JP2002260572A - Mass spectroscope and mass spectrometry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably measure a hydride generating element with high sensitivity wherein, with an element contained in a measurement sample is combined with hydrogen to generate a gaseous hydride, the gaseous hydride is guided into a plasma ion source mass spectrometer for measuring the hydride generating element. SOLUTION: A hydride generating device is connected to the plasma ion source mass spectrometer to measure a hydride generating element. Here, the flow rate of gas guided into the plasma ion mass spectrometer from the hydride generating device is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a gaseous hydride obtained by combining an element contained in a measurement sample with hydrogen, and introducing the gaseous hydride into a plasma ion source mass spectrometer. The present invention relates to a mass spectrometer and a mass spectrometry method for measuring generated elements.

[0002]

2. Description of the Related Art Conventional microwave induced plasma [Microw
ave Induced Plasma (MIP)] mass spectrometer or inductively coupled plasma (IC
P)] In a mass spectrometer, arsenic (A
Elements such as s) and selenium (Se) have high energy for ionization, and it has been difficult to measure them on the order of ng / L. In order to measure these elements with high sensitivity, it is conceivable to take measures such as reducing the amount of water introduced into the plasma together with the target element and not lowering the temperature of the plasma.

[0003] As for elements such as As and Se by using a hydride generator and introducing them as gaseous hydrides into the measuring section, the sensitivity can be improved by 100 times or more by using an atomic absorption spectrometer or an ICP emission spectrometer. Is widely known.

In a plasma ion source mass spectrometer such as a MIP, a hydride generation method for suppressing the introduction of water by reacting a target element with hydrogen to generate a gaseous hydride is disclosed in As, Se and the like. It is considered as one of the techniques for analyzing elements with high sensitivity.

[0005] However, MIP has a high internal pressure in the sample introduction section, and ICP has difficulty in adjusting the matching, and it is difficult to introduce gaseous hydride. When the entire amount of gas generated by the hydride generator is introduced, ion signals are generated. There was a problem in the reliability of the analysis values, such as drifting of the intensity. In addition, there is a problem that sodium salt derived from the reaction reagent used in the hydride generator adheres to the sampling cone and sensitivity drift occurs, and the hydride generator is connected to the MIP or ICP mass spectrometer to perform stable measurement. Was difficult to do.

In Japanese Patent Application Laid-Open No. Hei 9-145675, gas eluted from a column of a gas chromatograph is reduced with hydrogen to convert the constituent elements of a compound contained in the gas eluted into hydride, and the reduced gas is converted to a hydride. The eluted gas is introduced into the mass spectrometer, ionized by the EI method (electron impact ionization method), and peaks of mass numbers selected as characteristics of each element are determined. Based on those peaks, qualitative analysis of each element is performed. Further, a technique for determining the content ratio is disclosed.

Japanese Patent Application Laid-Open No. Hei 4-177157 does not relate to a technique in which an element contained in a measurement sample is combined with hydrogen to form a gaseous hydride. By diluting highly accurately with a gas containing no impurities such as He gas) and analyzing the diluted gas with a high-sensitivity analyzer such as an API-MS device, analysis of impurity gas over a wide concentration range contained in the sample gas. The technology which makes it possible is disclosed.

[0008]

As described above, the MIP
Alternatively, in a mass spectrometer using ICP as an ion source, elements such as As and Se contained in a sample have high energy for ionization, and it has been difficult to measure them on the order of ng / L.

[0009] Japanese Patent Application Laid-Open No. Hei 9-145675 discloses a technique for introducing an eluted gas converted to hydride into a mass spectrometer. I am not aware of adjusting the flow rate of the gas introduced into the mass spectrometer.

Japanese Patent Application Laid-Open No. 4-177157 discloses a technique of supplying a diluent gas to a high-sensitivity analyzer through a flow control valve and discharging excess gas to the outside. However, the gas flow rate control described in the publication is only for controlling the flow rate of the combined gas of the gas from the sample gas pipe and the gas from the zero gas pipe, and the mass targeted by the present invention. In a mass spectrometer using a plasma as an ion source, such as a spectrometer, ie, a plasma ion source mass spectrometer for introducing gaseous hydride, elements such as As and Se contained in the sample are energy for ionization. Is high, and it is difficult to measure in the order of ng / L.

