Quantification of N-acetylcysteine in pharmaceuticals using cobalt phthalocyanine modified graphite electrodes.
Flow injection analysis (FIA) with amperometric detection was employed for the quantification of N-acetylcysteine (NAC) in pharmaceutical formulations, utilizing an ordinary pyrolytic graphite (OPG) electrode modified with cobalt phthalocyanine (CoPc). Cyclic voltammetry was used in preliminary studies to establish the best conditions for NAC analysis. In FIA-amperometric experiments the OPG-CoPc electrode exhibited sharp and reproducible current peaks over a wide linear working range (5.0×10(-5)-1.0×10(-3) mol L(-1)) in 0.1 mol L(-1) NaOH solution. High sensitivity (130 mA mol(-1) cm(2)) and a low detection limit (9.0×10(-7) mol L(-1)) were achieved using the sensor. The repeatability (R.S.D.%) for 13 successive flow injections of a solution containing 5.0×10(-4) mol L(-1) NAC was 1.1%. The new procedure was applied in analyses of commercial pharmaceutical products and the results were in excellent agreement with those obtained using the official titrimetric method. The proposed amperometric method is highly suitable for quality control analyses of NAC in pharmaceuticals since it is rapid, precise and requires much less work than the recommended titrimetric method.
Universidade de São Paulo, Instituto de Química, São Paulo, SP, Brazil.
Iranaldo Santos
IS
da Silva
Marcelo Fernando Antão
MF
Araújo
Henrique Augusto
HA
Ferreira
Jaldyr de Jesus Gomes
Jde J
Varela
Sônia Maria Carvalho Neiva
SM
Tanaka
Auro Atsushi
AA
Tanaka
Lúcio
L
Angnes
D000111:Acetylcysteine / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*
D007211:Indoles; D009942:Organometallic Compounds; D004364:Pharmaceutical Preparations; C063633:cobalt phthalocyanine; D006108:Graphite; D000111:Acetylcysteine