Chemical Metrology Division, National Metrology Laboratory of Costa Rica (LCM), San José, Costa Rica.
Chemical Metrology Division, National Metrology Laboratory of Costa Rica (LCM), San José, Costa Rica.
Talanta. 2021 Sep 1;232:122286. doi: 10.1016/j.talanta.2021.122286. Epub 2021 Apr 20.
The quantification of Cr (VI) in the cement matrix is highly important, given the possibility of suffering illnesses including dermatitis, induced nasal carcinoma, and DNA damage produced by inhalation of and/or direct contact with this substance by construction workers. This study presents an analytical validation of the determination of water-soluble Cr (VI) using Ultraviolet-Visible Spectroscopy (UV-Vis) with 1.5-diphenylcarbazide. To do so, different performance characteristics were determined: working interval, analytical sensitivity, linearity, limits of detection (LOD) and quantification (LOQ), as well as measurement uncertainty, in order to provide better metrological information about the performance of this method. The study also focused on evaluating the impact of use of different types of standard sands (ASTM C-778 and CEN) for preparing mortar cement and extracting water soluble Cr (VI) present in the cement. For this purpose, two cements with different concentrations (2.01 ± 0.21 and 0.75 ± 0.09 mg-kg) of Cr (IV) were created to evaluate extraction using three types of treatments: oxidized with potassium peroxidisulfite, non-oxidized, and an alternative method using cement paste. It was observed that mortar cement using ASTM C-778 sand tends to underestimate Cr (IV) content when concentrations are below 0.8 mg kg, while at higher concentrations of ~2.0 mg kg it does not generate different results compared to those obtained using mortar cement made with CEN-standard sand. An alternative method called "paste extraction" also showed statistically comparable results with respect to standard mortar for both concentration levels evaluated. Finally, samples of cement marketed in Costa Rica were analyzed using different types of water soluble Cr (IV) extraction methods. The results show concentrations between 0.70 ± 0.13 mg kg and 1.30 ± 0.13 mg kg, demonstrating that they comply with the limits established by international standards and national regulations in Costa Rica.
水泥基质中六价铬（Cr(VI)）的定量分析非常重要，因为建筑工人可能会因吸入和/或直接接触这种物质而患上包括皮炎、诱导性鼻癌和 DNA 损伤在内的疾病。本研究使用 1.5-二苯基卡巴肼对紫外可见光谱（UV-Vis）法测定水溶性六价铬（Cr(VI)）进行了分析验证。为此，确定了不同的性能特征：工作间隔、分析灵敏度、线性、检测限（LOD）和定量限（LOQ）以及测量不确定度，以便提供有关该方法性能的更好计量信息。该研究还侧重于评估使用不同类型的标准砂（ASTM C-778 和 CEN）制备砂浆水泥以及提取水泥中存在的水溶性六价铬（Cr(VI)）对结果的影响。为此，制备了两种 Cr(IV)浓度不同（2.01 ± 0.21 和 0.75 ± 0.09 mg-kg）的水泥，以评估使用三种处理方法（过二硫酸钾氧化、非氧化和使用水泥浆的替代方法）进行的提取。结果表明，当浓度低于 0.8 mg kg 时，使用 ASTM C-778 砂的砂浆水泥往往会低估 Cr(IV)含量，而在浓度约为 2.0 mg kg 时，与使用 CEN 标准砂制成的砂浆水泥相比，不会产生不同的结果。另一种称为“浆体提取”的替代方法在评估的两个浓度水平下与标准砂浆相比也显示出统计学上可比的结果。最后，使用不同类型的水溶性 Cr(IV)提取方法分析了哥斯达黎加市售水泥的样品。结果表明浓度在 0.70 ± 0.13 mg kg 和 1.30 ± 0.13 mg kg 之间，表明它们符合国际标准和哥斯达黎加国家标准规定的限值。
