Getting there

I have continued my GC-MS measurements during the last 2 weeks and I have come up with some encouraging results.

First of all I have modified the inlet with a special SPME liner (with a low diameter and volume for splitless injection) that should improve peakshapes – and it indeed does. My peaks are sharper and better separated, which is good, because I still have a considerable number of peaks that are bleeding (although a lot fewer since the replacement of the liner).

As a result, some of the compounds that I could not detect in previous runs (or just a few fragments indicating their presence) are now appearing more clearly. I could identify 1- and 1,2-chlorobenzene, toluene and some other compounds in my urban samples, confirming results from last year’s measurements.

The downside is that I am not quite there yet. Levels seem to be a lot lower than last year, which needs to be explained (e.g. snow properties,…) and some compounds, which I should find due to the heavy traffic just off-campus, still have not turned up.

And some more maintenance

Well, looks like the GC-MS needs a lot of attention recently. After a fatal crash (or rather more than one), the connection between the computer and the instrument was down for good. Well after uninstalling the software and some additional cleaning up by hand, we have reinstalled and reconfigured the software.

All problems solved – and the beast is running nicely again. No data were lost either – so the operation was a success. A couple of hours well spent. Tomorrow is my day on the instrument and I am looking forward to some improved results (*keepingmyfingerscrossed* despite being a scientist).

Column bleeding all over (but no violence ;)

Thanks to a nightshift of a colleague of mine, the GC-MS is up and running again. The baseline is still pretty elevated (4x as high as before), but that could also be due to the inefficiency of the previous filament. Anyway, the baseline seems to be fine.

But the column bleeding is not. I have made some tests, as a performance check:
1 – Instrument background, no injection
2- Fiber backgrounds (PDMS/DVB and Polyacrylate fibers) after conditioning
3- MilliQ blanks with both fibers

… and I have found a lot (read: too much) of bleeding in all of them. I am working in splitless mode and I purge after 3 min with 50 mL/min.

For comparison reasons, I have also tried to work in split mode (ratio 10:1, otherwise identical conditions) for one of my samples. This reduces the column bleeding significantly (to an acceptable level), but also it also reduces the sensitivty too much in order to detect compounds that I see in splitless mode *sigh*.

Finally, I ended up changing/checking the liner – and this was good, there was already quite a bit of junk accumulated. I have also moved the glasswool packing a bit towards the end in order to avoid any contact with the fiber. Additionally, I can now place the fiber more centrally in the liner during desorption – placing it closer to the column and near the temperture optimum. Ultimately, I would like to use a liner that is better suited for SPME usage with splitless injection (smaller volume and narrower bore) in order to optimise the focusing of desorbed compounds.

Some first experiments with the blank fiber showed significant improvements, most of the bleeding is gone – even in splitless mode . Let’s see, if that continues, when used with samples – I am hopeful.


Well – things have been going up and down recently, although the metaphor of the rollercoaster is probably a bit exaggerated – I am still pretty happy.

Good news are that I can and will stay at McGill with my current research group for another year. Things need to get tied up and finally my output should be better too. It also seems that a trip into the Arctic will be possible – watch out for an update soon. A lot of discussions with knowledgeable people have encouraged me to continue with my research – it looks relevant and important. If the methodology that I (plan to) use is good enough still remains to be seen, but I definitely feel that I am on the right track.

This is also true for a journal article that got rejected, but, nevertheless, earned very positive criticism from the reviewers (except for the fact that it was submitted to the wrong journal and some other – rather minor – issues). So up and down it goes, but at the moment it just motivates me more – to get my stuff out and my thoughts straight.

Looking for some sampling space …

Right after the symposium I have started to compile a list of potential sampling sites in the Arctic and Subarctic. At the moment I am aiming for quantity rather than quality, but once my list is filled, I will start checking out the places and contact the responsible persons.

