Abstract

The optimum chromatographic separation conditions, polyatomic ions interference correction, and extraction parameters were investigated for simultaneous extraction and quantification of As(III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), As(V) and Cr(VI) with excellent resolution. The ammonium salts (NH₄H₂PO₄ and NH₄NO₃) were examined as mobile phases at different pH values by altering the composition during the chromatographic run in gradient elution mode using high-performance liquid chromatography – inductively coupled plasma – mass spectrometry (HPLC-ICP-MS). The 10 mM and 70 mM NH₄NO₃ composition at pH 8.7 enabled sufficient baseline separation of the target As and Cr species at a total run time of 18 minutes. The identified polyatomic ion interferences were corrected by an inter-element method using mathematical equations. The optimum extraction conditions containing a mixture of 0.375 M (NH₄)₂HPO₄ and 50 mM EDTA at neutral pH as an extraction buffer, extraction temperature of 150 °C and volume of 15 mL were attained by a factorial design technique. The lowest concentrations of the selected elemental species that can be reliably detected by the procedure were in the range from 0.064 to 0.682 ng g⁻¹. The accuracy of the developed procedure was demonstrated by achieving percentage recoveries of 96.8% for As(V) and 97.7% for Cr(VI) using San Joaquin Soil standard reference material 2709a. Proposed method was validated by achieving percentage recoveries from 84.9 to 104% for As species and Cr(VI) using spiking and recovery studies at 3x and 25x the limit of quantification values of the target species. The selected As and Cr species in real sediment were monitored using the optimized analytical method. The differences in concentrations of Cr(VI), As(III), MMA and As(V) between the seasonal state of the river were statistically significant (p ˂0.05) at a 95% confidence level as determined by analysis of variance (ANOVA).

摘要

研究了最佳的色谱分离条件，多原子离子干扰校正和萃取参数，用于同时萃取和定量分析As（III），二甲基ar酸（DMA），一甲基ar酸（MMA），As（V）和Cr（VI）。解析度。通过使用高效液相色谱–电感耦合等离子体–质谱法在梯度洗脱模式下改变色谱运行过程中的组成，检查了铵盐（NH ₄ H ₂ PO ₄和NH ₄ NO ₃）在不同pH值下作为流动相的情况。（HPLC-ICP-MS）。10 mM和70 mM NH ₄ NO ₃pH 8.7的高浓度组合物能够在18分钟的总运行时间内实现目标As和Cr物质的足够基线分离。使用数学方程式，通过元素间方法校正识别出的多原子离子干扰。通过析因设计技术，获得了最佳萃取条件，该萃取条件为在中性pH下包含0.375 M（NH ₄）₂ HPO ₄和50 mM EDTA的混合物作为萃取缓冲液，萃取温度为150°C，体积为15 mL。可以通过该程序可靠检测的所选元素种类的最低浓度为0.064至0.682 ng g ^-1。使用San Joaquin土壤标准参考材料2709a，砷（V）的回收率百分比为96.8％，铬（VI）的回收率百分比为97.7％，证明了所开发方法的准确性。通过使用加标和回收率研究，分别以目标物种定量值的3倍和25倍，对As物种和Cr（VI）的回收率从84.9％提高到104％，验证了所建议的方法。使用优化的分析方法对实际沉积物中选定的As和Cr物种进行监测。根据方差分析（ANOVA），在河流的季节性状态之间，Cr（VI），As（III），MMA和As（V）的浓度差异在95％置信水平下具有统计学意义（p p0.05）。 ）。