Comparison of Two Methods for The Determination of Potassium in Vitreous Humor

The estimation of time since death is one of the important issues faced in the daily forensic practice. The well-known and largely adopted methods of investigation in an early phase, however, cannot be applied after the first 24 hours from death. Several body parts and fluids have been analyzed over the years in order to find a correlation between biochemical markers and the postmortem interval. Among those methods, the study of the concentration of potassium in vitreous humor demonstrated a time-related increase. The methods for the determination of potassium concentration published in the literature are of common use in clinical chemistry laboratory, even if we should consider the well-known matrix effect given that such instruments are validated for plasma or urine analysis. The aim of the present research is to compare a gold standard method not affected by this effect with the low cost and easily available indirect potentiometric method provided by an automatized system.