Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University of Mainz, D-55128 Mainz, Germany.
Environ Sci Technol. 2010 Jul 1;44(13):5061-6. doi: 10.1021/es100395p.
In this paper we present the evaluation and optimization of a new approach for the quantification of gaseous molecular iodine (I(2)) for laboratory- and field-based studies and its novel application for the measurement of radioactive molecular iodine. alpha-Cyclodextrin (alpha-CD) in combination with (129)I(-) is shown to be an effective denuder coating for the sampling of gaseous I(2) by the formation of an inclusion complex. The entrapped (127)I(2) together with the (129)I(-) spike in the coating is then released and derivatized to 4-iodo-N,N-dimethylaniline (4-I-DMA) for gas chromatography-mass spectrometry (GC-MS) analysis. The (127)I(2) collected can be differentiated from the (129)I(-) spike by MS. A set of parameters affecting the analytical performances of this approach, including amount of alpha-CD and (129)I(-) applied, denuder length, sampling gas flow rate and sampling duration, relative humidity, sample storage period, and condition of release and derivatization of iodine, is extensively evaluated and optimized. The collection efficiency is larger than 98% and the limit of detection (LOD) obtained is 0.17 parts-per-trillion-by-volume (pptv) for a sampling duration of 30 min at 500 mL min(-1). Furthermore, the potential use of this protocol for the determination of radioactive I(2) at ultra trace level is also demonstrated when (129)I(-) used in the coating is replaced by (127)I(-) and a multiple denuder system is used. Using the present method we observed 25.7-108.6 pptv (127)I(2) at Mweenish Bay, Ireland and 10(8) molecule m(-3 129)I(2) at Mainz, Germany.
本文介绍了一种新的气态分子碘（I(2)）定量方法的评估和优化，该方法可用于实验室和现场研究，并将其应用于放射性分子碘的测量。α-环糊精（α-CD）与（129）I(-)结合可有效地作为气体 I(2)的采样捕集涂层，通过形成包络复合物。包埋在涂层中的（127）I(2)与（129）I(-)一起被释放出来，并衍生为 4-碘-N,N-二甲基苯胺（4-I-DMA），用于气相色谱-质谱（GC-MS）分析。收集到的（127）I(2)可通过 MS 与（129）I(-)分离。本文广泛评估和优化了影响该方法分析性能的一组参数，包括α-CD 和（129）I(-)的用量、捕集器长度、采样气流速率和采样持续时间、相对湿度、样品储存期、碘的释放和衍生化条件。该方法的收集效率大于 98%，在 500 mL min(-1)的采样流速下，采样 30 min 的检测限（LOD）为 0.17 pptv。此外，当涂层中（129）I(-)被（127）I(-)取代并使用多级捕集器系统时，该方法还可用于测定痕量放射性 I(2)。使用本方法，我们在爱尔兰的 Mweenish Bay 观测到 25.7-108.6 pptv（127）I(2)，在德国的 Mainz 观测到 10(8)分子 m(-3 129)I(2)。
