Do anions form in an ICPMS device?
We have investigated this question. An ICPMS usually only detects cations. Fluorine is an element that is difficult to measure by argon-ICPMS with relatively high detection limits. However, fluorine is the most electronegative of all elements and could potentially form anions in an argon plasma efficiently. The how and where of ion formation was tested with a modified commercial device. Halogens, including fluorine, do not form anions in the plasma, but in the "interface", the cooler zone after the plasma. Detection limits achieved for fluorine are currently in the range of what can be achieved with a standard ICPMS. There are indications that changes in the "interface" would result in improved sensitivity to fluorine.