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This paper describes the concept of parallel electromembrane extraction (Pa-EME) with flat membranes in a multiwell format for the first time. The setup is based on a multiwell plate and provided simultaneous and selective isolation, cleanup, and enrichment of several human plasma samples as well as LC-MS-compatible extracts within 8 min of extraction. Undiluted human plasma samples spiked with four antidepressant drugs were added to separate wells in the donor plate. Subsequently, the samples were extracted with Pa-EME. The four drugs migrated electrokinetically from undiluted human plasma through a flat polypropylene membrane impregnated with 2-nitrophenyl octyl ether, and were isolated into formic acid. Extraction time, extraction voltage, agitation rate, sample volume, and acceptor solution volume were all optimized with an experimental design. The optimal conditions were as follows: The agitation rate was 1,040 rpm, and an extraction voltage of 200 V was applied. The sample volume and acceptor solution volume was 240 and 70 μL, respectively. The extraction was continued for 8 min. Eventually, the extracts were analyzed by LC-MS/MS. The combination of Pa-EME with LC-MS/MS provided quantitation limits below the therapeutic level and reported relative standard deviations in the range 5-13 %. Linear calibration curves were obtained for all analytes, and the correlation coefficients were above 0.9974 in the range 1-400 ng mL. The drug concentrations from two subjects treated with quetiapine and sertraline were successfully determined with Pa-EME combined with LC-MS/MS. Post-column infusion experiments demonstrated that Pa-EME provided extracts free from interfering matrix components. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, extraction kinetics was investigated experimentally and theoretically in hollow fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) with the basic drugs droperidol, haloperidol, nortriptyline, clomipramine, and clemastine as model analytes. In HF-LPME, the analytes were extracted by passive diffusion from an alkaline sample, through a (organic) supported liquid membrane (SLM) and into an acidic acceptor solution. In EME, the analytes were extracted by electrokinetic migration from an acidic sample, through the SLM, and into an acidic acceptor solution by application of an electrical potential across the SLM. In both HF-LPME and EME, the sample (donor solution) was found to be rapidly depleted for analyte. In HF-LPME, the mass transfer across the SLM was slow, and this was found to be the rate limiting step of HF-LPME. This finding is in contrast to earlier discussions in the literature suggesting that mass transfer across the boundary layer at the donor–SLM interface is the rate limiting step of HF-LPME. In EME, mass transfer across the SLM was much more rapid due to electrokinetic migration. Nevertheless, mass transfer across the SLM was rate limiting even in EME. Theoretical models were developed to describe the kinetics in HF-LPME, in agreement with the experimental findings. In HF-LPME, the extraction efficiency was found to be maintained even if pH in the donor solution was lowered from 10 to 7–8, which was below the pKa-value for several of the analytes. Similarly, in EME, the extraction efficiency was found to be maintained even if pH in the donor solution increased from 4 to 11, which was above the pKa-value for several of the analytes. The two latter experiments suggested that both techniques may be used to effectively extract analytes from samples in a broader pH range as compared to the pH range recommended in the literature. [Copyright &y& Elsevier]

Abstract: Citalopram, loperamide, methadone, paroxetine, pethidine, and sertraline were extracted exhaustively with electromembrane extraction (EME) by increasing the number of hollow fibers from one to three. Experiments reported recoveries in the range 97–115% from 1000μl spiked water samples. EME was accomplished with 200V as extraction voltage, the extraction time was set to 10min (equilibrium), and the extraction unit was subjected to 1200 revolutions per minute (rpm). The same experiment with different geometry in a stagnant system conducted with 21μl acceptor solution provided recoveries from 50μl undiluted human plasma (pH 7.4) in the range of 56–102% for the six basic model substances. In each experiment the acceptor solution was distributed into three separately hollow fibers in the same sample vial. The importance of an electrical field was verified by comparing EME with liquid-phase microextraction (LPME) under optimal conditions and demonstrated that the time needed to reach equilibrium was reduced by EME. EME–LC/MS provided linearity >0.99 (r 2 values) for the six basic model substances, and the repeatability within the low therapeutic range (10ng/ml) was in the range 5.1–21.4% RSD. LC–MS provided estimated limit of quantification (S/N =10) in the range 0.6–3.2ng/ml. Eventually, patient samples from a reference laboratory were analyzed and provided reliable results with a relative difference <14% compared to stated values from the reference laboratory. [Copyright &y& Elsevier]

In this instalment of "Sample Preparation Perspectives," Norwegian authors from the University of Oslo describe the practical aspects of hollow fibre liquid-phase microextraction in the three-phase mode (HF3LPME). The guest authors highlight important practical issues related to the supported liquid membrane, the hollow fibre and the extraction itself. They also discuss practical work with electromembrane extraction (EME), which is related to HF3LPME but uses an electrical potential as the driving force for the extraction. [ABSTRACT FROM AUTHOR]

