Objective: To investigate the differences and applicability of free silica detection methods of different crystal forms in dust, and to provide a basis for the selection of various methods. Methods: From December 2021 to June 2022, dust samples from 20 enterprises in different industries in 18 cities in Henan Province were randomly selected as the investigation objects. X-ray diffraction (XRD) method was used to analyze the samples and classify the samples. Based on GBZ/T 192.4-2007 "Determination of Dust in the Air of Workplace-Part 4: Content of Free Silica in Dust", pyrophosphate method and infrared spectrophotometry were used for quantitative determination. The measured results were analyzed by paired sample t test to evaluate the advantages and disadvantages of the two methods and their applicable scope. Results: The XRD results of 20 dust samples could be divided into α, β, γ crystal types and the mixed type of α and γ. There was no significant difference between pyrophosphate method and infrared spectrophotometry (P=0.180). The pyrophosphate method results of β, γ and α, γ mixed crystalline free silica were significantly higher than those of infrared spectrophotometry, and the difference was statistically significant (P<0.001) . Conclusion: Pyrophosphate method and infrared spectrophotometry are suitable for α-type free silica, while pyrophosphate method is suitable for β, γ and α, γ mixed crystalline free silica.
目的： 探讨粉尘中不同晶型游离二氧化硅检测方法的差异性与适用性，为各种检测方法的选择提供依据。 方法： 2021年12月至2022年6月，随机选择河南省内18地市不同行业20家企业粉尘样品作为调查对象，采用X线衍射（XRD）法对样品进行晶型分析，并对晶型分类后样品进行归类，再依据GBZ/T 192.4-2007《工作场所空气中粉尘测定 第4部分：游离二氧化硅含量》中焦磷酸法和红外分光光度法进行定量测定，结果进行配对样本t检验分析，评价方法优劣和适用范围。 结果： 20份粉尘样品XRD法检测结果晶型可分为α、β、γ型及α、γ混合型。其中α型游离二氧化硅的焦磷酸法和红外分光光度法检测结果差异无统计学意义（P=0.180）；β、γ型和α、γ混合型游离二氧化硅的焦磷酸法测定结果明显高于红外分光光度法，差异有统计学意义（P<0.001）。 结论： 焦磷酸法和红外分光光度法均适用于α型游离二氧化硅的检测，β、γ型及α、γ混合型游离二氧化硅的检测方法适宜选用焦磷酸法。.
Keywords: Crystal form; Dust; Free silica; Pyrophosphate method; Spectrophotometry, infrared; X-ray diffraction.