The determination of potassium concentration in vitreous humor by low pressure ion chromatography and its application in the estimation of postmortem interval

An analytical method was developed for the determination of potassium in vitreous humor by low pressure ion chromatography (LPIC). Experimental conditions for LPIC analysis were optimized. High sensitivity and selectivity were obtained using this method. The LOD and LOQ were 1 and 2 mmol l−1, respectively. The linearity was demonstrated from 2 to 20 mmol l−1. The intra- and inter-day precision (CV) based on three concentrations was less than 5.0%. It was a simple and fast method to measure potassium and was suitable for evaluating the postmortem interval (PMI) in relatively well-preserved bodies. Sixty-two samples from medical-legal autopsies with known PMI were analyzed. A linear correlation equation for potassium concentration in the vitreous humor and PMI was established: [K+] = 0.1702PMI + 5.5678, r = 0.8692.