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Indirect determination of D-penicillamine in pharmaceuticals by using atomic absorption spectrometry

This work describes the development of indirect atomic absorption spectrometric method for determination of D-penicillamine (PEN) in pharmaceutical preparations. The method is based on the complexation of PEN with Ag(I) ion. The optimum conditions for complexation reaction were determinated: 25 min at temperature 40°C and pH = 3.0. The unreacted Ag(I) ions from reaction solution were adsorbed on cation exchanger Amberlite IR 120 by batch process. The solution with retained complex, after required dilutation in 0.2 % HNO3, was subjected to electrothermal atomic absorption spectrometer (ETAAS). The absorbance linearly increases with increasing PEN concentration in range 10-70 g/mL (R2 = 0.993) with no need to use the standard addition method. Limit of detection (LOD) and limit of quantitation (LOQ) were obtained, 5.26 g/mL and 7.19 g/mL, respectively. The effect of resin dosage, pH, contact time and temperature on the adsorption of Ag(I) on ion exchange resin was studied. Also, graphite furnace temperature program and concentration of matrix modifier were optimized. Temperature of 800°C and 1600°C were selected for the pyrolysis and atomization steps, respectively, using a mixture of Pd and Mg(NO3)2 as a matrix modifier (at concentrations of 1g/L and 0.001 g/L, respectively). After some preliminary experiments for standards and samples no interfering effects were observed from the sample matrix. The method developed was applied to the determination of PEN in commercial available pharmaceuticals with mean recovery 101.8 %.

penicillamine; atomic absorption spectrometry; indirect determination; complexation with Ag(I)

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