDEs, calculated as three times the signal-to-noise ratio (S/N) were within the range 9-44 pg g(-1) wet weight. The calibration graphs were linear within the concentration range of 53-500,000 pg g(-1), 66-500,000 pg g(-1), 89-500,000 pg g(-1) and 151-500,000 pg g(-1) for BDE-47, BDE-100, BDE-99 and BDE-153, respectively; and the coefficient of determination (r(2)) exceeded 0.9992 for all analytes. The proposed methodology was compared with a reference solid-phase extraction technique. The applicability of the methodology for the screening of PBDEs has been demonstrated by analyzing spiked and real samples of biological nature (fish, egg and chicken) with different lipid content as well as reference material (WELL-WMF-01). Recovery values ranged between 75% and 114% and the measured concentrations in certified material showed a reasonable agreement with the certified ones. BDE-47, BDE-100 and BDE-99 were quantified in three of the seven analyzed samples and the concentrations ranged between 91 and 140 pg g(-1). In addition, this work is the first description of PBDEs detected in fish of Argentinean environment., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A simple non-chromatographic method for the determination of mercury (Hg(2+)), methylmercury (MeHg(+)), dimethylmercury (Me(2)Hg), and phenylmercury (PhHg(+)) employing atomic fluorescence spectrometry (AFS) as detection technique was developed. Mercury species showed a particular behavior in the presence of several reagents. In a first stage SnCl(2) was employed for Hg(2+) determination; in a second step, [Hg(2+)+PhHg(+)] concentration was determined using SnCl(2) and UV radiation. MeHg(+) decomposition was prevented adding 2-mercaptoethanol. In a third stage, [Hg(2+)+PhHg(+)+MeHg(+)] concentration was determined using K(2)S(2)O(8). Finally, the four species were determined employing NaBH(4). Reagents concentration and flow rates were optimized. The extraction technique of mercury species involved the use of 2-mercaptoethanol as ion-pair reagent. The limits of detection for Hg(2+), PhHg(+), MeHg(+), and Me(2)Hg were 1, 40, 68, and 99 ng L(-1) with a relative standard deviation of 1.5, 3.1, 4.7 and 5.8%, respectively. Calibration curve was linear with a correlation factor equal to 0.9995. The method was successfully applied to the determination of the mercury species in two Antarctic materials: IRMM 813 (Adamussium colbecki) and MURST-ISS-A2 (Antarctic Krill)., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

A new, simple, and selective method for preconcentration and determination of Cr(VI) in aqueous samples. After adsorption in "batch mode" on Aliquat 336-AC, determinations were made directly on the solid by X-ray fluorescence spectrometry, which had the advantage of not requiring the step of elution of the chromium retained. The enrichment factor was calculated considering that the tablets obtained from 10 mL solution of Cr(VI) (1000 μg L(-1)) had a final thickness of 0.64 mm and a diameter of 16.7 mm; the volume deposited on the pellet was 0.14 cm(3). The preconcentration factor obtained was 71-fold, which was highly satisfactory for chromium trace analysis by XRF. Finally, the method was successfully applied to the determination of Cr(VI) in drinking water samples.

An interference-free, fast, and simple method is proposed for Pb determination in environmental solid samples combining slurry sampling and electrothermal atomic absorption spectrometry. Samples were ground to an adequate particle size and slurries were prepared by weighing from 0.05 g to 0.20 g of dry sediment, adding nitric acid, and a solution containing 0.1% Triton X-100. Ultrasonic agitation was employed for slurries homogenization. Analytical variables including acid pre-treatment conditions, particle size, slurry stability, temperature program of the graphite furnace, and type and concentration of the chemical modifier were studied. The undesirable effects of potential non-specific and spectral interferences on Pb signal were also taken into account. Continuum source and self-reversal methods for background correction were evaluated and compared. For calibration, synthetic acid solutions of Pb were employed. Calibration was linear within the range 1-30 microg L(-1) and 5-30 microg L(-1) when the 217.0 nm and 283.3 nm analytical lines were used. Correlation coefficients of 0.9992 and 0.9997 were obtained. Using optimized conditions, limits of detection (3sigma) of 0.025 microg g(-1) and 0.1 microg g(-1) were achieved for the 217.0 nm and 283.3 nm analytical lines, respectively. The method was successfully applied to the determination of lead in soil, contaminated soil, municipal sludge, and sediment samples. The accuracy was assessed by the analysis of two certified reference materials: municipal sludge (QC MUNICIPAL SLUDGE A) and lake sediment (TRAP-LRM from IJS)., (Copyright 2010 Elsevier B.V. All rights reserved.)

