The 10,000-4,000 cm(-1) spectra recorded in the reflectance mode were used to detect and det. ascorbic acid in intact tablets of 5 com. prepns. The NIR data compared well with those found by TLC and potentiometric iodometry used as the ret. methods. Full qual. and quant. assay took 30 min, a test time acceptable for large-lot production. Each app. to be used in series measurements requires an individual quant procedure.