Search

Fatty acid analysis is an essential step in evaluating the potential of macroalgae for biodiesel production. An extraction method was developed to simultaneously analyze up to five types of biodiesel-fuel-related fatty acids (myristic acid, palmitic acid, cis -palmitvaccenic acid, stearic acid, and oleic acid) in macroalgae using liquid chromatography and tandem mass spectrometry (LC-MS/MS). Lypophilization and solid-phase extraction (SPE) techniques were applied to improve the extraction efficiency and effectively purify samples. The optimal conditions for SPE were set by comparing the recoveries according to the various solvent conditions for each step (loading, washing, and elution). In addition, the introduction of trimethylaminoethyl (TMAE) derivatives to the hydroxyl group of the target analyte increased the ionization efficiency and sensitivity. The derivatized samples were analyzed using the LC-MS/MS method with electrospray ionization in the positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 13.5 min using a CAPCELL PAK C18 MGII S3 column. Gradient elution was performed using distilled water and acetonitrile containing 5 mM ammonium acetate. This method offers a reliable and sensitive tool for the analysis of macroalgae samples for their potential use in biodiesel production. To the best of our knowledge, this is the first report on the simultaneous determination of fatty acids in macroalgae using LC-MS/MS with TMAE derivatization.

Estimating the measurement uncertainty (MU) is becoming increasingly mandatory in analytical toxicology. This study evaluates the uncertainty in the quantitative determination of urinary amphetamine (AP) and 4-hydroxyamphetamine (4HA) using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method based on the dilute-and-shoot approach. Urine sample dilution, preparation of calibrators, calibration curve, and method repeatability were identified as the sources of uncertainty. To evaluate the MU, the Guide to the Expression of Uncertainty in Measurement (GUM) approach and the Monte Carlo method (MCM) were compared using the R programming language. The MCM afforded a smaller coverage interval for both AP (94.83, 104.74) and 4HA (10.52, 12.14) than that produced by the GUM (AP (92.06, 107.41) and 4HA (10.21, 12.45)). The GUM approach offers an underestimated coverage interval for Type A evaluation, whereas the MCM provides an exact coverage interval under an abnormal probability distribution of the measurand. The MCM is useful in complex settings where the measurand is combined with numerous distributions because it is generated from the uncertainties of input quantities based on the propagation of the distribution. Therefore, the MCM is more practical than the GUM for evaluating the MU of urinary AP and 4HA concentrations using LC-MS/MS.

Perchlorate contamination in groundwater poses a serious threat to human health, owing to its interference with thyroid function. The high solubility and poor adsorption of perchlorate ions make perchlorate degradation a necessary technology in groundwater contaminant removal. Here, we demonstrate the perchlorate degradation by employing nano zero-valent iron (nZVI) embedded in biocompatible silica alginate hybrid beads fabricated using calcium chloride (1 wt%) as a crosslinker. The concentration of precursors (sodium alginate, sodium silicate) for bead formation was standardized by evaluating the thermal stability of beads prepared at different sodium silicate and alginate concentrations. Thermal degradation of silica alginate hybrid samples showed a stepwise weight loss during the thermal sweep, indicating different types of reactions that occur during the degradation process. The formation of the silica alginate hybrid structure was confirmed by FT-IR spectroscopy. Scanning electron microscopy (SEM) data revealed the surface morphology of silica alginate hybrid changes by varying sodium silicate and alginate concentrations. nZVI-loaded alginate-silicate polymer bead (nZVI-ASB) exhibited excellent perchlorate degradation efficiency by degrading 20 ppm of perchlorate within 4 h. Our study also showed the perchlorate degradation efficiency of nZVI-ASB is maximum at neutral pH conditions.

