National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
Analyst. 2013 Nov 21;138(22):6930-7. doi: 10.1039/c3an00112a.
A system for continuous generation and analysis of formaldehyde (HCHO) in a nitrogen gas mixture prepared using a permeation method was fabricated in order to evaluate the permeability of HCHO and water (H2O) through a permeation tube. Specifically, the mass balance of HCHO and H2O through a permeation tube was evaluated using the system. The results indicated that the mass loss in the permeation tube accounted for the amount of HCHO and H2O measured using a spectrometer. The permeability of HCHO was calculated by subtracting the mass loss of H2O from the permeation tube per unit of time as determined from the mass balance results. The calculated permeability of HCHO was 75.7 ± 3.4 mg min(-1) (k = 2) for the HCHO gas mixture prepared by the permeation method using a permeation tube filled with paraformaldehyde that was vacuum-dried at 95 °C. The calculated permeability agreed with the permeability obtained using the dinitrophenylhydrazine-derivatization method (72.7 ± 4.4 mg min(-1) (k = 2)) within the level of uncertainty. This technique, in which the mass loss of H2O from the permeation tube is subtracted, can therefore provide a reference gas mixture with an accurate HCHO concentration using the permeation method.
为了评估渗透管中甲醛（HCHO）和水（H2O）的渗透性，我们采用渗透法制备了一种氮气混合气体中连续生成和分析甲醛的系统。具体而言，我们使用该系统评估了渗透管中 HCHO 和 H2O 的质量平衡。结果表明，渗透管中的质量损失与使用分光光度计测量的 HCHO 和 H2O 量相当。通过从质量平衡结果中减去渗透管在单位时间内的 H2O 质量损失，计算出 HCHO 的渗透系数。使用真空干燥在 95°C 下填充多聚甲醛的渗透管制备的 HCHO 气体混合物的渗透系数为 75.7 ± 3.4 mg min-1（k = 2）。计算出的 HCHO 渗透率与使用二硝基苯肼衍生化法获得的渗透率（72.7 ± 4.4 mg min-1（k = 2））在不确定度范围内一致。因此，通过减去渗透管中 H2O 的质量损失，该技术可以使用渗透法提供具有准确 HCHO 浓度的参考气体混合物。
