Analysis of total thiol concentrations in environmental samples using ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS)
Analysis of total thiol concentrations in environmental samples using ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS)
复制标题
DOI：
10.1016/j.chemgeo.2023.121837
复制
发表时间：
2023-11-30
期刊：
影响因子：
3.9
通讯作者：
Fein，Jeremy B.
中科院分区：
文献类型：
--
作者：
Yu，Qiang;Fein，Jeremy B.
在这项研究中，我们开发了一种超高效液相色谱-质谱法（UHPLC-MS）的方法来测量总的反应性硫醇结合位点的浓度在一系列类型的环境样品中，通过监测减少一溴-（三甲基铵基）-bimane（qBBr）引起的硫醇qBBr结合反应。我们首先检查了qBBr的稳定性和可能降低UHPLC-MS方法准确性的潜在副反应。我们发现，由于qBBr降解和其他副反应，如氯溴取代反应，在水溶液中不存在硫醇的情况下，2-4 h后qBBr发生显著损失。为了解决这些问题，在我们的方法中，我们在过量qBBr的存在下进行巯基-qBBr结合反应仅1小时，并且我们将无巯基qBBr标准品中未结合qBBr的MS信号与含巯基qBBr标准品中未结合qBBr的MS信号进行比较，以计算由巯基-qBBr结合引起的溶液中游离qBBr浓度的降低。使用100-600 nM N-乙酰-L-半胱氨酸（ACYS）作为2 μM qBBr标准品中的模型硫醇，我们发现未结合qBBr的MS信号的测量降低与添加ACYS的浓度线性相关，R2为0.988，表明监测未结合qBBr的降低可用于计算样品中总硫醇位点的浓度。我们证明了新的UHPLC-MS方法在测量200-500 nM范围内的一系列单一和混合硫醇标准品时产生准确的结果，测量值范围为已知硫醇浓度的86%至109%。除了上述控制测试外，我们还使用UHPLC-MS方法测量了几个湖水样品中溶解的硫醇浓度。这些测量结果表明，每个湖泊含有低μM水平的总硫醇，不仅证明了分析方法确定天然沃茨中硫醇位点浓度的能力，而且还表明这些位点在控制这些系统中亲硫元素行为方面的广泛重要性。UHPLC-MS方法不仅可用于测定nM水平的溶解巯基位点的浓度，还可用于测量其他环境样品（如土壤、沉积物和固相有机物表面）上巯基结合位点的浓度。
In this study, we developed an ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) approach to measure the concentration of total reactive thiol binding sites in a range of types of environmental samples by monitoring the decrease of monobromo-(trimethylammonio)-bimane (qBBr) caused by thiol-qBBr binding reactions. We first examined the stability of qBBr and potential side reactions that could reduce the accuracy of the UHPLC-MS approach. We found that significant loss of qBBr occurs in the absence of thiols in aqueous solutions after 2–4 h due to qBBr degradation and other side reactions, such as a chloride-for-bromide substitution reaction. To address these issues, in our approach we conduct the thiol-qBBr binding reaction in the presence of excessive qBBr for only 1 h, and we compare the MS signal of unbound qBBr in a thiol-free qBBr standard with that in a thiol-bearing qBBr standard in order to calculate the decrease in the concentration of free qBBr in solution that is caused by thiol-qBBr binding. Using 100–600 nM of N-Acetyl-L-cysteine (ACYS) as a model thiol in a 2 μM qBBr standard, we found that the measured decrease in the MS signal of unbound qBBr linearly correlates to the concentration of added ACYS, with a R2of 0.988, demonstrating that monitoring the decrease in unbound qBBr can be used to calculate the concentration of total thiol sites in a sample. We demonstrate that the new UHPLC-MS approach yields accurate results when measuring a series of single and mixed thiol standards in the 200–500 nM range, with measured values ranging from 86% to 109% of the known concentration of thiols. In addition to the above control tests, we also used the UHPLC-MS approach to measure dissolved thiol concentrations in several lake water samples. These measurements revealed that each lake contained low μM levels of total thiols, not only demonstrating the ability of the analytical approach to determine thiol site concentrations in natural waters, but also suggesting the widespread importance of these sites in controlling chalcophile element behavior in these systems. The UHPLC-MS approach not only can be used to determine the concentration of dissolved thiol sites at nM levels, but can also be adapted to measure the concentration of thiol binding sites on other environmental samples such as soil, sediment, and solid-phase organic matter surfaces.