EFEKTIVITAS METODE DESTRUKSI DENGAN MICROWAVE UNTUK ANALISIS KALSIUM DAN MAGNESIUM DALAM DAUN PEGAGAN; EFFECTIVENESS OF THE MICROWAVE DIGESTION FOR THE DETERMINATION OF CALCIUM AND MAGNESIUM IN THE PEGAGAN LEAVES

D I A R I Z K I S E P T I A N A, Roto

2011 | Disertasi | PROGRAM STUDI S2 ILMU KIMIA

Sample preparation methods by wet ashing and dry ashing are commonly used to decompose biological materials. However both methods have many disadvantages including loss of analytes. The present work was undertaken to develop a simple and inexpensive sample preparation method for the analysis of Ca and Mg in Pegagan (Centella asiatica) leaves using microwave oven. The ratio of nitric acid and hydrogen peroxide mixtures were compared to find out the effectiveness of sample dissolution. Calcium and magnesium were analyzed by atomic absorption spectroscopy (AAS). Ratio values of Ca obtained following microwave digestion method using a mixture of HNO3/H2O2 (2:1, v/v) were 103.02% with relative standard deviation (RSD) of 1.84%. The ratio values for Mg obtained following microwave digestion method using a mixture of HNO3/H2O2 (1:2, v/v) were 99.87% with RSD of 2.06%. Statistical test of the results of analysis show good agreement between wet ashing and microwave digestion method with HNO3/H2O2 1:2 (v/v) and 2:1 (v/v) respectively. In addition, dry ashing gives low ratio values but high relative standard deviation (RSD). The results show that microwave digestion method with HNO3/H2O2 1:2 (v/v) or 2:1 (v/v) provides an alternative sample preparation method for plants samples for mineral analysis with reasonable ratio values and RSD.

Kata Kunci : destruksi, microwave, kalsium, magnesium