[0011] An object of the present invention is to combine an element contained in a measurement sample with hydrogen to form a gaseous hydride, and introduce the gaseous hydride into a plasma ion source mass spectrometer to produce a hydride-forming element. It is an object of the present invention to provide a mass spectrometer and a mass spectrometry method capable of measuring the hydride-forming element with high sensitivity and high stability when measuring the hydride.

[0012]

The object of the present invention is to provide a method for connecting a hydride generator and a plasma ion source mass spectrometer to measure a hydride generating element. This is achieved by adjusting the flow rate of the gas introduced into the meter.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A mass spectrometer uses a hydride generator, MIP or ICP as an ion source, and a quadrupole, sector, ion trap, TOF (Time
of flight).

Usually, when measuring an element in an unknown sample, the unknown sample is atomized by a nebulizer and then directly introduced into a MIP or ICP for measurement. However, when the concentration of the element contained in the sample is on the order of ng / L, measurement may not be performed due to insufficient sensitivity. In such a case, an operation such as concentration or extraction of the sample is required, and a complicated operation is required to perform the measurement with high sensitivity. An analysis method that combines a hydride generator and a MIP or ICP mass spectrometer reacts hydrogen gas with an element such as As or Se to generate a gaseous hydride, which is efficiently ionized by an ion source. This is a method for performing analysis with high sensitivity. In normal measurement, water is introduced into the plasma at the same time as the target element, so that the temperature of the plasma is lowered, making it difficult to measure elements with high ionization energy (elements that are difficult to ionize) with high sensitivity. The hydride generation method can suppress the introduction of water, As, S
A hydride generating element such as e can be measured with high sensitivity.

An example of the embodiment of the present invention will be described with reference to a plasma ion source mass spectrometer using an MIP as an ion source and an ion trap type mass spectrometer as a mass spectrometer.

FIG. 1 shows the measurement principle of the hydride generation MIP mass spectrometer.

The sample 1 is introduced into the hydride generator 2 by a sample introduction capillary and turned into a gaseous hydride, and then the hydride introduction amount adjusting valve 3 for connecting the hydride generator 2 to the sample introduction system 5 is operated. The sample is introduced into the sample introduction system 5 via the attached tube 4, carried to the plasma 6 as an ion source, and is efficiently ionized. The tube 4 with a hydride introduction amount adjusting valve has a valve 3 to which a tube for connection to the hydride generator 2, a tube for connection to the sample introduction system 5, and a tube for gas discharge are attached.
The amount of gas introduced into the plasma 6 is stabilized by dividing the gaseous hydride generated by the hydride generator 2 into the plasma 6 by the valve 3 and discharging the gaseous hydride to the exhaust system. . The ionized element passes through the nickel sampling cone 7 and is ionized by the ion lens 9.
The light enters the ion trap type mass spectrometer 10 while drawing a trajectory like a trajectory 8. Here, information on the target ion is obtained by sorting and counting the ions for each mass number. The obtained result is processed by the operation / data processing personal computer 11, and the result of the target element can be known.

The procedure for optimizing the amount of hydride gas introduced will be described with reference to FIG. 1 and FIG. 2 by taking As measurement using MIP-MS as an example.

After the apparatus is started, a standard solution of As is sucked from the hydride generator 2 and As is introduced into the plasma 6 as hydride. Then, using the apparatus condition setting screen, the hydride introduction amount adjusting valve 3 is used. The amount of hydride gas introduced into the plasma 6 is changed stepwise, for example, to 100 ml or 200 ml, and the change in the ion signal intensity of As is monitored. Also, by keeping the changed gas amount at the same flow rate for a certain period of time, for example, about 15 minutes, the change over time of the ion signal amount is measured, and the gas flow rate at which the change over time of the ion signal amount is small and the ion signal amount becomes maximum is determined. Send to analytical conditions and perform quantitative analysis.

FIG. 3 shows the flow from the start of the apparatus to the output of the result.

After the apparatus is started, the amount of hydride gas introduced is automatically increased or decreased on the apparatus condition setting screen, and the signal intensity of the measured element is monitored. After finding a higher introduction amount, the optimum introduction amount is automatically set. Select "Quantitative analysis" as the measurement mode, and send necessary information to the PC 11.
On the screen of. After that, a sample is introduced and quantitative analysis is performed, and the result is output to the screen of the personal computer 11. This flow will be described using an example of tap water analysis.

