Derivative spectrophotometric determination of nitrate in plant tissue.

A derivative spectrophotometric method was developed to determine NO3(-)-N in plant tissues. The method is based on measurement of the first-derivative spectrum of nitrosalicylic acid in basic solution. The nitrosalicylic acid was obtained by reaction of samples with salicylic acid in concentrated sulfuric acid and was used by Cataldo et al.

Development and validation of an UV derivative spectrophotometric determination of Losartan potassium in tablets.

Development and validation of an analytical UV derivative spectrophotometric method to quantify Losartan potassium used as a single active principle in pharmaceutical forms were done. Pharmacopeias have not yet provided an official method for its quantification. A study was carried out of all the parameters established by USP XXIV to validate an analytical method for a solid pharmaceutical form, i.