ISSN:0173-0835    

DOI:10.1002/elps.1150190102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractCapillary electrophoresis was developed for the analysis of low explosive residue, because a significant amount of inorganic anions and cations remain after deflagration. Certain high explosives, such as emulsion explosives, produce a vast quantity of inorganic ions after a blast and can readily be analyzed using capillary electrophoresis. Often, trace amounts of explosive residues may be present on physical evidence submitted in criminal cases. Trace amounts of inorganic ions such as nitrate, chlorate, and ammonium may be detected using capillary electrophoresis owing to the low detection limit of these species. The utility of capillary electrophoresis in the analysis of explosive residues is in its ability to simultaneously analyze trace explosives and ionic products present on physical evidence.

ISSN:0173-0835    

DOI:10.1002/elps.1150190103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractCapillary ion analysis (CIA) is a form of capillary electrophoresis which uses the differential electrophoretic mobility of ions to perform a separation of an ionic mixture. Application of this technique for direct detection of potassium concentrations in human vitreous humor was the purpose of this investigation. CIA was performed using a Waters Quanta 4000 Capillary Electrophoresis System with a 745 Data Module using a 75 μm × 60 cm capillary and a run electrolyte of 67.7 mg hydroxyisobutyric acid (HIBA), 52.8 mg 18‐crown‐6 ether and 64 μL UV‐CAT‐1 reagent (4‐ethylbenzylamine) in a volume of 100 mL water (18 Mohm) with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: ammonium ion, 2.86 min; potassium, 3.24 min; calcium, 3.84 min; sodium, 3.98 min; barium (internal standard), 4.68 min; and lithium, 4.79 min. Correlation coefficients (r) between peak area ratios and concentration ranges of 2.5–144 mmole/L (100–1000 ppm) were from 0.9855 to 0.9999. Coefficients of variation (CV) ranged from 1.45 to 13.8% between days and from 1.38 to 9.43% within‐day. Application of this methodology to twenty‐five vitreous humor specimens from forensic cases was compared to analysis by ion‐specific electrode for potassium concentration. Comparison of CIA to ion‐specific electrode analysis of vitreous humor potassium concentrations revealed a correlation coefficient of 0.9642. CIA is applicable to forensic analysis of potassium concentration in forensic vitreous humor specimens. Quantitation of numerous cation concentrations is possible by dire

ISSN:0173-0835    

DOI:10.1002/elps.1150190104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractCapillary electrophoresis (CE) is compared with high performance liquid chromatography (HPLC) and atomic absorption spectrometry (AA) for the determination of trace concentrations of selected metals in human hair. CE and HPLC methods are based upon the chelation of the metals with 2‐(5′‐bromo 2′‐pyridylazo)‐5‐diethylamino phenol (5‐Br‐PADAP) followed by ultraviolet‐visible (UV‐Vis) detection. Large volume sample stacking (LVSS)‐CE using injection times of up to 300 s is applied to the simultaneous determination of Co and Zn providing lower limits of detection (LODs) of 4.2 × 10−8mol dm−3and 6.0 × 10−8mol dm−3, respectively, than can be achieved by conventional CE. The LVSS procedure could not be applied to hair samples due to a higher run current existing when the sample is introduced into the capillary. Conventional CE with cetyltrimethylammonium bromide (CTAB) present in the run buffer to retain the ligand in solution is used for the determination of metal concentrations in hair samples. Only Zn could be determined in this way as it exists at relatively high levels in hair. Co, Ni and Hg could be detected when spiked hair samples were analysed with estimated LODs of 5.0 × 10−7mol dm−3, 1.0 × 10−6dm−3and 3.0 × 10−5mol dm−3, respectively. HPLC was successfully used to determine Co and Cu in hair samples, with levels of 57.6 ppb and 17.31 ppm being found, respectively, and corresponded closely to results produced by AA. Fe also gave a signal together with unidentified coeluting species. In a separate HPLC study the determination of Ni and Hg as their complexes with hydrogen peroxide and 5‐Br‐PADAP was also investigated and LODs of 2.0 × 10−6mol dm−3and 5.0 × 10−6mol dm−3, respectively, were achieved. AA was used as a reference method to determine levels of Co, Cu, Fe, Pb and Zn in hair and the results produced were i

