Data quality in water analysis: validation of combustion-infrared and combustion-chemiluminescence methods for the simultaneous determination of Total Organic Carbon (TOC) and Total Nitrogen (TN)

摘要

Total Organic Carbon (TOC) and Total Nitrogen (TN) were simultaneously determined in water samples, applying the high-temperature (720 ℃) catalytic combustion (Pt/Al_2O_3) oxidation method. The detection of TOC and TN was performed using an infrared or a chemiluminescence detector, respectively. Following current law legislations as well as the need to provide accurate and repeatable results, a systematic work has been successfully undertaken for the accreditation according to EN ISO 17025/99. Method characteristics (range of measurement, calibration, method detection level, repeatability, reproducibility, precision, accuracy) and measurement uncertainties were determined, while participation in proficiency testing schemes was also implemented. The above methods were tested for the study of water purification from organic pollutants. To this end, organic dyes have been used as model organic pollutants and anionic hydrogels have been used as sorbents. With respect to the colorimetric techniques, TOC-TN characterization is proved to be a reliable tool with significantly lower detection limits of the organic load.