[Toxic effects of sublethal acetochlor with sublethal doses on earthworms in soil using multi-endpoints system]. / äºšè‡´æ­»å‰‚é‡ä¹™è‰èƒºå¯¹èš¯èš“çš„æ¯’æ€§æ•ˆåº”åŠæ•æ„Ÿç”Ÿç‰©æ ‡è®°ç‰©.

In this study, we examined the toxic effect of sublethal doses of acetochlor (1, 2, 4, 8 mg·kg-1) on earthworms by exogenous addition. The growth inhibition rate, cytochrome P450 isozymes (CYP1A2, 2C9 and 3A4) activities and the metabolomics were analyzed after seven days of exposure, to infer the toxicity threshold of acetochlor, screen the sensitive biomarkers from the levels of the individual, detoxified enzymes and small molecular metabolites, and elucidate the underlying toxicity mechanism. The results showed that CYP1A2, 2C9 and 3A4 activities were all significantly inhibited, and that the levels of ten metabolites (fructose-6-diphosphate, cytosine monophosphate, uridine monophosphate, adenosine monophosphate, adenosine, xanthine, fumaric acid, dihydroxyglutaric acid, ornithine and 16-hydroxyeicosatetraenoic acid) were significantly decreased by acetochlor exposure. The levels of six metabolites (adenosine succinic acid, succinic acid, arginine, tryptophan, asparagine and phenylalanine) were significantly increased when earthworms being exposed to 2-8 mg·kg-1 acetochlor. Acetochlor exposure caused oxidative damage to earthworms, weakened the glycolysis, disturbed the tricarboxylic acid cycle, disordered the purine and pyrimidine metabolism, and impaired the amino acids metabolism. Compared with the end point at individual level, the above 16 small molecule metabolites and CYP isozymes activities were more sensitive to acetochlor exposure. It was thus recommended that CYP isozymes (1A2, 2C9, and 3A4) activities and small molecular metabolites could be used as a set of biomarkers to diagnose the acetochlor pollution, given their high sensitivity and accuracy.

Sensitive Determination of Acetochlor, Alachlor, Metolachlor and Fenthion Utilizing Mechanical Shaking Assisted Dispersive Liquid-Liquid Microextraction Prior to Gas Chromatography-Mass Spectrometry.

A green, sensitive and accurate dispersive liquid-liquid microextraction (DLLME) method was used to preconcentrate four selected pesticides in dam lake water samples for determination by gas chromatography-mass spectrometry (GC-MS). Conditions of the DLLME method were comprehensively investigated and optimized according to type/volume of extraction solvent, type/volume of dispersive solvent, and type/period of mixing. The developed method was validated according to the limits of detection and quantitation, accuracy, precision and linearity. Under the optimum conditions, limit of detection values calculated for alachlor, acetochlor, metolachlor and fenthion were 1.7, 1.7, 0.2 and 7.8 µg/kg (mass based), respectively. The method recorded 202, 104, 275 and 165 folds improvement in detection power values for acetochlor, alachlor, metolachlor and fenthion, respectively, when compared with direct GC-MS measurements. In order to evaluate the accuracy of the developed method, real sample application with spiking experiments was performed on dam lake water samples, and satisfactory percent recovery results in the range of 81%-120% were obtained.

Development of a Multiresidue Method for Endocrine-Disrupting Pesticides by Solid Phase Extraction and Determination by UHPLC-MS/MS from Drinking Water Samples.

A rapid and efficient method based on solid phase extraction and liquid chromatography-tandem mass spectrometry was validated, allowing the determination of the endocrine-disrupting herbicides (acetochlor, alachlor, amitrole and atrazine), fungicides (carbendazim, triadimefon, penconazole and propiconazole), and insecticides (carbaryl and carbofuran) in drinking water. Low method detection limits (0.01-0.64 ng/L) and method quantification limits (0.03-2.13 ng/L) were obtained with satisfactory recoveries and precision for the endocrine-disrupting pesticides. The method was applied for real drinking water samples collected in the area of the city of Hangzhou (Zhejiang, China); the results showed that carbendazim, atrazine and acetochlor were detected in the drinking water samples and acetochlor was the most detected analyte.

