scholarly journals A simplified approach for determination of urinary ethyl glucuronide by gas chromatography–mass spectrometry

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shayani Ghosh ◽  
Raka Jain ◽  
Satpal Singh ◽  
Ravindra Rao ◽  
Ashwani Kumar Mishra ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Human Urine ◽  
Impact Ionization ◽  
Limit Of Detection ◽  
Extraction Procedure ◽  
Ethyl Glucuronide ◽  
Gas Chromatography Mass Spectrometry ◽  
Limit Of Quantification ◽  
Chromatography Mass Spectrometry

AbstractUrinary ethyl glucuronide (EtG), an alcohol biomarker, plays an essential role in monitoring alcohol abstinence and relapse during treatment for alcohol dependence. Detection of this biomarker has become a routine in many clinical and forensic laboratories over the last few years. Most previously published methods commonly use hyphenated chromatographic techniques along with extensive extraction procedure before analysis. This work aimed to develop and validate an electron impact ionization mode gas chromatography–mass spectrometry method to measure ethyl glucuronide levels in human urine. For its determination, urine samples were dried under a gentle stream of nitrogen, derivatized with N,O-bis(trimethylsilyl) trifluoroacetamide, incubated, and injected into the instrument. The analysis was performed using single quadrupole gas chromatography–mass spectrometry (GC-MS) technology and validation was performed according to the guidelines of the German Society of Toxicology and Forensic Chemistry (GTFCh). The linearity of urinary EtG was obtained in the range of 30–5000 ng/ml with a correlation coefficient (r) above 0.999. The extraction recoveries exceeded 80%, and the obtained inter-day and intra-day precisions were below 15%. The achieved limit of detection was 10 ng/ml and limit of quantification achieved was 30 ng/ml. The electron ionization gas chromatography–mass spectrometry technique proves to be a feasible option for determining EtG in human urine when other sophisticated techniques are unapproachable. This method provides a good sensitivity and proves to be cost-effective, robust, and advantageous for both clinical as well as forensic settings.

scholarly journals Determination of Phytosterols in vegetable oils by GC-MS method

2020 ◽  
Vol 3 (4) ◽  
pp. 36-42
Author(s):  
Hien Dang Thu ◽  
Ngoc Anh Mai Thi ◽  
Hong Ngoc Nguyen Thi ◽  
◽  
◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Vegetable Oils ◽  
Limit Of Detection ◽  
Alkaline Media ◽  
Gas Chromatography Mass Spectrometry ◽  
Limit Of Quantification ◽  
Chromatography Mass Spectrometry ◽  
Trimethylsilyl Ethers

In this study, a method for determination of six phytosterols by gas chromatography-mass spectrometry with derivatization in vegetable oils was validated. The samples were hydrolyzed in an alkaline media at 70°C for 60 min. Then, the samples were performed liquid-liquid extraction with toluene. The phytosterols are derivatized to trimethylsilyl ethers and then analyzed by gas chromatography-mass spectrometry. The limit of detection and limit of quantification was 5 and 15 mg/kg, respectively. Recoveries of six phytosterols were between 93.5% and 101%.

scholarly journals Determination of Morphine and Codeine in Human Urine by Gas Chromatography-Mass Spectrometry

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Xiaoqian Zhang ◽  
Mengchun Chen ◽  
Gaozhong Cao ◽  
Guoxin Hu
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Human Urine ◽  
Forensic Identification ◽  
Gas Chromatography Mass Spectrometry ◽  
Linear Calibration ◽  
Selected Ion Monitoring ◽  
Limit Of Quantification ◽  
Chromatography Mass Spectrometry

A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the determination of morphine and codeine in human urine. The GC-MS conditions were developed. The analysis was carried out on a HP-1MS column (30 m × 0.25 mm, 0.25 μm) with temperature programming, and Helium was used as the carrier gas with a flow rate of 1.0 mL/min. Selected ion monitoring (SIM) mode was used to quantify morphine and codeine. The derivation solvent, temperature, and time were optimized. A mixed solvent of propionic anhydride and pyridine (5 : 2) was finally used for the derivation at 80°C for 3 min. Linear calibration curves were obtained in the concentration range of 25–2000.0 ng/mL, with a lower limit of quantification of 25 ng/mL. The intra- and interday precision (RSD) values were below 13%, and the accuracy was in the range 87.2–108.5%. This developed method was successfully used for the determination of morphine and codeine in human urine for forensic identification study.

Steroids in equine testes: the identification of endogenous 19-hydroxy and 19-nor neutral steroids by gas chromatography–mass spectrometry

1989 ◽  
Vol 120 (2) ◽  
pp. 223-229 ◽  
Author(s):  
M. C. Dumasia ◽  
E. Houghton ◽  
M. Jackiw
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Aldol Reaction ◽  
Extraction Procedure ◽  
Testicular Tissue ◽  
Enzyme Hydrolysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry ◽  
Trimethylsilyl Ethers ◽  
Conjugated Steroids

ABSTRACT After homogenization of testicular tissue from stallions aged 1, 2 and 5 years, the unconjugated and conjugated steroids were isolated by a combined solvent–solid extraction procedure. The conjugates were further separated into glucuronides and sulphates by chromatography using Sephadex LH-20. After enzyme hydrolysis and solvolysis of the respective conjugate classes, the three extracts, unconjugated steroids, aglycones and solvolysed sulphates, were purified by chromatography using Kieselgel 60H columns. Five fractions were resolved from each extract; an aliquot of each fraction was derivatized to form the methoxime-trimethylsilyl ethers and the steroids were identified by combined gas chromatography–mass spectrometry. The results have shown that in stallion testes (1) steroidogenesis proceeds by both the 4-ene and the 5-ene pathways, (2) age-linked changes occur in both unconjugated and sulphoconjugated steroid fractions and (3) 19-hydroxy androgens and the 19-nor (C18) neutral steroids (19-norandrostenedione and 19-nortestosterone) are detected only in the unconjugated fraction whereas oestrone, the isomers of oestradiol and of 5(10)-oestrene-3,17-diol are the only steroids detected in the sulphoconjugate fraction. It is suggested that the unconjugated 19-oxygenated androgens present in stallion testes are converted to 19-nor neutral steroids by a reverse aldol reaction and a mechanism showing the putative intermediates in their formation is illustrated. Journal of Endocrinology (1989) 120, 223–229

Simultaneous Determination of Alachlor, Metolachlor, Atrazine, and Simazine in Water and Soil by Isotope Dilution Gas Chromatography/Mass Spectrometry

1989 ◽  
Vol 72 (2) ◽  
pp. 349-354 ◽  
Author(s):  
Lee Q Huang
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Simultaneous Determination ◽  
Isotope Dilution ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Chromatography Mass Spectrometry

Abstract A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of 15N,13C-alachlor and 2H5-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.

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