I am trying to do LCMS to measure creatinine in urine. All the literature says to store the NIST and samples in glass vials. I am wondering why this is and if it is okay to use a plastic plate.
Hi Katelyn, I think has more due to with convention than practicality. According to the creatinine structure it is more likely stick to polar surfaces that hydrophobic ones.
But, when there is an accepted assay in place it is almost impossible to change it.
There is a very important reason why glass vials are used in principle when MS is involved. All sorts of chemicals may leach into your sample from a plastic container (e.g. plasticizers such as phthalates, etc.). For the same reason you shouldn't microwave food in plastic containers: it is a demonstrable fact that phthalates transfer to the food during microwaving. On the other hand, glass vials have their own set of quirks, such as irreversible adsorption of a sample onto the glass surface or leaching into the sample of the iron that is used to make vials brown (for light-sensitive samples). I'd suggest you get the two priceless books by S. Kromidas about problem solving in HPLC.