I have already had a few suggestions from visiting scientits, people I have collaborated with, … so I am not short on places. In order to find a sound basis for decision making, I am also trying to summarize the potential research program that has been sitting in my head for a while now and is growing more and more (at least the ideas – not sure, if everything makes sense) ;). Well and I have not even thought about the money yet, except that I am going to need loads of cash.

The filament is burnt – and I am checking out other things

The filament of the GC-MS ion source needs to be replaced (after only 2 months). While a colleague of mine is sorting out the details, I am busy with other things.

I have given a talk at the McGill Environmental Research Symposium and I found it to be an excellent meeting. Short talks from people with very different backgrounds (science, philosophy, education) highlighted the variety of environmental research done at McGill.

I have had very interesting discussions with several people focusing on sampling opportunities in the Arctic and possibilities for modeling the movements of particles in snow. I am currently following up on some of these issues.

Snow from Alaska – it is here

Finally – after an uncounted number of phonecalls, enquiries and discissions, I have fetched the cooler with the snow samples from Barrow, AK at 8 pm from the UPS facility in Lachine, after less than 40 hours in transit. In the afternoon there were a few hectic, but successful phonecalls on order to get it released from Canadian customs in time – although I would still like to contest the $40.- GST that I had to pay (for snow?).

The reward of this effort were snow samples that were still frozen! The cooler insulated the stuff well and additional snow for insulation provided even more cooling capacity. The arrival also means that my sampling campaign is over for this season – measurements and data analysis lie ahead from now on.

GC-MS measurements in full swing

Yesterday was another one with instrument time and things went well. I am still tweaking a couple of parameters (mainly injection conditions), but I am already collecting data (and I see quite a few species – some of them confirming earlier results). I am still struggling with two aspects of the measurements (that have to do with the splitless injection):

(1) Column bleeding
(2) Decay of fiber signal after desorption

I can reduce significantly (1) by choosing a short time until purging (1.5 min), but obviously my signals suffer. If I go by the typical desorption time of 5 min (resulting in purging after 5 min as well), I have a lot of column bleeding, which is not necessarily overlapping with analyte peaks, but messung up my chromatogram considerably.

The same is true for (2) – after desorption I observe a large peak of (mainly) water desorbing from my fiber. By purging early, I can avoid that some of the water is loaded onto the column, resulting in a acceptable baseline earlier (and thus making this timeframe available for additional peaks), but of course my sensitivity suffers.

Well, probably, it is going to be somewhere in the middle, although I lack a good selection criterion so far. But on the whole, it is going well.

The needle in the haystack

Trying to get a cooler from Barrow to Montreal is not easy. For days now, I have called UPS, the logistics coordinator at BASC-NARL in Barrow, Canadian Customs,… in order to find out, where my cooler is. It should have arrived last Thursday, but it did not even make it on to the UPS tracking system. Finally, I had some success.

After identifying all subcontractors for UPS and calling them in Barrow, Anchorage and other places – the cooler was found. And contrary to my worst nightmares (it being stuck in a UPS storage facility in Florida in blazing sunshine) … it was still in Barrow. The contractor changed and they forget to pass my cooler on to the new guys. Well, I tried to put everything in place and the box should be on its way now – although it is still not showing up on the system (I keep my fingers crossed and the phones ringing). At least it was stored properly and if transportation is fast and smooth, everything will be alright.

Waiting for samples from far up North …

Finally, all administrative problems were solved (although I still keep my fingers crossed until I receive them in person) and the samples from Barrow should be on their way to Montreal today. With a bit of luck (and the skills of UPS) they should be here by Thursday.

I have been constantly in touch with the researcher, who has collected the samples for my and it was a good experience. He has collected quite a few samples for me (although not as many as I had hoped for, due to the circumstances he encountered at Point Barrow – c’est la vie). Anyway I am looking forward to receiving some frost flower samples (together with snow samples) for analysis of VOC. That is going to be interesting.