The finding of melatonin, the often called "hormone of darkness" in plants opens an interesting perspective associated to the plethora of health benefits related to the moderate consumption of red wine. In this study, the implementation of a new method for the determination of melatonin in complex food matrices by CEC with immobilized carboxylic multi-walled carbon nanotubes as stationary phase is demonstrated. The results indicated high electrochromatographic resolution, good capillary efficiencies and improved sensitivity respect to those obtained with conventional capillaries. In addition, it was demonstrated highly reproducible results between runs, days and columns. The LOD for melatonin was 0.01 ng/mL. The method was successfully applied to the determination of melatonin in red and white wine, grape skin and plant extracts of Salvia officinalis L.

Ultrasound-assisted leaching-dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (USAL-DSPE-DLLME) technique has been developed as a new analytical approach for extracting, cleaning up and preconcentrating polybrominated diphenyl ethers (PBDEs) from sediment samples prior gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. In the first place, PBDEs were leached from sediment samples by using acetone. This extract was cleaned-up by DSPE using activated silica gel as sorbent material. After clean-up, PBDEs were preconcentrated by using DLLME technique. Thus, 1 mL acetone extract (disperser solvent) and 60 microL carbon tetrachloride (extraction solvent) were added to 5 mL ultrapure water and a DLLME technique was applied. Several variables that govern the proposed technique were studied and optimized. Under optimum conditions, the method detection limits (MDLs) of PBDEs calculated as three times the signal-to-noise ratio (S/N) were within the range 0.02-0.06 ng g(-1). The relative standard deviations (RSDs) for five replicates were <9.8%. The calibration graphs were linear within the concentration range of 0.07-1000 ng g(-1) for BDE-47, 0.09-1000 ng g(-1) for BDE-100, 0.10-1000 ng g(-1) for BDE-99 and 0.19-1000 ng g(-1) for BDE-153 and the coefficients of estimation were > or =0.9991. Validation of the methodology was carried out by standard addition method at two concentration levels (0.25 and 1 ng g(-1)) and by comparing with a reference Soxhlet technique. Recovery values were > or =80%, which showed a satisfactory robustness of the analytical methodology for determination of low PBDEs concentration in sediment samples., (Copyright 2010 Elsevier B.V. All rights reserved.)

An approach for the separation and determination of inorganic thallium species is described. A new sorbent, L-tyrosine-carbon nanotubes (L-tyr-CNTs), was used and applied to the analysis of tap water samples. At pH 5.0, L-tyr was selective only towards Tl(III), while total thallium was determined directly by stabilized temperature platform furnace-electrothermal atomic absorption spectrometry (STPF-ETAAS). The Tl(III) specie, which was retained by L-tyrosine, was quantitatively eluted from the column with 10% of nitric acid. An on-line breakthrough curve was used to determine the column capacity, which resulted to be 9.00 micromol of Tl(III) g(-1) of L-tyr-CNTs with a molar ratio of 0.14 (moles of Tl bound to moles of L-tyr at pH 5). Transient peak areas revealed that Tl stripping from the column occurred instantaneously. Effects of sample flow rate, concentration and flow rate of the eluent, and interfering ions on the recovery of the analyte were systematically investigated. The detection limit for the determination of total thallium (3sigma) by STPF-ETAAS was 150 ng L(-1). The detection limit (3sigma) for Tl(III) employing the separation system was 3 ng L(-1), with an enrichment factor of 40. The precision of the method expressed as the relative standard deviation (RSD) resulted to be 3.4%. The proposed method was applied to the speciation and determination of inorganic thallium in tap water samples. The found concentrations were in the range of 0.88-0.91 microg L(-1) of Tl(III), and 3.69-3.91 microg L(-1) of total thallium.