Determination of pararosaniline hydrochloride in workplace air.

Pararosaniline hydrochloride (CPR) is a dye used for colouring paper, leather and natural and artificial fibres. It is also used in analytical and microbiological laboratories. It is a carcinogenic substance of category 1B. In analytical chemistry, it is used for detecting the following among others: bromates, formaldehyde, ozone, sulphite and sulfur dioxide. CPR is a dye commonly used in microbiology for staining preparations, for staining bacteria, antibodies or other organisms. In Poland, about 800 employees were exposed to this substance. The lack of methods for the determination of pararosaniline hydrochloride in workplace air makes it impossible to assess the occupational exposure of workers to this substance. For this reason, a determination method has been developed, which allows for the determination of pararosaniline hydrochloride in the air. This method makes it possible to determine the concentration of CPR in the air at the workplace within the range from 0.002 to 0.04 mg/m3 (for an air sample of 120 L). The method is based on the adsorption of pararosaniline hydrochloride present in the workplace air on a polypropylene filter, eluting the substance deposited on the filter with methanol and analysing the solution thus obtained using high-performance liquid chromatography with a diode array detector (wavelength of 544 nm). Using an Ultra C18 (250 mm length) chromatographic column at a temperature of 23 °C and the mobile phase of methanol:0.1% phosphoric acid(V) (95:5, v/v) at flow rate of 0.6 mL/min makes it possible to determine the content of pararosaniline hydrochloride in the presence of aniline, nitrobenzene and 4-tolylamine. Limit of detection and limit of quantification were 0.17 ng/mL and 0.51 ng/mL, respectively.

Determination of neonicotinoids and 199 other pesticide residues in honey by liquid and gas chromatography coupled with tandem mass spectrometry.

Current work presents a modified QuEChERS method for the determination of 207 pesticide residues in honey by LC-MS/MS and GC-MS/MS. Acetate buffered acetonitrile extraction with Z-Sep+ and PSA dispersive-SPE clean-up were used for sample preparation. Optimised conditions allows determination of neonicotinoids as well as other insecticides, fungicides, herbicides, acaricides, growth regulators and veterinary drugs in honey samples. Validated method enable sensitive analysis at least at concentrations from 0.001, 0.005 or 0.01 mg/kg for 45%, 41% and 14% of pesticides, respectively. Method was utilised for the analysis of 155 honey samples from Poland during 2015-2017. Residues of 21 pesticides were determined in honey. Cyano-substituted neonicotinoids (acetamiprid, thiacloprid) were quantified in 77% of samples and were the most frequently detected pesticides. Concentrations of acetamiprid was from 0.001 to 0.13 mg/kg whilst thiacloprid from 0.001 to 0.2 mg/kg. Fungicides were determined in 50% and amitraz metabolites in 35% of honey samples.

Determination of residue levels of the avicide 3-chloro-4-methylaniline hydrochloride in red-winged blackbirds (Agelaius phoeniceus) by gas chromatography-tandem mass spectrometry.

The avicide 3­chloro­4­methylanaline hydrochloride (chloro­p­toluidine hydrochloride, CPTH, DRC-1339) is used to control pest bird species that damage agricultural crops. A specific and sensitive gas chromatography-tandem mass spectrometry method was developed and validated for the determination of CPTH in avian breast muscle, GI tract, kidney, and liver. Tissue samples were extracted with a solution of acidified water and acetonitrile. The sample was made basic and cleaned up with a combination of liquid-liquid partitioning and solid phase extraction. Separation was achieved using a HP-5 ultra-inert GC column (15 M, 0.25 µm film) with detection on a triple quadrupole mass spectrometer in multiple reaction monitoring (MRM) mode. The monitored transition for CPTH was m/z 140.9 → 106.2 for quantitation and 139.9 → 105.2 and 139.9 → 77.2 for confirmation. The linear range was 5 to 5000 ng/mL. The precision for the determination of CPTH in all tissues averaged 7.2% and the accuracy averaged 6.7%. The recovery of CPTH fortified at 5 different levels averaged 101% in liver, 98.8% in GI tract, 92.9% in breast muscle, and 87.9% in kidney. The established method was successfully used to determine CPTH residue levels in red-winged blackbirds exposed to three different doses of CPTH.

