Webber James S, Czuhanich Alex G, Carhart Laurie J
New York State Department of Health, Wadsworth Center, Albany, New York 12201, USA.
J Occup Environ Hyg. 2007 Oct;4(10):780-9. doi: 10.1080/15459620701588385.
This article presents findings related to characteristics of membrane filters that can affect the recovery of asbestos and the quality of preparations for transmission electron microscopy (TEM) analysis. Certain applications and preparation steps can lead to unacceptable performance of membrane filters used in analysis of asbestos by TEM. Unless substantial care is used in the collapsing of mixed-cellulose ester (MCE) filters with an acetone hot block, grid preparations can suffer and fiber recoveries can be compromised. Calibration of the etching depth of MCE filters, especially at differing locations in an asher's chamber, is critical for reliable fiber recovery. Excessive etching of MCE filters with aerosol-deposited asbestos can lead to loss of short fibers, while insufficient etching of MCE filters with aqueous-deposited asbestos can, paradoxically, also lead to loss of short fibers. Interlaboratory precision on MCE filters is improved by aerosol-deposited asbestos, as opposed to aqueous deposition. In comparison, straightforward preparation, improved solvents, and reduced contamination make PC filters an increasingly acceptable alternative. Variations in the geometric configuration during application of carbon films can lead to fiber loss and unacceptable grid quality for either type of filter.
本文介绍了与膜滤器特性相关的研究结果，这些特性可能会影响石棉的回收率以及透射电子显微镜（TEM）分析用制剂的质量。某些应用和制备步骤可能会导致用于TEM石棉分析的膜滤器性能不佳。除非在使用丙酮热块折叠混合纤维素酯（MCE）滤器时格外小心，否则网格制备可能会受到影响，纤维回收率也会降低。校准MCE滤器的蚀刻深度，尤其是在灰化室的不同位置，对于可靠的纤维回收至关重要。用气溶胶沉积的石棉对MCE滤器过度蚀刻会导致短纤维损失，而用水性沉积的石棉对MCE滤器蚀刻不足，矛盾的是，也会导致短纤维损失。与水性沉积相比，气溶胶沉积的石棉提高了不同实验室对MCE滤器测量的精度。相比之下，简单的制备、改良的溶剂和减少的污染使聚碳酸酯（PC）滤器成为越来越可接受的替代品。在应用碳膜过程中几何构型的变化可能会导致纤维损失以及两种类型滤器的网格质量都不符合要求。
