Elimination efficiency of different reagents for the memory effect of mercury using ICP-MS

The present study was carried out to solve the problems of long washout time and non-linear calibration curves encountered in mercury analysis using inductively coupled plasma mass spectrometry. Comparisons of the washing efficiency for different reagents to eliminate the mercury memory effect were made. Of all the selected washing reagents, mercapto reagents such as 2-mercaptoethanol and L-cysteine could efficiently clean the instrument. Taking the toxicity and odor of mercaptoalkanol into account, L-cysteine was preferred as the most suitable washing reagent and was added into the standard and sample solutions. A good linear calibration curve was obtained with the correlation coefficient of 0.9999. The detetion limit for addition of L-cysteine was 0.024 mu g l(-1). Addition of 0.18% L-cysteine into the sample solution also facilitates the washout of mercury even using deionized water. The recoveries of mercury in certified reference materials, i.e. human hair and dogfish muscle, were 97.2% and 98.3%, respectively, when using 0.18% L-cysteine in the sample solutions.