TIC should do the same purpose as SIM if there is no co-eluting analyte that contributes to the TIC peak. You can further identify this by running SIM mode and monitoring all possible fragments that come from the analyte of interest. Inject your standard and pure solvent separately. Make sure that the solvent doesn't contribute to that peak where the analyte elutes.

What is the solvent for your standard? Did you inject a pure solvent before you've injected the standard to make sure no additional peaks are coming from the solvent not the analyte of interest?

"TIC" is not an acceptable signal to use for any type of quantitative analysis. TIC is just a total count of ions BASED on the actual METHOD used. It is far from quantitative. Very useful when running an analysis to get an idea of what types of compounds are seen or "picked up" (plenty of things may not be detected, but are there). In basic terms, TIC plots are somewhat qualitative at best, but only if used with a high quality HPLC method and the method is shown to be selective for the sample.

With all MS detectors, the specific method used AND the training of the operator determine the quality of data generated. This is a very complicated technique. Subject to a lot of misinformation and error. Getting data out is easy. Obtaining useful, accurate data is another matter. "MS" is not a 'universal' detector (UV/VIS is also not a universal detector) and there are no universal HPLC methods.

Thank you for your answer, Mukhtar A Kareem Jaderson. I have used HLPC grade solvent for the analysis and the column is clean (determined by a blank run), yet I see multiple peaks. I was hoping to get a relative concentration of the peak of interest compared to the other peaks on the TIC.

Thank you for your answer, William Letter. I understand that the MS will not detect compounds which cannot ionise. But is it possible to get a relative concentration of the compounds to each other detected by the MS by area integration of TIC?

"Relative", no. Response may be different for different compounds (similar to UV) so unless you use standards and a fully developed method, comparison of peaks to each other can not be assumed equivalent. These are basic to the fundamentals of LC-MS analysis and key to understanding how this analytical 'tool' works.

Your real question..... Additionally, you appear to be making an assumption that your results should equal the results obtained by the supplier for your sample ( a reasonable starting assumption, but the real question, and answer, are far more complicated). There are thousands of variables present in any LC-MS analysis. Any "purity" values assigned to a compound are relative to the EXACT method of analysis used, on that system. With LC-MS (or MS, MS-MS) analysis, the instrument operator, the settings (and their are a LOT of settings), the HPLC method and the specific instrument used all contribute to the results obtain. Just as with your method, the original method used to determine "purity" may or may not be comprehensive (we have no idea). All methods need to be evaluated by professionals to insure they are fit-for-purpose and selective for the sample under analysis before any conclusions are drawn.

Any MS system can output data that is or is not accurate. The system is just a "dumb" tool and to obtain quality output requires a very skilled user with a great deal of practical experience.