Development of flow procedures based on multicomutation for the determination of anti-hypertensive drugs

Author(s)

Mariana Amorim Sanchez

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2010-11-05

Examining board members

Fabio Rodrigo Piovezani Rocha; Lúcio Angnes; Orlando Fatibello Filho; Maria Encarnacion Vazquez Suarez Iha; Helena Redigolo Pezza

• Advisor: Fabio Rodrigo Piovezani Rocha

Abstract

This thesis focused the development of flow-based analytical procedures exploiting multicommutation for the determination of anti-hypertensive drugs. The reduction of Cu(II) in the presence of captopril, followed by the reaction of Cu(I) with 4,4-dicarboxy-2,2-bichinoline disodium salt (BCA) was employed for captopril determination. The procedure showed a sampling rate of 47 determinations per hour, coefficient of 2.2% (n = 20) and consumption of 290 µg BCA per determination. The results for pharmaceutical samples agreed with those obtained by iodometric titration. The procedure was applied to dissolution studies of pharmaceutical preparations using an alternative apparatus, yielding results in agreement with the literature. One of the analytical procedures for diltiazem determination was based on the reaction between the drug and ClO-, followed by the reaction between N,N-diethyl-p-phenylenediamine (DPD) and the remaining ClO-. The methodology showed a detection limit of 7.0 µmol/L, sampling rate of 34 determinations per hour and coefficient of variation of 0.9% (n = 10), but application was hindered by matrix effects. Thus, on-line liquid-liquid microextraction was evaluated, based on the ion pair formation between diltiazem and bromothymol blue in acidic medium. Detection limit of 0.9 µmol/L, sampling rate of 78 determinations per hour and extraction efficiency of 60% were attained. The CHCl3 consumption was only 50 µL, with waste generation of 383 µL per determination. The results for diltiazem determination in commercial pharmaceutical preparations agreed with the reference procedure. Finally, a procedure for losartan determination was developed based on flow injection liquid-liquid microextraction of the ion pair formed between the drug and orange-II in acidic medium. Sampling rate of 77 determinations per hour and coefficient of variation of 0.9% (n = 10) were achieved, consuming 150 µL of CHCl3 per determination. However, selectivity was poor, differently that observed in the analogous batch procedure. (AU)