磷酸法应用于工作场所粉尘中游离二氧化硅测定方法改进的研究

Study on determination of free silica in dust of workplace by phosphoric acid.

对工作场所粉尘中游离二氧化硅(SiO_(2))的测定方法进行改进,并予以探讨。采集呼吸带高度沉降尘,经干燥、冷却,称取0.1000-0.2000 g粉尘样品于100 mL锥形瓶中,加85%磷酸,在可调电阻炉上加热。利用加热浓磷酸的酸性、配位性,溶解碳酸盐、金属氧化物及硅酸盐矿物等,使其转变为二氧化碳、可溶性金属盐类等。进一步加热至240土5℃,磷酸转化成焦磷酸,使难溶硅酸盐进一步变为磷硅杂多酸完全溶解。热蒸馏水稀释,趁热过滤分离、灼烧并称量。运用磷酸法对实际样品和实验室盲样测定,都能有效提高游离SiO_(2)测定结果准确性,缩短检测时间,减少误差,提高精密度。本方法适用于工作场所粉尘中游离SiO_(2)检测,操作性强,实验条件易控制,适合批量检测。

Collecting the settling dust at respiration zone,dry and cool,0.1—0.2 g of dust sample is weighed and put into 100 mL Erlenmeyer flask.Heating the mixture of the sample and 85%phosphoric acid,the mixture is changed into carbon dioxide,soluble metal salts,more acid and so on.Further heating to 240±5℃,the phosphoric acid is changed into pyrophosphate acid,and the silicate is further changed into phosphosilicate heteropoly acid,which is completely dissolved.Dilute the sample with hot distilled water,filter and separate while it is hot,burn and weigh the sample.Used to determine the actual samples and unknown samples in the laboratory,the phosphoric acid method can effectively improve the accuracy of free SiO_(2) determination results,shorten the detection time,reduce the error and improve the precision.This method is easy to operate and control the experimental conditions,and is suitable for batch testing.