The John and Willie Leone Family Department of Energy and Mineral Engineering, Penn State University, University Park, PA 16802-5000, USA.
J Occup Environ Hyg. 2012;9(10):572-9. doi: 10.1080/15459624.2012.713763.
A study was conducted to examine whether there are significant differences between organic vapor concentrations measured using charcoal tubes with three different configurations: uncovered sample holder (open tube), SKC, and Buck brand covered sample holders. A fractional factorial experimental design was used with the following factors and levels: vapor (n-hexane vs. m-xylene), pump type (pulsating vs. continuous), exposure profile (variable vs. constant), flow rate (30 mL/min vs. 200 mL/min), duration (30 min vs. 80 min), and sample placement (mannequin vs. free hanging). Two of each sampler configuration (six total) were placed in an exposure chamber, and a dynamic test-atmosphere generation system was used to prepare atmospheres containing approximately 12-15 ppm n-hexane or m-xylene with exposure profiles and sampling conducted according to a run sheet generated for the experimental design. A total of 24 runs were completed with six samplers per run, yielding 144 samples that were analyzed by gas chromatography/flame ionization detector. Concentration results for each pair of SKC and Buck covered sample holders were averaged and normalized by dividing by the average result for the open tube sampler from the same run to eliminate the effect of daily variation in chamber concentrations. The resulting ratio of covered sample tube holder and open tube concentrations was used as the response variable. Results of analysis of variance using the general linear model (MINITAB 16) identified statistically significant main effects and/or interactions for pump type, exposure profile, flow rate, and sample holder. However, the magnitude of the effects was generally less than 10%, and overall mean concentration ratios were 0.989 and 1.02 for the Buck and SKC sample holders, respectively. These results show good agreement between covered sample holder results and open tube measurements and demonstrate that exposure assessment errors resulting from the use of covered sorbent tube sample holders for organic vapor monitoring are relatively small (<10%) and not likely to be of practical importance.
一项研究旨在检验使用三种不同配置的活性炭管（未覆盖样品架、SKC 和 Buck 品牌覆盖样品架）测量有机蒸气浓度是否存在显著差异。采用部分因子实验设计，考虑了以下因素和水平：蒸气（正己烷与间二甲苯）、泵类型（脉冲式与连续式）、暴露剖面（变化与恒定）、流速（30mL/min 与 200mL/min）、持续时间（30min 与 80min）和样品放置位置（人体模型与自由悬挂）。每种采样器配置各放置两个（共计六个）在暴露室内，使用动态测试气氛生成系统来制备含有约 12-15ppm 正己烷或间二甲苯的气氛，按照为实验设计生成的运行表进行暴露剖面和采样。共完成 24 次运行，每次运行使用 6 个采样器，产生 144 个样品，通过气相色谱/火焰离子化检测器进行分析。将每个 SKC 和 Buck 覆盖样品架的结果进行平均，并通过除以同一运行中开放管采样器的平均结果进行归一化，以消除室内浓度日常变化的影响。覆盖样品管架与开放管浓度的比值作为响应变量。使用通用线性模型（MINITAB 16）进行方差分析的结果确定了泵类型、暴露剖面、流速和样品架的统计学显著主效应和/或交互作用。然而，效应的幅度通常小于 10%，Buck 和 SKC 样品架的总体平均浓度比分别为 0.989 和 1.02。这些结果表明，覆盖样品架结果与开放管测量结果之间具有良好的一致性，并且暴露评估误差使用覆盖吸附管采样器进行有机蒸气监测相对较小（<10%），不太可能具有实际意义。
