Pysanenko Andriy, Wang Tianshu, Spanel Patrik, Smith David
Institute for Science and Technology in Medicine, School of Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB, UK.
Rapid Commun Mass Spectrom. 2009 Apr;23(8):1097-104. doi: 10.1002/rcm.3963.
Urine is commonly analysed in clinical practice by a variety of liquid-phase techniques to check for excessive ketone bodies, proteins and salts to name just a few compounds. However, little work has been carried out to measure the volatile compounds emitted by urine since these do not yet have an established role in clinical diagnosis. There is, however, a growing body of evidence that these volatile compounds can be indicators of adverse physiological conditions and disease and with the advent of sensitive gas-phase analytical methods they can be quickly quantified in urine headspace and potentially provide valuable support for clinical diagnosis. Thus, we are developing selected ion flow tube mass spectrometry, SIFT-MS, for the real-time analysis of urine headspace, ultimately to support rapid diagnosis in the clinical environment. In this paper we focus on volatile ketones in the headspace of aqueous solutions and urine donated by three healthy volunteers. Using SIFT-MS, we have unambiguously quantified in urine headspace acetone, by far the most abundant ketone, butanone, pentanone, hexanone and heptanone using NO(+) precursor ions. Further to this, we have determined the Henry's Law coefficients, HLC, for these ketones in aqueous solution to allow the liquid-phase concentrations in urine to be estimated from headspace levels of their vapours. In addition, the influence of the addition of physiological amounts of dissolved urea, sodium chloride and hydrochloric acid on the partitioning of these ketones between the aqueous phase and gas phase has been investigated and found to be small, which gives greater credence to the use of the HLC obtained using aqueous solutions for the estimation of ketone concentrations in urine. Finally, parallel measurements of the levels of acetone in exhaled breath and urine headspace have been obtained and shown to be very similar, which gives support to the previous deduction from breath analysis that acetone is a truly systemic compound.
在临床实践中，尿液通常通过各种液相技术进行分析，以检测过量的酮体、蛋白质和盐等多种化合物。然而，由于挥发性化合物在临床诊断中尚未确立其作用，因此对尿液中释放的挥发性化合物进行测量的工作开展得很少。然而，越来越多的证据表明，这些挥发性化合物可能是不良生理状况和疾病的指标，随着灵敏的气相分析方法的出现，它们可以在尿液顶空中快速定量，有可能为临床诊断提供有价值的支持。因此，我们正在开发选择离子流管质谱法（SIFT-MS）用于尿液顶空的实时分析，最终为临床环境中的快速诊断提供支持。在本文中，我们重点研究了三名健康志愿者捐赠的水溶液和尿液顶空中的挥发性酮类。使用SIFT-MS，我们已经明确地对尿液顶空中的丙酮进行了定量，丙酮是迄今为止含量最丰富的酮类，此外还对丁酮、戊酮、己酮和庚酮进行了定量，使用的是NO(+)前体离子。除此之外，我们还测定了这些酮类在水溶液中的亨利定律系数（HLC），以便根据其蒸汽的顶空水平估算尿液中的液相浓度。此外，还研究了添加生理量的溶解尿素、氯化钠和盐酸对这些酮类在水相和气相之间分配的影响，发现影响很小，这使得使用通过水溶液获得的HLC来估算尿液中的酮类浓度更具可信度。最后，我们对呼出气体和尿液顶空中丙酮的水平进行了平行测量，结果显示非常相似，这支持了之前通过呼气分析得出的推断，即丙酮是一种真正的全身性化合物。
