JPH0972882A - Micro sample analysis method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To efficiently analyze a minute amount of metal element in an aqueous solution sample. In an analysis method using inductively coupled plasma mass spectrometry, a double focusing mass meter is used to improve mass resolution, and a signal of an analysis target element and a signal of an interfering molecular ion are separated, A method for analyzing a small amount of sample, which comprises fixing the measurement mass number to the mass number of an element and measuring the detection signal of the sample introduced by the heating vaporization method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for analyzing a metal element dissolved in an aqueous solution.

[0002]

2. Description of the Related Art Conventionally, when a metal element dissolved in an aqueous solution sample is quantified by an inductively coupled plasma mass spectrometer, a spraying method or a heating vaporization method is mainly used as a sample introduction method. In addition, inductively coupled plasma mass spectrometry is an inductively coupled plasma quadrupole mass spectrometer that uses a quadrupole mass spectrometer in the mass spectrometer, or a double focusing mass spectrometer in the mass spectrometer. There is an inductively coupled plasma double-focusing mass spectrometry method used.

[0003]

Among the above-mentioned sample introduction methods, in the spraying method, the sample amount required for measurement is several ml, and when analyzing a small sample having a total sample amount of 1 to 1000 μl, However, it is necessary to dilute the sample to several ml, and as a result, there is a problem that the sensitivity is lowered. The heating vaporization method is a method of vaporizing a sample using a resistance heating of a carbon furnace or a filament, and it is possible to analyze a small sample of 1 to 100 μl, but the detection signal is temporary,
You can only get about 1-3 seconds.

Regarding the inductively coupled plasma mass spectrometer, the inductively coupled plasma quadrupole mass spectrometer has a very high scanning speed and can measure 1 second or less per element. However, because the mass resolution cannot be increased,
Depending on the element, interference with molecular ions due to plasma gas, atmosphere, sample solvent, etc. causes an increase in background, and as a result, the lower limit of quantification becomes high.

The inductively coupled plasma double-focusing mass spectrometry method can increase the mass resolution of measurement by using an electric field and a magnetic field. For example, mass number 55.9349
When measuring Fe of 4, increasing the mass resolving power makes use of the slight difference in mass number, and the Fe signal and A
The signal of the interfering molecule ion composed of rO and having a mass number of 55.96189 can be measured separately.

As a result, Fe can be measured with high sensitivity in a very low background. However, the double-convergence mass spectrometer has a slow scanning speed, and it takes several seconds to scan one isotope, and it is difficult to use the heating vaporization method in which a detection signal can be obtained only for about 1 to 3 seconds. The present invention provides a method for increasing the resolution and suppressing the influence of interfering molecular ions to analyze a minute amount of sample.

[0007]

The analysis method of the present invention is an inductively coupled plasma mass spectrometry method, which uses a double-focusing mass meter to improve the mass resolution, and to detect the signal of an element to be analyzed and the signal of interfering molecular ions. In the separated state, the measurement mass number is fixed to the mass number of the element to be analyzed, and the detection signal of the sample introduced by the heating vaporization method is measured.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In inductively coupled plasma mass spectrometry, a double-focusing mass spectrometer is used to increase the mass resolution to separate signals of an element to be analyzed from interfering molecular ions. The mass resolution required for separation depends on the element to be analyzed and the matrix of the sample solution. For example, when measuring Fe and Cr in pure water, the mass resolution is 3
In the case of measuring As in a hydrochloric acid solution, the mass resolution must be 8,000 or more.

With the mass resolution increased, the measured mass number is fixed to the mass number of the element to be analyzed. By measuring the detection signal of a fixed mass number, it is possible to obtain a signal of only the element to be analyzed without interference of molecular ions without performing time-consuming scanning. In this state, the sample is introduced by the heating vaporization method, and a temporary detection signal from the sample is measured.

The peak height or area of the obtained profile is compared with the peak height or area of the profile obtained from the standard sample solution of which concentration is known in advance to obtain the concentration of the target element. The sample amount and heating conditions in the heating vaporization method may be the same as those used in the conventional inductively coupled plasma quadrupole mass spectrometry.

[0011]

EXAMPLE FIG. 1 shows a mass spectrum obtained by measuring 100 ppt Fe using the inductively coupled plasma double-focusing mass spectrometry. The mass resolution was adjusted to 3000. The sample introduction method uses a spray method, and the amount of the sample used for measurement is 1 ml.

By increasing the mass resolution to 3000, Fe having a mass number of 55.93494 and Ar having a mass number of 55.96189 can be obtained.
The signal of the interfering molecular ion consisting of O can be separated. With the mass resolution increased in this way, the measured mass number is 55.
Fix it to 93494 and introduce the sample into the inductively coupled plasma mass spectrometer by the heating vaporization method.

FIG. 2 shows that the Fe concentration is 100 by the heating vaporization method.
The detection signal of mass number 55.93494 when the sample of ppt is introduced is shown. The amount of the sample used was 10 μl, and the sample was heated and vaporized using a carbon furnace. By fixing the measurement mass number and measuring, it became possible to measure a temporary signal from a small amount sample introduced by the heating vaporization method.

Table 1 shows a comparison of the lower limit of quantification of main elements and the sample amount required for measurement in the analytical method of the present invention and the conventional method. The analysis method of the present invention enables analysis with a sample amount of 1/100 as compared with the case where the spray method is used as the sample introduction method.

Further, it is understood that by increasing the mass resolution, eliminating the influence of interfering molecular ions, and measuring the signal of only the element to be analyzed, it is possible to perform analysis with higher sensitivity than inductively coupled plasma quadrupole mass spectrometry. .

[0016]

[Table 1]

[0017]

EFFECTS OF THE INVENTION The analysis method of the present invention is a geological structure in which it is difficult to quantify silicon wafer surface sludge elements whose sampling amount is extremely small, metal elements in in-vivo samples, or treatment of matrix in sample decomposition solution. It is used for sample analysis, etc. and has a great effect on each field.

[Brief description of drawings]

FIG. 1 is a mass spectrum measured by a conventional method.

FIG. 2 is a detection signal measured by the analysis method of the present invention.

Claims (1)

[Claims] 1. An analysis method using inductively coupled plasma mass spectrometry, characterized in that a double-focusing mass spectrometer is fixed to a specific mass number, and a detection signal of a sample introduced by a heating vaporization method is measured. A method for analyzing a small amount of sample.