Abstract: Amitriptyline, citalopram, fluoxetine, and fluvoxamine were isolated by electro membrane extraction (EME) from 70μl of untreated plasma (pH 7.4), through a supported liquid membrane (SLM) of 1-ethyl-2-nitrobenzene immobilized in the pores of a porous polypropylene hollow fiber, and into 30μl of 10mM HCOOH as acceptor solution inside the lumen of the hollow fiber. The driving force of the extraction was a 9V potential sustained over the SLM with a common battery, with the positive electrode placed in the plasma sample and the negative electrode placed in the acceptor solution. Extractions were performed under totally stagnant conditions with a very simple device for 1min (kinetic regime), and subsequently the acceptor solution was analyzed directly by liquid chromatography–mass spectrometry (LC–MS). Recoveries were 12, 13, 22, and 17% for fluoxetine, amitriptyline, citalopram, and fluvoxamine, respectively. Sample clean-up was comparable to reversed-phase solid-phase extraction (SPE), but EME required substantially less time than SPE. The time advantage of EME was further improved by parallel extraction of three samples (for 1min) with the same 9V battery. EME from plasma combined with LC–MS provided limits of quantification (S/N=10) in the range 0.4–2.3ng/ml, linearity in the range 1–1000ng/ml with r 2-values of 0.998–0.999, and repeatability in the range 3.2–8.9% RSD in the mid-therapeutic window (100ng/ml). [Copyright &y& Elsevier]

Abstract: In hollow fiber membrane liquid-phase microextraction (LPME), target analytes are extracted from aqueous samples and into a supported liquid membrane (SLM) sustained in the pores in the wall of a small porous hollow fiber, and further into an acceptor phase present inside the lumen of the hollow fiber. The acceptor phase can be organic, providing a two-phase extraction system compatible with capillary gas chromatography, or the acceptor phase can be aqueous resulting in a three-phase system compatible with high-performance liquid chromatography or capillary electrophoresis. Due to high enrichment, efficient sample clean-up, and the low consumption of organic solvent, substantial interest has been devoted to LPME in recent years. This paper reviews important applications of LPME with special focus on bioanalytical and environmental chemistry, and also covers a new possible direction for LPME namely electromembrane extraction, where analytes are extracted through the SLM and into the acceptor phase by the application of electrical potentials. [Copyright &y& Elsevier]

Abstract: The present work has for the first time demonstrated electromembrane extraction (EME) at voltages obtainable by common batteries. Five basic drugs were extracted from acidified aqueous sample solutions, across a supported liquid membrane (SLM) consisting of 1-isopropyl-4-nitrobenzene impregnated in the walls of a hollow fiber, and into an acidified aqueous acceptor solution present inside the lumen of the hollow fiber with potential differences of 1–10V applied over the SLM. Extractions from 1ml standard solutions prepared in 10mM HCl for 5min and with a potential of 10V demonstrated analyte recoveries of 50–93% in 25μl of 10mM HCl as acceptor solution. This corresponds to enrichment factors of 20–37. Similar results were obtained with a common 9V battery as power supply. Recoveries from low-voltage EME on human plasma, urine, and breast milk diluted with acetate buffer (pH 4) demonstrated recoveries in the range of 37–55% after 5min of extraction. Excellent selectivity was demonstrated as no interfering peaks were detected. Standard curves in the range of 0.0625–0.625μg/ml demonstrated correlation coefficients of 0.994–0.999. Extraction recoveries from human plasma, urine or breast milk were not found to be sensitive towards individual variations. The results show that low-voltage EME has a future potential as a simple, selective, and time-efficient sample preparation technique of biological fluids. [Copyright &y& Elsevier]

Abstract: The present work has for the first time compared extraction of basic analytes across a supported liquid membrane (SLM) based on (1) passive diffusion in a pH gradient sustained over the SLM and (2) electrokinetic migration in an electrical field sustained over the SLM. For the passive diffusion experiments, performed as liquid-phase microextraction (LPME), five basic drugs were extracted under strong agitation from alkaline samples (10mM NaOH), through 2-nitrophenyl octylether immobilized in the pores of a porous hollow fibre of polypropylene (SLM), and into 25μl of 10mM HCl as the acceptor solution. The experiments based on electrokinetic migration, performed as electro membrane isolation (EMI), were conducted under strong agitation from acidic samples (10mM HCl), through the same SLM as in LPME, and into 25μl of 10mM HCl as the acceptor solution. Whereas LPME relied on diffusion and to some extent also convection as the principal mechanisms of mass transfer, mass transfer in EMI also included a strong contribution from electrokinetic migration. Thus, extraction kinetics was improved by a factor between 6 and 17 utilizing EMI instead of LPME. This major difference in terms of speed was especially pronounced from small sample volumes (150μl), and suggest that EMI may be a very interesting future concept for miniaturized sample preparation. In addition to improved extraction kinetics, extraction rates were strongly compound dependent in EMI, opening the possibility to control the extraction selectivity by the extraction time. [Copyright &y& Elsevier]

