For quantitative determination of xanthine and drug effects on its metabolism. Key Features: Sensitive and accurate. Use as little as 10 µ L samples. Linear detection range in 96-well plate for 30 minute incubation: 0.01 to 2.5 mM xanthine for colorimetric assays and 3 to 250 µ M for fluorimetric assays. Simple and convenient. The procedure involves addition of a single working reagent and incubation for 30 min at room temperature. Fast and high-throughput. Assays using 96-well plates and liquid handling system could allow simultaneous processing tens of thousands of samples per day. Method: OD570nm, FL530/585nm. Samples: Cell lysate, serum, and other biological samples. Species: All. Procedure: Assay takes 30 min. Kit size: 100 tests. Detection limit: FL 3 µ M; OD 10 µ M.