High resolution - ESI/APCI/APPI - FIA

Pechar

The polarity of the sample has to be taken into account in order to choose the appropriate analytical technique. ESI is suitable for analytes of medium-high polarity that dissolve in polar solvents such as water or methanol. APCI is suitable for analytes of low-medium polarity that dissolve in non-polar solvents such as dichloromethane or chloroform; and APPI is suitable for samples that have chromophore groups.

Samples should come in identified and labelled vials or tubes, with a minimum user-supplied quantity of 0.1 mg, indicating suitable solvents (if possible, solvents such as DMF or DMSO should not be used). If they are in solution, the solvent used should be indicated. In addition, the presence of salts may interfere with sample acquisition and results. In this case, a separate desalting can be performed with Zip-Tip Desalting (chargeable service).

The analyser used is a time-of-flight (TOF) that will allow high-resolution measurements. Thus, the measurement obtained indicates, with high precision (less than 5 ppm error with respect to the theoretical value), the composition of the chemical elements of the molecule and its isotopic profile.

The ESI/APCI/APPI-FIA high-resolution service has a complementary Accurate Mass Measurement service for a molecule of interest at no additional cost. The report provided gives information on the spectrum of the requested molecular ion, measured at high resolution and, at the same time, the accurate mass measurement of the experimental peak with respect to the theoretical mass, with the error committed expressed in ppm (always lower than 5 ppm) and a statistical mSigma value that indicates the reliability of the measurement, not only by looking at the error committed in ppm of the first mono-isotopic peak, but also the height of the peaks compared to the theoretical profile; the lower the mSigma value, the better the profile fits (optimal values would be below 50), the number of unsaturations is defined by DBE (Double Bond Equivalents).