A simplified reflectometric method for the rapid determination of dipyrone in pharmaceutical formulations

Abstract

Este artigo descreve um método simples, portátil e ambientalmente amigável para a rápida determinação de dipirona em medicamentos empregando a espectroscopia de reflectância difusa. O método proposto está baseado nas medidas de reflectância do composto alaranjado produzido na reação de spot-test entre dipirona e p-dimetilaminocinamaldeído (p-DAC), em meio ácido, usando papel de filtro como suporte sólido. Metodologias de planejamento de experimentos foram utilizadas para a otimização das condições experimentais. Todas as medidas de reflectância foram efetuadas em 510 nm e o intervalo linear foi de 1,42 × 10 -4 -2,85 × 10 -3 mol L -1 , com coeficiente de correlação de 0,999. Os limites de detecção (LOD) e de quantificação (LOQ) foram de 1,20 × 10 -5 mol L -1 e 4,00 × 10 -5 mol L -1 , respectivamente. A precisão intradia e interdia foi avaliada na análise de uma solução de dipirona 7,90 × 10 -4 mol L -1 (n = 10). Os coeficientes de variação foram 1,1 e 0,9%, respectivamente. O método proposto foi aplicado com êxito na determinação de dipirona em amostras comerciais de medicamentos. Não foram observadas interferências dos excipientes comuns em formulações farmacêuticas. Os resultados obtidos pelo método proposto estão em boa concordância com aqueles obtidos pelo procedimento da Farmacopéia Brasileira num nível de confiança de 95%. This paper describes a simple, portable and environmentally friendly method for the rapid determination of dipyrone in pharmaceuticals by using diffuse reflectance spectroscopy. The proposed method is based on the reflectance measurements of the orange compound produced from the spot test reaction between dipyrone and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using a filter paper as solid support. Experimental design methodologies were used to optimize the measurement conditions. All reflectance measurements were carried out at 510 nm and the linear range was from 1.42 × 10 -4 -2.85 × 10 -3 mol L -1 , with a correlation coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.20 × 10 -5 mol L -1 and 4.00 × 10 -5 mol L -1 , respectively. The intraday precision and interday precision were studied for 10 replicate analyses of 7.90 × 10 -4 mol L -1 dipyrone solution. The coefficients of variation were 1.1 and 0.9%, respectively. The proposed method was applied successfully to the determination of dipyrone in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those given by the Brazilian Pharmacopoeia procedure at 95% confidence level.

Spot-test identification and rapid quantitative sequential analysis of dipyrone

“…Some methods have been developed for dipyrone determination, such as titrimetry [1], HPLC [10], spectrophotometry [11][12][13][14][15], potentiometry [16], amperometry [17,18], turbidimetry [19], voltammetry [20], and reflectometry [21]. The iodometric titration of dipyrone is recommended by the Pharmacopoeia [1] but this procedure is very slow and laborious, thus less applicable to large-scale analysis.…”

Versatility of a Multicommuted Flow System in the Spectrometric Determination of Three Analytes

“…1 These new methodologies aim to: guarantee drug content, identify adulterants in pharmaceutical formulations which represent health risks, 2 and reduce (or replace) materials harmful to human health and environment. 3 In this sense, flow systems are excellent tools for dealing with solutions in wet chemical analysis.…”

Simultaneous Determination of Metamizole, Thiamin and Pyridoxin Using UV-Spectroscopy in Combination with Multivariate Calibration

“…Some analytical methods have been reported for the determination of MET, B1 and B6, either alone or in combination with other medicines in pharmaceutical products. Several analytical methods for determination MET such as electrochemical and electrophoretic, 5 reflectometric, 6 spectrophotometry, 7 HPLC 8 and liquid chromatography-mass spectrometry (LC/MS) for bioequivalence study. 9 Furthermore, several analytical methods for quantification B1 and B6 such as densitometry and spectrofotometry in combination with multivariate calibration, 10 capilary zone electrophoresis, 11 HPLC, 12,13 and LC/MS 14,15 have beed used.…”