Mass spectrometry using plasma ion source

Patent metadata

Field	Value
Publication number	US-10510522-B2
Application number	US-201816219414-A
Country	US
Kind code	B2
Filing date	Dec 13, 2018
Priority date	Dec 15, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

To correct spectral interference due to a divalent ion of an interfering element on a measurement ion of an analysis element measured by a mass spectrometer using a plasma ion source by accounting for a mass-bias effect of the mass spectrometer, measurement values of ionic strength of divalent ions of two isotopes having different, odd mass numbers among isotopes of the interfering element are used. In measuring to obtain a measurement value where a correction method of the present invention is applied, it is suitable to set a mass resolution of the mass spectrometer to be higher than a time of normal analysis.

First claim

What is claimed is:

1. A method of correcting spectral interference due to a divalent ion of an interfering element on a measurement ion of an analysis element in a sample measured by a mass spectrometer using a plasma ion source, where at least one type of interfering element having three different isotopes is present in the sample, the three different isotopes being a first isotope having an odd mass number, a second isotope having an odd mass number, and a third isotope, the method comprising:
using, from the at least one type of interfering element, a measurement value of ionic strength of a divalent ion of the first isotope in the sample and a measurement value of ionic strength of a divalent ion of the second isotope in the sample to calculate an interference amount of spectral interference due to a divalent ion of the third isotope on the measurement ion of the analysis element; and
subtracting the interference amount calculated for the at least one type of interfering element from a measurement value of ionic strength at a mass-to-charge ratio of the measurement ion of the analysis element in the sample measured by the mass spectrometer to seek a corrected value of ionic strength at the mass-to-charge ratio of the measurement ion of the analysis element.

2. The method of claim 1 , wherein when, for each of the at least one type of interfering element, the measurement value of ionic strength of the divalent ion of the first isotope and the measurement value of ionic strength of the divalent ion of the second isotope are respectively defined as C1 and C2; isotope abundance ratios of the first isotope, the second isotope, and the third isotope are respectively defined as A1, A2, and A3; and mass-to-charge ratios of the divalent ion of the first isotope, the divalent ion of the second isotope, and the divalent ion of the third isotope are respectively defined as M1, M2, and M3,
the interference amount of spectral interference due the divalent ion of the third isotope of each of the at least one type of interfering element is calculated as
C 2×( A 3/ A 2)×[(1+ a ×( M 3− M 2)],

where a=[1/(M2−M1)]×[(C2/C1)/(A2/A1)−1].

3. The method of claim 1 , wherein the mass spectrometer comprises a quadrupole mass spectrometer, and a mass resolution of the mass spectrometer is set to no greater than 0.4 amu (FWHM).

4. The method of claim 1 , wherein the analysis element is As or Se.

5. The method of claim 1 , wherein the analysis element and the at least one type of interfering element are selected from the group consisting of:
the analysis element is As, and the at least one type of interfering element is any one of Nd and Sm or Nd and Sm; and
the analysis element is Se, and the at least one type of interfering element is any one of Gd and Dy or Gd and Dy.

6. The method of claim 1 , wherein the at least one type of interfering element is selected from Nd, Sm, Gd, and Dy.

7. The method of claim 1 , wherein the calculating of the interference amount and the seeking of the corrected value are carried out by a computing device external to the mass spectrometer.

8. The method of claim 1 , wherein the calculating of the interference amount and the seeking of the corrected value are carried out by a data processing means built into the mass spectrometer.

9. The method of claim 1 , wherein the mass spectrometer is an inductively coupled plasma mass spectrometer (ICP-MS), a microwave plasma mass spectrometer, or a glow-discharge mass spectrometer (GDMS).

10. A mass spectrometer, wherein the mass spectrometer is an inductively coupled plasma mass spectrometer (ICP-MS), a microwave plasma mass spectrometer, or a glow-discharge mass spectrometer (GDMS), and the mass spectrometer is configured for carrying out the method of claim 1 .

Assignees

• Agilent Technologies Inc

Inventors

• Sugiyama Naoki
• Omori Mineko
• Nakano Kazumi

Classifications

• H01J49/26

  Mass spectrometers or separator tubes · CPC title

• G01N27/626

  using heat to ionise a gas · CPC title

• H01J49/105

  using high-frequency excitation, e.g. microwave excitation, Inductively Coupled Plasma [ICP] · CPC title

• H01J49/12

  using an arc discharge, e.g. of the duoplasmatron type · CPC title

• H01J49/0036 Primary

  Step by step routines describing the handling of the data generated during a measurement · CPC title