Tap water contains trace amounts of heavy metals derived from raw water, alkalis and alkaline earths. Further, sodium hypochlorite is added for disinfection, and a large amount of chloride ions is present. When performing quantitative analysis of As or Se in tap water with the mass spectrometer 10, calcium and chloride ions present in a large amount in the sample form molecular ions,
Since the same detection result as the mass number of s or Se is obtained, an error is given to the quantitative result. Further, a large amount of alkali or alkaline earth salt may adhere to the sampling cone 7 and cause a sensitivity drift. In this embodiment, the hydride generation element 2 and the sample introduction system 5 are connected by the tube 4 with a hydride introduction amount adjusting valve, so that the hydride generation element can be measured with good sensitivity and stability by the mass spectrometer 10. be able to.

Further, by using a sampling cone made of nickel shown by reference numeral 7 in FIG. 1 or a nickel pedestal having a conical portion made of platinum,
The sensitivity drift is suppressed by reducing the adhesion of the sodium salt generated from the reaction reagent used in the hydride generator 2 to the sampling cone, and the measurement of the hydride forming element by the mass spectrometer 10 is more sensitive and more stable. It can be carried out. FIG. 4 shows a sampling cone in which only the conical portion is made of platinum on a nickel base. FIG. 5 shows the results of Se1μ using copper and nickel sampling cones.
The comparison data when g / L is continued is shown.

It can be seen that the sensitivity is reduced in a short time in the copper sampling cone and the stability is lacking, but the nickel sampling cone provides stable data for a long time.

[0025]

According to the present invention, an element contained in a measurement sample is combined with hydrogen to form a gaseous hydride, and the gaseous hydride is introduced into a plasma ion source mass spectrometer to obtain a hydride. When measuring the produced element, the hydride producing element can be measured with high sensitivity and high stability. In addition, the time and labor of the sample pretreatment operation can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a plasma ion source mass spectrometer.

FIG. 2 is a diagram for explaining optimization of a hydride gas introduction amount.

FIG. 3 is a view showing a flow sheet of a measurement method.

FIG. 4 is a view showing a sampling cone in which a conical portion is made of platinum on a nickel base.

FIG. 5 is a diagram showing continuous measurement data using sampling cones made of copper and nickel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... sample, 2 ... hydride generator, 3 ... hydride introduction amount adjustment valve, 4 ... tube, 5 ... sample introduction system, 6 ... plasma, 7 ... nickel sampling cone, 8 ... ion orbit, 9 ... ion lens , 10: mass spectrometer, 11: personal computer for operation and data processing.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Shirasaki 1040 Ichimo Ichiki, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Science Systems Co., Ltd. Inside Science Systems (72) Inventor Hideyuki Sakamoto 1040 Ichimo, Oaza, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Science Systems Co., Ltd. Group F-term (reference) 5C038 EE01 EE02 EF01 EF12 GG09 GH04 GH11 GH13 GH15 HH03 HH26 HH28

Claims (4)

[Claims] 1. A hydride generator that combines an element contained in a measurement sample with hydrogen to form a gaseous hydride, and a plasma ion that introduces the gaseous hydride to measure a hydride-forming element. A mass spectrometer comprising: a source mass spectrometer; and a means for adjusting a flow rate of gas introduced from the hydride generator to the plasma ion source mass spectrometer. 2. The quantitative analysis gas according to claim 1, wherein the signal flow rate of the measurement element is measured by changing the gas flow rate of the hydride introduced into the plasma, and the gas flow rate having a high signal strength and a small change in the signal strength with time is determined. Mass spectrometer set as flow rate. 3. The mass spectrometer according to claim 1, wherein the sampling cone for introducing the ions generated by the plasma into the mass spectrometric means is made of nickel, or the conical portion is made of platinum on a nickel base. 4. A mass spectrometry method using a hydride generator, a plasma ion source mass spectrometer, and a valve connected between the hydride generator and the plasma ion source mass spectrometer for controlling a flow rate of a hydride. The detection is performed by the plasma ion source mass spectrometer while the flow rate from the hydride generator to the plasma ion source mass spectrometer is changed stepwise at predetermined time intervals. A mass spectrometric method comprising setting the flow rate based on a signal amount and continuing analysis.