TO-15 + PAMS + TO-11A = China’s HJ759 + PAMS + HJ683

It is very fitting that I write this blog while I am in Shanghai, China. The impetus for this blog, and the blogs to follow, is that the Chinese Ministry of Ecology and Environment (formerly the Ministry of Environmental Protection) published their “VOCs Monitoring Scheme of Environmental Air Quality.” In short, this standard outlines the sampling and analysis of 117 VOCs via the following three methods: HJ759, PAMS, and HJ683. These methods are very similar to U.S. EPA Methods TO-15, PAMS, and TO-11A, respectively. They have done so, because PM2.5 is not solely responsible for hazy skies and VOCs play a critical role in atmospheric reactions, which generate ozone, smog, etc. The following picture illustrates why the People’s Republic of China (PRC) is interested in VOCs:

In the photo, those are large shipping boats on the Yangtze river. I took this photo on final approach at 4 pm, and no, it was not rainy or overcast. This was smog. And it gets better… I could actually see the sun today, which I did not see during my 13 day visit in November of 2018. So, this was a good day! Okay, you get the point.

Before we break down HJ759 and PAMS, let us quickly review up to present day: I have spent the last several years presenting at conferences, publishing blogs, and writing application notes on TO-15. However, there is also the Photochemical Assessment Monitoring Stations (PAMS) network, which utilizes a lesser-known and -discussed canister-based method; since this method is executed by government monitoring sites and laboratories. We have countless blogs, chromatograms, etc. for TO-15, but we have never blogged about PAMS and confess that we only have one PAMS chromatogram. Despite our lack of focus, PAMS is interesting. Long story short, the PAMS network was put in place for the monitoring of ozone. Therefore, this network focuses in on aliphatic, aromatic, and carbonyl VOCs. Whereas, TO-15 has some overlap, but places more of an emphasis on halogenated VOCs. Overall, the sampling and analysis is very similar between the two methods. The divergence is in the target analyte lists. For more on PAMS, be sure to check out the EPA’s website.

Now for present day: The PRC has used TO-15 as the model for HJ759. Most of the method is very similar, which makes sense. And PAMS is simply PAMS. Why reinvent the wheel, when the U.S. already tackled the same problems over 3 decades ago. However, there appears to be a new trend coming out of the PRC, which is a push for one sampling and analytical approach for all the VOCs found in To-15 (HJ759 in China), PAMS (PAMS in China), and TO-11A (HJ683 in China). I have the following mixed feelings about this movement:

1. I love the fact that manufacturers/providers like Restek are being pushed to develop innovative approaches for meeting the PRC's desire for one analytical method.
2. There is a reason TO-11A requires the sampling of carbonyls by derivatization on cartridges and not by collection into canisters in the U.S. We already know this does not work well in canisters. However, despite the PRC document specifying the use of cartridges for carbonyls, some of the air sampling community in the PRC seems to think otherwise. For the record, today’s blog will only focus on combing TO-15 and PAMS, and not TO-11A. More blogs to follow on this specific topic later.

The concept of combining the TO-15 and PAMS target analyte lists into one analytical run is not new. In fact, I have been presenting a lot of my canister cleaning work at the National Environmental Monitoring Conference (NEMC), Air and Waste Management Association (A&WMA), and to the U.S. EPA since 2014; for all of which I used the following single analysis combining TO-15 and PAMS target analyte lists:

As you may see in the above chromatogram, there were 116 compounds (i.e., 111 target analytes, 3 internal standards, and BFB). There were only 2 critical coelutions (2-Methylpentane and vinyl acetate; and n-hexane and ethyl acetate), which I never bothered to work out, because this method was only used internally. Not sure why I never published this method until now.  Wait, I take that back! Here are the following reasons:

1. I believe most laboratories do not have interest in the above, as they are conducting either TO-15 or PAMS, not both; and/or not in one analysis. This is evident since we have never received a request.
2. This method requires on-column cooling, which labs tend to avoid.

That is of course until now! The PRC is pushing the envelope and asking for just that (i.e., the single analytical method). It would be nice to know that we just have to work out those 2 critical coelutions and have a solution. But it is not quite that simple. We need to develop further because:

1. Preconcentrator instrument manufacturers have moved away from using liquid nitrogen to cool their traps. These makes on-column cooling that much less attractive.
2. The C2 compounds in PAMS (ethylene, acetylene, ethane) do not respond well on a mass spec, so the desired detection limits (200 pptv) may be hard to achieve.

Okay, I have reached my personal blog size limit and jet lag remains present. So, stay tuned for the next blog where we show you a dual column GC-FID-MS analysis with all 116 TO-15 (HJ759) and PAMS compounds resolved.