Comparison of palladium-magnesium nitrate and ammonium dihydrogenphosphate modifiers for cadmium determination in honey samples by electrothermal atomic absorption spectrometry

摘要

The occurrence of certain trace elements, such as cadmium, in honey been can be considered as an indication of environmental pollution. In the present work, two methods for Cd determination in honey by electrothermal atomic absorption spectrometry, using palladium-magnesium nitrate and ammonium dihydrogenphosphate as chemical modifiers, have been developed. In none of these cases honey samples required pretreatment. Honey was diluted in water (20% w/v), and hydrogen peroxide, nitric acid, and Triton X-100 were added to minimize the matrix effect. For the first method, 21.6 μg of palladium and 4.5 μg of magnesium were added as chemical modifier; for the second method, 60 μg of ammonium dihydrogenphosphate were employed. The limits of detection obtained were 0.32 ng g~(-1) for ammonium dihydrogenphosphate method and 0.54 ng g~(-1) for palladium-magnesium nitrate method. The characteristic mass was 0.7 and 1.0 pg for amonium dihydrogenphosphate and palladium-magnesium nitrate methods, respectively. The relative standard deviation (< 10%) and the analytical recovery (98-105%) were comparable in both methods. The optimised methods were applied to the determination of the cadmium content in unpolluted Galician honey samples. Cd has been detected the analysed samples in the range (n.d. -4.3 ng g~(-1)).