A comparison of the results obtained by derivation absorption spectrophotometry in the ultraviolet region and those obtained by HPLC and other instrumental methods of quantitative analysis of drugs reveals that derivation spectrophotometry can be an economically advantageous alternative in many cases. The results of the determination of one drug on an interfering background or of two substances beside one another are usually comparable; for the evaluation of the determination of three or more substances enough data are not available.

        Key words: derivation spectrophotometry – drug analysis – other instrumental methods