Shortcomings of 24-hour sampling for formaldehyde, acetaldehyde, and acrolein with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents – A multi-blog series on airborne carbonyls, part I.27 Mar 2012
If you use the U.S. Environmental Protection Agency’s (EPA) Compendium Method TO-11A (i.e., aldehyde and ketone (carbonyls) sampling with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents), or some derivation thereof (e.g., California Air Resources Board (CARB) Method 1004), then you definitely want to continue reading on. This multi-blog series will present to you several significant shortcomings associated with U.S. EPA TO-11A that most end-users do not know, but definitely need to know.
There is high demand for accurate and reliable airborne carbonyl measurement methods due to the human health and environmental impacts of carbonyls and their effects on atmospheric chemistry. Carbonyl sampling methodologies based on derivatization with DNPH-coated solid sorbents could unequivocally be considered the “gold” standard. Originally developed in the late 1970s, these methods have been extensively evaluated and developed up to the present day. However, more recent studies have demonstrated formaldehyde interferences from 2,4-dinitrophenylazide (DNPA) and 2,2-dinitrochlorobenzene (DNCB); low acetaldehyde collection efficiencies for 24-hour sampling; and numerous acrolein sampling interferences. Despite the publication of these shortcomings in the peer-reviewed literature, most U.S. EPA TO-11A end-users are unaware of them.
Most end-users of U.S. EPA TO-11A, or any other standardized method for that matter, do not have the time to scour the peer-reviewed literature. Most end-users follow Standard Operating Procedures (SOPs), which at some point in time were generated based on a standardized method… the same standardized method that is only periodically up-dated with peer-reviewed literature and findings. Hence this multi-blog series. I am taking advantage of ChromaBLOGraphy to reach an audience I may not have historically touched. I say historically, because everything I am about to share I have already published in peer-reviewed manuscripts.
The several blogs to follow will discuss the sampling issues associated with DNPH-coated solid sorbents, the potential for remedies, and will provide recommendations and areas for future research. Most important to me and you, the information I will present here is vital to the air community, because it seems clear that carbonyl data produced utilizing DNPH-based methods are being reported without acknowledgment of several significant method shortcomings and/or how to best address them.