FECAL OCCULT BLOOD: A COMPARISON OF CHEMICAL AND IMMUNOCHEMICAL TESTS.

BACKGROUND: Colorectal bleeding is a warning sign that may be identified by fecal occult blood testing. A positive fecal occult blood test result requires a subsequent colonoscopy, a costly and invasive examination. Therefore, the use of diagnostic tests with optimal sensitivity and specificity is warranted. In this study, we evaluated four different fecal occult blood tests in 176 patients undergoing colonoscopy and compared their results. OBJECTIVE: To assess the sensitivity, specificity and predictive values of chemical and immunochemical fecal occult blood tests in patients undergoing colonoscopy and to evaluate the degree of concordance between the tests and colonoscopy. METHODS: Patients with indications for colonoscopy also underwent fecal occult blood testing by chemical (toluidine test) and immunochemical methods, employing three commercially available kits. Based on the endoscopic findings, the colonoscopy was rated as positive or negative for colorectal bleeding. The degree of concordance between the fecal occult blood tests and the colonoscopy was evaluated by the kappa index. RESULTS: Forty-four (25%) colonoscopies were categorized as positive for colorectal bleeding. The toluidine test presented lower concordance than the immunochemical tests, which showed moderate concordance with the colonoscopy. The toluidine test had the least sensitivity, specificity, and positive and negative predictive values. CONCLUSION: The immunochemical fecal occult blood tests showed greater sensitivity, specificity and predictive values in detecting colorectal bleeding. The immunochemical tests had superior indexes of agreement with colonoscopy compared to the toluidine test.

Sangue oculto nas fezes: uma comparação entre os métodos químico e imunoquímico / Fecal occult blood: a comparison of chemical and immunochemical tests

ABSTRACT BACKGROUND: Colorectal bleeding is a warning sign that may be identified by fecal occult blood testing. A positive fecal occult blood test result requires a subsequent colonoscopy, a costly and invasive examination. Therefore, the use of diagnostic tests with optimal sensitivity and specificity is warranted. In this study, we evaluated four different fecal occult blood tests in 176 patients undergoing colonoscopy and compared their results. OBJECTIVE: To assess the sensitivity, specificity and predictive values of chemical and immunochemical fecal occult blood tests in patients undergoing colonoscopy and to evaluate the degree of concordance between the tests and colonoscopy. METHODS: Patients with indications for colonoscopy also underwent fecal occult blood testing by chemical (toluidine test) and immunochemical methods, employing three commercially available kits. Based on the endoscopic findings, the colonoscopy was rated as positive or negative for colorectal bleeding. The degree of concordance between the fecal occult blood tests and the colonoscopy was evaluated by the kappa index. RESULTS: Forty-four (25%) colonoscopies were categorized as positive for colorectal bleeding. The toluidine test presented lower concordance than the immunochemical tests, which showed moderate concordance with the colonoscopy. The toluidine test had the least sensitivity, specificity, and positive and negative predictive values. CONCLUSION: The immunochemical fecal occult blood tests showed greater sensitivity, specificity and predictive values in detecting colorectal bleeding. The immunochemical tests had superior indexes of agreement with colonoscopy compared to the toluidine test.

