Reagents and methods for using automated laboratory equipment to determine whether the specific gravity of a urine sample is out of normal range as an indication of adulteration. The sodium (Na+) and potassium (K+) normally found in a urine sample can be used as markers. A sodium-potassium dependent β-galactosidase can be utilized with o-nitrophenylgalactoside (o-NPG) which is cleaved into o-nitrophenol, which turns the sample yellow. The sample can be analyzed by spectrophotometry methods utilized in most clinical analyzers at a pre-determined primary wavelength to obtain a Specific gravity Index (SGI). Measurements of the SGI that are outside a known normal range can indicate that the sample integrity has been compromised.