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以《工作场所空气中粉尘测定第4部分:游离二氧化硅含量》(GBZ/T192.4—2007)焦磷酸法为基础对三种不同游离SiO2含量的粉尘(用1、2、3号表示)进行测定,溶解时间为10 min、15 min、20 min,过滤过程采用四种不同来源的慢速定量滤纸进行比对,灰化过程分别采用两种型号马弗炉(用Ⅰ、Ⅱ号表示),灰化时间为30 min、45 min、60min。不同溶解时间测定1号粉尘的游离SiO2含量差异无统计学意义(P>0.05),不同溶解时间测定的2、3号粉尘的游离SiO2含量差异有统计学意义(P<0.05),其中溶解时间10min测定的游离SiO2结果明显高于溶解时间≥15 min的测定结果 (均P<0.05)。采用四种来源的慢速定量滤纸过滤测定1、2、3号粉尘的游离SiO2含量差异均无统计学意义(均P>0.05)。Ⅰ号马弗炉30 min的灰化时间测定三种粉尘游离SiO2含量结果均高于标准参考值(P<0.05),Ⅱ号马弗炉不同灰化时间(30 min、45 min、60 min)测定三种粉尘的游离SiO2含量结果差异均无统计学意义(P>0.05)。焦磷酸法测定粉尘中游离SiO2含量时,溶解时间应不低于标准要求的15min,实验过程中应加强对滤纸过滤效果和马弗炉灰化温度的质控,必要时应适当延长灰化时间。
The dust with three different free SiO2 contents based on the pyrophosphoric acid method of “Determination of dust in workplace air - Part 4: Free silica” (GBZ / T192.4-2007) ), The dissolution time was 10 min, 15 min, 20 min, the filtration process using four different sources of slow quantitative filter paper for comparison, the ashing process were used two models muffle furnace (with Ⅰ, Ⅱ, said ), Ashing time is 30 min, 45 min, 60min. There was no significant difference in the free SiO2 content of No 1 dust (P> 0.05) at different dissolution time. The free SiO2 content of No.2 and No.3 dust was significantly different at different dissolution time (P <0.05), and the dissolution time The results of free SiO2 measured at 10 min were significantly higher than those at the dissolution time> 15 min (all P <0.05). There was no significant difference in the free SiO2 content of the dusts 1, 2 and 3 when using the four types of slow quantitative filter paper filter (all P> 0.05). The results of the determination of the free SiO2 content of the three kinds of dust were all higher than those of the standard reference (P <0.05). The different ashing times (30 min, 45 min and 60 min) There was no significant difference in the determination of free SiO2 between the three kinds of dust (P> 0.05). Pyrophosphorimetric method for the determination of free SiO2 in the dust, the dissolution time should not be less than the standard requirements of 15min, during the experiment should be to strengthen the filter paper filter effect and muffle furnace ash temperature control, if necessary, should be extended ashing time .