Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring.

1981 ◽  
Vol 27 (7) ◽  
pp. 1165-1170 ◽  
Author(s):  
E M Finlay ◽  
S J Gaskell
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
High Resolution ◽  
External Quality Assessment ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Internal Standards ◽  
Metastable Peak ◽  
Chromatography Mass Spectrometry

Abstract Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. [2H3]Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r = 0.997; y = 1.008x + 0.564 nmol/L).

scholarly journals Determination of dimethoxyphenethylamine derivatives in urine by deuterium labeled internal standards

2008 ◽  
Vol 73 (12) ◽  
pp. 1223-1233 ◽  
Author(s):  
Ya-Zhu Xu ◽  
Huei-Ru Lin ◽  
Ahai-Chang Lua ◽  
Chinpiao Chen
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Forensic Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Internal Standards ◽  
Chromatography Mass Spectrometry ◽  
Accuracy And Precision

The use of gas chromatography-mass spectrometry (GC-MS) in forensic analysis is increasing. To exploit fully the capabilities of MS, labeled standards, that can be used to improve the performance of the quantitative analysis, and to increase accuracy and precision, are required. A series of deuterated internal standards, corresponding to the 2C-series of phenethylamine derivatives, including 4-bromo-2,5-dimethoxyphenethylamine-d6 (2C-B), 4-chloro- 2,5-dimethoxyphenethylamine-d6 (2C-C), 4-iodo-2,5-dimethoxy-phenethylamine-d6 (2C-I), 4-ethylthio-2,5-dimethoxy-phenethylamine-d6 (2C-T-2) and 2,5-dimethoxy-4-n-propylthiophenethylamine-d6 (2C-T-7), were synthesized. These deuterated compounds were used to analyze for the corresponding unlabeled compounds in urine. The analysis was performed using GC-MS, with the selected ion monitoring (SIM) technique, whereby good results were achieved.

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.

Determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylethylene glycol, and 3,4-dihydroxyphenylmandelic acid in urine by mass fragmentography, with use of deuterium-labeled internal standards.

1978 ◽  
Vol 24 (11) ◽  
pp. 2001-2008 ◽  
Author(s):  
F A Muskiet ◽  
D C Fremouw-Ottevangers ◽  
G T Nagel ◽  
B G Wolthers ◽  
J A de Vries
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Mass Fragmentography ◽  
Decarboxylase Inhibitor ◽  
Purification Method ◽  
Internal Standards ◽  
Chromatography Mass Spectrometry ◽  
Catecholamine Metabolites

Abstract We report the determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylmandelic acid, and 3,4-dihydroxyphenylethylene glycol in urine, by use of gas chromatography/mass spectrometry in combination with a simple purification method and deuterium-labeled internal standards. Normal excretion values in terms of creatinine, expressed as a function of age, are given, together with results obtained for patients with neuroblastoma, pheochromocytoma, or parkinsonism treated with L-DOPA + peripheral decarboxylase inhibitor, and for a patient receiving dopamine. We were unable to identify 3, 4-dihydroxyphenyllactic acid in urine. The results obtained and their relation to other catecholamine metabolites and catecholamine-precursor metabolites in urine are discussed.

scholarly journals Determination of Mammalian Lignans in Biological Samples by Modified Gas Chromatography/Mass Spectrometry

2007 ◽  
Vol 90 (3) ◽  
pp. 641-646 ◽  
Author(s):  
Ajay Bommareddy ◽  
Bhanu L Arasada ◽  
Duane P Mathees ◽  
Chandradhar Dwivedi
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Serum Samples ◽  
Selected Ion Monitoring ◽  
Beneficial Effects ◽  
Chromatography Mass Spectrometry ◽  
Flaxseed Meal

Abstract Lignans in flaxseed have been part of the human diet for centuries. In 1955, the isolation and structure of the lignan derivative secoisolariciresinol diglucoside (SDG) was reported. The biological role of SDG and mammalian lignan metabolites enterodiol and enterolactone was initially reported 20 years later. Experimental evidences showed the beneficial effects of lignans on breast, colon, and thyroid cancer. A modified gas chromatography/mass spectrometry (GC/MS) assay was developed for lignans in serum and colon samples of rats fed flaxseed meal. The method developed for the analysis of metabolites involves extraction and derivatization of samples and quantitative analysis by selected ion monitoring using GC/MS. The levels of lignan metabolites enterodiol and enterolactone were determined to be 0.013 and 0.23 M in serum samples and 0.008 and 1.63 M in colon samples.

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