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- Posts: 6
- Joined: Wed Feb 14, 2018 2:07 am
I hope you can help me with this problem i'm currently having or have any experience with this issue. I'm developing a 37 analyte "dilute and shoot" method on a ThermoFisher Quantis. I'm noticing the Peak areas for only Benzodiazepines are doubling over time. If i Inject 20 injections back to back the RSD of the areas are great but if i let the vial sit for an extended period of time and then re-inject the Benzodiazepine peak areas double but other analyte classes in the method such as opiates/opioids and amphetamines are not.
currently my sample prep is 100uL of standard (made in Surine from Ceriiliant ref material) mixed with 10uL of ITSD (1000ng/mL) and 50uL of a Beta-Glucoronide Enzyme Mix for hydrolysis. After incubation 95uL of MeOH is added and then centrifuged. 25uL of the Supernatant is then diluted to 500uL in H20. The injection volume is 10uL and the mobile phases are A: 0.1% Formic Acid in H2O and B: 0.1% Formic Acid in MeOH. The column is a Phenomnex BiPhenyl.
Im lost over what it could be considering its only Benzos!
Any help would be amazing!