ABSTRACT
With the use of high pure HF and HNO3 reagents, and autoclaves made of high purity Rerfluoroalkoxy ( PFA ) material, a solution sample digestion technique effective for phosphate samples, subjected to high temperature fusion, was established. The whole procedure was concise, fast and of low blank value. Key factors such as the amount and ratios of the reagents, the digestion temperature and time, were systematically optimized, it was found that within 0. 5 h at 150 ℃, only 1. 7 mL of total reagent consumption could lead to a complete sample decomposition. Most importantly, the samples were not required to be ground to fine powder, which greatly reduced the risk of contamination. In addition, an effective liquid_liquid extraction procedure based on 5_nonylsalicylaldehyde oxime as the extractant was established for matrix separation and analyte preconcentration. Under the optimal extraction conditions of 5 mL of 15% extractant, 0. 5% HNO3 of extraction acidity and 20% HNO3 of back_extraction acidity, a matrix separation efficiency of over 99. 999% could be realized and a preconctration factor of 10 could be obtained, which resulted in complete elimination of the matrix_induced interference and great enhancement of the analytical sensitivity. After optimization of the operation parameters of ICP_MS, high signal to background detection of Cu in 20%HNO3 at 840 W of plasma power and low sample uptake rate were realized. The detection limits of 2. 5 ng/g, RSD of 3. 3% for six detections of parallel samples, and the recovery of 94. 3% for spike test were obtained, respectively. The method was finally applied to three real samples analysis, and the results agreed well with the data from laser adsorption loss experiment.
ABSTRACT
AnewmethodwasdevelopedforfastdeterminationofAlresidueinpolyetherketoneketone ( PEKK) special polymer material by graphite furnace atomic absorption spectrometry ( GF-AAS) . Instead of high temperature ashing, sample was dissolved in concentrated sulfuric acid and diluted by tetrahydrofuran, then was directly analyzed by GF-AAS. Systematical investigation was made on sample preparation, it was found that for 0. 2 g of sample weight, a clear sample solution could be obtained by heating at 220 ℃ with 2 mL of concentrated H2 SO4 for 4 min, and the obtained solution was ready for the subsequent mixing with tetrahydrofuran for sample dilution or dispersion before analysis. Redesign of the GF-AAS temperature program was also made, on the basis of the recommended program a pre-ashing step was added, which greatly helped increasing the analytical precision when the temperature was set at 400 ℃ and the total time was set at 40 s. The detection limits ( 3σ) were 38. 5 ng/g, the RSD for six parallel determinations of real samples was 2. 2%, and the recoveries for spiked tests were 99%-105%, respectively. In comparison with the traditional high-temperature ashing technique, the established method was more concise, faster and less exposed to contamination during sample preparation.