Determination of S-phenylmercapturic acid by GC-MS and ELISA: a comparison of the two methods.
S-phenylmercapturic acid (PMA) is a specific urinary biomarker of benzene at exposure levels lower than 1 ppm. However, measuring PMA in urine is an expensive task by either GC or HPLC due to the necessity of extensive sample pretreatment. In the present study, a commercial chemiluminescence enzyme-linked immunosorbent assay (ELISA) test for PMA and GC-MS were used for screening urine samples of 60 workers employed in petrochemical settings. The ELISA results were evaluated by comparison with the GC-MS. Overall, the ELISA test proved sensitive (limit of detection=0.1 microg l(-1)), rapid, robust and reliable, affording results in good agreement with the GC-MS (54% of measurements) and no false-negatives. On the other hand, 46% of the ELISA assays were assigned as false-positives (arbitrarily established when ELISA >5 microg l(-1), GC-MS <5 microg l(-1) and a correlation coefficient of 0.687 was calculated between the two methods. It appears that urinary PMA routine biomonitoring on large numbers of samples is carried out in a cost-effective and rapid approach by preliminary screening with the ELISA assay followed by GC-MS confirmation of concentrations exceeding the biological exposure index for PMA.
Marrubini
G
G
Department of Pharmaceutical Chemistry, University of Pavia, Pavia, Italy. giorgio.marrubini@unipv.it
Dugheri
S
S
Pacenti
M
M
Coccini
T
T
Arcangeli
G
G
Cupelli
V
V
Manzo
L
L
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine; D001554:Benzene / Q000633:toxicity*; D015415:Biomarkers / Q000652:urine*; D002138:Calibration; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005188:False Negative Reactions; D005189:False Positive Reactions; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis*; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; C053003:S-phenyl-N-acetylcysteine; D001554:Benzene; D000111:Acetylcysteine