A study was performed to assess the performance of aminoacids immobilized on carbon nanotubes (CNTs) for their employment as a sorbent for solid phase extraction systems. An immobilization method is introduced and the aminoacid L-tyrosine was chosen as a case study. A spectrophotometric study revealed the amount of aminoacid immobilizated on CNTs surface, and it turned to be of 3174 micromol of L-tyrg(-1). The material was tested for Co retention using a minicolumn inserted in a flow system. At pH 7.0, the amount of Co retained by the column was of 37.58+/-3.06 micromol Co g(-1) of CNTs. A 10% (v/v) HNO(3) solution was chosen as eluent. The pH study revealed that Co binding increased at elevated pH values. The calculation of the mol ratio (moles of Co bound at pH 9 to moles of l-tyr) turned to be 3:1. The retention capacity was compared to other bivalent cations and showed the following tendency: Cu(2+)>Ni(2+)>Zn(2+)>>Co(2+). The analytical performance was evaluated and an enrichment factor of 180 was obtained when 10 mL of 11.37 microg L(-1)Co solution was loaded onto the column at pH 9.0; reaching a limit of detection (LoD) of 50 ng L(-1). The proposed system was successfully applied to Co determination in QC-LL2 standard reference material (metals in natural water).

Many aromatic compounds can be found in the environment as a result of anthropogenic activities and some of them are highly toxic. The need to determine low concentrations of pollutants requires analytical methods with high sensitivity, selectivity, and resolution for application to soil, sediment, water, and other environmental samples. Complex sample preparation involving analyte isolation and enrichment is generally necessary before the final analysis. The present paper outlines a novel, simple, low-cost, and environmentally friendly method for the simultaneous determination of p-nitrophenol (PNP), p-aminophenol (PAP), and hydroquinone (HQ) by micellar electrokinetic capillary chromatography after preconcentration by cloud point extraction. Enrichment factors of 180 to 200 were achieved. The limits of detection of the analytes for the preconcentration of 50-ml sample volume were 0.10 microg L(-1) for PNP, 0.20 microg L(-1) for PAP, and 0.16 microg L(-1) for HQ. The optimized procedure was applied to the determination of phenolic pollutants in natural waters from San Luis, Argentina.

A simple microextraction technique based on room temperature ionic liquids (RTILs) for trace V(IV) and V(V) species separation and preconcentration in water samples was developed in this work. Vanadium species microextraction was achieved with a minimal amount of the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) as vanadium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (V-5-Br-PADAP) complex. The speciation analysis was performed based on a modern technique defined as temperature-controlled ionic liquid dispersive liquid phase microextraction (TILDLME). The level of V(IV) species was calculated by difference of total V and V(V) levels. Selectivity among V species was obtained with the use of 1,2-cyclohexanediaminetetraacetic acid (CDTA) as masking agent. Determination of V was developed by direct injection of the RTIL phase into the electrothermal atomic absorption spectrometer (ETAAS). A preconcentration factor of 40 was achieved with only 2 mL of sample. The limit of detection (LOD) obtained under optimum conditions was 4.9 ng L(-1) and the relative standard deviation for 10 replicate determinations at the 0.5 microg L(-1) V level was 4.3%, calculated at peak heights. A correlation coefficient of 0.9961 was achieved. The method was successfully applied for the speciation analysis of V in tap and river water samples.

The heavy metal mercury (Hg) is a neurotoxin known to have a serious health impact even at relatively low concentrations. A slurry method was developed for the sensitive and precise determination of mercury in human serum blood samples by cold vapor generation coupled to atomic fluorescence spectrometry (CV-AFS). All variables related to the slurry formation were studied. The optimal hydrochloric concentration and tin(II) chloride concentration for CV generation were evaluated. Calibration within the range 0.1-10 microg L(-1) Hg was performed with the standard addition method, and compared with an external calibration. Additionally, the reliability of the results obtained was evaluated by analyzing mercury in the same samples, but submitted to microwave-assisted digestion method. The limit of detection was calculated as 25 ng L(-1) and the relative standard deviation was 3.9% at levels around of 0.4 microg L(-1)Hg.

