A lab mate and I are discussing how to properly interpret LCMS results and coming to different conclusions. We are taking a solid food sample and extracting it with 50:50 acetonitrile/water to determine the concentration of melamine in the food sample. Standard solutions were made that range between 0 and 5ppm of melamine. The question is whether we read the LCMS results at face value. For example, we could take 100mg of food sample and extracted it with 10mL of solution. If the LCMS reads that the sample has 0.2ppm of melamine in the sample, I don't think that represents what was in the solid. I think we would have to calculate it as the mass of melamine in the LCMS sample to be 0.002mg and because we used 100mg of food sample, then that means the food sample actually contains 20ppm of melamine. So the question is do we read the LCMS results at face value or do a calculation based on the amount of food sample used?