It is time to recap and wrap this series up. In part I I simply highlighted the fact that the sampling and analysis of airborne aldehydes and ketones (carbonyls) with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents (i.e., United States (U.S.) Environmental protection Agency\u2019s (EPA) Compendium Method TO-11A or some derivation thereof (e.g., California Air Resources Board (CARB) Method 1004)) are plagued by several important issues. Specifically, I focused on formaldehyde, acetaldehyde, and acrolein (what I like to term the \u201cbig three\u201d), because of their environmental and human health importance.<\/p>\n\n\n\n
In part II I covered the short-comings associated with sampling formaldehyde, a known human carcinogen. In case you did not read that blog (not really sure why???), the take away points were as follows:<\/p>\n\n\n\n
In part III I discussed the difficulties associated with sampling acetaldehyde, a probable human carcinogen. The take away message was:<\/p>\n\n\n\n
In part IV I discussed the multiple short-comings associated with sampling acrolein, a potent lung and eye irritant. The take away note was:<\/p>\n\n\n\n
So what are we to do about all the TO-11A issues? Well\u2026 I am not saying the method is useless; you can certainly sample formaldehyde and acetaldehyde, but you better make sure you are doing so for only short-term (i.e., a few minutes to a few hours) sampling durations\u2026 oh don\u2019t forget your ozone scrubber\/denuder in case ozone is present\u2026 oh you should also mind your NO and NO2<\/sub> concentrations. MAN\u2026 that sure seems like a fair amount to be cognizant of just for two compounds. For the record, the issues surrounding the sampling of other carbonyls (my opinion is that they do exist) have not discussed here, because they have not been fully elucidated… YET!<\/p>\n\n\n\n I am of the opinion that we need to start exploring other derivatization agents. I know from personal experience that DNSH performed far better than DNPH. I have also read promising literature on benzylhydroxylamine (BHA). These are just two quick examples of alternatives that do exist. Bottom line, DNPH-coated solid sorbents have been around for over 30 years now. It they are not meeting all of our demands, then perhaps it is time to pursue other avenues. Who knows\u2026 maybe there is not a suitable substitute for DNPH? In that case, we need to use the method as is, but at a minimum the standardized methods need to be modified so as to accurately reflect the known limitations.<\/p>\n\n\n\n Lastly, whatever future endeavors researchers choose to explore\u2026 I urge them to focus on multi-component methods. Recently, acrolein has been such a hot topic that I have seen far too many methods aimed at collecting just acrolein and the other carbonyl species (which are equally important) have been overlooked.<\/p>\n\n\n\n