Due to the biochemical importance of cholesterol homeostasis in cardiovascular disease (CVD), this study was aimed to identify metabolic signatures of serum sterols according to atherosclerotic CVD severity. Biogically active free cholesterol and its 11 analogues in serum samples obtained from subjects who underwent cardiovascular intervention were quantitatively evaluated by gas chromatography-mass spectrometry (GCMS). Study groups were divided by 29 patients with stable angina (SA), 35 patients with acute coronary syndrome (ACS), and 41 controls. In all subjects, serum levels of cholesterol and its upstream precursors of 7-dehydrocholesterol, lathosterol, and lanosterol were closely associated with CVD risk factors, such as total cholesterol, low-density lipoprotein cholesterol (LDL-C), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (r = 0.407 ∼ 0.684, P < 0.03 for all). Metabolic ratios of lathosterol/cholesterol (control = 55.75 ± 34.34, SA = 51.04 ± 34.93, ACS = 36.52 ± 22.00; P < 0.03) and lanosterol/cholesterol (control = 12.27 ± 7.43, SA = 10.97 ± 9.13, ACS = 8.01 ± 5.82; P < 0.03), were remarkably decreased. Both metabolic ratios and individual concentrations of lathosterol and lanosterol were also decreased in subjects with statin treatment than those in the control group without statin treatment (P < 0.05 for all), whereas three metabolic ratios of dietary sterols (sitosterol, campesterol, and stigmasterol) to free cholesterol were increased after statin therapy (P < 0.05 for all) in both SA and ACS groups. The present metabolic signatures suggest that both lathosterol/cholesterol and lanosterol/cholesterol ratios corresponding to cholesterol biosynthesis may reflect statin response. Individual dietary sterols to cholesterol ratios resulted in higher intestinal cholesterol absorption after statin therapy., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Deterioration of our terrestrial environment due to decreasing soil quality brought on by crude oil spills and leakages is a major issue. In this study, soil samples were prepared by mixing clay (bentonite) and sand contaminated with 5 and 10 wt% crude oil (in order to study the effect of oil concentration), and weathered in a laboratory to simulate actual contaminated soil. Volatilization of light oil was inhibited in clay rich-soil, resulting in higher contamination after weathering. The efficiency of the pyrolytic treatment was evaluated by comparing the weight change and n-hexane extractable material (HEM) content of the soil samples. The working temperature influenced pyrolysis efficiency more than the reaction time. A residual amount of 0.29-0.61 wt% (below the soil pollution standard) was observed in the samples with high clay content and pollution level (by pyrolysis for 30 min at 400 °C). Infrared analysis of treated soil samples showed a reduction in alkyl functionality (CH), confirming a decrease in hydrophobicity and an improvement in water holding capacity (WHC). Seed germination and plant growth were relatively better in the pyrolyzed soil. The field applicability of the pyrolytic treatment process was confirmed at laboratory and pilot scale, as well as by treating soil samples collected from actual polluted sites., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Male pattern baldness (MPB) has been associated with dihydrotestosterone (DHT) expression. Finasteride treats MPB by inhibiting 5-alpha reductase and blocking DHT production. In this study, we aimed to identify metabolic differences in urinary metabolomics profiles between MPB patients after a one-year treatment with finasteride and healthy controls. Untargeted and targeted metabolomics profiling was performed using liquid chromatography-mass spectrometry (LC-MS). We hypothesized that there would be changes in overall metabolite concentrations, especially steroids, in the urine of hair loss patients treated with finasteride and normal subjects. Untargeted analysis indicated differences in steroid hormone biosynthesis. Therefore, we conducted targeted profiling for steroid hormone biosynthesis to identify potential biomarkers, especially androgens and estrogens. Our study confirmed the differences in the concentration of urinary androgens and estrogens between healthy controls and MPB patients. Moreover, the effect of finasteride was confirmed by the DHT/T ratio in urine samples of MPB patients. Our metabolomics approach provided insight into the physiological alterations in MPB patients who have been treated with finasteride for a year and provided evidence for the association of finasteride and estrogen levels. Through a targeted approach, our results suggest that urinary estrogens must be studied in relation to MPB and post-finasteride syndrome.

Etomidate (ET) is a commonly used sedative-hypnotic agent such as propofol to induce anesthesia, and it is rapidly metabolized to etomidate acid (ETA) in liver. Herein, a simple method to determine ET and ETA in urine simultaneously was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple sample preparation method reduced the total analysis time. For all analytes, the separation was achieved in 6.5 min using reversed-phase chromatography with gradient elution. The best separation and detection of ETA was achieved using a porous graphitic carbon column. The column temperature was maintained at 30 °C to improve the efficiency and sensitivity. The calibration curves were linear over the concentration ranges of 0.4-120.0 ng/mL (ET) and 1.0-300.0 ng/mL (ETA), obtained with a weighting factor of 1/x 2 . The coefficients of determination (r 2 ) were greater than 0.9958. The lower limits of quantification were 0.4 ng/mL (ET) and 1.0 ng/mL (ETA), intra-day (n = 6) and inter-day (n = 24) precision values for all compounds were less than 10.2% and 8.4%, respectively, while the intra- and inter-day accuracies were in the -9.9-2.9%, and -7.0-0.6%. The applicability of the method was examined by analyzing the urine samples obtained from ET users.

