AnalytiX Volume 7 Article 2
Aldehydes and ketones are ubiquitous air pollutants. Along with esters and ethers, they are major components of indoor air pollution and are therefore important for industrial hygiene applications. Analytical methods must provide reliable quantification to meet today’s requirements, as well as keep pace with newer and stricter regulations.
Derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) followed by GC analysis provides a fast and reliable way to quantify aldehydes and ketones in ambient air. As with any analytical method, the availability of high quality analytical standards is important to ensure precision and accuracy of the analysis. However, until now the PFBHA derivatives of aldehydes and ketones have not been commercially available. To meet this need, Sigma-Aldrich now offers these derivatives as high purity standards for GC-MS.
Derivatization with PFBHA avoids the disadvantages of 2,4-DNPH. PFBHA reacts quantitatively, even with conjugated aliphatic aldehydes. The PFBHA derivatives do not decompose at an elevated temperature. Neither do they require a time-consuming cleanup step. The resulting oximes can be easily resolved by GC.
Scheme 1. Reaction of PFBHA with aldehyde or ketone to form an oxime
Besides the PFBHA reagents, we offer products for both collection, preparation, and analysis of aldehydes and ketones.
SPME with on-fiber PFBHA derivatization has been applied to environmental monitoring of aldehydes and ketones. The references cited here use a PDMS-DVB fiber coating, which, because of its high affinity for amines, retains the oxime derivatives well. The procedure is simple: soak the fiber in the diluted derivatizing reagent and expose it to the sample headspace or to the air for TWA analysis.
The radiello® passive/diffusive samplers are ideal for long- and short-term sampling of aldehydes and ketones, along with many other analytes, in both indoor and outdoor air. The radial design offers higher capacity and faster uptake/sampling rates than traditional passive monitors.
For GC analysis of the PFBHA derivatives according to EPA Methods 556 and 556.1 “Determination of Carbonyl Compounds in Drinking Water”, we recommend a Supelco SLBTM-5ms capillary GC column (30 m x 0.25 mm I.D. x 0.25 μm df) as a primary column, and an Equity-1701 of the same dimensions as a confirmation column. These columns provide excellent resolution and fast, reproducible separations.