RESUMO CONTEXTO: O sangramento colorretal é considerado um sinal de alarme e não deve ser ignorado. O resultado positivo de um teste de pesquisa de sangue oculto nas fezes (PSOF) requer investigação complementar com colonoscopia, exame invasivo e de alto custo. Justifica-se, portanto, a aplicação de um teste diagnóstico mais sensível e específico. No presente estudo, foram avaliados quatro diferentes testes de PSOF em 176 pacientes submetidos à colonoscopia e seus resultados foram comparados. OBJETIVO: Avaliar a sensibilidade, a especificidade e os valores de predição dos testes químico e imunoquímico de PSOF em pacientes submetidos à colonoscopia e avaliar o grau de concordância entre os testes de PSOF e a colonoscopia. MÉTODOS: Pacientes com indicação de realizar colonoscopia foram submetidos também à PSOF pelo método químico (o-toluidina) e pelo método imunoquímico, empregando três kits comerciais disponíveis no mercado. Fundamentado nos achados endoscópicos, a colonoscopia foi categorizada em positiva ou negativa, de acordo com a possível fonte de sangramento colorretal. O grau de concordância entre os testes de PSOF foi avaliado pelo índice kappa. RESULTADOS: Quarenta e quatro (25%) colonoscopias foram categorizadas como positivas quanto à fonte de sangramento colorretal. O teste da o-toluidina mostrou menor concordância que os testes imunoquímicos, os quais apresentaram moderada concordância com a colonoscopia. O teste da o-toluidina revelou menor sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo. CONCLUSÃO: Os testes imunoquímicos revelaram maior sensibilidade, especificidade e valores de predição na detecção de sangramento colorretal. Os testes imunoquímicos apresentaram melhores índices de concordância com a colonoscopia, quando comparados ao teste da o-toluidina.

Comparison of Some Soil Fungi in Bioremediation of Herbicide Acetochlor Under Agitated Culture Media.

In this study, we aimed to find out the biodegradation efficiency of some soil fungi types on herbicide acetochlor with acetochlor active material, chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and total organic carbon (TOC) parameters. We also try to determine the population dynamics of these fungi via turbidity. The fungi cultures were isolated from agricultural field in in Thrace region of Turkey. Each fungi enriched in malt extract broth media and 1 mL of these enriched media was inoculated into 100 mL of acetochlor solutions that suggested for using application concantrations in agricultural field for farmers (11000 mg L-1) for sunflower and corn agriculture. Bioremediation results of acetochlor have shown different results according to the types of fungi. Our results indicate that Tolypocladium geodes and Cordyceps cicadae might be used in acetochlor bioremediation with a significant acetochlor, COD, TOC and BOD5 reduction and can be used for rehabilitation of agricultural fields or receiving environments for removal the opposite effects of acetochlor or other herbicides.

Rapid determination of six carcinogenic primary aromatic amines in mainstream cigarette smoke by two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry.

A fully automated, rapid, and reliable method for simultaneous determination of six carcinogenic primary aromatic amines (AAs), including o-toluidine (o-TOL), 2, 6-dimethylaniline (2, 6-DMA), o-anisidine (o-ASD), 1-naphthylamine (1-ANP), 2-naphthylamine (2-ANP), and 4-aminobiphenyl (4-ABP), in mainstream cigarette smoke was established. The proposed method was based on two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry (SPE/LC-MS/MS). The particulate phase of the mainstream cigarette smoke was collected on a Cambridge filter pad and pretreated via ultrasonic extraction with 2% formic acid (FA), while the gas phase was trapped by 2% FA without pretreatment for determination. The two-dimensional online SPE comprised of two cartridges with different absorption characteristics was applied for sample pretreatment. Analysis was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) under multiple reaction monitoring mode. Each sample required about 0.5h for solid phase extraction and analysis. The limit of detections (LODs) for six AAs ranged from 0.04 to 0.58ng/cig and recoveries were within 84.5%-122.9%. The relative standard deviations of intra- and inter-day tests for 3R4F reference cigarette were less than 6% and 7%, respectively, while no more than 7% and 8% separately for a type of Virginia cigarette. The proposed method enabled minimum sample pretreatment, full automation, and high throughput with high selectivity, sensitivity, and accuracy. As a part of the validation procedure, fifteen brands of cigarettes were tested by the designed method.

Determination of primary aromatic amines in cold water extract of coloured paper napkin samples by liquid chromatography-tandem mass spectrometry.

