We are currently working on some personal care products with LC-MS (single quad).
We can observe a nice peak for Bisphenol A (BPA) with direct infusion or FIA (like for 200ppb). However, when we injected some similar labelled compounds (Butylated hydroxytoluene-BHT and tert-Butylhydroquinone-TBHQ, try to use as internal standards), we could not see a nice peak for direct infusion or FIA, even with 1ppm. Does anyone know what's wrong? Any instrumental parameters that we should change?
P.S.: we also injected some estrogens which can also resulted in clear/nice peak on MS (infusion or FIA).