Arsenic can be easily found in our surrounding environment. Because of its ubiquitous nature, horse urine and blood invariably contain low levels of arsenic. Nevertheless, inorganic arsenic, despite its general use as a tonic for horses, is an effective doping agent having a deleterious effect because of its ability to induce gastroenteritis. The misuse of arsenic in horseracing has been controlled by an international urinary threshold of total arsenic at 0.3 μg/mL. However, an equivalent threshold for total arsenic in plasma is yet to be established. In this study, an inductively coupled plasma‐mass spectrometry method has been developed for quantifying total arsenic in equine plasma. Statistical analysis determined that the data from a population study of 1,552 post‐race and out‐of‐competition plasma samples fits a Gaussian mixture model with two Gaussian components. A rounded‐up provisional threshold for plasma total arsenic at 2.5 ng/mL was subsequently established. Results from administration trials with a sodium arsanilate‐containing supplement showed that both urinary and plasma arsenic was significantly elevated after administration. The maximum urinary detection time was around 22 h based on the international threshold. However, the maximum plasma detection time would be longer than 73 h if the provisional threshold of 2.5 ng/mL was adopted. In view of the high discrepancy between the urine and plasma detection times, a revised plasma threshold of 15 ng/mL is proposed to afford a comparable detection time in both matrices. The risk of a normal sample exceeding the proposed plasma total arsenic threshold is practically zero.

中文翻译：

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马血浆中总砷的兴奋剂控制分析。

在我们周围的环境中很容易找到砷。由于其无处不在的性质，马尿和血液总是含有低水平的砷。然而，尽管无机砷通常用作马的滋补品，但由于它能够诱发肠胃炎，因此它是一种具有有害作用的有效掺杂剂。赛马中砷的滥用已受到国际尿总砷阈值 0.3 μg/mL 的控制。然而，血浆中总砷的等效阈值尚未建立。在这项研究中，开发了一种电感耦合等离子体质谱法，用于量化马血浆中的总砷。统计分析确定，来自人口研究的数据为 1，552 个赛后和赛外血浆样本符合具有两个高斯分量的高斯混合模型。随后建立了一个四舍五入的血浆总砷临时阈值 2.5 ng/mL。含砷化钠补充剂的给药试验结果表明，给药后尿砷和血浆砷均显着升高。根据国际阈值，最大尿液检测时间约为 22 小时。然而，如果采用 2.5 ng/mL 的临时阈值，最大血浆检测时间将超过 73 小时。鉴于尿液和血浆检测时间之间的巨大差异，建议将血浆阈值修改为 15 ng/mL，以在两种基质中提供可比的检测时间。