Determination of hepatic tissue calcium levels by flame emission spectrophotometry

Hepatotoxicants are known to cause significant increases in total liver calcium content. These increases are postulated to be the key irreversible event leading to necrosis of hepatic parenchymal cells. An investigation is presented of the use of flame emission spectrophotometry as an alternative analytical method to atomic absorption spectrophotometry in the assessment of hepatic calcium levels following hepatotoxicant challenge, using a proven method of tissue digestion. Flame emission and atomic absorption spectrophotometry were found to be comparable in sensitivity with detection limits in the ppm range and correlation coefficients of > 0.99 for the standard curves. Tissue sample analysis demonstrated comparable precision for the two methods. The liver calcium levels determined for an untreated control rat were 105 ppm with a coefficient of variation of 2.9% for flame emission spectrophotometry vs 106 ppm with a coefficient of variation of 3.6% for atomic absorption spectrophotometry. Comparable precision was also found for the two methods when toxicant-damaged liver was analyzed. Flame emission spectrophotometry appears to be a useful alternative to atomic absorption spectrophotometry for tissue calcium analyses in experimental toxicologic studies.