Studies on the elimination of interfering absorption in spectrophotometry of pharmaceutical preparations Ⅱ.The application of first-derivative spectrometry to the determination of dihydrochlorothiazide in hypotensive tablets.

The derivative spectrometry is a new technique eliminating the interference in ultraviolet-visible spectra. This method is very simple and convenient to operate. This paper deals with the determination of dihydrochlorothiazide in hypotentive tablets by the first-derivative spectrometry using a recording double beam spectrophotometer with an attachment (UV-300) or a manual pectrophotometer (751G).The mean recoveries of dihydrochlorothiazide were found to be 99.51±0.47% and 99.14±0.45%( at the 95% confidence level), respectively.