Flow injection chemiluminescence determination of isoniazid using luminol and silver nanoparticles

The effect of silver colloidal nanoparticles (AgNPs) on the luminol-isoniazid system was investigated. It was found that AgNPs could act as a nanocatalyst on the luminol-isoniazid system to generate chemiluminescence (CL). The CL emission spectrum of the luminol-isoniazid-AgNPs system showed a peak with a maximum at 425 nm. It was suggested that the luminophor species was the excited state 3-aminophthalate. The reduction of dissolved O₂ to H₂O₂ by isoniazid and decomposition of H₂O₂ to the oxygen-related radicals were attributed to the catalytic effect of AgNPs. Under optimized conditions, the CL signal intensity was linear with the isoniazid concentration in the range of 10-1000 ng mL^{- 1}, with the correlation coefficient of 0.9996. The limit of detection was 2.7 ng mL^{- 1} isoniazid. The relative standard deviations for seven repeated measurements of 60 and 200 ng mL^{- 1} isoniazid were 1.4 and 2.4%, respectively. The effect of potent interfering compounds on the CL signal intensity of the proposed luminol-isoniazid-AgNPs system was investigated. The proposed method was successfully applied to the determination of isoniazid in a pharmaceutical sample.