The aim of this study was the optimisation of a multi-analyte method for the analysis of primary aromatic amines (PAAs) from napkins in order to support official controls and food safety. We developed a UHPLC-MS/MS method for the simultaneous determination of 36 toxicologically relevant PAAs for paper and board. Good regression coefficients of the calibration curves in a range of 0.992-0.999 and reproducibilities in a range of 2.3-15% were obtained. Limits of detections (LODs) were in the range of 0.03-1.4 µg l(-1) and recoveries were in a range of 21-110% for all the amines. A total of 93 coloured paper napkin samples from different European countries were bought and extracted with water to determine the PAAs. The results showed that 42 of 93 samples contained at least one PAA. More than half of the detected PAAs are considered as toxic, carcinogenic or probably carcinogenic to humans by the International Agency for Research on Cancer (IARC), or are classified as such in the European Union legislation on chemicals. Summed concentrations of PAAs in seven samples were higher than 10 µg l(-1), the limit of summed PAA in the European Union plastic food contact material regulation. Also, eight PAAs, classified as Category 1A and 1B carcinogen in the European Union legislation of chemicals, were detected at concentrations higher than 2 µg l(-1), exceeding the limit proposed by the Federal Institute for Risk Assessment in Germany. Aniline (n = 14) was most frequently present in higher concentrations followed by o-toluidine, o-anisidine, 2,4-dimethylaniline and 4-aminoazobenzene. Red, orange, yellow and multicoloured paper napkins contained the highest concentrations of total PAAs (> 10 µg l(-1)). Although the European Union has not harmonised the legislation of paper and board materials and, thus, there is no specific migration limit for PAAs from paper napkins, the present study showed that coloured paper napkins can contain toxic and carcinogenic PAAs at concentrations that are relevant for monitoring.

[Residual levels of pesticides in freshwater fish from Beijing aquatic product markets and health risk assessment].

Health risks by fish consumption were assessed following the investigation of the residual levels of 25 pesticides in four kinds of freshwater fish from 4 aquatic product markets in Beijing using ultrasonic extraction-GC-MS. Eighteen pesticides were detected from the 48 samples collected. Acetochlor (97.9%) and beta-HCH (93.8%) showed high detection rates. The pesticide detected in highest concentration was chlorothalonil (1 779.4 microg x kg(-1)), followed by deltamethrin (620.3 microg x kg(-1)). Coexistence of 2-10 kinds of pesticides in fish was found with the total pesticide concentration in range of 2.7-1932 microg x kg(-1). Based on the averaged fish consumption of Beijing residents, the health risk of the studied pesticides by freshwater fish consumption was calculated as 0.043 43, suggesting a relatively low health risk.

Sensitive ionization of non-volatile analytes using protein solutions as spray liquid in desorption electrospray ionization mass spectrometry.

RATIONALE: Desorption electrospray ionization (DESI) is the most popular ambient ionization technique for direct analysis of complex samples without sample pretreatment. However, for many applications, especially for trace analysis, it is of interest to improve the sensitivity of DESI-mass spectrometry (MS). METHODS: In traditional DESI-MS, a mixture of methanol/water/acetic acid is usually used to generate the primary ions. In this article, dilute protein solutions were electrosprayed in the DESI method to create multiply charged primary ions for the desorption ionization of trace analytes on various surfaces (e.g., filter paper, glass, Al-foil) without any sample pretreatment. The analyte ions were then detected and structurally characterized using a LTQ XL mass spectrometer. RESULTS: Compared with the methanol/water/acetic acid (49:49:2, v/v/v) solution, protein solutions significantly increased the signal levels of non-volatile compounds such as benzoic acid, TNT, o-toluidine, peptide and insulin in either positive or negative ion detection mode. For all the analytes tested, the limits of detection (LODs) were reduced to about half of the original values which were obtained using traditional DESI. The results showed that the signal enhancement is highly correlated with the molecular weight of the proteins and the selected solid surfaces. CONCLUSIONS: The proposed DESI method is a universal strategy for rapid and sensitive detection of trace amounts of strongly bound and/or non-volatile analytes, including explosives, peptides, and proteins. The results indicate that the sensitivity of DESI can be further improved by selecting larger proteins and appropriate solid surfaces.

Exposure to o-toluidine, aniline, and nitrobenzene in a rubber chemical manufacturing plant: a retrospective exposure assessment update.

