Abstract：
There has been increased interest in dissolved gallium (Ga) in natural waters due to its long residence time and its usefulness in tracking water masses; however, current analytical approaches are time consuming and labor intensive (e.g., magnesium hydroxide co-precipitation method, (Mg(OH)2)) or have concerns such as carryover and sample recovery (automated resin column extraction). Ocean observing programs, such as GEOTRACES, recover hundreds of samples per expedition. There are both logistical (sample volume) and analytical (person-hour) demands to economically collect and analyze Ga. We present an automated isotope dilution method (using 99.8% enriched 71Ga) to determine Ga in seawater utilizing commercially available equipment while addressing the challenges of a) sample volume and sample pre-concentration factor, b) instrumental interferences, c) sample-sample carryover, d) sample recovery variability, and e) improving sample detection limits, accuracy and precision. A seaFAST SC-4DXS pico (Elemental Scientific, Inc.; ESI) was used to pre-concentrate 20 mL of sample on a Nobias PA1 resin column 67-fold before analysis in medium resolution on a ThermoFisher high-resolution inductively-coupled plasma mass spectrometer (HR-ICP-MS) equipped with an APEX Q FAST enabled spray chamber (ESI) to increase signal intensity and decrease instrument interferences. The new automated seaFAST method reproduced Ga concentrations determined by the Mg(OH)2 method, but with greater precision (RSD <4%) and a lower detection limit (0.10 pmol L-1). This method is ideal for high throughput applications and can be easily implemented using commercially available equipment.
摘要：
由于其停留时间长及其在跟踪水团方面的有用性，对天然水中溶解镓（Ga）的兴趣日益增加；但是，当前的分析方法耗时耗力(例如，氢氧化镁共沉淀法,（Mg（OH）2）或具有诸如结转和样品回收（自动树脂柱提取）之类的问题。海洋观测计划，如GEOTRACES，每次探险回收数百个样本。经济地收集和分析Ga有后勤(样品体积)和分析(人-小时)需求。我们提出了一种自动同位素稀释方法（使用99.8％的富集71Ga），利用市售设备确定海水中的Ga，同时解决了a）样品体积和样品预浓缩因子的挑战，b)仪器干扰，c)样品-样品结转,d)样品回收率变异性，e)提高样品检测限，准确度和精度。一个seaFASTSC-4DXSpico(元素科学，Inc.;ESI）用于在NobiasPA1树脂柱上预浓缩20mL样品67倍，然后在配备有APEXQFAST功能喷雾室（ESI）的ThermoFisher高分辨率电感耦合等离子体质谱仪（HR-ICP-MS）上以中等分辨率进行分析，以增加信号强度并减少仪器干扰。新的自动化seeFAST方法再现了Mg（OH）2方法确定的Ga浓度，但具有更高的精密度(RSD<4%)和更低的检出限(0.10pmolL-1)。该方法对于高通量应用是理想的,并且可以使用市售设备容易地实施。