Abstract: Electrokinetic cross membrane extraction of acidic drugs was demonstrated for the first time. The acidic drugs were extracted from an alkaline aqueous donor solution (300μl), through a thin supported liquid membrane of 1-heptanol sustained in the pores of the wall of a porous hollow fiber, and into an aqueous alkaline acceptor solution (30μl) present inside the lumen of the hollow fiber by the application of a d.c. electrical potential. The negative electrode was placed in the donor solution, and the positive electrode was placed in the acceptor solution. Optimal extractions were accomplished with 1-heptanol as the supported liquid membrane, with 50V as the driving force, and with pH 12.0 in both the donor and acceptor solutions, respectively (NaOH). Equilibrium extraction conditions were obtained after 5min of operation with the whole assembly agitated at 1200rpm. Eleven different acidic drugs were extracted with recovery values between 8 and 100%, and initial data supported that electrokinetic cross membrane extraction provided repeatable data and linear response between original donor concentration and final acceptor concentration of the acidic model compounds. [Copyright &y& Elsevier]

Liquid-phase microextraction (LPME) based on disposable porous polypropylene hollow fibers was evaluated for the extraction of hydrophobic basic drugs from human breast milk. Direct LPME from breast milk samples provided low recoveries (18–38%) because the drugs were partially bound to the sample matrix (fat). Therefore, prior to extraction, the breast milk was acidified and the majority of fat was removed by centrifugation. The pH-reduction in the breast milk was performed to release drugs interacting with the matrix. From the supernatant, where pH was adjusted into the alkaline region with NaOH to deionize the analytes, the drugs were extracted through a thin layer of polyphenyl-methylsiloxane present in the pores of a porous hollow fiber and into 15 μl of 10 mM HCl as acceptor solution present inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to capillary electrophoresis (CE). For four antidepressant drugs, recoveries in the range 42–69% were obtained from breast milk, the drugs were enriched by a factor of 14–23 during LPME, excellent sample clean-up was observed, linearity (r>0.99) was obtained in the range 50–500 ng/ml, and the extractions were found to be independent of the fat content in the breast milk samples. [Copyright &y& Elsevier]

Mathematical descriptions for extraction recovery and enrichment were applied for liquid-phase microextraction (LPME) and comparison with conventional two- and three-phase liquid–liquid extraction techniques (LLE) was made. The LPME theoretical calculations were verified by experimental determination of actual partition coefficients and by data obtained with LPME in a robust hollow fibre formate. With hollow fibre LPME operated in the two-phase mode, analytes were extracted from 1 to 4 ml aqueous samples into 25–50 μl of an organic solvent present in the pores and in the lumen of the porous hollow fibres. Compared with conventional two-phase LLE, two-phase LPME provided substantially higher enrichments for compounds with relatively large partition coefficients (Korg/d>500). In contrast, because of the large volume of organic solvent relative to the sample volume, LLE provided high recovery and moderate enrichment even for compounds with relatively low partition coefficients (Korg/d>5). Thus, two-phase LPME may be used for substantially enhanced extraction selectivity and enrichment of relatively hydrophobic analytes as compared with LLE whereas conventional two-phase LLE is superior for more hydrophilic analytes. Similar results were found for three-phase LPME where analytes where extracted from 1 to 4 ml aqueous samples through approximately 20 μl organic solvent immobilized within the pores of the hollow fibre and into 25 μl of an aqueous acceptor solution inside the lumen of the hollow fibre. The fundamental differences of LPME and LLE were further demonstrated with practical experiments on extraction of the basic drugs promethazine, methadone, and haloperidol from human plasma and urine. [Copyright &y& Elsevier]

