Summar yIn order to adopt "screening analysis" in drinking water quality testing, which performs qualitative and quantitative analysis based on information registered in a database without measuring standard materials at the time of each testing, a validation test was conducted to evaluate the difference on the chromatogram data analysis by analysts. In the validation test, chromatograms of 6 water samples were analyzed using the same database and software by 16 analysts in 13 laboratories. Peak identification was performed based on Retention time (RT), (qualifier and target ion) QT ratio, and degree of matching of mass spectra, and if necessary, peak shapes in water samples were compared with those in calibration curve samples. Large differences were observed in the detection of pesticides among the analysts. There were two main reasons for the disagreement. The first is that the judgement of peak detection at low concentrations near the quantification limit of each pesticide, particularly below the concentration at three times of quantification limit, differed depending on the analyst. The other reason was that some analysts made clear misidentifications and identified wrong peaks close to the predicted retention time, despite the QT ratio and mass spectrum didnʼt match that in the database. In addition, there were some cases where the quantified values were reported by misidentifying the peaks of degradation products and metabolites, even when the peak detection was correctly judged. In order to use screening analysis practically by drinking water quality testing laboratories, it is important to conduct a validation test like this study in advance to use screening analysis and to coordinate criteria for peak identification and quantification among data analysts.
The environmental presence and drinking water contamination of per-and polyfluoroalkyl substances (PFAS) have been reported since the early 2000s. This study seeks to develop a liquid chromatography/ tandem mass spectrometry analytical method for the simultaneous determination of 21 perfluoroalkyl acids (PFAAs) in drinking water to support future regulations in Japan. Inter-laboratory tests were conducted in 16 laboratories using different instrument to verify the applicability of the developed method for a wide range of drinking water samples in Japan. Recovery tests of PFAA-fortified tap water samples obtained in each laboratory were conducted at set points of 1 and 10 ng/L. Calibration curve linearity, trueness (recovery), repeatability (RSD r ), and reproducibility (RSD R ) at these analyte concentrations were calculated using data obtained from the recovery tests. The trueness, RSD r , and RSD R of most PFAA analytes were satisfactory when the recoveries were corrected by 13 C-PFAA extraction standards with similar recovery to the corresponding PFAS analytes. The developed analytical method is valid for the quantification of the target PFAAs in drinking water. However, satisfactory PFAA quantification requires recovery adjustment using surrogates with similar recovery characteristics to the PFAA analytes.
We developed a liquid chromatography/mass spectrometry (LC/MS) or tandem mass spectrometry (LC/MS/MS) analysis method for the simultaneous determination of six anions (bromate, chlorate, chlorite, perchlorate, nitrate, and nitrite) in drinking water. Furthermore, we conducted a validation test along with 15 organizations to confirm that the analytical method developed in the present study is applicable to various types of drinking water and instruments. Recovery tests of the six anions spiked into drinking water were performed to evaluate the linearity of calibration curves, selectivity, accuracy (recovery) , repeatability, and intermediate precision of these anions. Regarding four anions (bromate, chlorate, chlorite, and perchlorate) , the accuracy, repeatability, and intermediate precision obtained by the recovery tests satisfied the criteria in the guideline for the validation of the testing method for drinking water provided by the Ministry of Health, Labour and Welfare, Japan. Therefore, we concluded that the analytical method developed in the present study is valid for the analysis of these four anions in drinking water. However, ethylenediamine must be used for the dechlorination of water samples because degradation of chlorite was observed by using sodium thiosulfate. In addition, proper ranges of calibration curves should be selected for the determination of these anions because the range of the linearity of calibration curves differed depending on the anion.
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