Mass analysis method and inductively coupled plasma mass spectrometer

An Inductively Coupled Plasma Mass Spectrometer (ICP-MS), for measuring pre-determined one or more target elements for multiple measuring object samples, the ICP-MS comprising:

• a) a plasma ionization part that plasma-ionizes the measuring object samples through an ICP;
• b) a mass analysis part that mass-separates ions generated in the plasma ionization part and detects the ions;
• c) a storage part that stores ion information, wherein the ion information is information about mass-charge ratios and presence ratios of isotopic ions of all elements assumptively contained in the measuring object samples, which contain the target elements, and mass-charge ratios and generation probabilities of compound ions and multivalent ions assumptively generated when the measuring object samples are plasma-ionized;
• d) a representative sample measuring part that plasma-ionizes, in the plasma ionization part, a representative sample as one of the multiple measuring object samples, and obtains a mass spectrum by scanning measurement in the mass analysis part;
• e) an element-containing inferring part that infers types of elements contained in the representative sample according to the position of a mass peak of the representative sample;
• f) an interference ion judgment part that, for respective ones of the target elements in the inferred elements, judges according to ion information whether there are isotopes without interference ions, wherein the interference ions are other ions having a mass-charge ratio identical with that of monovalent ions of the target elements;
• g) a determination part of measurement mass-charge ratio that, when there are the isotopes without the interference ions, determines the mass-charge ratio of the isotope whose a mass peak has the maximum intensity as a measurement mass-charge ratio being a mass-charge ratio for measurement of the target elements, and when the interference ions are present in all the isotopes, based on the ion information, calculates intensity of the mass peak of the interference ions according to detection intensity of monovalent ions of interference elements, and determines a mass-charge ratio of an isotope whose a mass peak has the maximum intensity obtained by subtracting the intensity as a measurement mass-charge ratio being a mass-charge ratio for measurement, wherein the interference elements are elements corresponding to the interference ions;
• and
• h) an all-sample measuring part that sequentially introduces the multiple measuring object samples into the plasma ionization part, and performs selected ion monitoring (SIM) measurement, which uses the measurement mass-charge ratio, on each sample.