ABSTRACT
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.e. linearity, range, accuracy, precision and specificity. All these parameters were found in accordance with the acceptance criteria of Comité de Guías Oficiales de Validación de la Dirección General de Control de Insumos para la Salud de México. Based on the spectrophotometric characteristics of Losartan potassium, a signal at 234 nm of the first derivative spectrum (1D234) was found adequate for quantification. The linearity between signal 1D234 and concentration of Losartan potassium in the range of 4.00-6.00 mg l(-1) in aqueous solutions presents a square correlation coefficient (r2) of 0.9938. The mean recovery percentage was 100.7+/-1.1% and the precision expressed as relative standard deviation (R.S.D.) 0.88%. In addition, the proposed method is simple, easy to apply, low-cost, does not use polluting reagents and requires relatively inexpensive instruments. Then, it is a good alternative to existing methods for determining Losartan potassium in tablets provided that the pharmaceutical dosage form does not contain hydrochlorothiazide as second drug.
Subject(s)
Antihypertensive Agents/analysis , Losartan/analysis , Excipients , Hydrogen-Ion Concentration , Indicators and Reagents , Pharmacopoeias as Topic , Reference Standards , Reproducibility of Results , Solutions , Spectrophotometry, Ultraviolet , Tablets , United StatesABSTRACT
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. in nonderivative spectrophotometry. The main strength of this technique is the lack of matrix background interference, typical of plant extracts in traditional spectrophotometric methods. This method is fast, inexpensive, easy-to-apply, and highly selective. The calibration graph was linear in the range of 0.1 and 1.0 mg/L N as NO3(-). Average recovery in real matrixes (lettuce and spinach) was 102.6%; average standard deviation was 3.3. This method has been applied to leaves of 4 types of lettuce.
