串联电导及紫外检测器-离子色谱法测定土壤中6种有机酸根和无机阴离子
IC Determination of 6 Organic and Inorganic Anions in Soil with Conductivity Detector and UV-Detector in Series
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摘要: 应用离子色谱法测定土壤样品中正丁酸根、草酸根、溴离子、碘离子、氯离子及硫酸根等6种有机酸根和无机阴离子的含量。样品(10.00 g)用50 mmol·L-1氢氧化钠溶液50 mL超声提取60 min,离心分离。取上清液,经0.22 μm滤膜过滤和OnGuardⅡP柱净化。流出液稀释5倍后通过IonPac AG18柱分离,用不同浓度的氢氧化钾溶液进行梯度淋洗,用串联的电导检测器和紫外检测器(236 nm)进行检测。前者用于除碘离子外的5种阴离子的测定,后者用于碘离子的测定。上述6种阴离子的峰面积分别在一定范围与其质量浓度呈线性关系,其检出限(3S/N)在0.013~0.095 μg·g-1之间。加标回收率在92.0%~112%之间,测定值的相对标准偏差(n=6)在1.2%~7.2%之间。Abstract: Six organic and inorganic anions including n-butyrate, oxalate, bromide, iodide, chloride and sulfate in soil were determined by ion chromatography (IC) with conductivity detector and UV-detector connected in series. The sample (10.00 g) was extracted ultarsonically with 50 mmol·L-1 NaOH solution (50 mL) for 60 min. After centrifugation, the supernatant was filtered with 0.22 μm membrane and purified on OnGuardⅡP column. The eluate after diluting 5 times with water was separated on IonPAC AG18 column using KOH solutions of different concentrations as mobile phase in gradient elution. The 5 anions besides I- were detected with conductivity detector and iodide ion was detected by UV-detector at 236 nm. Linear relationships between values of peak area and mass concentration of the 6 anions were kept in definite ranges with values of detection limits (3S/N) in the range of 0.013-0.095 μg·g-1. Values of recovery given by standard addition method were in the range of 92.0%-112%, with values of RSD′s (n=6) ranged from 1.2% to 7.2%.