Sample intake for premixtures
Posted: Wed May 08, 2019 7:23 am
I'm working on developing an LCMS analysis of fat-soluble vitamins A, D and E to replace our routine HPLC analysis. Most of our samples for this analysis are feed and premixtures. Premixtures contain vitamins in about 1000-2000x higher amounts than the feed they're being mixed into. In our HPLC procedure, we follow the same procedure for feed & premixtures and just dilute the premixture until it falls in the calibration curve.
The LCMS analysis in development, however, will make use of isotope labeled internal standards that should be added before the (saponification) sample prep. It is unrealistic, and like a waste really, to add like 1000x more internal standard to the premixture just to be able to dilute it to the calibration curve level in the end.
I solved a similar issue for water-soluble vitamins in supplements, by dissolving 100mg in 100mL buffer, and taking 1mL of this homogeneous mixture through the sample prep (adding the internal standard at this point).
I have less experience with premixtures. Is there any solvent (combination) that I can use that should make a homogeneous "solution" of a premixture that allows me to pre-dilute these kind of samples?
The LCMS analysis in development, however, will make use of isotope labeled internal standards that should be added before the (saponification) sample prep. It is unrealistic, and like a waste really, to add like 1000x more internal standard to the premixture just to be able to dilute it to the calibration curve level in the end.
I solved a similar issue for water-soluble vitamins in supplements, by dissolving 100mg in 100mL buffer, and taking 1mL of this homogeneous mixture through the sample prep (adding the internal standard at this point).
I have less experience with premixtures. Is there any solvent (combination) that I can use that should make a homogeneous "solution" of a premixture that allows me to pre-dilute these kind of samples?