Gas chromatography can be used to determine a water sample's propylene glycol content.
Propylene glycol is an odorless, clear substance that is used in many cosmetic, agricultural, food and industrial products. Propylene glycol is dangerous only in large doses, as it has a relatively low toxicity. If you want to determine the level of propylene glycol in a water sample you will need to subject the sample to gas chromatography with an appropriate detection mechanism. Once you have a gas chromatograph for your sample you'll need to submit your results to a trained professional for analysis.
Instructions
1. Set the column temperature of your gas chromatographer to just over 100 degrees Celsius, which is the boiling point of water. This will transform your water sample into vapor when it is introduced into the chromatographer.
2. Attach a flame ionization detector to your chromatographer. This is the best variety of detector for determining concentrations of propylene glycol in water. If you don't have a flame ionization detector then you may also use a Fourier transform infrared detector, although that type of detector can only reliably determine the concentration of propylene glycol to levels up to 120 mg per liter.
3. Directly inject the water sample into your gas chromatography system's input valve. You should inject the entire sample in a single plug, as slow introduction of the sample can result in inaccurate chromatography readings.
4. Open the gas chromatographer's flow valve. This will start a flow of an inert gas that will force your sample through the heated column and toward your chromatographer's flame ionization or Fourier transform infrared detector unit.
5. Check the printout from your chromatographer's recording device. The printout should feature a graph detailing the strength of all compounds that have been detected in the water sample.
6. Present the graph to a chromatography analyst. The procedure for determining the concentration of compounds in your sample requires in-depth knowledge of chemistry and integral calculus and can only be completed by a trained chromatography professional.
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