The use of guanidinium chloride in the preparation of stable cellular homogenates containing ATP.

Rat eye lenses were prepared for ATP determination by homogenization in 8 M guanidinium chloride-0.01 M EDTA. Standards of ATP were made up in the same solution. ATP appears to be quite stable in this solution in both standards and lens homogenates whether storage is at room temperature, 4 degrees C, or -20 degrees C for up to several weeks. ATP was measured using a luciferin-luciferase preparation in Hepes buffer, pH 7.75. The photons of light produced were detected by a bioluminescence counter.