Environmental Health Laboratory Branch, California Department of Public Health, Richmond, California 94804, USA.
J Environ Sci Health B. 2013;48(3):177-82. doi: 10.1080/03601234.2013.730021.
Urinary dialkyl phosphate metabolites (DAPs) are used as biomarkers to evaluate human exposure to organophosphate pesticides. The objective was to evaluate potential artifacts in urinary DAPs analysis during sample preparation and method calibration. Diluted urine pools were commonly used to prepare calibration standards to minimize the effects due to the complexity of urine matrix. Matrix effects on measurements of DAPs were evaluated by spiking known amount of standards into distilled water, synthetic urine and diluted urine pool. Different matrices resulted in similar concentrations detected for all target compounds, except dimethylphosphate (DMP) with the deviation of measurement as large as eight times the spiked amount. In this study, we also found that urinary particles, which usually appeared after thawing frozen human urine samples, could affect the measurements of DAPs, especially DMP and diethylthiophosphate (DETP). Results of DAPs measurements in three types of sample matrices, i.e. urine without particles, urine with particles and particles only were compared. DETP could be subject to large error during this preparation step. The use of deuterated and (13)C(12)-labeled DAPs as internal standards is also evaluated. Overall, these issues can cause misidentification and inaccuracies, which may significantly affect the data quality.
尿中二烷基磷酸酯代谢物（DAPs）被用作评估人体接触有机磷农药的生物标志物。本研究旨在评估在样品制备和方法校准过程中尿中二烷基磷酸酯分析中潜在的人为因素。为了最小化尿液基质复杂性对校准标准的影响，通常使用稀释尿池来制备校准标准。通过将已知量的标准品加入去离子水、合成尿和稀释尿池中，评估了基质效应对 DAPs 测量的影响。不同基质对所有目标化合物的检测浓度相似，但二甲基磷酸酯（DMP）除外，其测量偏差高达标准品加入量的 8 倍。在这项研究中，我们还发现，冷冻人尿样解冻后通常会出现尿颗粒，这可能会影响 DAPs 的测量，特别是 DMP 和二乙基硫代磷酸酯（DETP）的测量。比较了三种样品基质（无颗粒尿、有颗粒尿和仅颗粒）中 DAPs 的测量结果。在这个制备步骤中，DETP 可能会产生较大的误差。还评估了氘代和（13）C（12）标记的 DAPs 作为内标物的使用。总的来说，这些问题可能会导致错误识别和不准确，从而显著影响数据质量。
