Abstract

To prevent the recidivism of criminals with mental disorders, e.g., bipolar disorder, the Republic of Korea introduced the therapeutic order system in 2016 to ensure that these individuals receive systematic treatment and management, including medication administration and regular monitoring of treatment compliance. However, the International Organization for Standardization (ISO) requires laboratories performing quantitative analysis to include measurement uncertainties in the quantitative results to ensure reliable outcomes. Therefore, in this study, the measurement uncertainty of the determination of Li in urine using ion chromatography (IC) was established. The standard addition method of weighted calibration without an internal standard was employed to quantify urinary Li. Sample preparation involved centrifuging the urine and diluting the supernatant with deionized H2O, and the Li+ in the urine was analyzed using IC. The potential factors that contribute to the uncertainty of the final result were examined and evaluated. The major contributing factors influencing the combined standard uncertainty were the calibration curve and repeatability, whereas the preparation of the standard solution and sample dilution were minor factors. The relative expanded uncertainty of the measured concentration in a forensic urine sample was 35.3 %.