EFFECTIVENESS OF PALLADIUM AS A CHEMICAL MODIFIER FOR DIRECT SILVER AND MANGANESE DETERMINATION IN COCAINE AND HEROIN BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

Methods for the direct determination of silver and manganese in cocain e and heroin by electrothermal atomic absorption spectrometry using pa lladium as chemical modifier have been developed. Cocaine samples, 0.5 g, were dissolved in 2 ml of 35.0% (m/v), HNO3 diluting to 10 ml with ultrapure water. A comparative study of palladium, magnesium nitrate, palladium-magnesium nitrate and nitric acid used as chemical modifier s was carried out, and it was found that palladium alone is adequate t o stabilize silver and manganese at charring temperatures of 1000 and 1300 degrees C respectively. A study was made on the insertion of a co oling step before the atomization step, and this approach was not adva ntageous. Limits of detection of 2.3 and 6.9 mu g kg(-1) were obtained for silver and manganese respectively. The analytical recovery oscill ated between 95.9 and 103.6% for silver and between 99.7 and 103.0% fo r manganese. Finally, a study of some interferences and a study of the precision and analytical recovery of the amount of sample were also c arried out.