The National Institute for Occupational Safety and Health previously conducted a retrospective cancer incidence and mortality study of workers employed at a rubber chemical manufacturing plant. Compared with New York State incidence, the bladder cancer risk was 6.5 times higher for workers considered to have definite exposure to ortho-toluidine and aniline, and 4 times higher for workers with possible exposure. Exposure characterization in the original study utilized a surrogate measure based only on departments in which each worker was ever employed. As part of an update of that study, some departments in the three original exposure groups were reclassified based on a follow-up site visit; interviews with employees, management, and union representatives; and review of records including exposure data. An additional evaluation of department-job combinations, rather than only departments, was used to stratify exposure into four categories. An approximate rank of "relative" exposure level for each department-job-year combination was also assigned using a ranking scale of 0 to 10. The ranks were supported by quantitative exposure levels and by professional judgment. The numerical ranking scale was applied to each worker by multiplying the exposure rank by duration for each job held based on comprehensive individual work histories. The cumulative rank scores for this cohort ranged from 0 to 300 unit-years. The medians of the cumulative rank scores for the exposure categories showed very good agreement with increasing exposure classifications (e.g., 0.72, 4.6, 11, 14 unit-years for the four exposure categories). Workers' breathing zone air sampling data collected at this plant from 1976-2004 were well below published occupational exposure limits for these chemicals, but additional cases of bladder cancer have been reported. The exposure assessment revisions and rank estimates will be used to analyze the updated bladder cancer incidence data.

Comparison of exposure to selected cigarette smoke constituents in adult smokers and nonsmokers in a European, multicenter, observational study.

BACKGROUND: This multicenter, observational study was conducted in three European countries (Germany, Switzerland, and the United Kingdom) to determine the exposure of adult cigarette smokers and nonsmokers to selected cigarette smoke constituents: 1,3-butadiene, 2-naphthylamine, 4-aminobiphenyl, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), acrolein, benzene, carbon monoxide, nicotine, pyrene, and o-toluidine. METHODS: Smokers were grouped by tar category (TC) according to the tar yield of their regular cigarette brand: TC1: ≤4 mg tar, TC2: 5-7 mg tar, and TC3: ≥8 mg tar [to the legal tar yield ceiling in the respective countries (10 or 12 mg tar)]. Levels of biomarkers of exposure to the aforementioned cigarette smoke constituents were compared between smokers and nonsmokers, and within smokers across tar categories. RESULTS: The full population consisted of 1,631 subjects (1,223 smokers and 408 nonsmokers). Biomarkers of exposure were analyzed for 1,558 subjects (valid case population) as follows: 1,159 smokers (TC1: n = 402, TC2: n = 379, TC3: n = 378), and 399 nonsmokers. Exposure levels were higher in smokers than nonsmokers and increased with increasing tar yield and cigarette consumption. An association of tar category and exposure level was observed for all smoke constituents, except pyrene, 4-aminobiphenyl, and o-toluidine, whereas only NNK exposure was different in all three tar categories. CONCLUSIONS: Smoking status and, among smokers, daily cigarette consumption and tar yield were observed to affect biomarker of exposure levels. IMPACT: This research provides a comprehensive evaluation of smoke constituent exposure of adult cigarette smokers and nonsmokers in three European countries.

Simultaneous determination of acetochlor and propisochlor residues in corn and soil by solid phase extraction and gas chromatography with electron capture detection.

A sensitive and simple method for simultaneous analysis of acetochlor and propisochlor in corn and soil has been developed. Two herbicides were extracted from soil and corn matrices with methanol/water and acetone, respectively, followed by solid phase extraction (SPE) to remove co extractives, prior to analysis by gas chromatography with electron capture detection (GC-ECD). Primary secondary amine (PSA) SPE cartridges (500 mg, 3 mL) were used for sample preparation. The analytes from corn and soil matrices were eluted with 5 mL petroleum ether-acetic ether (95/5, v/v) and 3 mL petroleum ether-acetic ether (95/5, v/v), respectively. The recoveries of two pesticides ranged from 73.8% to 115.5% with relative standard deviations (RSD) less than 11.1% and sensitivity of 0.01 mg/kg, in agreement with directives for method validation in residue analysis. The method was successfully applied to determine the fate of acetochlor and propisochlor in real corn and soil samples. For acetochlor and propisochlor, the half-life times (t1/2) in soil was 5.541 and 6.074 days, respectively. No acetochlor and propisochlor residues (<0.01 mg/kg) were detected in corn at harvest time withholding period of 2.5 months after treatments of the pesticides. Direct confirmation of the analytes in samples was achieved by gas chromatography-mass spectrometry (GC-MS).