A novel method for cobalt preconcentration by cloud point extraction with on-line phase separation in a PTFE knotted reactor and further determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed. The cloud point system was formed in the presence of non-ionic micelles of polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) and it was retained on the inner walls of a knotted reactor (KR). The surfactant rich-phase was removed from the knotted reactor with 75 microL of methanol acidified with 0.8 mol L(-1) nitric acid, directly into the dosing hole of the L'Vov graphite tube. An enrichment factor of 15 was obtained with a preconcentration time of 60 s, with respect to the direct determination of cobalt by ETAAS in aqueous solutions. The value of the detection limit for the preconcentration of 5 mL of sample solution was 10 ng L(-1). The precision, expressed as the relative standard deviation (R.S.D.), for 10 replicate determinations at 0.5 microg L(-1) Co level was 4.5%. Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1640e "Trace elements in natural water"). The method was successfully applied to the determination of cobalt in drinking water samples.

We investigated the effect of exposition to cadmium (Cd, 15ppm for 8 weeks) through drinking water on liver lipid metabolism in adult male Wistar rats. As compared to metal non-exposed (control) rats, the serum triglycerides, cholesterol and LDL+VLDL cholesterol concentrations increased. This was associated to a decrease of lipoprotein lipase activity in post heparinic plasma. The VLDL secretion from liver was not modified. Cd treatment increased triglycerides and decreased esterified cholesterol contents in liver. The high triglyceride mass was related to the increased glycerol-3-phosphate acyltransferase mRNA expression. In addition, the liver fatty acids synthesis increased, as determined by an increment of fatty acid synthetase and isocitrate dehydrogenase activities, and [(14)C]-acetate incorporation into saponifiable lipid fraction. The relative percentage of palmitic acid (16:0) and total saturated fatty acids were increased compared with control. Hepatic glucose-6-phosphate dehydrogenase, malic dehydrogenase and cholesteryl ester hydrolase activities were unchanged. In liver, the Cd treatment decreased triglyceride and cholesterol in mitochondria, also increased triglyceride in cytosol, and cholesterol and phospholipid contents in nuclei, compared with control. In addition, an increase of nuclei phosphatidylcholine synthesis was observed. Cd exposure alters directly or indirectly the serum lipid content and liver lipid metabolism.

Cloud point extraction (CPE) has been used for the pre-concentration of mercury, after the formation of a complex with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP), and later analysis by electrothermal atomic absorption spectrometry (ETAAS) using polyethyleneglycolmono-p-nonyphenylether (PONPE 7.5) as surfactant. The chemical variables affecting the separation step were optimized. Under the optimum conditions, i.e, pH 8.5, cloud point temperature 80 degrees C, 5-Br-PADAP=4x10(-5) mol L(-1), PONPE 7.5=0.2%, sample volume=1.0 mL, an enhancement factor of 22-fold was reached. The lower limit of detection (LOD) obtained under the optimal conditions was 0.01 microg L(-1). The precision for 10 replicate determinations at 2.0 microg L(-1) Hg was 4.0% relative standard deviation (R.S.D.). The calibration graph using the pre-concentration system for mercury was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 16 microg L(-1). The method was successfully applied to the determination of mercury in biological samples and in certified reference material (QC METAL LL3).

A study was undertaken to ascertain the analytical capabilities of combined ICP-OES with ultrasonic nebulization to perform on-line preconcentration and speciation of inorganic V species in urine samples using a micro-column packed with l-methionine immobilized on controlled pore glass (CPG) as solid phase extractant. At pH 5.0, l-methionine is selective only towards V(V) while, total vanadium was quantitatively adsorbed by the solid phase at pH 9.0 [as V(V)] due to V(IV) oxidation in alkali media. Vanadium species retained by l-methionine were quantitatively eluted from the column with 10% HCl. Effects of acidity, sample flow rate, concentration of eluent and interfering ions on the recovery of the analytes have been systematically investigated. The detection limit (3sigma) of V is 0.008ngmL(-1) for USN-ICP-OES with an enhancement factor of 900 (10 for USN and 90 for l-methionine), and the relative standard deviation (R.S.D.) is better than 2%. The proposed method has been applied to the determination of inorganic V(V) and V(IV) in urine.