Background: Few studies have used individual person data to study whether contemporary trends in the incidence of coronary heart disease are associated with changes in modifiable coronary risk factors.Methods and Results: We identified 29 582 healthy men and women ≥25 years of age who participated in 3 population surveys conducted between 1994 and 2008 in Tromsø, Norway. Age- and sex-adjusted incidence rates were calculated for coronary heart disease overall, out-of-hospital sudden death, and hospitalized ST-segment-elevation and non-ST-segment-elevation myocardial infarction. We measured coronary risk factors at each survey and estimated the relationship between changes in risk factors and changes in incidence trends. A total of 1845 participants had an incident acute coronary heart disease event during 375 064 person-years of follow-up from 1994 to 2010. The age- and sex-adjusted incidence of total coronary heart disease decreased by 3% (95% confidence interval, 2.0-4.0; P<0.001) each year. This decline was driven by decreases in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in coronary risk factors accounted for 66% (95% confidence interval, 48-97; P<0.001) of the decline in total coronary heart disease. Favorable changes in cholesterol contributed 32% to the decline, whereas blood pressure, smoking, and physical activity each contributed 14%, 13%, and 9%, respectively.Conclusions: We observed a substantial decline in the incidence of coronary heart disease that was driven by reductions in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in modifiable coronary risk factors accounted for 66% of the decline in coronary heart disease events. [ABSTRACT FROM AUTHOR]

Objective: We aimed to describe the progression rate into manifest aortic stenosis (AS) in subjects with normal aortic valves or in an early phase of calcific aortic valve disease.Methods: Participants were recruited from the Tromsø Study, a population-based health survey. In our prospective cohort study, we performed two echocardiographical examinations (2001 and 2008) of a random sample of 1884 participants. AS was defined as a mean aortic valve gradient ≥15 mm Hg or a peak flow exceeding 2.6 m/s. Those with lesser values were stratified into three groups based on mean gradients (cut-off 5 and 10 mm Hg) and peak aortic flow (cut-off 1.5 and 2 m/s).Results: At baseline, 71 participants had gradients from 10 to 14.9 mm Hg, of whom 32.4% developed AS during follow-up. AS developed in only 3.6% of those with a baseline gradient of 5-9.9 mm Hg and in 0.3% of those with a gradient <5 mm Hg. Almost identical separations were obtained among the three flow velocity groups. Of the 45 subjects who developed incident AS, 56% acquired mild, 33% moderate and 11% severe AS. Their mean gradient progression rate was 2.7 mm Hg/year.Conclusions: The results support that subjects with a mean aortic valve gradient of 10-15 mm Hg or aortic flow >2.0 m/s should be followed routinely. This group identifies about half of those who develop AS in the following 7 years. [ABSTRACT FROM AUTHOR]

Objective: To assess prevalence, incidence, prognosis and progression of degenerative valvular aortic stenosis (AS). Setting: The Tromsø Study and the University Hospital of North Norway. Design: Population based prospective study. Population: Over a 14 year span we performed three repeated echocardiographic examinations (1994, 2001 and 2008) of a random sample of initially 3273 participants. Data from the only hospital serving this population were included. Results: There were 164 subjects with AS. Prevalence consistently increased with age, average values being 0.2% in the 50-59 year cohort, 1.3% in the 60-69 year cohort, 3.9% in the 70-79 year cohort and 9.8% in the 80-89 year cohort. The incidence rate in the study was 4.9‰/year. The mean annual increase in mean transvalvular pressure gradient was 3.2 mm Hg. The increase was lower in mild AS than in more severe disease, disclosing a non-linear development of the gradient, but with large individual variations. Mortality was not significantly increased in the asymptomatic AS-group (HR=1.28), nor in those who received aortic valve replacement (n=34, HR=0.93), compared with the general population. Conclusion: This is the first study to document the incidence and prognosis of AS in a general population with surgery as a treatment option. It reveals an accelerated progression of the aortic mean gradient as the disease advances. The prognosis of AS seems to be comparable with the normal population in the asymptomatic stage and after successful surgery, indicating that the follow-up and timing of surgery has been adequate for this patient group. [ABSTRACT FROM AUTHOR]

Abstract: Electromembrane extraction (EME) at low voltage (0–15V) of 29 different basic model drug substances was investigated. The drug substances with log P <2.3 were not extracted at voltages less than 15V. Extraction of drug substances with log P ≥2.3 and with two basic groups were also effectively suppressed by the SLM at voltages less than 15V. Drug substances with log P ≥2.3 and with one basic group were all extracted at low voltages and with a strong compound selectivity which appeared to have some influence from the polar surface area of the compound. For this group of substances, recoveries varied between 0 and 23% at 5V, whereas, recoveries varied between 5.5 and 51% at 15V. Based on mass transfer differences related to charge, polarity, and polar surface, highly selective extractions of drug substances were demonstrated from human plasma, urine, and breast milk. An initial evaluation at low voltage (5V) was compared with similar extractions at a more normal voltage level (50V), and this supported that reliable data can be obtained under these low-voltage (mild) conditions by EME. [Copyright &y& Elsevier]

