A safe method to acid digest small samples of biological tissues for graphite furnace atomic absorption analysis of aluminum.

A method was developed to prepare small biological tissue samples (approximately 100 mg) for flameless atomic absorption analysis of aluminum (Al). Screw cap Teflon containers were used in which the samples were dried, acid digested, acid evaporated, and diluted for analysis, minimizing contamination and sample loss. A heatable, semiclosed system was developed in which the nitric and perchloric acids used in tissue digestion could be safely evaporated from the sample containers and collected. Several spectrophotometer operating conditions for Al determination were compared, and a suitable condition was adopted. Analyses for aluminum levels in acid digested samples were conducted at two absorption wavelengths (309.3 and 396.2 nm) and by two analytical procedures (comparison of sample absorbance to standard absorbance and the method of standard additions). The developed method is suitable for analysis of the low levels of aluminum found in biological tissues and probably other elements as well. The method incorporates procedures designed to minimize contamination and the hazards of acid tissue digestion.