Patent ID: 7556933

Claim:
A method of estimating cellular adenosine triphosphate (ATP) based on the actual measurement of both extracellular ATP and total ATP in a sample, which comprises the step of applying a reagent system to the sample, the reagent system comprising: a first reagent which includes a high pH having a range of about pH 9.9 to 12 phosphate buffer; and a second reagent which includes luciferase, luciferin, a magnesium salt and an enzyme stabilizer, said second reagent having a low pH range of about 6 to 8.5 and a buffer with a pK which is near the optimum pH for activity of luciferase; wherein the application of said first and second reagents to said sample is operable for measuring extracellular ATP in said sample, and wherein the application to said sample of said first reagent together with a cationic surfactant and said second reagent is operable for measuring total ATP in said sample.