A study was undertaken to ascertain the analytical capabilities of L-methionine immobilized on controlled pore glass for Sb preconcentration and speciation. A fully automated on-line system, implemented with hydride generation (HG) and inductively coupled plasma optical emission spectrometry (ICP OES), was used. Sb(III), at pH 10 was selectively retained in the column containing the immobilized aminoacid, while Sb(V) was not retained at all. A 30% HCl solution was used as eluent agent. Prior to total Sb determination, a pre-reduction step with thiourea was necessary. An on-line pH adjusting and pre-reduction of Sb(V) was achieved in a fully automated system. The detection limit for the preconcentration of 10 mL of an aqueous solution was 70 ng L(-1) with a relative standard deviation of 2%. An enrichment factor of 20 was achieved when 10 mL of sample was passed through the system, reaching a throughput of 23 samples per hour. The method was successfully applied to the determination of Sb(III) and total Sb in urine.

An alternative and new system for on-line preconcentration of arsenic by sorption on a mini-column associated to hydride generation--inductively coupled plasma--optical emission spectrometry determination was studied. It is based on the sorption of arsenic on a column packed with ethyl vinyl acetate (EVA) turnings and the use of La(III) as co-precipitant reagent. This polymeric material was employed here for the first time as filling material for column preconcentration. It could work both as adsorbent and as sieve material. Sample and co-precipitant agent (lanthanum nitrate) were off-line mixed and merged with ammonium buffer solution (pH 10.0), which promoted precipitation and quantitative collection on the small EVA turnings. The arsenic preconcentrated by co-precipitation with lanthanum hydroxide precipitate was subsequently eluted with hydrochloric acid, which was the medium used for hydride generation. Considering a flow rate of 5 ml/min, three enrichment factors were obtained, 28-, 38- and 45-fold at three different sampling times, 60, 120 and 180s; respectively. The detection limits (3s) obtained for each case were 0.013, 0.009 and 0.007 microg/l. Additionally, the calculated precisions expressed as relatively standard deviation (R.S.D.) were 0.9, 1.3 and 1.1%. Satisfactory results were obtained for the determination of arsenic in standard reference material NIST 1643e Trace Elements in Water and drinking water samples.

An on-line procedure for the determination of traces of total mercury in environmental and biological samples is described. The present methodology combines cold vapor generation associated to atomic absorption spectrometry (CV-AAS) with preconcentration of the analyte on a minicolumn packed with activated carbon. The retained analyte was quantitatively eluted from the minicolumn with nitric acid. After that, volatile specie of mercury was generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the atomizer device. Optimizations of both, preconcentration and mercury volatile specie generation variables were carried out using two level full factorial design (2(3)) with 3 replicates of the central point. Considering a sample consumption of 25mL, an enrichment factor of 13-fold was obtained. The detection limit (3sigma) was 10ngL(-1) and the precision (relative standard deviation) was 3.1% (n=10) at the 5microgL(-1) level. The calibration curve using the preconcentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limit up to at least 1000microgL(-1). Satisfactory results were obtained for the analysis of mercury in tap water and hair samples.

A simple, accurate, sensitive and selective method was described for rapid determination of ultra-trace quantities of selenium. Selenium(IV) was collected on activated carbon (AC) after reduction to elemental Se by l-ascorbic acid. The collected selenium was then dissolved by oxidation reaction with bromate in acidic media and was indirectly determined through the bromide formation using square-wave voltammetry (OSWV). The total amount of Se(IV) and Se(VI) was collected on AC after its reduction by hydrazine. Selenium in the range 0.01-20 microg L(-1) could be determined by this method. The method was used to the determination of Se(IV) and Se(VI) in natural water with satisfactory results.