Data and data and more data, oh my

The heat wave blazed on and so did the mass spectometers. I cannot express how much of a relief it is to have nearly four weeks of meticulous SPM sample, calibration standard, and calibration blank preparation behind me. Time is a loose concept when sharing lab space, and it drags on as the hum of various machines keep the beat. The saying "watching paint dry" is not far from a typical response when in the lab; but instead of paint drying, it's ethyl acetate or methanol. Yes, you have to literally watch samples dry, in order to ensure that only a minimal amount of SPM flies out of the vial and into the great unknown.

But once everything is diluted, eluted, spiked, bottled, and capped for analysis...

The Q Exactive Hybrid Quadrupole Orbitrap Mass Spectrometer can identify compounds in a mass range of between 50 to 6,000 m/z with a mass accuracy of <1 ppm RMS internally and <5 ppm RM externally, with a resolution of 140,000 at m/z 200. This means that each vial of compounds prepared and placed into the cooling chamber set inside of the Q Exactive, 33 vials in all, can be analyzed for known and unknown chemical compounds based on their expected retention time and mass: charge ratio and fragmentation in about 45 minutes. Multiply 33 samples by a handful of different processes, such as liquid chromatography using electron spray positive ionization, negative ionization, and gas chromatography using harsher methods of ionization, and you have a good week of non-stop scans being run and tens of thousands of rows of data being produced.

Since all of my SPM samples were spkied with a water internal standard and my calibration standards were spiked with the water internal standard, water mix, and PAH mix, I can compare chemicals identified in my SPM samples to ones identified in my calibration standards, and using a TraceFinder program and method-specific analysis, find significance in the presence of certain compounds. So far, my positive and negative scans for LC has come back, so I spent the week converting the data into manageable excel files and analyzing the identified compounds based on peak area (in how many scans a compound shows up), peak height (how much of a compound comes up in scans), my calibrations' standard deviation from each other and the accepted value of standard, and the calibrations' linear regression and r-squared values. I also tried to start to compare my excel results to that which is shown in TraceFinder, but I need to familiarize myself more with that program before I can see what results are meaningful.

All in all, it has been an exciting week for my research, and I am ecstatic to finally see data being produced from the samples I've been preparing for the last month. As I start to identify chemicals and compounds present in the Danube river, it is already evident that there are some pesticides and herbicides present in at least a minute quantity at some points in the river. It is something that we are told and know, but to see it with my own eyes (okay, maybe masked in a few layers of data analysis, but still) is a pretty powerful thing. I can't help but really worry for the health of the US' river systems, as our pesticide (or "Plant Protective Product," as some may call it) usage is much less restricted than in Europe, as Roundup and chlorpyrifos are still being used on both small and large scales with little plan to restrict their usages.

I hate to end a post on such a negative note, so I will take this moment to praise the EU's Water Framework Directive, which is moving to define more concrete measures of water health and safety. In an era where populations are increasing and the importance of both food security and water health is undeniable, it is hard to find a good compromise between pesticide usage and promoting organic produce. But at least we are having the discussion.