Measurement and Results - Positive interference mercury (Hg) mass 202

The interference is due to the molecular oxide of W186O16 = 202 mass. Have you tried to minimize the interference by cutting back on the sample (nebulizer) Ar flow? To use a correction equation for this type of interference would require an MO mass different from 202 where WO can be measured. The problem is that all of these masses have an Hg line present. If there was a 'clean' WO mass to measure, then the calculation for the interference correction would be simple. Alternatively, you can measure solutions that only contain W and monitor all Hg masses (in addition to all W masses). The ratios of WO/W can be used to determine an 'average' WO intensity for a given W concentration at specific instrument settings, and this information can used to provide a tungsten oxide correction for Hg. In addition, interference corrections can be unsuitable in cases where the intensity of the interference is equal to or greater than the intensity of the analyte mass. In this case, the only fix we know of is to go to the Hg 201 mass, provided the WO interference can't be reduced to insignificance by reduction in the sample Ar flow. Finally, we don't think that running a 'cool plasma' will help for Hg, but it's worth asking the instrument manufacturer about this possibility.