[Determination of trace elements of Gentiana macrophlla and Gentiana straminea by microwave digestion-FAAS].
An acid-assisted microwave digestion procedure is optimized for the determination of trace elements in traditional Chinese medicine by the use of flame atomic absorption spectrometric (FAAS) techniques. Microwave-assisted digestion has the advantages of reduced time for sample dissolution, fewer possibilities for technical errors caused by spilling of hot digestion solutions, use of less chemicals, and lower losses of volatile metals. In addition, modern microwave ovens are safer and simpler and provide more controlled and reproducible conditions than hot plate or block digesters. Flame atomic absorption spectrometry (FAAS) is more commonly applied techniques in the de termination of trace elements. The accurate measurement of trace elements concentrations in samples of traditional Chinese medicine is an important goal in research for medical effects of traditional Chinese medicine. The purpose of this study was to determine the contents of the trace elements in Gentiana macrophlla and Gentiana straminea. In order to identify the accuracy of the procedure, the operating conditions was selected before the determination of trace elements. In order to gauge the effectiveness of digestion, the selection of digestion conditions of the technique was undertaken. The results showed HNO3-H2O2 (5 : 1) as a microwave digestion agent with suitable temperature and time was optimum choice in the digestion procedure. Analysis limits were also selected according to the low detection limits and the good precision. They were Fe(248.3 nm), Mn (279.5 nm), Ni (232.0 nm), Cu(324. 8 nm), Zn (2.139 nm), Ca (422.7 nm), Mg (285.2 nm) and Cr (357.9 nm), respectively. The working curves were obtained by using multi-elemental standard solutions and line relation was good. Under the selected conditions, the contents of trace elements Fe, Mn, Ni, Cu, Zn, Ca, Mg and Cr in Gentiana macrophlla and Gentiana straminea were directly determined using working curve methods. The relative standard deviations (RSD) and recovery of the method have been undertaken to obtain reliable results for trace element determinations. The recovery rates obtained by standard addition method were between 88.1%-114.5%, and the relative standard deviations (RSD) were lower than 3.12% after optimization of the operating conditions. These figures showed that the method gave good recoveries and accuracy. The analytical results indicated that there were comparatively rich elements in Gentiana macrophila and Gentiana straminea, such as Ca, Mg, Fe, Mn and Zn, especially the concentration of Ca and Mg. However, concentrations of Ni and Cr in Gentiana macrophlla and Gentiana straminea were very low, especially the concentration of Ni. The worse value obtained for Ni was probably due to its inhomogeneous distribution and very low concentration in Gentiana macrophlla and Gentiana straminea. In addition, a comparison of the contents of trace elements between Gentiana macrophlla and Gentiana straminea indicated that Gentiana macrophlla was rich in the trace elements such as Fe, Mn, Ni and Mg, and Gentiana straminea was rich in the trace elements such as Zn, Cu, Ca and Cr. The result will provide scientific datas for discussing the relationship between the contents of these elements in Gentiana macrophlla and Gentiana straminea and the medical effects. Furthermore, our study provides new scientific foundation for further study and general application of Gentiana macrophlla and Gentiana straminea.
Zhou
Yu-Shan
YS
Department of Chinese Herb, Gansu College of Traditional Chinese Medicine, Lanzhou 730000, China. yushanzhou2003@163.com
Zhang
Xi-Ling
XL
Wang
Rong-Bin
RB
Xia
Qi
Q
An
Xia
X
D030012:Gentiana / Q000737:chemistry*; D008872:Microwaves; D013054:Spectrophotometry, Atomic / Q000379:methods*; D014131:Trace Elements / Q000032:analysis*
D014131:Trace Elements