Lab Methods

“What’s happening to my kit?”

Have you ever wondered what’s happening to your kit once you put it in the mail? Well, here is a run down of the chemistry and methods involved in the final analysis of your collected sample:

Filtration: After your sample has passed quality control, it has to be pre-filtered to get rid of the gunk/debris (sediment, leaves, sea kelp, and/or other solids) contained within the bottle.

Note: Many people have been concerned with sending us samples that have lots of debris in them.  We can get it out, but we ask that you try to avoid large pieces of debris – there’s really no way to avoid it altogether!

This debris inhibits our ability to analyze your sample, so we must filter it out. After your sample has been pre-filtered, we acidify it with hydrochloric acid. Due to our concern about potential degradation of the sample, this acidification allows for preservation of the compounds contained within your water sample and prepares it for the next step.

Figure 1. (A) the apparatus for filtering samples with identification of the sample and filter rig, (B) a filter covered in debris that was contained within a water sample.

Extraction: After filtration, we need to separate the compounds that are freely floating in the water sample from the water itself.  Using a technique called solid phase extraction, we send the water through a cartridge-like apparatus, allowing the compounds to get “trapped” on a sorbent pad contained within the cartridge.  Since the compounds of interest are now trapped in the cartridge, we discard the water.

Figure 2. (A) a cartridge placed on the vacuum manifold with identification of the absorbent pad which collects the compounds of interest, (B) eight SoundCitizen samples being extracted.

Elution: Now, we need to get the compounds off of that sorbent pad. This step involves flushing the cartridge with a solvent, but this time, instead of discarding the fluid, we collect it in a test tube and discard the cartridge. Now the sample is ready for the final step!

Figure 3. (A) Allison preparing the sample cartridges for elution by pipetting in the solvent that will grab the compounds of interest off of the cartridges, (B) eluted cartridges with the final sample collected in the identified test tubes contained within the vacuum manifold.

Run on LC-MS: This is the last step of analysis. We now have the compounds of interest in a particular solvent, ready to be injected on the Liquid Chromatograph – Mass Spectrometer (LC-MS).  We use the results from the LC-MS to identify what compounds are present and how much much of those compounds were in the sample. All of these steps are performed on your sample(s)!

Figure 4. (A) Jaqui investigating the samples before they are injected onto the GC-TruTOF-MS, (B) the GC-TruTOF-MS all prepped and ready to analyze your samples!