Two polymorphs of AgVO 3 , namely the α- and β- forms, were prepared and their physical, structural, optical, electrochemical, and photoelectrochemical characteristics were compared using a battery of experimental and theoretical tools. A two-step method, previously developed in the our laboratory for the electrodeposition of inorganic semiconductor films, was applied to the electrosynthesis of silver vanadate (AgVO 3 ) films on transparent, conducting oxide surfaces. In the first step, silver was cathodically deposited from a non-aqueous bath containing silver nitrate. In the second step, the silver film was anodically stripped in an aqueous medium containing ammonium metavanadate. The anodically generated silver ions at the interface underwent a precipitation reaction with the vanadate species to generate the desired product in situ. Each of these steps were mechanistically corroborated via the use of electrochemical quartz crystal microgravimetry, used in conjunction with voltammetry and coulometry. As-deposited films were crystalline and showed p-type semiconductor behavior. Theoretical insights are provided for the electronic origin of the α→β phase transformation in AgVO 3 and the disparate optical band gaps of the two polymorphs. Finally, implications for the application of this material in solar cells are provided., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A comprehensive ecotoxicological evaluation of a sulfamethazine (SMZ) and sulfamethoxazole (SMX) mixture was conducted using an indicator microalga, Scenedesmus obliquus. The toxicological effects of this mixture were studied using microalgal growth patterns, biochemical characteristics (total chlorophyll, carotenoid, carbohydrate, fatty acid methyl ester), and elemental and Fourier-transform infrared spectroscopy analyses. The 96-h half maximal effective concentration (EC 50 ) of the SMZ and SMX mixture was calculated to be 0.15 mg L -1 according to the dose-response curves obtained. The chlorophyll content decreased with elevated SMZ and SMX concentrations, while the carotenoid content initially increased and then decreased as concentration raised. The unsaturated fatty acid methyl esters (FAMEs) content was enhanced with higher SMZ and SMX concentrations, while that of saturated FAMEs simultaneously decreased due to SMZ and SMX stress. Elemental analyses showed an improved percentage of nitrogen and sulfur in the microalgal biomass as SMZ and SMX concentrations increased. The microalga S. obliquus was shown to biodegrade the chemicals tested and removed 31.4-62.3% of the 0.025-0.25 mg SMZ L -1 and 27.7-46.8% of the 0.025-0.25 mg SMX L -1 in the mixture after 12 days of cultivation. The greater biodegradation observed at higher SMZ and SMX concentrations indicates that microalgal degradation of SMZ and SMX could act as an efficient adaptive mechanism to antibiotics., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A simultaneous quantitative profiling method for androgens and prostaglandins using ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated to evaluate urinary androgen and prostaglandin levels. Solid-phase extraction and liquid-liquid extraction steps were combined during the sample preparation. β-Glucuronidase/arylsulfatase was also used in the enzyme hydrolysis step. Chemical derivatization was performed using 2-hydrazinopyridine for simultaneous determination of androgen and prostaglandin in the same ionization mode. The analytes were all separated and measured using multiple reaction monitoring in the positive ion mode within a run time of 22 min. The method was validated, achieving overall recoveries ranging from 81.0 to 102.9% with limits of quantification ranging from 0.01 to 2 ng/mL. The intra-day accuracy and precision ranged from 6.5 to 14.3% and from 77.1 to 106.8%, respectively. The inter-day accuracy and precision ranged from 8.9 to 18.2% and 89.9 to 101.4%, respectively. The linearity was expressed using the correlation coefficient, which was >0.99. The method developed herein was used to investigate the effects of a one-year finasteride treatment through differences in urinary androgen and prostaglandin levels between treated male pattern baldness patients and normal controls. The urinary androgen and prostaglandin levels were not significantly different between the two groups because of the administration of finasteride. The results confirmed that finasteride affects androgens and PGs related to hair regrowth and growth length, and a one-year finasteride treatment is effective for MPB. The mass spectrometry-based quantitative profiling method used herein for the investigation of male pattern baldness also holds great potential for the evaluation of androgens and prostaglandins associated with the metabolism of various inflammatory diseases., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Electrospray ionization mass spectrometry ESI-MS is a powerful technique for the characterization of macromolecules and their noncovalent binding with guest ions. We herein evaluate the feasibility of using ESI-MS as a screening tool for predicting potentiometric selectivities of ionophores. Ion-selective electrodes based on the cyclic peptide, cyclosporin A, were developed, and their potentiometric selectivity pattern was evaluated. Optimized electrodes demonstrated near-Nernstian slopes with micromolar detection limits toward calcium. ESI-MS and ESI-MS/MS were employed to determine the relative association strengths of cyclosporin A with various cations. The observed MS intensities of ion-ionophore complexes correlate favorably with the potentiometric selectivity pattern that was demonstrated by cyclosporin-based electrodes. This correlation was found to hold true for other established ionophores, such as valinomycin and benzo-18-crown-6. Taken together, these experiments demonstrate that mass spectrometry could be used to predict the selectivity patterns of new ionophores for potentiometric and optical ion sensors. Further, this approach could be useful in screening mixtures or libraries of newly-synthesized compounds to identify selective ionophores.

Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully verified with human urine samples from drug users (n=21). Direct urine sample injection and optimized mobile phases were introduced for simple sample preparation and high-sensitivity with the desired separation., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Six microalgal species were examined in this study to determine their effectiveness in the coupling of piggery wastewater treatment and biodiesel production. The dry biomasses of Ourococcus multisporus, Nitzschia cf. pusilla, Chlamydomonas mexicana, Scenedesmus obliquus, Chlorella vulgaris, and Micractinium reisseri were 0.34 ± 0.08, 0.37 ± 0.13, 0.56 ± 0.35, 0.53 ± 0.30, 0.49 ± 0.26, and 0.35 ± 0.08 g dwt/L, respectively. The highest removal of nitrogen (62%), phosphorus (28%), and inorganic carbon (29%) were achieved by C. mexicana. In the absence of microalgae, the spontaneous precipitation of phosphorus, calcium, and inorganic carbon occurred at slightly alkaline pH. The highest lipid productivity and lipid content (0.31 ± 0.03 g/L and 33 ± 3%, respectively) were found in C. mexicana. The fatty acid compositions of the studied species were mainly palmitic, linoleic, α-linolenic, and oleic. The results of our study suggest that C. mexicana is one of the most promising candidates for simultaneous nutrient removal and high-efficient biodiesel production., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The aim of this study is to evaluate the removal efficiency of iopromide using electron beam (E-beam) irradiation technology, and its degradation characteristics with hydroxyl radical (OH) and hydrated electron (e(aq)(-)). Studies are conducted with different initial concentrations of iopromide in pure water and in the presence of hydrogen peroxide, bicarbonate ion, or sulfite ion. E-beam absorbed dose of 19.6 kGy was required to achieve 90% degradation of 100 μM iopromide and the E-beam/H(2)O(2) system increased the removal efficiency by an amount of OH· generation. In the presence of OH scavengers (10 mM sulfite ion), the required dose for 90% removal of 100 μM iopromide was only 0.9 kGy. This greatly enhanced removal was achieved in the presence of OH· scavengers, which was rather unexpected and unlike the results obtained from most advanced oxidation process (AOP) experiments. The reasons for this enhancement can be explained by a kinetic study using the bimolecular rate constants of each reaction species. To explore the reaction scheme of iopromide with OH· or e(aq)(-) and the percent of mineralization for the two reaction paths, the total organic carbon (TOC), released iodide, and intermediates were analyzed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Urushiol is a major component of the lacquer tree which has been used as a folk remedy for the relief of abdominal discomfort in Korea. The aim of this study was to evaluate the antibacterial effects of the urushiol on Helicobacter pylori., Materials and Methods: Monomer and 2-4 polymer urushiol were used. In the in vitro study, pH- and concentration-dependent antibacterial activity of the urushiol against H. pylori were investigated. In addition, the serial morphological effects of urushiol on H. pylori were examined by electron microscopy. In vivo animal study was performed for the safety, eradication rate, and the effect on gastritis of urushiol. The expression of pro-inflammatory cytokines was checked., Results:   All strains survived within a pH 6.0-9.0. The minimal inhibitory concentrations of the extract against strains ranged 0.064-0.256 mg/mL. Urushiol caused separation of the membrane and lysis of H. pylori within 10 minutes. Urushiol (0.128 mg/mL × 7 days) did not cause complications on mice. The eradication rates were 33% in the urushiol monotherapy, 75% in the triple therapy (omeprazole + clarithromycin + metronidazole), and 100% in the urushiol + triple therapy, respectively. H. pylori-induced gastritis was not changed by urushiol but reduced by eradication. Only the expression of interleukin-1β in the gastric tissue was significantly increased by H. pylori infection and reduced by the urushiol and H. pylori eradication (p = .014)., Conclusions: The urushiol has an antibacterial effect against H. pylori infection and can be used safely for H. pylori eradication in a mouse model., (© 2011 Blackwell Publishing Ltd.)