ISSN:0173-0835    

DOI:10.1002/elps.1150190105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractTobacco products regulated by the Bureau of Alcohol, Tobacco and Firearms (ATF), are classified at different excise tax rates according to the Code of Federal Regulations. These include the smoking (cigars, cigarettes, pipe tobacco and roll‐your‐own) and smokeless (chewing tobacco and snuff) tobacco products. The active principal components in all tobacco products belong to a class of compounds known as alkaloids. Nicotine is the major tobacco alkaloid, comprising about 98% of the total alkaloids. It is also the primary determinant of what constitutes a tobacco product from a regulatory standpoint. Nornicotine, anabasine and anatabine constitute the minor tobacco alkaloids of importance and interest to ATF. We have previously shown capillary electrophoresis (CE) to be a powerful analytical tool for monitoring nicotine in ATF‐regulated products. Here we have extended those CE studies to (i) quantitate nicotine in ATF‐regulated tobacco products and (ii) to characterize these different tobacco products according to their alkaloid profiles. Results from these studies will be pr

ISSN:0173-0835    

DOI:10.1002/elps.1150190106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractWhile the hallucinogenic mushroomsPsilocybe semilanceatahave previously been analyzed for the indole alkaloids psilocybin and baeocystin by capillary zone electrophoresis (CZE) at pH 11.5, the present work focused on the development of an alternative and complementary capillary electrophoretic method for their identification. Owing to their structural similarity and zwitterionic nature, the compounds were difficult to resolve based on different interactions with cationic or anionic micelles. However, while the attempts with micellar electrokinetic chromatography (MEKC) were unsuccessful, rapid derivatization with propyl chloroformate and reanalysis by CZE at pH 11.5 was effective to support identification of the two indole alkaloids. Psilocin was difficult to analyze by CZE at pH 11.5 owing to comigration with the electroosmotic flow. For this compound, the pH of the running buffer was reduced to 7.2 to effectively enhance the electrophoretic mobility.

ISSN:0173-0835    

DOI:10.1002/elps.1150190107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractInformation on the identity of inks adds to the circumstantial evidence in legal cases involving fraudulent documents. In combination with optical methods, multiple thin‐layer chromatography (TLC) is currently the analytical tool used by forensic chemists to separate, compare and distinguish inks based on their dye composition. In our studies, capillary electrophoresis (CE) was used for the analysis of water‐soluble fountain pen inks. Inks are complex mixtures of synthetic organic and inorganic dyes, surfactants, resins and other components. The investigations included the development of an electrophoretic separation method, the optimization of an extraction procedure for inks from paper as well as the evaluation of ultraviolet/visible (UV/VIS) absorbance and laser‐induced fluorescence (LIF) detection for the analysis of inks by CE. Good results for the separation of 17 blue and black inks of different manufacturers and countries of origin were obtained with 100 mM borate buffer, pH 8.0, containing 20% methanol. The electropherograms of the inks and their extracts from paper showed patterns that were in most cases distinctly different from each other. Ultraviolet/visible scans can be used to compare spectra of the separated main and trace components of inks. Fluorescence detection at different excitation and emission wavelengths was more sensitive, but added to the complexity of the electropherograms due to the excitation of coextracted fluorescing paper components. The resolution power of CE combined with the information content provided by the detection modes investigated prove CE to be a powerful tool for the identification of water‐soluble inks used on paper do

