Bancon-Montigny Chrystelle, Maxwell Paulette, Yang Lu, Mester Zoltán, Sturgeon Ralph E
Institute for National Measurement Standards, National Research Council Canada, Ottawa, Ontario.
Anal Chem. 2002 Nov 1;74(21):5606-13. doi: 10.1021/ac0258002.
A unique approach was developed to improve the precision of quantification of tributyltin (TBT) in sedimentsby solid phase microextraction (SPME) using isotope dilution GC/MS. The precision of the analytical technique was initially evaluated using standard calibration solutions. In selective ion monitoring (SIM) mode, the relative standard deviation (RSD) obtained for TBT based on peak area response was 18% (n = 11). When an internal standard, tripropyltin (TPrT), was used, the RSD decreased to 12%. A significant improvement in the precision using SPME was noted when a 117Sn-enriched TBT spike was employed; the RSD decreased 4-fold to 3%. Detection limits of 0.2 and 20 ng(Sn) L(-1) were achieved with SPME sampling and liquid-liquid extraction, respectively. Six analyses were performed for determination of TBT in PACS-2 sediment Certified Reference Material using both standard additions and isotope dilution procedures. For the latter, a 117Sn-enriched TBT spike was used. A concentration of 0.88 +/- 0.03 microg g(-1) (RSD 3.4%) obtained using standard additions was in good agreement with the certified value of 0.98 +/- 0.13 microg g(-1) as tin. Concentrations found using isotope dilution were 0.895 +/- 0.015 microg g(-1) (RSD 1.73%) as tin and 0.874 +/- 0.014 microg g(-1) (RSD 1.66%) as tin using a liquid-liquid extraction and SPME sampling, respectively. A 2-fold improvement in the precision of TBT concentration measurement using isotope dilution was clearly achieved, demonstrating its superiority in providing more accurate and precise results as compared to the method of standard additions. The isotope dilution technique eliminated the problem of poor reproducibility, which typically plagues SPME.
开发了一种独特的方法，通过使用同位素稀释气相色谱/质谱联用的固相微萃取（SPME）来提高沉积物中三丁基锡（TBT）定量的精度。首先使用标准校准溶液评估分析技术的精度。在选择离子监测（SIM）模式下，基于峰面积响应得到的TBT相对标准偏差（RSD）为18%（n = 11）。当使用内标三丙基锡（TPrT）时，RSD降至12%。当采用富集117Sn的TBT加标时，注意到使用SPME的精度有显著提高；RSD降低了4倍，降至3%。使用SPME采样和液液萃取分别实现了0.2和20 ng(Sn) L(-1)的检测限。使用标准加入法和同位素稀释法对PACS-2沉积物标准参考物质中的TBT进行了六次分析测定。对于后者，使用了富集117Sn的TBT加标。使用标准加入法得到的浓度为0.88±0.03 μg g(-1)（RSD 3.4%），与认证值0.98±0.13 μg g(-1)（以锡计）高度一致。使用同位素稀释法得到的浓度，采用液液萃取时以锡计为0.895±0.015 μg g(-1)（RSD 1.73%），采用SPME采样时以锡计为0.874±0.014 μg g(-1)（RSD 1.66%）。使用同位素稀释法在TBT浓度测量精度上明显提高了2倍，证明了其与标准加入法相比在提供更准确和精确结果方面的优越性。同位素稀释技术消除了通常困扰SPME的重现性差的问题。