Bismuth telluride (Bi 2Te 3 ) is a benchmark material for thermoelectric power generation and cooling applications. Electrodeposition is a versatile technique for preparing thin films of this material; however, it affords films of variable composition depending on the preparation history. A simple and rapid assay of electrodeposited films, therefore, has both fundamental and practical importance. In this study, a new protocol for the electroanalysis of Bi 2Te 3 thin films is presented by combining the two powerful and complementary techniques of electrochemical quartz crystal microgravimetry (EQCM) and stripping voltammetry. First, any free (and excess) tellurium in the electrodeposited film was reduced to soluble Te ( 2- ) species by scanning to negative potentials in a 0.1 M Na 2SO 4 electrolyte, and the accompanying frequency increase (mass loss) was used to determine the content of free tellurium. The film was again subjected to cathodic stripping in the same medium (to generate Bi (0) and soluble Te (2-) from the Bi 2 Te 3 film component of interest), and the EQCM frequency change was used to determine the content of chemically bound Te in the Bi 2Te 3 thin film and thereby the compound stoichiometry. Finally, the EQCM frequency change during Bi oxidation to Bi (3+) and the difference between total Bi and Bi in Bi 2Te 3 resulted in the assay of free (excess) Bi in the electrodeposited film. Problems associated with the chemical/electrochemical stability of the free Bi species were circumvented by a flow electroanalysis approach. Data are also presented on the sensitivity of electrodeposited Bi 2Te 3 film composition to the electrodeposition potential. This newly developed method can be used for the compositional analysis of other thermoelectric thin-film material candidates in general.

A competitive enzyme-linked immunosorbent assay for dopamine (DA) has been optimized and characterized. DA is sensitive to oxygen and light according to a function of the pH on the DA oxidation process. The phenolic groups in DA are readily oxidisable to a quinoid form and thus, free DA deteriorates in alkaline media. Thus, effect of factors such as pH, enzyme-label with substrate, ionic strength and reaction time was considered on performance of ELISA. Assay was performed with 5 microg mL(-1) of BSA-DA and 1/7500 dilution of anti-DA antibody. A dose-response curve was constructed, and a limit of detection and a dynamic range for DA were accomplished to 1.0x10(-9) M (0.19 microg L(-1)) and five orders (3.2x10(-8) M to 3.2x10(-3) M) of magnitude, respectively. The correlation diagram of the absorbance obtained both in buffer and in serum has shown good agreement with correlation coefficient (R(2) = 0.9947): Abs. (in serum) = 0.6128 x Abs. (in buffer) + 0.2926. The cross-reactivity was examined with the structurally similar compounds. And the results demonstrated that epinephrine and 3-methoxytyramine showed cross-reactivity (18.9% each), whereas 3,4-dihydroxyphenylacetic acid and homovanillic acid showed low cross-reactivity (<1%). And percent recoveries of DA in serum were quite satisfactory. This provides usefulness of the present assay to monitor DA in serum.

A simple and selective one-step solid-phase extraction procedure using chemically modified polymer resin (Amberlite XAD-4) with crown ether was investigated for the measurement of urinary catecholamines. After loading the urine samples (adjusted to pH 4) on the synthesized adsorbent cartridge, the column was washed with methanol followed by water and then the adsorbed catecholamines were eluted by 1.0 mL of 6.0 M acetic acid. The effectiveness of sample clean-up method was demonstrated by reversed-phase ion-pair high-performance liquid chromatography with electrochemical detection. Under optimal condition, the recoveries of epinephrine, norepinephrine, and dopamine from spiked urine sample were >86% for all catecholamines. The detection limits (n=5) for epinephrine, norepinephrine, and dopamine were 37, 52, and 46 nmol/L, respectively.

Since hollow-fiber flow field-flow fractionation (HF FIFFF) utilizes a cylindrical channel made of a hollow-fiber membrane, which is inexpensive and simple in channel assembly and thus disposable, interests are increasing as a potential separation device in cells, proteins, and macromolecules. In this study, performance of HF FIFFF of proteins is described by examining the influence of flow rate conditions and length of fiber (polyacrylonitrile or PAN in this work) on sample recovery as well as experimental plate heights. The interfiber reproducibility in terms of separation time and recovery was also studied. Experiments showed that sample recovery was consistent regardless of the length of fiber when the effective field strength (equivalent to the mean flow velocity at the fiber wall) and the channel void time were adjusted to be equivalent for channels of various fiber lengths. This supported that the majority of sample loss in HF FIFFF separation of apoferritin and their aggregates may occur before the migration process. It is finally demonstrated that HF FIFFF can be applied for characterizing the reduction in Stokes' size of low density lipoproteins from blood plasma samples obtained from patients having coronary artery disease and from healthy donors.

