Holmstrand Henry, Andersson Per, Gustafsson Orjan
Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50007, 104 05 Stockholm, Sweden.
Anal Chem. 2004 Apr 15;76(8):2336-42. doi: 10.1021/ac0354802.
Improved sensitivity in the analysis of stable chlorine isotopes of organochlorines (delta(37)Cl-OCl) has been established using sealed tube combustion in conjunction with thermal ionization mass spectrometry (TIMS). TIMS of chlorine isotopes was performed on <85 nmol of Cl with an achievable precision of <0.25 per thousand for pure inorganic chloride samples and 0.46 per thousand for chloride liberated from organochlorines (OCls). This makes possible significant reductions in the overall sample size requirement, as compared to the techniques of gas source stable isotope ratio mass spectrometry (SIRMS). Yields in excess of 99% were demonstrated in the dechlorination of <0.14 micromol 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and the overall yield, including purification of liberated chloride, was 86-97%. The accuracy of TIMS in the measurement of chlorine isotopes derived from OCls was confirmed by analysis of a DDT sample previously analyzed with SIRMS.(9) Using the described method for TIMS, the DDT sample gave a bulk chlorine isotope ratio of delta(37)Cl -4.42 +/- 0.46 per thousand (1sigma). The reported value from SIRMS analysis is -4.34 +/- 0.25 per thousand, indicating the conformity of the two methods.
通过将密封管燃烧与热电离质谱法（TIMS）相结合，已实现了对有机氯中稳定氯同位素（δ(37)Cl - OCl）分析的灵敏度提高。对于氯同位素的TIMS分析，使用的Cl量小于85 nmol，对于纯无机氯化物样品，可达到的精度小于0.25‰，对于从有机氯（OCls）中释放出的氯化物，精度为0.46‰。与气体源稳定同位素比率质谱法（SIRMS）技术相比，这使得总体样品量需求大幅减少成为可能。在对小于0.14 μmol的1,1,1 - 三氯 - 2,2 - 双（对氯苯基）乙烷（DDT）进行脱氯时，脱氯产率超过99%，包括对释放出的氯化物进行纯化后的总产率为86 - 97%。通过对一个先前用SIRMS分析过的DDT样品进行分析，证实了TIMS在测量源自OCls的氯同位素方面的准确性。(9) 使用所描述的TIMS方法，该DDT样品的总氯同位素比率为δ(37)Cl - 4.42 ± 0.46‰（1σ）。SIRMS分析报告的值为 - 4.34 ± 0.25‰，表明两种方法结果一致。
