SAMPLE PREPARATION STUDY BY THE ACID DIGESTION ASSISTED BY MICROWAVE RADIATION IN CLOSED SYSTEM FOR DETERMINATION OF INORGANIC CONTAMINANTS IN COCAINE SAMPLES BY ICP OES

Knowledge of the inorganic composition of cocaine makes it possible to correlate the drug with its refining and dilutions1, it is important to emphasize that when it is intended to study the adulteration/production of street cocaine, it is interesting to carry out the total solubilization of the sample2. Thus, acid digestion using closed-microwave microwave radiation is a widely used technique because of the speed and efficiency of digestion3. Thus, acid solubilization procedures and acid digestion assisted by microwave radiation of the sample were studied, varying the mass of the sample (0.050g, 0.100g, 0.200g and 0.500g) and concentration of the HNO3 solution (5%, 10%, 30%, 40% and 50% v/v). For sample preparation using direct acid solubilization it was found that for a part of the samples there was no complete solubilization, independent of the acid concentration and the mass of the sample used. For the different samples, it was verified that the use of 6 mL of 5% v/v HNO3 was already efficient for the total digestion using microwave radiation, regardless of the mass used, this concentration was adopted and there was no need for Using a higher acidity, which could lead to interference during the quantification of the elements by ICP OES. In order to verify if the different sample preparation procedures and the final acidity interfere in the quantification of the studied analytes, ICP OES analyzes of a high purity sample prepared by direct solubilization and digestion were carried out. The results of the test of the intensities for the Co, Cu, Mo, Pb and Zn elements, with final acidity of 2% or 4% v/v HNO3, showed that samples prepared by direct solubilization or microwave digested with The final values of HNO3