An analytical method was developed for evaluating the cannabidiol (CBD), cannabinol (CBN), and delta9-tetrahydrocannabinol (delta9-THC) level in human hair using gas chromatography-mass spectrometry (GC-MS). Hair samples (50 mg) were washed with isopropyl alcohol and cut into small fragments (< 1 mm). After adding a deuterated internal standard, the hair samples were incubated in 1.0 M NaOH for 10 min at 95 degrees C. The analytes from the resulting hydrolyzed samples were extracted using a mixture of n-hexane-ethyl acetate (75:25, v/v). The extracts were then evaporated, derivatized, and injected into the GC-MS. The recovery ranges of CBD, CBN, and delta9-THC at three concentration levels were 37.9-94.5% with good correlation coefficients (r2 >0.9989). The intra-day precision and accuracy ranged from -9.4% to 17.7%, and the inter-day precision and accuracy ranged from -15.5% to 14.5%, respectively. The limits of detection (LOD) for CBD, CBN, and delta9-THC were 0.005, 0.002, and 0.006 ng/mg, respectively. The applicability of this method of analyzing the hair samples from cannabis abusers was demonstrated.

Carisoprodol (CSP) is a musculoskeletal relaxant whose active metabolite is meprobamate (MPB). This drug has recently been noticed to be abused as an inexpensive alternative to illicit drugs in Korea. A method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) was developed for the determination of CSP and MPB in human hair. Hair samples (30 mg) were washed with distilled water and acetone, cut into small fragments (<1 mm), incubated in 1.0 M HCl overnight at 50 degrees C, and then adjusted to pH 6.5. The drugs were extracted from the resulting hydrolyzed solutions using a SPE column. The eluents were evaporated to dryness, then derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) at 120 degrees C for 30 min. The derivatized extract (1 microL) was injected into the GC/MS system. Recoveries were in the range of 91.5-93.1% for CSP and 85.5-93.0% for MPB. The linear ranges were 0.5-10.0 ng/mg for both CSP and MPB with good correlation coefficients (r(2) = 0.995). The intra-day precision and accuracy ranged from 1.5 to 9.3% and -17.5 to 3.6%, respectively, and the inter-day precision and accuracy ranged from 3.9 to 6.2% and -15.0 to -3.9%, respectively. The limits of detection for CSP and MPB were 0.13 and 0.12 ng/mg, respectively. The applicability of the method was proven by analyzing a hair sample from an authentic abuser., (Copyright (c) 2005 John Wiley & Sons, Ltd.)

In this study, we investigate how oxidative stress alters the urinary F2-isoprostanes' level and we examine the correlation between 8-isoPGF(2alpha) and thyroid hormones in female patients with Graves' hyperthyroidism. We quantitatively determined the concentrations of urinary F2-isoprostanes using gas chromatography-mass spectrometry in the selected ion-monitoring mode. We recruited individuals in the following three groups of subjects for this study: (1) female hyperthyroidism patients (n = 14, 21-71 years), (2) female hypothyroidism patients (n = 16, 16-66 years), and (3) female age-matched normal controls (n = 10, 20-61 years). The average concentration of 8-iso prostaglandin F(2alpha) (8-isoPGF(2alpha)) in hyperthyroidism patients was significantly higher than that in the healthy controls (P < 0.05). The concentration of 8-isoPGF(2alpha) in hypothyroidism patients was similar to that in normal controls. Although the level of 8-isoPGF(2alpha) in two of the patients was slightly elevated, the P value was not significant (NS). Our data suggest that the increased level of urinary 8-isoPGF(2alpha) may reflect possible oxidation injuries in hyperthyroidism patients due to the high level of thyroid hormones. Therefore, the elevated 8-isoPGF(2alpha) in patients could be used as an important biomarker for hyperthyroidism disease.

Isoprostanes, novel markers of oxidative injury, are generated by the free radical-mediated peroxidation of arachidonic acid (AA). They are thought to be important in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). Using gas chromatography-mass spectrometry (GC-MS), we investigated the alteration of urinary F(2)-isoprostanes in AD patients compared to that of healthy subjects. Our results show that the levels of urinary F(2)-isoprostanes, sum of the prostaglandin F(2 alpha) isomer; prostaglandin F(2 alpha) (PGF(2 alpha)), prostaglandin F(2 beta) (PGF(2 beta)), and 8-isoprostaglandin F(2 alpha) (8-isoPGF(2 alpha)), significantly increased in AD patients (P < 0.05). The concentration of urinary 8-isoPGF(2 alpha), one of the biomarkers of oxidative stress, was not significantly different between 34 AD patients and 20 age-matched controls (P > 0.05). The PGF(2 alpha), formed by endoperoxide reductase from PGH(2), was significantly increased in AD patients, when compared with the levels of the normal controls (P < 0.05). The PGF(2 alpha), an enzymatic product of arachidonic acid, may affect the pathogenesis of AD. In addition, urinary F(2)-isoprostanes can play an important role as a biomarker in AD.