Abstract: For the first time, electromembrane extraction (EME) of six basic drugs of abuse from undiluted whole blood and post mortem blood in a totally stagnant system is reported. Cathinone, methamphetamine, 3,4-methylenedioxy-amphetamine (MDA), 3,4-methylenedioxy-methamphet-amine (MDMA), ketamine and 2,5-dimethoxy-4-iodoamphetamine (DOI) were extracted from the whole blood sample, through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene (ENB) immobilized in the pores of a hollow fiber, and into an aqueous acceptor solution inside the lumen of the hollow fiber. The SLM acts as a barrier with efficient exclusion of all macromolecules and acidic substances in the sample. Due to the application of the electrical field, only the cationic compounds of interest are extracted efficiently across the membrane, thus providing extremely clean extracts for analysis with liquid chromatography–mass spectrometry, LC–MS. Recoveries in the range 10–30% were obtained from 80μl whole blood within 5min extraction time and an applied voltage of 15V across the SLM. The optimized technique was tested on real forensic whole blood samples taken from three forensic autopsy cases and on five forensic whole blood samples from living persons. The results were in agreement with the analysis using standard sample preparation methods (liquid–liquid extraction) performed on the same samples by Norwegian Institute of Public Health (NIPH), Division of Forensic Toxicology and Drug Abuse Research. Evaluation data were acceptable, with limit of detections (LODs) in the range 40–2610pg/mL, well below concentrations associated with drug abuse; linearites in the range between 10 and 250ng/mL with r 2 values above 0.9939, and with repeatability (RSD) of 7–32%. [Copyright &y& Elsevier]

Abstract: For the first time, haloacetic acids and aromatic acetic acids were extracted from wastewater samples using electromembrane extraction (EME). A thin layer of toluene immobilized on the walls of a polypropylene membrane envelope served as an artificial supported liquid membrane (SLM). The haloacetic acids (HAAs) (chloroacetic acid, dichloroacetic acid, and trifluoroacetic acid) and aromatic acetic acids (phenylacetic acid and p-hydroxyphenylacetic acid) were extracted through the SLM and into an alkalized aqueous buffer solution. The buffer solution was located inside the membrane envelope. The electrical potential difference sustained over the membrane acted as the driving force for the transport of haloacetic acids into the membrane by electrokinetic migration. After extraction, the extracts were analyzed by high-performance liquid chromatography-ultraviolet detection. The detection limits were between 0.072 and 40.3ngL−1. The calibration plot linearity was in the range of 5 and 200μgL−1 while the correlation coefficients for the analytes ranged from 0.9932 to 0.9967. Relative recoveries were in the range of 87–106%. The extraction efficiency was found to be comparable to that of solid-phase extraction. [Copyright &y& Elsevier]

Abstract: Attenuated cardiac vagal regulation indicates an increased risk of cardiac events, but the reasons for this impaired regulation are not well known. Cardiac vagal regulation was measured in 5.408 subjects (2627 men and 2781 women) who underwent short term (100s) ECG recordings during controlled deep respiration (0.1Hz). Under these conditions, the power in the low frequency (LF) spectral band (0.05 to 0.15Hz) predominantly reflects cardiac vagal outflow. There was a strong inverse relationship between LF power and age in both genders (β=−0.033 in men and −0.035 in women; P<0.0005). There was a more rapid decline in women in the second and third decade in which LF power was significantly lower than in men (P=0.004). In both genders, there was an association between impaired cardiac vagal outflow and fibrinogen level. Altogether, the factors studied explained nearly 20% of the interindividual variation of LF power. In conclusion, in a general population, impaired cardiac vagal regulation is associated with many cardiovascular risk factors, including fibrinogen. Women have a more rapid decline of vagal regulation in the second and third decades. [Copyright &y& Elsevier]

Abstract: The simultaneous extraction of acidic and basic analytes from a particular sample is a challenging task. In this work, electromembrane extraction (EME) of acidic non-steroidal anti-inflammatory drugs and basic β-blockers in a single step was carried out for the first time. It was shown that by designing an appropriate compartmentalized membrane envelope, the two classes of drugs could be electrokinetically extracted by a 300V direct current electrical potential. This method required only a very short 10-min extraction time from a pH-neutral sample, with a small amount (50μL) of organic solvent (1-octanol) as the acceptor phase. Analysis was carried out using gas chromatography–mass spectrometry after derivatization of the analytes. Extraction parameters such as extraction time, applied voltage, pH range, and concentration of salt added were optimized. The proposed EME technique provided good linearity with correlation coefficients from 0.982 to 0.997 over a concentration range of 1–200μgL−1. Detection limits of the drugs ranged between 0.0081 and 0.26μgL−1, while reproducibility ranged from 6 to 13% (n =6). Finally, the application of the new method to wastewater samples was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500μL of 840mM NaOH was added to 3mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20μL of a stagnant aqueous solution of 10mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the μgL−1 level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30min extraction). Linearity was obtained in the range 0.1–10.0μgL−1, with r =0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1μgL−1 and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the suitability of three-phase LPME for the extraction of pesticides from citrus juices, suppressing any pretreatment step such as filtration or removal of the solid material from the sample, that may potentially involve a loss of analyte. [Copyright &y& Elsevier]

