Abstract
The effect of experimental parameters such as time of irradiation, analyte concentration, primary beam density, matrix selection and matrix additives on the beam‐induced dehalogenation of chlorpromazine in liquid secondary ion mass spectrometry (LSIMS) was investigated. It was found that dehalogenation of chlorpromazine in glycerol increased with increasing time of irradiation, analyte concentration and primary beam density. These results were compared with those obtained using 4‐chlorophenylalanine ethyl ester and the differences observed were rationalized in terms of compound surface activity. Evidence is given that matrix selection is the key experimental parameter affecting the extent of beam‐induced dehalogenation of chlorpromazine in LSIMS. Of the eleven matrices used, the greatest extent of dehalogenation was observed in glycerol. Sulfur‐containing matrices consistently exhibited a lower extent of dehalogenation than oxygen‐containing aliphatic matrices, implying that sulfur is implicated in mitigating the reduction process. Dehalogenation was totally inhibited in 2‐hydroxyethyl disulfide, 4‐hydroxybenzenesulfonic acid and 3‐nitrobenzyl alcohol. Similarly, the use of matrix additives such as 3‐nitrobenzyl alcohol and trifluoroacetic acid was found to be useful in inhibiting the extent of dehalogenation occurring in glycerol.