F(2)-isoprostanes are derived in vivo principally from the following: (1) the formation of positional peroxyl radicals of arachidonic acid, (2) endocyclization to prostaglandin G(2)-like structures, and (3) reduction to PGF(2)-like compounds. F(2)-isoprostanes have been proposed as biomarkers of lipid peroxidation, oxidative stress status, and the oxidation of low-density lipoprotein (LDL). Using gas chromatography-ion trap-mass spectrometry, we studied how hemodialysis (HD) affects plasma total F(2)-isoprostanes. We examined the plasma total F(2)-isoprostanes in end-stage renal disease (ESRD) patients, before HD, after HD, between HD, and in control subjects. Plasma concentrations of total F(2)-isoprostanes were significantly higher in the after HD ESRD patients than the before hemodialysis ESRD patients (P < 0.05). There is no difference between before HD ESRD patients and normal controls. Moreover, a positive or negative correlation was seen between LDL and plasma total F(2)-isoprostanes (P < 0.001), and between age and plasma total F(2)-isoprostanes (P < 0.001). This study indicates HD treatment may be the major contributor of oxidative stress in ESRD patients.

To explore the possible involvement of a relationship between steroids and polyunsaturated fatty acids (PUFAs) in thyroid cancer, we studied the concentration levels of 21 endogenous urinary androgens and glucocorticoids, and 6 urinary PUFAs in female patients with thyroid cancer (n=29, 49.4+/-12.6 years) and in normal female subjects (n=20, 48.3+/-11.9 years). Using gas chromatography-mass spectrometry in selected ion-monitoring mode, we performed quantification of androgens, glucocorticoids, and PUFAs. In the case of the urinary androgens and the glucocorticoids, the concentration of androgens was not altered between patients with thyroid cancer and normal controls. However, the concentration of glucocorticoid significantly decreased in patients with thyroid cancer compared to that of the normal controls. Also, in case of urinary PUFAs, the precursor of cholesterol, the concentration of linoleic acid, arachidonic acid, and docosahexaenoic acid (DHA) were decreased in patient with thyroid cancer (P<0.05). In this results, it can be concluded that the glucocorticoids milieu induced from the decreasing urinary concentration of DHA may exert an important influence upon thyroid cancer. Consequently, the change of urinary glucocorticoids concentration may play an important role in thyroid cancer.

An analytical method to improve the characterization of lipoprotein fractions is presented. Human plasma samples were treated with Sudan Black B to stain the lipid component in lipoproteins, then the stained lipoproteins were separated by frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF), according to the lipoprotein particle sizes, with the selective detection of eluting lipoprotein fractions, high-density lipoproteins (HDL), low-density lipoproteins (LDL) and very-low-density lipoproteins (VLDL), at 610 nm. The capability of this technique has been evaluated with plasma samples obtained from patients with coronary artery disease (CAD), and it showed that the retention profile of patients' lipoprotein samples was clearly distinct from those of healthy persons. The potential of this technique comes with the direct injection of a stained lipoprotein sample without a prior procedure such as ultracentrifugation for sample preparation, and the size calculation of lipoprotein particles from the experimental retention time by theory. Since sample relaxation was achieved hydrodynamically in an FI-AFlFFF channel, sample injection and separation processes were continuously made without stopping the separation flow. This study demonstrated the potential of the FI-AFlFFF technique to be utilized as a powerful tool for the determination of the LDL profiles of patients with CAD., (Copyright 2002 Elsevier Science B.V.)

A method for the determination of sertraline in human plasma using gas chromatography-mass spectrometry (GC-MS), with the selected ion-monitoring (SIM) mode, was described. The following was used in this study: (1) single liquid-liquid extraction at alkaline pH after deproteinization of plasma protein and (2) perfluoroacylation with HFBA, which has higher sensitivity (about 10-fold) compared with previous reported derivatization. The detection limit for the SIM of sertraline as an N-HFB derivative was 0.1 ng/ml, and its recovery was 80-85%. The linear response was obtained in the range of 0.2-10.0 ng/ml with a correlation coefficient of 0.999. The coefficient of variation (C.V.%) was less than 12.1% in the 1-30 ng/ml, and less than 18.2% at 0.2 ng/ml, and the accuracy was less than 10% at all of the concentration range. These findings indicate that this assay method has adequate precision and accuracy to determine the amount of sertraline in human plasma. After pharmacokinetics was performed with this assay method following oral administration of sertraline hydrochloride in man, moment analysis revealed that pharmacokinetic parameters for sertraline (Cmax, 10.3 ng/ml; Tmax, 8.0 h; T(1/2) 28.6 h) were similar to previously reported results. These results indicate that this simple and sensitive assay method is readily applicable to the pharmacokinetic studies of sertraline.

