3-Hydroxypropyl Mercapturic Acid Interlaboratory Method Standardization to Measure Acrolein Exposure in Human Urine

Abstract

PP-29-059 Background/Aims: An interlaboratory comparison was set up to measure the consistency of analysis of 3-HPMA (3-hydroxypropyl mercapturic acid), a biomarker of acrolein exposure, across 4 participating laboratories using LC-MS/MS. In the first phase, measurement differences between the laboratories were observed, and it was concluded that further method of standardization was required. A number of potential sources of variance, including differences in calibration standards used, were identified. Methods: Following a review of the 3-HPMA methods used by each laboratory, a second interlaboratory comparison study was initiated incorporating a common internal standard in the operating protocol (3-HPMA-13C3-15N). The objective of the new study was to validate 3-HPMA measurement capability by LC-MS/MS between the same 4 laboratories, using identical sets of samples and the same internal standard. Results: The results from this second interlaboratory study demonstrate that the use of a common internal standard improved the reproducibility of 3-HPMA quantification by lowering the average interlaboratory coefficient of variation (CoV) from >20% to 13%. This compares favorably with World Health Organization standardized clinical methods, which typically report average interlaboratory CoV above 10% (1–2). As expected, the repeatability of the quantification was not adversely affected by the new internal standard, given that no other changes were made to the overall procedures within the individual laboratories. Conclusion: In conclusion, the results from this new study demonstrate that the use of a common internal standard improved the interlaboratory reproducibility of 3-HPMA quantification between participating laboratories.