Study On Microwave-Assisted Sample-Preparation Technology For The Analysis Of Inorganic And Organic Components In Aloe

Aloe is widely used for pharmaceuticals and cosmetics because of its aromatic properties, bitter taste, the cathartic activity of anthraquinones and other pharmacological activities, such as emolliency, redudtion of inflammation and acceleration of wound healing. It will direct people to deal with Aloe correctly by studying on extraction method on the effective components and the determination of trace metal in the Aloe.Determination of trace metal in Aloe by microwave digestion-atomic absorption spectrometry, the Microwave-assisted Extraction of Barbaloin and aloe-emodin in Aloe and microwave-assisted extraction mechanism are studies in this paper.A microwave digestion procedure was developed for trace Zn,Mn,Cd and Pb in aloe –leaf cuticle and aloe-leaf gelatin, using the closed vessel microwave digestion system with pressure controlling part, and the amounts of these trace metallic elements were determined by atomic absorption spectrometry after microwave digestion. The effects of the composition of mixed acid, the ratio of mixed acid, the ratio between solid and liquid and the digestion time were discussed. From the results, the optimum conditions for the closed vessel microwave digestion for aloe samples were established. The optimum parameters for the closed vessel microwave digestion system were that the mixed acid was HNO3-HCl, the ratio of mixed acid HNO3-HCl was 8:3, the ratio between solid and liquid was 1:12 and the digestion time was 6 minute. Under the optimum condition, parallel experiments and recovery experiments were completed. The relative standard deviation is 0.3%~6.2% and the recovery is 95.0%~110.0%.The results show that this method is rapid,simple,minimized environmental contamination and the samples are completely digested, the chemical reagents were economized during the sample preparation. The precision and accuracy are satisfactory.Microwave extraction of barbaloin and aloe-emodin in aloe,using the closed vessel microwave digestion system, was studied in this paper. The effects on barbaloin of the solvent sort, solvent consistence, radiation time and microwave power were discussed in orthogonal experiments. The results showed that the optimized extraction parameters were ethanol-water 70:30, radiation time 4min, microwave power 340W The effects on aloe-emodin of the solvent , solvent to sample ratio, microwave irradiation time and microwave power were also discussed in the experiments. The optimized conditions of MAE of aloe-emodin can be concluded that the best solvent is 80% ethanol(v/v) solution, microwave irradiation is time 3min, microwave power is 340W . Compared with Soxhlet extraction and ultrosonic extraction, microwave extraction is a rapid method with higher yield, less solvent consumption. To study the microstructure destruction of plants in the processs of microwave-assisted extraction and its mechanism. Cell structures of fresh leaves of aloe were observed by Transmission Electronic Microscope. Also we contrast MAE with traditional solvents extraction method. The result showed that the cell structure changed when the leaves were under microwave radiation or solvent heating, and the cytoderm was broken in microwave-assisted extraction, while it was not broken in traditional solvent heating.