A gas chromatographic-mass spectrometric (GC-MS) method for the determination of ketoprofen, a non-steroidal anti-inflammatory drug (NSAID), in horse urine by selected ion monitoring (SIM) mode is described. Urine samples (2 mL) were extracted by liquid-liquid extraction with diethyl ether. The residues were then evaporated, derivatized and injected into the GC-MS system. Validation of the GC-MS method in the SIM mode using flurbiprofen as the internal standard (IS) included linearity studies (10-10 000 ng/mL), recovery (95%) and limit of quantitation (LOQ) (10 ng/mL). The response was linear, with a correlation coefficient (0.9998) for ketoprofen. When applied to horse urine samples, the present method allowed detection of ketoprofen up to 16 days in FULL SCAN mode after a topical application of 1.1 g of ketoprofen in a gel formulation.

A chemically modified polymeric adsorbent was synthesized to evaluate the availability as an adsorbent for solid-phase extraction (SPE) of phenol and chlorophenols. Commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) through the ketone linkage. Adsorption isotherms were obtained by batch experiments and the data were fitted to the Freundlich equation to calculate the adsorption parameters. Breakthrough volumes were measured by column experiments. Physical properties such as surface area, average pore diameter and micropore volume of resins were measured to correlate with the adsorption characteristics. As a result, adsorption capacity was increased for the chemically modified resins and it can be concluded that the increase of pi-pi interaction due to the introduction of the porphyrin molecule is the major factor for the increase of the adsorption capacity.

A variety of neutral carrier type ionophores for monovalent cations were employed to prepare solid-state cation-selective electrodes (SSEs) for use as a detector in single-column ion chromatography (IC). The polyurethane-based pseudoreference electrode made it possible to assemble an array type SSE detector for IC. An SSE-based detector provides not only the overall chromatogram for the separated ion species (monensin methyl ester-nonactin-based membrane), but also the enhanced chromatogram for specified ions of interest (valinomycin as K+ and nonactin for NH4+). This feature makes it possible to perform highly quantitative analysis with low detection limits even if the separation efficiency of the ion-exchange is not sufficient. Since SSE-based IC detectors are easily miniaturized and replaceable at low cost, they are an ideal component of a portable IC system.

A new type of disposable amperometric sensor is devised by screen printing thick-film electrodes directly on a porous nitrocellulose (NC) strip. The chromatographic NC strip is then utilized to introduce various sample pretreatment layers. As a preliminary application, a glucose biosensor based on hydrogen peroxide detection is constructed by immobilizing glucose oxidase (GOx) on the NC electrode strip and by formulating a strong oxidation layer (i.e., PbO2) at the sample loading area, placed below the GOx reaction band. The screen-printed PbO2 paste serves as a sample pretreatment layer that removes interference by its strong oxidizing ability. Samples applied are carried chromatographically, via the PbO2 paste, to the GOx layer, and glucose is catalyzed to liberate hydrogen peroxide, which is then detected at the electrode surface. The proposed NC/PbO2 strip sensor is shown to be virtually insusceptible to interfering species such as acetaminophen and ascorbic and uric acids and to exhibit good performance, in terms of the sensor-to-sensor reproducibility (standard deviation, +/-0.026 - +/-0.086 microA), the sensitivity (slope, -0.183 microA/mM), and the linearity (correlation coefficient, 0.994 in the range of 0-10 mM).

We have studied the distribution of toluene in glue sniffers' biological fluid samples by gas chromatography or gas chromatography/mass spectrometry. The determined toluene concentrations ranged from 0.1 to 40.3 mg/L in urine samples and from 0.1 to 74.7 mg/L in blood samples, respectively. Among the 120 urine samples, 61% of all cases ranged between 0.1 and 1.0 mg/L and 27% was between 1.0 and 5.0 mg/L, respectively. On the other hand, 39% and 46% of all 99 blood samples ranged between 0.1 and 1.0 mg/L, or 1.0 and 5.0 mg/L, respectively. In the fatal cases (36 cases), the distribution of toluene ranged from 0.3 to 40.5 mg/L in the blood samples.