Key comparison CCQM-K59 : determination of nitrite and nitrate in calibration solutions. Final report

In this key comparison anion calibration solutions of nitrate and nitrite were investigated. The mass fractions of the anions in both solutions were about 1 g/kg. For the nitrate comparison 8 participants provided results; 3 analytical techniques were used: ion chromatography, capillary electrophoresis and coulometry after ion exchange. The nitrite amount content was determined by 7 participants using one of the following 3 techniques: ion chromatography, titrimetry, and capillary electrophoresis. The following institutes participated in this key comparison: INTI (Argentina), KRISS (Korea), LNE (France), NIM (P.R.China), NIST (USA), NMIJ (Japan), SMU (Slovakia), and VNIIM (Russia). The variability (RSD) of the results is about 0.75% for both the nitrite and the nitrate solutions. Compared to the key comparison CCQM-K29 the results of CCQM-K59 were significantly worse. This is in part due to the measurement methods used, possibly also due to the standards used by the institutes. A pilot study (P89) was performed in parallel on the same calibration solutions used in this K59 comparisons study by laboratories preferring to participate in the pilot study and on a seawater sample containing about 0.1 mg/kg nitrite and 1 mg/kg nitrate. The results of the pilot study are reported separately.Fil: Máriássy, Michal. Slovak Institute of Metrology (SMU); EslovaquiaFil: Hioki, Akiharu. National Metrology Institute of Japan (NMIJ); JapónFil: Konopelko, Leonid A. D. I. Mendeleev Scientific and Research Institute for Metrology (VNIIM); RusiaFil: Hernández, Ana. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Lee, Joung Hae. Korea Research Institute of Standards and Science (KRISS); Corea del SurFil: Royer, Chantal. Laboratoire National de Métrologie et d’Essais (LNE); FranciaFil: Chao, Jingbo. National Research Center for Certified Reference Materials (NIM); ChinaFil: Turk, Gregory. National Institute of Standards and Technology (NIST); Estados Unido