A detector detection mode correction method developed based on inductively coupled plasma mass spectrometer
Inductively coupled plasma mass spectrometry is one of the powerful analytical methods for trace elements due to its high sensitivity and low detection limit.However,the simultaneous determination of major elements and trace elements is performed in many applications,which requires a wide linear dynamic range.Based on the dual-mode detector for inductively coupled plasma mass spectrometer(ICP-MS),a correction method for detection mode of this type of detector,namely Pulse Analog(PA)correction meth-od,was investigated.Firstly,according to the dynamic range desired,the negative high voltage and posi-tive high voltage of the detector was determined.The appropriate threshold voltage for this detector was obtained to ensure that the test signal was collected,and the noise signal was removed(the counting value at 220 u was less than 0.1 cps).Then the flow rate of helium(He)gas for collision reaction cell was de-termined,so that the counting value of test element at the concentration of 0.1 ng/L was less than 10 cps.Finally,the signal testing was conducted to determine the overlapping elements and their test data.The Pulse-Analog correction coefficient(abbreviated as PA coefficient)was calculated.Cubic polynomial fit-ting was performed to obtain the PA coefficients of elements in whole mass range.The fitting methods of spline interpolation and cubic polynomial were compared.The results showed that the fitting data by cubic polynomial were closer to the trend of original data within the whole mass range of 2-250 u.The proposed calibration method was validated using low,medium,and high mass number elements of Be,Cd,and U(0.1 ng/L-100 mg/L)with a linear dynamic range of 9 orders of magnitude.The results showed that the determination coefficients of calibration curves were all 1.000,and the determination coefficients of cali-bration curves were all higher than 0.999 5 under logarithmic coordinates of the test data.The superalloy certified reference material of GBW01636,which contained Cu,Ga,As,and Bi with content span in four orders of magnitude,was selected for verification,and the results showed that the test values were basical-ly consistent with the certified values.The proposed correction method could achieve the simultaneous de-termination of major and trace elements with a linear dynamic range of up to 9 orders of magnitude,which could meet the test requirements of wide concentration range in certain applications.
inductively coupled plasma mass spectrometer(ICP-MS)detection modepulse-analog(PA)cor-rectionlinear dynamic rangedata fitting
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