scholarly journals Methylmalonic acid quantification by stable isotope dilution gas chromatography-mass spectrometry from filter paper urine samples

1996 ◽  
Vol 42 (6) ◽  
pp. 910-914 ◽  
Author(s):  
M T McCann ◽  
M M Thompson ◽  
I C Gueron ◽  
B Lemieux ◽  
R Giguère ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Stable Isotope ◽  
Isotope Dilution ◽  
Filter Paper ◽  
Methylmalonic Acid ◽  
Urine Samples ◽  
Gas Chromatography Mass Spectrometry ◽  
Urinary Creatinine ◽  
Stable Isotope Dilution

Abstract A specific method for quantification of methylmalonic acid (MMA) from urine samples dried onto filter paper is described. The method involves stable isotope dilution gas chromatography-mass spectrometry with [methyl-2H3]-MMA as the internal standard. MMA is stable in dry paper samples stored at room temperature for at least 2 weeks. The extraction efficiency of MMA from paper was 56-58%. The concentration of urinary MMA in dried filter paper specimens from 190 normal controls was 1.21 +/- 1.34 (mean +/- SD) mmol/mol of urinary creatinine. Age-related reference values are also reported. The concentrations, normalized to the urinary creatinine concentration, decrease with age. The applicability of this method to rapid screening for cobalamin (vitamin B12)-related disorders and methylmalonic aciduria is demonstrated.

Determination of lead in urine and whole blood by stable isotope dilution gas chromatography-mass spectrometry

1994 ◽  
Vol 40 (8) ◽  
pp. 1494-1502 ◽  
Author(s):  
S K Aggarwal ◽  
M Kinter ◽  
D A Herold
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Stable Isotope ◽  
Memory Effect ◽  
Isotope Dilution ◽  
Whole Blood ◽  
Gas Chromatography Mass Spectrometry ◽  
Pb Isotope ◽  
Stable Isotope Dilution

Abstract A stable isotope dilution gas chromatography-mass spectrometry (GC-MS) method is described for the determination of lead (Pb) in urine and whole blood. The use of lithium bis(trifluoroethyl)dithiocarbamate Pb(FDEDTC) as a chelating agent showed strong memory effect, restricting the range of Pb isotope ratios that can be measured in unknown samples. To overcome this carryover problem, we further derivatized the Pb(FDEDTC)2 chelate with 4-fluorophenyl magnesium bromide to form Pb(FC6H4)4. The sequential analyses of solutions of natural Pb and enriched 204Pb with Pb(FC6H4)4 chelate by GC-MS demonstrated no observable memory effect. Precision and accuracy of Pb isotope ratio measurements with Pb(FC6H4)4 were established, and the isotope dilution GC-MS method was validated by determining Pb concentrations in urine standards from the National Institute of Standards and Technology, urine and blood reference materials from the New York State Department of Health, and blood Pb survey samples from the College of American Pathologists.

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