On-line technique for the determination of the delta37Cl of inorganic and total organic Cl in environmental samples.
On-line technique for the determination of the delta37Cl of inorganic and total organic Cl in environmental samples.
复制标题
DOI：
10.1021/ac0490200
复制
发表时间：
2004-11
影响因子：
7.4
通讯作者：
L. Wassenaar;G. Koehler
中科院分区：
文献类型：
--
作者：
L. Wassenaar;G. Koehler
本文介绍了一种在线测量含氯盐类、水体和有机物质的(37)Cl值的方法，该方法采用多收集连续流动同位素比值质谱仪(CF-IRMS)。将水、无机盐和生物样品中的总氯定量得到纯氯化银，在抽真空的10mL塞式密封玻璃瓶中与碘甲烷反应生成甲基氯气。GV Instruments多采集器CF-IRMS采用优化的CH(3)Cl收集器几何结构进行了改进，以适应在GC柱之前的顶空单样气进样口。色谱柱为2m的Porapak-Q填充柱，保持在160℃。将分解的样品CH(3)Cl以氦气流的形式通过开口裂解引入IRMS源。通过测量m/z为52/50的CH(3)Cl，并与校准到标准平均海洋氯化物的CH(3)Cl的参考脉冲进行比较，计算了Delta(37)Cl值。样品CH(3)Cl的分析时间约为6min。注入40微升的纯CH(3)Cl气体，对Delta(37)Cl(n=10)的重复性(+/-SD)为+/-0.06‰。气相色谱和红外光谱联用测定CH(3)Cl的源线性度为0.2‰/nA(V)峰高。以海水和氯化钠标准溶液的处理为基础的外部重复性优于+/-0.08‰。用该方法分析Delta(37)Cl的最小样品约为0.2微摩尔。来自流域和生物样本研究的精选结果说明了在线氯同位素分析在环境污染研究中的潜力。
Here we describe an on-line method for measuring delta(37)Cl values of chloride bearing salts, waters, and organic materials using multicollector continuous-flow isotope ratio mass spectrometry (CF-IRMS). Pure AgCl quantitatively derived from total Cl in water, inorganic Cl salts, and biological samples was reacted with iodomethane in evacuated 10-mL stopper sealed glass vials to produce methyl chloride gas. A GV Instruments Multicollector CF-IRMS with CH(3)Cl optimized collector geometry was modified to accommodate a headspace single-sample gas injection port prior to a GC column. The GC column was a 2-m Porapak-Q packed column held at 160 degrees C. The resolved sample CH(3)Cl was introduced to the IRMS source in a helium stream via an open split. delta(37)Cl values were calculated by measurement of CH(3)Cl at m/z 52/50 and by comparison to a reference pulse of CH(3)Cl calibrated to standard mean ocean chloride. Sample CH(3)Cl analysis time was approximately 6 min. Injections of 40 microL of pure CH(3)Cl gas yielded a repeatability (+/-SD) of +/-0.06 per thousand for delta(37)Cl (n = 10). Combined GC and IRMS source linearity for CH(3)Cl was <0.2 per thousand/nA (V) peak height. External repeatability, based on processing of seawater and NaCl reference solutions, was better than +/-0.08 per thousand. The smallest sample for delta(37)Cl analysis by this method was approximately 0.2 micromol of Cl. Selected results from a river basin and biological samples study illustrate the potential of on-line chlorine isotope assays in environmental pollution studies.