Monteiro Carlos E, Cobelo-Garcia Antonio, Caetano Miguel, Correia Dos Santos Margarida M
Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal; IPMA-Portuguese Institute of Sea and Atmosphere, Division of Environmental Oceanography and Bioprospection, Av. Brasilia, 1449-006 Lisbon, Portugal.
Bioxeoquímica Mariña, Instituto de Investigacións Mariñas IIM-CSIC, Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain.
Talanta. 2017 Dec 1;175:1-8. doi: 10.1016/j.talanta.2017.06.067. Epub 2017 Jun 27.
The determination of Platinum-group elements (PGE) in relevant environmental matrices is a challenging task. Sensitive and accurate analytical procedures for simultaneous determination of Pt and Rh are still needed. In this study, we report for the first time on the use of second derivative signal transformation to the ultra-trace simultaneous determination of Pt and Rh by Adsorptive Cathodic Stripping Voltammetry (AdCSV). With that step, the ill-defined peaks typically observed in the original voltammograms are transformed into well-shaped peaks, resulting in accurate detection. The experimental conditions were investigated and optimised: a suitable electrolyte for both elements, with less reagents consumption, (0.25M HSO, 0.05M HCl, 0.01M FA and 0.5mM HZ), deposition time (t) and deposition potential (E). For t = 120s and E = -0.75V, linear relationships r > 0.999 were obtained in the concentration range up to 5.8ngL (27 pM) for Pt and up to 3.4ngL (34 pM) for Rh. Limits of detection were 0.2ngL for Pt and 0.08ngL for Rh. Lower values can be achieved by increasing the deposition time. Limits of quantification, LOQ, calculated as 3 times LOD, were 0.5ngL for Pt and 0.2ngL for Rh. The sensitivity of Pt was affected by elevated Zn concentrations, whereas a minor effect was observed for Rh. However, Pt and Rh determinations were not influenced using the standard addition method. Precision as intermediate precision and expressed as relative standard deviation, based on Pt and Rh spiked solutions and digested road dust CRM BCR-723 was 17% and 20% for Pt and Rh, respectively. Recoveries of CRM were around 90% for both elements. The method was successfully applied in the simultaneous determination of Pt and Rh in sediments from Tagus estuary and, for the first time, dissolved Rh was determined in water samples of a waste water treatment plant. Application of this technique in a multidisciplinary approach will be a relevant contribution to the current understanding of PGE cycle and fate in the environment.
测定相关环境基质中的铂族元素（PGE）是一项具有挑战性的任务。目前仍需要灵敏且准确的同时测定铂和铑的分析方法。在本研究中，我们首次报道了利用二阶导数信号转换，通过吸附阴极溶出伏安法（AdCSV）对铂和铑进行超痕量同时测定。通过这一步骤，原始伏安图中通常观察到的不清晰峰被转换为形状良好的峰，从而实现准确检测。对实验条件进行了研究和优化：确定了适合两种元素的电解质，其试剂消耗量较少（0.25M HSO、0.05M HCl、0.01M FA和0.5mM HZ），以及沉积时间（t）和沉积电位（E）。当t = 120s且E = -0.75V时，在铂浓度高达5.8ng/L（27 pM）和铑浓度高达3.4ng/L（34 pM）的范围内，线性关系r > 0.999。铂的检测限为0.2ng/L，铑的检测限为0.08ng/L。通过增加沉积时间可以获得更低的值。计算得出的定量限（LOQ）为检测限的3倍，铂的定量限为0.5ng/L，铑的定量限为0.2ng/L。锌浓度升高会影响铂的灵敏度，而对铑只有轻微影响。然而，使用标准加入法时，铂和铑的测定不受影响。基于铂和铑加标溶液以及经消解的道路灰尘标准物质BCR - 723，以相对标准偏差表示的中间精密度，铂和铑分别为17%和20%。两种元素对标准物质的回收率均约为90%。该方法成功应用于塔霍河河口沉积物中铂和铑的同时测定，并且首次测定了污水处理厂水样中的溶解铑。将该技术应用于多学科方法将为当前对环境中铂族元素循环和归宿的理解做出重要贡献。
