Category: research

I have put together some results from recent measurements that were collected using the splitless GC-MS method. I have not only identified the compounds, but also quantified 12 different hydrocarbons as I have done previously (http://www.nomad.priv.at/researchblog/?p=48).

It was nice to see that repeatability of duplicate measurements is now below 10% for most species, which is a good improvement compared to the now published manuscript (http://www.nomad.priv.at/researchblog/?p=53). Concentrations were similar in all locations, indicating a more complex relationsship between location and compound concentrations than remote vs. urban. Snow properties such as age and density seem to play a crucial role. Concentration were in the lower µg/L range – well above the LOD, which is around 0.003 µg/L for most compounds.

The method is definitely fit for the arctic snow samples that I will be collecting in May at Alert, Nunavut.

… is going well after a few problems at the start. After a few discussions and a missing permit we have abandoned the plan of going to Resolute and I will be going to Alert instead. This has several (scientific and logistical) advantages, e.g. a cleaner environment, cheaper transfer of scientific equipment. I will be carrying out VOC-in-snow measurements on site, because I will ship a GC-FID for SPME measurements on site.

I will be at Alert from May 16 to June 7 and measurements and sample collection will be made for snow and near surface air apart from standard ancillary measurements.

I currently do some more background work on available VOC data, mainly fluxes of organic compounds between the snow pack and the atmosphere. And there is … almost nothing. Surprisingly few articles have been published so far (there is much more data on inorganic species, though).

Other stuff concerns snow cover and snow depth measurements as well as residence time of the snow cover, depending on surface temperatures. And there is more on that – in fact there is lots (satellite data, ground data and model results). Most articles are available by just pressing a couple of buttons – some articles from less known journals I have to order, but that can be done online as well. Nice.

It took a while, but finally it is done. After circulating the draft, good reviews and some modifications, which consisted mostly of removing content, the first paper on my research will get published in Analytical and Bioanalytical Chemistry. Watch the “Online First” section for an online pre-release soon.

For the final version, we have condensed the article to the method presentation and removed results from filter and irradiation experiments that were not only fairly preliminary, but also a step ahead of the original method development. The article title is “Determination of a Wide Range of Volatile and Semivolatile Organic Compounds in Snow Using Solid Phase Micro-Extraction (SPME)” and this what it is about. We present qualitative data for numerous compounds in snow obtained from the headspace and liquid phases of a melted snow sample and quantitative data for 12 selected VOC in the lower [µg/L] range.

To our knowledge it is the first application of SPME for the determination of VOC in snow and has some remarkable advantages, such as suitability for field measurements and solvent-less application, which facilitates easy sample collection in remote and ecologically sensitive areas.

I have been to a meeting with some veteran Arctic researchers to inform myself about research opportunities in Resolute, NU. I would like to do some sampling and measurements there next spring (in April) and they have provided me with a lot of information on administrative stuff that has to be dealt with and some valuable information on sampling sites, contacts – everything is still in the infancy stage and I am not even sure, if it will work, but it doesn’t hurt to start planning 😉 I have also started a draft with research objectives and methodologies – to get some structure in my thoughts.

More news to follow for sure!

I am currently in San Francisco attending the AGU Fall meeting. And it is pretty amazing. 11,500 Earth Scientists coming together for a meeting. This is not only utterly overwhelming, but also a good opportunity for me to have a look outside my field and engage in discussions with other scientists. All provided that you are well prepared or you will find yourself staring helplessly into the 540 page program.

And I was quite well prepared – time on the plane helps 😉 I have already presented my poster and I am very satisfied with the discussions. I have received some good feedback and was encouraged by several people to make measurements that are part of a larger campaign in order to put my data into perspective (… and I am working on that …). I have also participated in an OASIS meeting – a project that would like to be part of, one way or the other (http://www.oasishome.net/). There were quite a few sessions on atmosphere-snow interactions and I think that my research fits in well here.

Apart from research related sessions (I have mostly attended atmospheric, aerosol and cryosphere sessions) I have also attended sessions that deal with communication of scientists with the media and the general public, which I found quite interesting and partly somewhat controversial. Objectivity, translation of scientific results and communicating uncertainties (e.g. in models or measurements) – who should do the translating – scientists or policy advisors, were the core of this discussion. Furthermore, I am pretty busy writing up some stuff, which I didn’t have time for in the past weeks. Lot’s of work, but interesting and fun.

I have now data from all samples that I have collected in Montreal, Parc Tremblant and Mont Saint Hilaire. The latter two sampling spots were 2.5 hrs north and 40 min east of Montreal respectively. The profile of determined compounds is pretty anthropogenic with a lot of substituted benzenes (with some chlorinated compounds). A lot of aliphatic aldehydes (e.g. nonanal), alcohols and ketones (octanol. MEK) are also part of the mix.

What is interesting is that the large chunk of biogenic and halogenated compounds that I have detected in last year’s samples are not there, despite the significantly improved detection limit. Also, concentrations were 10-100x smaller. There could be a lot of reasons for his – sampling location, meteorological conditions, snow properties/age … and I will try to get an idea by using ancillary and snow properties data in order to shed some light on this issue, although I am not sure,if I will be successful.

I have also increased the number of compounds that I can now quantify – from 6 to 12, a nice step forward. I can now quantify most aromatic compounds; oxygenated compounds are next.

Good news: In my recent blank measurements there was just nothing – nada – rien – nix. A week before I found some organic species that should not have been there (obviously) – until I noticed that I had used non-acid washed flasks that I had not rinsed properly. A good sign that my cleaning procedure is doing its job.

I still find column bleeding in the blanks – and in all the samples that I run. That is sometimes a problem for the determination of the peak area – although I observe this overlap rarely. My baseline varies between 2000 and 3000 counts, when scanning a mass range between 15 and 500 amu and a threshold of only 150 counts. So this is not bad at all.

My guess is that the column is coming to the end of its life (at least for the trace work that I do) and I am currently working on a solution for a new column – together with a separate injector port and and switchbox, just before the effluent is entering the MS; the price of the package will decide, if I can implement this solution. It would keep my column clean and would reduce the number of liner changes significantly.

I have conducted some standard runs in the past weeks and set up 13 calibration curves for aromatic species. These include toluene, benzene, benzaldehyde and several others. I have also removed the water as described below and achieved some very good results.

My sensitivity has increased by about 2 orders of magnitude – my smallest standard used to be 1.25 ug/L, now it is 0.01 ug/L and I think that I can still go lower for most of the species. The reason is the reduced amount of water that enters the system, giving me a better gain on the splitless injection, which loads all of my analytes on the column. I have not calculated an LOD yet, because I need more replicates for that, but it will improve drastically.

My first calibration line covers a concentration range from 0.01 – 1000 ug/L with decent linearity. However, with increasing concentration I have observed saturation of fiber, i.e. the loading capacity has been reached, leading to a plateau at high concentrations, suggesting a curvilinear calibration line.

As a consequence I will set up different calibration lines for several concentration ranges and add more standards. I will also consider diluting highly concentrated samples, should this be necessary. From what I have seen so far, this should not be necessary, because observed concentrations were considerably lower than last year.

I have received a question from a guy in Singapore recently, about a European Union project that I was part of during my PhD studies. It was about a reference concerning the Daily Tolerable Intake of Zearalenone for swine. He was asking about details of the feeding study.

As I did not write this article myself nor had the reference, I gave him the contact details of the author, a consulter living in the UK. Within a day, he had the feeding study on his desk in Singapore and I had received a Thank you-email here in Montreal. It is just amazing with how little effort this is all possible 🙂