Abstract: In the current work, droplet-membrane-droplet liquid-phase microextraction (LPME) under totally stagnant conditions was presented for the first time. Subsequently, implementation of this concept on a microchip was demonstrated as a miniaturized, on-line sample preparation method. The performance level of the lab-on-a-chip system with integrated microextraction, capillary electrophoresis (CE) and laser-induced fluorescence (LIF) detection in a single miniaturized device was preliminarily investigated and characterized. Extractions under stagnant conditions were performed from 3.5 to 15μL sample droplets, through a supported liquid membrane (SLM) sustained in the pores of a small piece of a flat polypropylene membrane, and into 3.5–15μL of acceptor droplet. The basic model analytes pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted from alkaline sample droplets (pH 12), through 1-octanol as SLM, and into acidified acceptor droplets (pH 2) with recoveries ranging between 13 and 66% after 5min of operation. For the acidic model analytes Bodipy FL C5 and Oregon Green 488, the pH conditions were reversed, utilizing an acidic sample droplet and an alkaline acceptor droplet, and 1-octanol as SLM. As a result, recoveries for Bodipy FL C5 and Oregon Green 488 from human urine were 15 and 25%, respectively. [Copyright &y& Elsevier]

Context: Recently, concern has been raised about the safety of folic acid, particularly in relation to cancer risk.Objective: To evaluate effects of treatment with B vitamins on cancer outcomes and all-cause mortality in 2 randomized controlled trials.Design, Setting, and Participants: Combined analysis and extended follow-up of participants from 2 randomized, double-blind, placebo-controlled clinical trials (Norwegian Vitamin Trial and Western Norway B Vitamin Intervention Trial). A total of 6837 patients with ischemic heart disease were treated with B vitamins or placebo between 1998 and 2005, and were followed up through December 31, 2007.Interventions: Oral treatment with folic acid (0.8 mg/d) plus vitamin B(12) (0.4 mg/d) and vitamin B(6) (40 mg/d) (n = 1708); folic acid (0.8 mg/d) plus vitamin B(12) (0.4 mg/d) (n = 1703); vitamin B(6) alone (40 mg/d) (n = 1705); or placebo (n = 1721).Main Outcome Measures: Cancer incidence, cancer mortality, and all-cause mortality.Results: During study treatment, median serum folate concentration increased more than 6-fold among participants given folic acid. After a median 39 months of treatment and an additional 38 months of posttrial observational follow-up, 341 participants (10.0%) who received folic acid plus vitamin B(12) vs 288 participants (8.4%) who did not receive such treatment were diagnosed with cancer (hazard ratio [HR], 1.21; 95% confidence interval [CI], 1.03-1.41; P = .02). A total of 136 (4.0%) who received folic acid plus vitamin B(12) vs 100 (2.9%) who did not receive such treatment died from cancer (HR, 1.38; 95% CI, 1.07-1.79; P = .01). A total of 548 patients (16.1%) who received folic acid plus vitamin B(12) vs 473 (13.8%) who did not receive such treatment died from any cause (HR, 1.18; 95% CI, 1.04-1.33; P = .01). Results were mainly driven by increased lung cancer incidence in participants who received folic acid plus vitamin B(12). Vitamin B(6) treatment was not associated with any significant effects.Conclusion: Treatment with folic acid plus vitamin B(12) was associated with increased cancer outcomes and all-cause mortality in patients with ischemic heart disease in Norway, where there is no folic acid fortification of foods.Trial Registration: clinicaltrials.gov Identifier: NCT00671346. [ABSTRACT FROM AUTHOR]

The article offers information on a study which investigated the effects of treatment with B vitamins on cancer outcomes and all-cause mortality. A total of 6837 patients were recruited to participate in two randomized, double-blind, placebo-controlled clinical trials conducted in Norway between 1998 and 2005, and followed up through December 31, 2007. Treatment interventions included oral treatment with folic acid combined with vitamin B12 and vitamin 6, folic acid combined with vitamin B12, vitamin 6 alone and placebo. Presented in details are the research findings.

