Martos P A, Pawliszyn J
The Guelph [Formula: see text] Waterloo Centre for Graduate Work In Chemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
Anal Chem. 1998 Jun 1;70(11):2311-20. doi: 10.1021/ac9711394.
Gaseous formaldehyde is sampled by derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) adsorbed onto poly (dimethylsiloxane)/divinylbenzene solid-phase microextraction fibers. The product of the reaction is an oxime which is thermally very stable and insensitive to light. The oxime can be analyzed by gas chromatography with flame ionization detection and other detectors. Loading PFBHA on the fiber is by room-temperature headspace extraction from aqueous solutions of PFBHA. The process of loading and desorption of unreacted PFBHA, and oxime formed, is both highly reproducible and reversible, with more than 200 loading, sampling, and analysis steps possible with one fiber. The standard formaldehyde gas concentrations studied ranged from 15 to 3200 ppbv with sampling times from 10 s to 12 min. Quantification can be achieved via interpolation from calibration curves of area counts as a function of formaldehyde concentration for a fixed sampling time. Sampling for 10 s yields a method detection limit of 40 ppbv and at 300 s the method detection limit is 4.6 ppbv. This is equal to or better than all other conventional grab sampling methods for gaseous formaldehyde employing sampling trains or passive sampling techniques. Alternatively, gaseous formaldehyde can be quantified with an empirically established apparent first-order rate constant (0.0030 ng/(ppbv s) at 25 °C) for the reaction between sorbed PFBHA and gaseous formaldehyde. This first-order rate constant allows for quantitative analyses without a calibration curve, only requiring detector calibration with the oxime. This new method was used for the headspace sampling of air known to contain formaldehyde, as well as other carbonyl compounds, and from various matrixes such as cosmetics and building products.
气态甲醛通过与吸附在聚（二甲基硅氧烷）/二乙烯基苯固相微萃取纤维上的盐酸邻（2,3,4,5,6 - 五氟苄基）羟胺（PFBHA）衍生化进行采样。反应产物是一种肟，它热稳定性非常高且对光不敏感。肟可以通过带有火焰离子化检测和其他检测器的气相色谱法进行分析。将PFBHA加载到纤维上是通过从PFBHA水溶液中进行室温顶空萃取。未反应的PFBHA以及形成的肟的加载和解吸过程具有高度的可重复性和可逆性，一根纤维可以进行200多次加载、采样和分析步骤。所研究的标准甲醛气体浓度范围为15至3200 ppbv，采样时间为10秒至12分钟。对于固定的采样时间，可以通过根据甲醛浓度的函数关系从面积计数校准曲线进行插值来实现定量。采样10秒时方法检测限为40 ppbv，采样300秒时方法检测限为4.6 ppbv。这等同于或优于所有其他采用采样装置或被动采样技术的气态甲醛传统采集采样方法。或者，气态甲醛可以通过经验确定的吸附的PFBHA与气态甲醛之间反应的表观一级速率常数（25℃时为0.0030 ng/(ppbv s)）进行定量。这个一级速率常数允许在无需校准曲线的情况下进行定量分析，仅需要用肟对检测器进行校准。这种新方法用于对已知含有甲醛以及其他羰基化合物的空气进行顶空采样，这些空气来自各种基质，如化妆品和建筑产品。
