The Experts below are selected from a list of 1245 Experts worldwide ranked by ideXlab platform
Susan Luong - One of the best experts on this subject based on the ideXlab platform.
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Detection and identification of 2-nitro-morphine and 2-nitro-morphine-6-glucuronide in nitrite adulterated urine specimens containing morphine and its glucuronides.
Drug testing and analysis, 2013Co-Authors: Susan LuongAbstract:In vitro urine adulteration is a well-documented practice adopted by individuals aiming to evade detection of drug use, when required to undergo mandatory sports and workplace drug testing. Potassium nitrite is an effective urine adulterant due to its oxidizing potential, and has been shown to mask the presence of many drugs of abuse. However, limited research has been conducted to understand its mechanism of action, and to explore the possibility of the drugs undergoing direct oxidation to form stable reaction products. In this study, opiates including morphine, codeine, morphine-3-glucuronide and morphine-6-glucuronide were exposed to potassium nitrite in water and urine to mimic the process of nitrite adulteration. It was found that two stable reaction products were detected by liquid chromatography-mass spectrometry (LC-MS) when morphine and morphine-6-glucuronide were exposed to nitrite. Isolation and elucidation using spectrometric and spectroscopic techniques revealed that they were 2-nitro-morphine and 2-nitro-morphine-6-glucuronide, respectively. These reaction products were also formed when an authentic morphine-positive urine specimen was fortified with nitrite. 2-Nitro-morphine was found to be stable enough to undergo the enzymatic hydrolysis procedure and also detectable by gas chromatography-mass spectrometry (GC-MS) after forming a Trimethylsilyl Derivative. On the contrary, morphine-3-glucuronide did not appear to be chemically manipulated when exposed to potassium nitrite in urine. These reaction products are not endogenously produced, are relatively stable and can be monitored with both LC-MS and GC-MS confirmatory techniques. As a result, these findings have revealed the possibility for the use of 2-nitro-morphine and 2-nitro-morphine-6-glucuronide as markers for the indirect monitoring of morphine and morphine-6-glucuronide in urine specimens adulterated with nitrite. Copyright © 2013 John Wiley & Sons, Ltd.
Thomas Daldrup - One of the best experts on this subject based on the ideXlab platform.
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gas chromatographic mass spectrometric determination of lysergic acid diethylamide lsd in serum samples
Forensic Science International, 1997Co-Authors: Frank Musshoff, Thomas DaldrupAbstract:Abstract A sensitive method for the detection and quantification of lysergic acid diethylamide (LSD) in serum samples is described. After liquid-liquid extraction the Trimethylsilyl Derivative of LSD is detected by gas chromatography — mass spectrometry. Experiments with spiked samples resulted in a recovery of 76%, the coefficient of variation was 9.3%. Excellent linearity was obtained over the range 0.1–10 ng ml −1 . Additionally experiments demonstrating the light sensitivity of LSD are presented together with casuistics.
K Torkos - One of the best experts on this subject based on the ideXlab platform.
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determination of phenols and chlorophenols as Trimethylsilyl Derivatives using gas chromatography mass spectrometry
Journal of Chromatography A, 2008Co-Authors: Agnes Kovacs, Aniko Kende, Maria Mortl, Gabor Volk, T Rikker, K TorkosAbstract:Abstract A rapid and simple method is described for the simultaneous determination of 6 phenols (phenol, o -, m -, p -cresol, catechol and resorcinol) and 19 chlorophenols (all mono-, di-, tri-, and tetrachlorophenol isomers and pentachlorophenol) present in aqueous samples. The method is based on derivatization with Trimethylsilyl- N , N -dimethylcarbamate (TMSDMC). In contrast to other derivatization agents, TMSDMC instantaneously reacts with the phenolic compounds at room temperature and no further sample processing is necessary prior to instrumental analysis. The determination of the Derivatives was performed by capillary gas chromatography–mass spectrometry (GC–MS). The stability of the most instable Trimethylsilyl Derivative (pentachlorophenol) was studied using different excess levels of the derivatization reagent. The derivatization method was tested on spiked water samples preconcentrated by solid phase extraction on Isolute ENV+ cartridge. The overall method gave detection limits of 0.01–0.25 μg/L for all compounds and
Frank Musshoff - One of the best experts on this subject based on the ideXlab platform.
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gas chromatographic mass spectrometric determination of lysergic acid diethylamide lsd in serum samples
Forensic Science International, 1997Co-Authors: Frank Musshoff, Thomas DaldrupAbstract:Abstract A sensitive method for the detection and quantification of lysergic acid diethylamide (LSD) in serum samples is described. After liquid-liquid extraction the Trimethylsilyl Derivative of LSD is detected by gas chromatography — mass spectrometry. Experiments with spiked samples resulted in a recovery of 76%, the coefficient of variation was 9.3%. Excellent linearity was obtained over the range 0.1–10 ng ml −1 . Additionally experiments demonstrating the light sensitivity of LSD are presented together with casuistics.
Agnes Kovacs - One of the best experts on this subject based on the ideXlab platform.
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determination of phenols and chlorophenols as Trimethylsilyl Derivatives using gas chromatography mass spectrometry
Journal of Chromatography A, 2008Co-Authors: Agnes Kovacs, Aniko Kende, Maria Mortl, Gabor Volk, T Rikker, K TorkosAbstract:Abstract A rapid and simple method is described for the simultaneous determination of 6 phenols (phenol, o -, m -, p -cresol, catechol and resorcinol) and 19 chlorophenols (all mono-, di-, tri-, and tetrachlorophenol isomers and pentachlorophenol) present in aqueous samples. The method is based on derivatization with Trimethylsilyl- N , N -dimethylcarbamate (TMSDMC). In contrast to other derivatization agents, TMSDMC instantaneously reacts with the phenolic compounds at room temperature and no further sample processing is necessary prior to instrumental analysis. The determination of the Derivatives was performed by capillary gas chromatography–mass spectrometry (GC–MS). The stability of the most instable Trimethylsilyl Derivative (pentachlorophenol) was studied using different excess levels of the derivatization reagent. The derivatization method was tested on spiked water samples preconcentrated by solid phase extraction on Isolute ENV+ cartridge. The overall method gave detection limits of 0.01–0.25 μg/L for all compounds and