ISSN:0173-0835    

DOI:10.1002/elps.1150190108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThe importance of the chiral analysis of amphetamine‐related substances in both clandestine preparations and biological samples is widely recognized. For this purpose, capillary electrophoresis was successfully applied by several authors, but only few reports concerned ring‐substituted amphetamines, which represent the main components of “ecstasy”, a widely abused “recreational” substance. In the present work, the simultaneous chiral analysis of ephedrine, amphetamine, methamphetamine, 3,4‐methylenedioxymethamphetamine (MDMA), 3‐4‐methylenedioxyamphetamine (MDA) and 3,4‐methalenedioxyethylamphetamine (MDE) is reported, by using capillary electrophoresis with native β‐cyclodextrin (15 mM) as the chiral selector. After preliminary tests at different pH values (phosphate buffer 100 mM, pH 2.5–9.0) and with bare or coated fused‐silica capillaries, the optimized conditions were: pH 2.5 phosphate, uncoated capillary (45 cm × 50 μm inner diameter), potential 10 kV. Detection was either by fixed wavelength (200 nm) or multiwavelength (190–400 nm) UV absorbance. Under these conditions, good resolution was obtained for all the analytes, with excellent chiral selectivity and efficiency. The sensitivity for the individual enantiomers was better than 0.2 μg/mL, analytical precision was characterized by relative standard deviation values<0.8% (⩽ 0.15% with internal standardization) for migration times intra‐day and<2.0% (⩽ 0.54% with internal standardization) day‐to‐day; linearity, in the range 0.156–40 μg/mL, and accuracy were also satisfactory. After a simple liquid‐liquid extraction, urine samples could be analyzed with a sensitivity well below the recommended NIDA cut‐off of 500 ng/mL. For hair samples, it was necessary to increase the sensitivity by applying a field‐amplified sample stacking procedure, which allowed the chiral determination of MDA, MDMA and MDE at concentrations occurring in real samples from ecstasy users, with th

ISSN:0173-0835    

DOI:10.1002/elps.1150190109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThe analysis of by‐products and impurities in illicit cocaine, including the isomeric truxillines, is important for derivation of both strategic and tactical intelligence. In the present study, various capillary electrophoresis techniques were investigated for this purpose. The use of the anionic β‐cyclodextrin sulfobutyl ether IV as a run buffer additive at pH 8.6 gave a good separation of the truxillines and similar high molecular weight impurities in less than eight minutes. These impurities were first isolated from the bulk cocaine matrix using liquid‐liquid extraction and size‐exclusion high performance liquid chromatography. There was a red shift in the UV spectra obtained for the truxillines using photodiode array (PDA) UV detection during CE analysis. This anomalous behavior is attributed to photo‐degradation of the truxillines during the PDA‐UV irradiation process. Laser‐induced fluorescence detection using a UV krypton/fluoride laser provided greater selectivity and sensitivityversusUV detection for certain uncharacterized high molecular wei

ISSN:0173-0835    

DOI:10.1002/elps.1150190110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThis paper characterizes competitive binding, electrokinetic capillary‐based immunoassays for urinary methadone using reagents which were commercialized for a fluorescence polarization immunoassay. After incubation of 25 μL urine with the reactants, a small aliquot of the mixture is applied onto a fused‐silica capillary and the unbound fluorescein‐labeled methadone tracer is monitored by capillary electrophoresis with on‐column laser‐induced fluorescence detection. Configurations in presence and absence of micelles were investigated, found to be capable of recognizing urinary methadone concentrations ⩾ 10 ng/mL, and shown to be suitable for rapid methadone screening of patient urines. Based upon shorter run times and a much better separation of free tracer and antibody‐tracer complex, conditions without micelles are preferred. For confirmation analysis of urinary methadone and its major metabolite, 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine (EDDP), capillary electrophoresis in a pH 4.6 ammonium acetate‐acetic acid buffer was interphased to an atmospheric pressure ionization triple quadrupole mass spectrometry system. Using positive ion electrospray ionization and the tandem mass spectrometry mode with collision‐induced dissociation in the collision cell, fragmentation of the two substances was determined. For confirmation via direct urine injection or application of a urinary extract, in‐source fragmentation was employed and the first quadrupole was operated in the selected ion monitoring mode by switching between the masses of relevant precursor/product ion sets for methadone (m/z= 310, 265) and EDDP (m/z= 278, 249, 234). This capillary electrophoresis – mass spectrometry approach is shown to permit the confirmation of methadone and EDDP in patient urines that tested positive for methadone using electrokinetic capillary‐based immunoassays, a fluorescence polarization immunoassay, and capillary electropho

ISSN:0173-0835    

DOI:10.1002/elps.1150190111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY