Pyon K H, Kracko D A, Strunk M R, Bechtold W E, Dahl A R, Lewis J L
Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87185, USA.
J Anal Toxicol. 1997 Sep;21(5):363-8. doi: 10.1093/jat/21.5.363.
A gas chromatography-mass spectrometry (GC-MS) method using isotope dilution was developed to measure trace levels of xylene metabolites in brain tissues. The primary metabolites of xylene are dimethylphenol (DMP), methylbenzyl alcohol (MBA), toluic acid (TA), and methylhippuric acid (MHA). The internal standard was a mixture of deuterated DMP-d3, TA-d7, and MHA-d7. DMP-d3 was commercially available and was used as the internal standard for both DMP and MBA. TA-d7 and MHA-d7 were biosynthesized by administering xylene-d10 to rats and collecting their urine. Based on the noise peaks in 10 blank samples, the on-column limits of quantitation (mean +10 SD of noise peaks) were approximately 305, 1220, 545, and 386 pg for DMP, MBA, TA, and MHA, respectively. Analyte detection and recovery tests from brain tissues of control rats were conducted by spiking the tissues with 32 nmol/g of each analyte, together with the deuterated metabolites. The tissues were homogenized, extracted with ethyl acetate, and derivatized by trimethylsilylation. One microliter of the sample was injected into the GC-MS. The recoveries of the analytes were 104 +/- 8%, 80 +/- 9%, 93 +/- 10%, and 92 +/- 11% (mean +/- SD, n = 7) for DMP, MBA, TA, and MHA, respectively. The tissue preparation efficiency, which was indicated by absolute recoveries of internal standards, was approximately 33% for DMP, MBA, and TA and approximately 80% for MHA. No metabolites were detected in untreated control tissues. This simple and sensitive method to simultaneously detect major xylene metabolites in brain tissues could also be used for the analysis of blood and urine samples from workers to monitor p-xylene exposure.
建立了一种采用同位素稀释的气相色谱 - 质谱联用（GC - MS）方法来测定脑组织中痕量水平的二甲苯代谢物。二甲苯的主要代谢物是二甲基苯酚（DMP）、甲基苄醇（MBA）、甲苯酸（TA）和甲基马尿酸（MHA）。内标物是氘代DMP - d3、TA - d7和MHA - d7的混合物。DMP - d3有商业产品，用作DMP和MBA的内标物。TA - d7和MHA - d7通过给大鼠施用氘代二甲苯（xylene - d10）并收集其尿液进行生物合成。基于10个空白样品中的噪声峰，DMP、MBA、TA和MHA的柱上定量限（噪声峰的平均值 + 10倍标准差）分别约为305、1220、545和386 pg。通过向对照大鼠的脑组织中加入每种分析物32 nmol/g以及氘代代谢物进行分析物检测和回收率测试。将组织匀浆，用乙酸乙酯萃取，然后通过三甲基硅烷化进行衍生化。将1微升样品注入GC - MS。DMP、MBA、TA和MHA的分析物回收率分别为104±8%、80±9%、93±10%和92±11%（平均值±标准差，n = 7）。以内标物的绝对回收率表示的组织制备效率，DMP、MBA和TA约为33%，MHA约为80%。在未处理的对照组织中未检测到代谢物。这种用于同时检测脑组织中主要二甲苯代谢物的简单灵敏方法也可用于分析工人的血液和尿液样本以监测对二甲苯暴露情况。