Abstract: Electromembrane extraction (EME) of basic drugs from 10μL sample volumes was performed through an organic solvent (2-nitrophenyl octyl ether) immobilized as a supported liquid membrane (SLM) in the pores of a flat polypropylene membrane (25μm thickness), and into 10μL 10mM HCl as the acceptor solution. The driving force for the extractions was 3–20V d.c. potential sustained over the SLM. The influence of the membrane thickness, extraction time, and voltage was investigated, and a theory for the extraction kinetics is proposed. Pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted from pure water samples with recoveries ranging between 33% and 47% after only 5min of operation under totally stagnant conditions. The extraction system was compatible with human urine and plasma samples and provided very efficient sample pretreatment, as acidic, neutral, and polar substances with no distribution into the organic SLM were not extracted across the membrane. Evaluation was performed for human urine, providing linearity in the range 1–20μg/mL, and repeatability (RSD) in average within 12%. [Copyright &y& Elsevier]

Abstract: Hollow fiber protected liquid-phase microextraction (LPME) was developed for large sample volume extractions in a single step, with special emphasis on extraction of basic drugs from environmental waters. Five antidepressant drugs were extracted from 1100 or 100mL water samples, through approximately 50μL of dihexyl ether immobilized in the pores in the wall of a porous hollow fiber (liquid membrane), and into 20μL of 10mM HCl or HCOOH as the acceptor solution. Extractions were performed for 60 or 120min supported by magnetic stirring at 800rpm, and hereafter the acceptor solution was directly injected in HPLC-UV or HPLC-MS. Compared with earlier work on LPME from small sample volumes, both closing the hollow fiber and the type of liquid membrane was found to be critical for large volume extractions. The hollow fibers were carefully closed with a small piece of metal wire, dihexyl ether was used as the liquid membrane, and pH in the sample was adjusted to 11.8 with NaOH. Recoveries from 1100mL samples were in the range 33–49%, and enrichments were in the range 18,000–27,000 after 120min of extraction. With HPLC-MS, the drugs were detected down to the 5–30pgL−1 level. Within-day precision was within 12.4–20.6% R.S.D. (n =6), whereas between-day precision was within 17.6 and 37.2% R.S.D. Linearity was obtained in the range 1–500ngL−1 with r 2-values between 0.982 and 0.994. The proposed LPME system was utilized to detect the five antidepressants in wastewater from the city of Tromsø in Northern Norway. [Copyright &y& Elsevier]

Aims: To assess left ventricular function by conventional and pulsed wave tissue Doppler (PWTD) echocardiography in subjects with mild secondary hyperparathyroidism, and to evaluate whether PWTD would be more sensitive than conventional echocardiography in detecting subtle changes in LV systolic and diastolic function. Methods: In the fifth Tromsø study (2001) serum PTH and calcium were measured in 7,954 subjects. One hundred subjects with secondary hyperparathyroidism (SHPT; serum PTH >6.40 pmol/l and serum calcium <2.40 mmol/l) and 106 control subjects with normal PTH and calcium levels and with no history of cardiovascular disease were examined at the follow-up 6–12 months later. Results: Conventional transthoracic echocardiography and PWTD of mitral annulus were successfully performed in 83 cases and 88 controls. At follow-up mean serum PTH values were 6.0 ± 2.2 versus 3.2 ± 1.3 pmol/l (p < 0.05) and mean calcium 2.28 ± 0.10 versus 2.33 ± 0.08 mmol/l (p < 0.05) in cases and controls, respectively. Unpaired t test and multiple linear regression analyses were used. No significant differences in conventional echocardiographic parameters were found. However, PWTD showed reduced systolic velocity in septal, lateral and anterior mitral annulus (p < 0.05) and also reduced early diastolic velocity in septal and anterior mitral annulus (p < 0.05). Conclusion: Subjects with mild SHPT have impaired left ventricular long axis function as evaluated by PWTD compared to conventional echocardiography. PWTD seems to be a more sensitive tool in detecting minor changes in left ventricular function and the new modality should routinely be included in studies evaluating left ventricular function, especially the long axis function. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Recently, we demonstrated for the first time liquid-phase microextraction (LPME) of polar drugs based on carrier mediated transport. In this new extraction technique, selected analytes were extracted as ion-pairs from small volumes of biological samples, through a thin layer of a water immiscible organic solvent immobilised in the pores of a porous hollow fibre (liquid membrane), and into a μl volume of an acidic aqueous acceptor solution placed inside the lumen of the hollow fibre. In the current paper, this new extraction technique was combined with liquid chromatography–mass spectrometry (LC–MS) for the first time. Carrier mediated LPME was evaluated for several new model drugs (0.01&#60;log P &#60;1.76), the sample clean-up aspects were investigated in detail, and this new extraction technique was fully validated for the first time. Extractions were performed from 50μl of human plasma samples, which provided sufficient material in combination with LC–MS. Sodium octanoate (50mM) was added to the sample as carrier, 1-octanol (≈15μl) was used as the liquid membrane in the wall of the hollow fibre, and 50mM HCl was utilized as acceptor solution in the lumen of the hollow fibre. The addition of carrier to the samples was found to significantly improve extraction recoveries for the polar drugs tested, providing recoveries in the range 16–78%. Validation was accomplished for atenolol and cimetidine. Limits of quantification (S/N=5) from 50μl of plasma were 25 and 50ng/ml for atenolol and cimetidine, respectively. The intra-day precision (R.S.D.) ranged from 7.8 to 17.2% and from 9.5 to 14.1% for atenolol and cimetidine, respectively, and corresponding inter-day precisions (R.S.D.) were within 6.7–1.4% and 7.7–20.3%. The method was linear in the range 25–1500ng/ml for atenolol (r =0.992), and 50–3500ng/ml for cimetidine (r =0.976). The accuracy of the method was found to be in range 89.1–99.6% and 83.4–86% for atenolol and cimetidine, respectively. The sample clean-up obtained by carrier mediated LPME was excellent, providing a significantly lower back-ground level in total ion current chromatograms by LC–MS as compared to protein precipitation. [Copyright &y& Elsevier]

