Using labelled internal standards to improve needle trap micro-extraction technique prior to gas chromatography/mass spectrometry

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.

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Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography-mass spectrometry

Journal of Separation Science ◽

10.1002/jssc.201600561 ◽

2016 ◽

Vol 40 (3) ◽

pp. 753-766 ◽

Cited By ~ 3

Author(s):

Xiaobing Pang ◽

Alastair C. Lewis ◽

Marvin D. Shaw

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Carbonyl Compounds ◽

Stir Bar Sorptive Extraction ◽

Extraction Technique ◽

Gas Chromatography Mass Spectrometry ◽

Chemical Derivatization ◽

Sorptive Extraction ◽

Chromatography Mass Spectrometry

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Rapid Analysis of Metanephrine and Normetanephrine in Urine by Gas Chromatography-Mass Spectrometry

Clinical Chemistry ◽

10.1093/clinchem/48.2.332 ◽

2002 ◽

Vol 48 (2) ◽

pp. 332-337 ◽

Cited By ~ 18

Author(s):

David K Crockett ◽

Elizabeth L Frank ◽

William L Roberts

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Solid Phase ◽

Correlation Coefficients ◽

Hplc Method ◽

Gas Chromatography Mass Spectrometry ◽

Internal Standards ◽

Rapid Decomposition ◽

Chromatography Mass Spectrometry ◽

Deming Regression

Abstract Background: Widely used HPLC methods for quantification of metanephrine and normetanephrine in urine often have long analysis times and are frequently plagued by drug interferences. We describe a gas chromatography-mass spectrometry method designed to overcome these limitations. Methods: Metanephrine and normetanephrine conjugates were converted to unconjugated metanephrine and normetanephrine by acid hydrolysis. To avoid the rapid decomposition of the deuterated internal standards (metanephrine-d3 and normetanephrine-d3) under hydrolysis conditions, the internal standards were added after hydrolysis. Solid-phase extraction was used to isolate the hydrolyzed metanephrines from urine. Samples were concentrated by evaporation, then derivatized simultaneously with N-methyl-N-(trimethylsilyl)trifluoroacetamide and N-methyl-bis-heptafluoro-butryamide at room temperature. Results: The assay was linear from 25 to 7000 μg/L. The intraassay CVs were <5% and the interassay CVs <12%. Comparison with a routine HPLC method (n = 192) by Deming regression yielded a slope of 1.00 ± 0.02 μg/L, an intercept of −5.8 ± 7.8 μg/L, and Sy|x = 50.6 μg/L for metanephrine and a slope of 0.94 ± 0.03, intercept of 19 ± 11 μg/L, and Sy|x = 60 μg/L for normetanephrine. The correlation coefficients (r) were calculated after log transformation of the data and gave r = 0.97 for metanephrine and r = 0.97 for normetanephrine. Interference from common medications or drug metabolites was seen in <1% of samples. The time between sequential injections was <7 min. Conclusions: This new gas chromatography-mass spectrometry assay for total fractionated metanephrines is rapid, compares well with a standard HPLC assay, and avoids most drug interferences that commonly affect HPLC assays for urine metanephrines.

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