Determination Of Regional Geochemical Exploration Samples Of21Elements Emission Spectrometry

The method of atomic emission spectroscopy(AES) can directly analyze solid samples in geochemical exploration analysis with less samples, high analysis speed, and good precision. Meanwhile, the method of inductively coupled plasma-atomic emission spectrometry (ICP-AES) has many excellent features, such as high sensitivity, low detection limits, great accuracy, and multi-element determination. In this paper, making use of advantages from both AES and ICP-AES, the method of combining AES and ICP-AES was introduced, with the ability of determinating the twenty one major, minor and trace elements of Calcium, Magnesium, Sodium, Iron, Barium, Beryllium, Cerium, Cobalt, Copper, Lanthanum, Lithium, Manganese, Nickel, Scandium, Strontium, Vanadium, Zinc, Silver, Tin, Lead, and Molybdenum involved in geochemical exploration analysis.In ICP-AES analysis, hydrochloric acid, nitric acid, hydrofluoric acid and perchloric acid were firstly added into samples and aged overnight. In the next day samples were heated until the white smoke of perchloric acid was over, after that samples were dissolved by adding hydrochloric acid and diluted for determination. This method can minimize the tedious steps of chemical pre-treatment of samples and the introduction of the substrate impurities. Besides, the dissolution method and the main operating parameters of the instrument of ICP-AES were also optimized, such as the carrier gas flow rate, the observed height and so on. The excitation light source of AES is direct-current arc (DC), and CTFE powder, aluminum oxide, potassium, sulfur powder, carbon powder, magnesium oxide were mixed and used as the buffer. Cadmium and antimony were used as internal standard in two meters WPP-2type plane grating spectrograph, and vertical electrode were used for perturbation spectrum. At the end, combining the above conditions, photometry and Excel2003were used for fitting the standard curve and calculating the results. In AES, buffer was added to suppress substantial evaporation of the matrix elements, reduce or eliminate the interference of the matrix elements to improve the stability of the light source, and increase the spectral intensity, which lead to reduce the detection limit of the test element ultimately.The matching analysis method combined the advantages of two light sources of emission spectra, with multiple elements analysed and short analysis cycle involved. This method was tested by geochemical reference materials of the State-level, with the precision (RSD, n=12) under10%. The elements detection limits, precision and accuracy have met the requirements of Geology and Mineral laboratory testing and quality management practices (DZI T0130-2006) and regional geochemical exploration norms (DZ/T0167-95), It has been applied in analysis elements of regional geochemical survey project by our work unit, which led to the reducing of the analysis cost and the great boosting of work efficiency.