Sampling and Determination of Formaldehyde Using Solid-Phase Microextraction with On-Fiber Derivatization

Abstract

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.

Determination of thiol compounds by automated headspace solid‐phase microextraction with in‐fiber derivatization

“…[27][28][29] The simplest way to carry out this process is to dope the fiber with a derivatization reagent and expose it to the sample. Then, the analytes are extracted and converted to derivatives that exhibit a high affinity for the coating ( Figure 1).…”

“…The agitation speed was set at 500 rpm for the loading of the derivatization reagent in order to accelerate the transfer of the reagent onto the SPME fiber coating. Based on the results of similar experiments, [27][28][29] 50°C and 1 h were adopted as the temperature and time for HS-SPME extraction. The results of the screening illustrated that, of all the commercially available SPME fibers, PDMS-DVB fiber had the best extraction performance for the N-phenylmaleimide derivatives over the rest of the fibers (Figure 2).…”

Optimization of methods for the determination of DBPs

“…Small polar aldehydes and ketones (such as formaldehyde, glyoxal and acetone) and also dicarbonyl compounds have been extracted from water by pentafluorobenzylhydroxylamine (PFBHA) derivatization followed by LLE (Glaze et al, 1989), SPE (Yamada and Soniya, 1989), PT (Yang et al, 1995) or SPME (Bao et al, 1998;Martos and Pawliszyn, 1998;Keszler et al, 1998;Cancho et al, 2002). PFBHA reacts with the carbonyl group and imparts nonpolar character to carbonyl-containing molecules, allowing them to be extracted from water and analyzed (Glaze et al, 1989;Yamada and Soniya, 1989).…”

Determination of formaldehyde in shiitake mushroom by ionic liquid-based liquid-phase microextraction coupled with liquid chromatography

“…In recent years, chromatographic methods including GC [6,7] and HPLC [9][10][11] have been the most frequently reported one for the determination of formaldehyde. The most commonly used sample preparation procedure for chromatographic determination of formaldehyde is based on its reaction with 2,4-dinitrophenylhydrazine (DNPH) to form the corresponding hydrazone (DNPHo), which is extracted by liquid-liquid extraction [12], solid-phase extraction [11] or solid-phase microextraction [7,8]. Although the DNPH derivation method has relatively good selectivity, extraction is commonly used as sample clean-up procedure before chromatographic separation [14].…”