A chiral capillary electrophoresis (CE) system allowing simultaneous enantiomer determination of citalopram (CIT) and its pharmacologically active metabolite desmethylcitalopram (DCIT) was developed. Excellent chiral separation was obtained using 1% sulfated-β-cyclodextrin (S-β-CD) as chiral selector in combination with 12% ACN in 25 mM phosphate pH 2.5. Samples were prepared by liquid-phase microextraction (LPME) based on a rodlike porous polypropylene hollow fibre. CIT and DCIT were extracted from 1 ml plasma made alkaline with NaOH, into dodecyl acetate impregnated in the pores of a hollow fibre, and into 20 mM phosphate pH 2.75, inside the hollow fibre. The acceptor solution was directly compatible with the CE system. Efficient sample clean-up was seen, and the recoveries were 46 and 29% for the enantiomers of CIT and DCIT, respectively, corresponding to 31 and 19 times enrichment. The limit of quantification (S/N=10) was <11.2 ng/ml, intra-day precision was <12.8% RSD, and inter-day precision was <14.5% RSD, for all enantiomers. The validated method was successfully applied to simultaneous determination of enantiomer concentrations of CIT and DCIT in plasma samples from nine patients treated with racemic citalopram. The results confirm LPME-CE as a suitable and promising tool for enantiomeric determination of chiral drugs and metabolites in biological matrices. [Copyright &y& Elsevier]

Basic studies on carrier-mediated transport as a mechanism to extract polar drugs by hollow fibre-based liquid-phase microextraction are presented for the first time. Hydrophilic alkaline drugs with log P (octanol/water partition coefficient) values less than 1 were selected as model substances. Sodium octanoate served as carrier and was added to the sample solution at pH 7 to form hydrophobic ion-pair complexes with the analytes. The ion-pair complexes were extracted into octanol as liquid membrane immobilised in the pores of the hollow fibre. Further extraction into an aqueous acceptor phase inside the lumen of the hollow fibre was facilitated by counter transport of protons from the acceptor solution to the sample solution. Protons from the acceptor solution released the analytes at the liquid membrane–acceptor interface and neutralized the carrier. The acceptor phase was analysed by capillary electrophoresis. The studies show that high extraction recoveries of ionic hydrophilic drugs can be obtained at a sample–acceptor volume ratio of 10. Linear calibration graphs and clean electropherograms indicate that carrier-mediated transport is a promising technique in microextraction of polar drugs from biological matrices. [Copyright &y& Elsevier]

A disposable device for liquid-phase microextraction (LPME) based on porous polypropylene hollow fibres has recently been introduced. In the present paper, LPME was combined with capillary electrophoresis (CE) and the combination was for the first time evaluated for chiral determination of drugs in biological matrices. The chiral antidepressant drug mianserin was selected as model compound. The mianserin enantiomers were extracted from 0.5 ml of plasma added internal standard and made alkaline with 0.25 ml of 2 M NaOH. The unionised analytes were extracted into di-n-hexyl ether impregnated in the pores of the hollow fibre, and into an acidic solution inside the hollow fibre. This resulted in a three-phase system where the extracts were aqueous, and hence directly compatible with the CE system. Efficient sample clean-up was seen and the extraction recovery was 80% for both enantiomers. Discrimination between the enantiomers in the extraction system was not observed. The limit of quantitation (S/N=10; 12.5 ng/ml for both enantiomers) and the limit of detection (S/N=3; 4 ng/ml for both enantiomers) were below the therapeutic range for mianserin. The method was validated and successfully applied to determine R- and S-mianserin in plasma samples from seven patients treated with mianserin, indicating that LPME–CE is a promising combination for analysis of racemic drugs present in low concentrations in biological matrices. [Copyright &y& Elsevier]