样品经过筛和烘干后,分取约0.2 g,进行高温-常压消解法或微波消解法溶样。将样品置于100 mL聚四氟乙烯烧杯中,加入10 mL硝酸、5 mL氢氟酸和1 mL高氯酸,加盖后于120℃消解3 h,再于200℃加热至高氯酸冒烟约3 min,冷却,冲洗杯壁后继续加热至高氯酸冒烟,即得高温-常压消解法消解液。将样品置于消解罐中,用少量水润湿,加入2 mL硝酸、2 mL氢氟酸和1 mL高氯酸,在程序升温条件下消解样品,冷却至室温后,将溶液全部转入30 mL聚四氟乙烯烧杯中,于200℃加热至高氯酸冒烟约3 min,冷却,冲洗杯壁后继续加热至高氯酸冒烟,冷却后即得微波消解法消解液。在上述消解液中加入4.0 mol·L^-1盐酸溶液10 mL,于80℃加热30 min,冷却后加入10 g·L^-1(以铁计)三氯化铁溶液10 mL (可有效掩蔽共存离子W³⁺、Cu²⁺、Zn²⁺和Bi³⁺的干扰),用4.0 mol·L^-1盐酸溶液稀释至50 mL,静置至澄清,分取适量上清液进入以4.0 mol·L^-1盐酸溶液为载流液、20 g·L^-1硼氢化钠溶液为还原剂的原子荧光光谱仪,在400 mL·min^-1载气流量下测定。结果显示,硒、碲的质量浓度均在0.10~20.00 μg·L^-1内与其对应的荧光强度呈线性关系,检出限(3s)分别为0.008,0.006 μg·L^-1;对标准物质(GBW 07240、GBW 07241和GBW 07284)平行测定5次,高温-常压消解法和微波消解法所得硒、碲测定值均在认定值的不确定度范围内,测定值的相对标准偏差(n=5)均小于4.0%;方法应用于实际钨矿石样品的分析,高温-常压消解法的测定值和微波消解法的基本一致。

After sieving and drying, about 0.2 g of sample was taken and dissolved by methods of high temperature-atmospheric pressure digestion or microwave digestion. The sample was digested at 120 ℃ for 3 h in a covered 100 mL-teflon beaker with 10 mL of nitric acid, 5 mL of hydrofluoric acid and 1 mL of perchloric acid, and continuously heated at 200 ℃ until perchloric acid smoked for about 3 min. After cooling to room temperature and rinsing walls of the beaker, the mixture was heated until perchloric acid smoked, and the high temperature-atmospheric digestion solution was obtained. The sample was put into a digestion tank, wetted with a small amount of water, and digested with 2 mL of nitric acid, 2 mL of hydrofluoric acid and 1 mL of perchloric acid under temperature-programmed condition. After cooling to room temperature, the solution was transferred into a 30 mL-teflon beaker, and heated at 200 ℃ until perchloric acid smoked for about 3 min. After cooling and rinsing walls of the beaker, the mixture was heated continuously until perchloric acid smoked, and the microwave digestion solution was obtained. The above solution was mixed with 10 mL of 4.0 mol·L^-1 hydrochloric acid solution, and the mixed solution was heated at 80 ℃ for 30 min. After cooling, 10 mL of 10 g·L^-1 (calculated by iron) ferric chloride solution was added, to effectively mask the interference of coexisting ions including W³⁺, Cu²⁺, Zn²⁺ and Bi³⁺, and the mixed solution was diluted to 50 mL with 4.0 mol·L^-1 hydrochloric acid solution. After settling until clear, an appropriate amount of supernatant was taken, introduced into the hydride generation atomic fluorescence spectrometer with 4.0 mol·L^-1 hydrochloric acid solution as carrier liquid and 20 g·L^-1 sodium botohydride solution as reducing agent, and detected at 400 mL·min^-1 carrier gas flow. It was shown that linear relationships between values of the mass concentration and corresponding fluorescence intensity of selenium and tellurium were kept in the range of 0.10-20.00 μg·L^-1, with detection limits (3s) of 0.008, 0.006 μg·L^-1, respectively. The standard substances (GBW 07240, GBW 07241 and GBW 07284) were determined 5 times in parallel, and the determined values of selenium and tellurium obtained by methods of high temperature-atmospheric pressure digestion and microwave digestion were within the uncertainty ranges of the certified values, with RSDs (n=5) of the determined values less than 4.0%. The proposed method was applied to the analysis of actual tungsten ore samples, and the determined values of the high temperature-atmospheric pressure digestion method were basically consistent with those of the microwave digestion method.