DNA adducts of ortho-toluidine in human bladder.

BACKGROUND: 4-Aminobiphenyl (4-ABP) and o-toluidine are known human bladder carcinogens, but only 4-ABP-releasing DNA adducts are known. METHODS: Determination of 4-ABP and o-toluidine-releasing DNA adducts in epithelial and submucosal bladder tissues of sudden death victims (SDV: n=46), and bladder tumours (n=12) by gas chromatography/mass spectrometry. RESULTS: Above background, 4 and 11 of 12 tumour samples contained adducts of 4-ABP (0.057 ± 0.125 fmol/µg DNA) and o-toluidine (8.72 ± 4.49 fmol/µg DNA), respectively. Lower adduct levels were present in both epithelial and submucosal bladder tissues of SDV (4-ABP: 0.011 ± 0.022 and 0.019 ± 0.047 fmol/µg DNA; o-toluidine: 0.24 ± 0.63 and 0.27 ± 0.70 fmol/µg DNA). CONCLUSION: Detection of o-toluidine-releasing DNA adducts support the carcinogenicity of o-toluidine in the human bladder.

Simultaneous determination of amitraz and its metabolite residue in food animal tissues by gas chromatography-electron capture detector and gas chromatography-mass spectrometry with accelerated solvent extraction.

A new method has been developed for determination and confirmation of amitraz and its main metabolite, 2,4-dimethylaniline, in food animal tissues using gas chromatography-electron capture detector (GC-ECD) and gas chromatography-mass spectrometry detector (GC-MS). This method is based on a new extraction procedure using accelerated solvent extraction (ASE). It consists of an n-hexane/methanol extraction step, a cleaning-up step by BakerBond octadecyl C(18) silica bonded cartridge, hydrolysis and derivatization to 2,4-dimethyl-7-F-butyramide for GC-ECD analysis. For confirmation using GC-MS, hydrolysis and derivatization were not needed. Parameters for extraction pressure, temperature and cycle of ASE, clean-up, derivatization and analysis procedure have been optimized. Spike recoveries from 50 to 300 microg/kg levels were found to be between 72.4 and 101.3% with relative standard deviation less than 11.5% in GC-ECD, from 5 to 20 microg/kg levels were found to be between 77.4 and 107.1% with relative standard deviation less than 11.6% in GC-MS. The LOD and LOQ are 5 and 10 microg/kg, respectively, for these two analytes using GC-ECD. For GC-MS, LOD and LOQ were 2 and 5 microg/kg, respectively. The rapid and reliable method can be used for characterization and quantification of residues of amitraz and its main metabolite, 2,4-dimethylaniline, in liver and kidney samples of swine, sheep and bovine.

A rapid and simple high-performance liquid chromatography assay for the leflunomide metabolite, teriflunomide (A77 1726), in renal transplant recipients.

Leflunomide (Arava), a drug with immunosuppressive and antiviral effects, is being used in renal transplant recipients, primarily for its action against BK polyomavirus (BKV), which affects 1% to 10% of renal transplant recipients and often causes failure of grafted kidneys. Leflunomide effects are solely due to an active metabolite, teriflunomide (formerly A77 1726). Trough blood concentrations of teriflunomide exceeding 40 microg/mL (148 micromol/L) are associated with progressive clearance of BKV. Toxic effects become increasingly apparent at higher concentrations. We have developed a rapid, simple, and robust high-performance liquid chromatography (HPLC) method for therapeutic monitoring of teriflunomide in renal transplant recipients. Sample preparation is rapid, and each HPLC separation takes about 7 minutes. Intraday and interday coefficients of variation were 1.5% or less and 5.6% or less, respectively. The method was linear to 200 microg/mL (740 micromol/L), which is well above teriflunomide concentrations that are likely to be observed.