JPH1123470A - Icp analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ICP analyzer in which pulsation can be suppressed in the liquid supply through a peristaltic pump. SOLUTION: A spray chamber 7 for supplying a sample aerosol to a plasma torch 8 is fixed with two nebulizers 5, 6 of same type at an equal distance to the plasma torch connection port of the spray chamber 7. Each nebulizer 5, 6 is connected with a peristaltic pump 3, 4 of the same type in order to supply a liquid sample 2 in a sample container 1 to each nebulizer 5, 6. When pulsation is detected in the emission intensity, a control means 10 shifts the rotation of one peristaltic pump to reduce fluctuation of air pressure in the spray chamber 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ICP (high frequency inductively coupled plasma) emission spectrometer and an ICP-mass spectrometer (MS).

[0002]

2. Description of the Related Art In a sample introduction device of a general ICP analyzer, as a method of feeding a sample into a nebulizer, a new method is performed using suction of a carrier gas by negative pressure.
A matte nebulizer is used. However, a sample with high viscosity has a weak suction force and is difficult to suck up. However, if the flow rate of the carrier gas is increased, the plasma flame becomes unstable or the plasma temperature becomes low, resulting in poor excitation efficiency. Can not be more.
Peristaltic pumps may be used to assist with this.

FIG. 3 shows a conventional I-type pump using a peristaltic pump.
This is a CP analyzer, in which a liquid sample 2 in a sample container 1 is transferred to a nebulizer 5 by a peristaltic pump 3, the liquid sample 2 is atomized by the nebulizer 5, and a triple tube structure is formed via a spray chamber 7. The sample is introduced into the plasma torch 8 and excited by the high-frequency magnetic field generated by the high-frequency coil 9 to emit and ionize the atomized sample for analysis.

As shown in FIG. 4, the peristaltic pump 3 comprises a flexible tube between a plurality of pressure-feeding rollers 12 mounted on a rotor 11 and a pressing member 13. The liquid sample 2 is pumped in a peristaltic manner by successively pressing the liquid sample 14. When such a peristaltic pump 3 is used, the liquid sample 2 is naturally drawn from the sample container 1 by the negative pressure in the nebulizer 5. In comparison with the above, it is considered that a constant amount of the liquid sample 2 is always supplied to the plasma torch 8 when viewed on a time average without being affected by the liquid level or viscosity of the liquid sample 2. As described above, the pump 3 is a pump for pumping the liquid sample 2 in a peristaltic manner by means of a plurality of pressure feeding rollers 12 so that the amount of liquid sent to the nebulizer 5 is constant even on a time average. In a short period of time, It varies with a periodicity of rotation of the motor 11.

[0005]

The conventional sample introduction device for ICP analysis is constructed as described above. However, since the amount of liquid sent to the nebulizer by the peristaltic pump has a periodicity at regular intervals, it is difficult to achieve the above. As a result, the air pressure in the spray chamber pulsates, and as a result, the intensity of light emission and ionization in the plasma torch fluctuates. This effect is particularly remarkable when the buffer in the spray chamber is small. For this reason, there have been problems that the measured values vary and the analysis accuracy is reduced, and that it is necessary to increase the integration time for photometry.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a sample introduction device for ICP analysis in which the accuracy of analysis is improved by eliminating the influence of pulsation caused by the transfer operation of a peristaltic pump. With the goal.

[0007]

In order to achieve the above object, the ICP analyzer of the present invention is characterized in that a plurality of nebulizers are arranged in a spray chamber, and a peristaltic pump is connected to each of the nebulizers. And

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a sample introduction device of an ICP analyzer according to an embodiment of the present invention, and portions corresponding to the above-mentioned conventional example are denoted by the same reference numerals.

In FIG. 1, reference numeral 1 is a sample container, 2 is a liquid sample, 3 and 4 are peristaltic pumps, 5 and 6 are nebulizers, 7 is a spray chamber, 8 is a plasma torch, 9 is a high-frequency coil, 10 Is control means.

In this embodiment, in order to eliminate the influence of the pulsation caused by the peristaltic pump and to improve the analysis accuracy, a spray is used.
Two nebulizers attached to the chamber are arranged, and a peristaltic pump is connected to each of the nebulizers, and a control means for shifting a period of a liquid sample sending operation by the peristaltic pump is provided.

That is, the spray chamber 7 for supplying the sample aerosol to the plasma torch 8 is provided with two identical-type spray chambers arranged at an equal distance from the plasma torch connection port of the spray chamber 7. Nebulizers 5 and 6 are attached, and one peristaltic pump 3 and 4 of the same type are connected to each of the nebulizers 5 and 6, respectively.
The liquid sample 2 inside is sent to each of the nebulizers 5 and 6. Then, the control means 10 controls the rotation cycle of the peristaltic pump 3 or 4.

In the above configuration, at the time of analysis, two peristaltic pumps 3 and 4 are operated to pump the liquid sample 2 to the nebulizers 5 and 6, respectively. It is considered that the phase of the pulsation due to liquid feeding is appropriately shifted even if no control is performed due to the difference in the pumping position and the starting position of the pump. However, these operations are not always constant and vary and operate. I do.

Therefore, when the pulsation state is detected by monitoring the emission intensity of the plasma and monitoring its fluctuation, the control means 10 shifts the rotation cycle of one of the peristal pumps 3 and 4. To do.

Thus, the two nebulizers 5 and 6
The pulsation of the liquid sample pumping discharged from the nozzle is eliminated, and the periodic fluctuation of the atmospheric pressure in the spray chamber is suppressed.

In the above embodiment, two nebulizers 5 and 6 each have one peristaltic pump 3 and 4.
And a control means for controlling the rotation of the peristaltic pump 3 or 4 is used. However, if pulsation is allowed to some extent, or if the mutual operation state of the two systems is stable, two peristaltic pumps are used. A series of rotors are juxtaposed, the rotors of the two rotors are shifted and assembled (the amount of shift can be varied for one pitch of the rotor), and two rotors are provided for each rotor. In this case, the length of the two tubes becomes the same by passing through the tube, and the liquid feeding operation is mechanically and semi-fixedly shifted, and a system without using control means can be adopted.

In the above embodiment, the cyclone chamber of the pneumatic nebulizer is shown, but the present invention can be applied to a normal pneumatic coaxial nebulizer as shown in FIG.

Two nebulizers 5 are provided in the spray chamber 7.
The use of the ICP analyzer of the present invention in which (6) and (6) are arranged makes it possible to prepare a calibration curve similar to the standard addition method.

A method of preparing a calibration curve similar to the standard addition method will be described with reference to the embodiment of FIG. In FIG.
Reference numeral 1 denotes a sample container, 2 denotes a liquid sample, 5 denotes a nebulizer for a sample, 15 denotes a standard sample container, 16 denotes a standard solution, and 6 denotes a nebulizer for a standard solution. 7, 8, and 9 are the same as those in FIG. 1 described above, and a detailed description thereof will be omitted.

When a calibration curve is prepared, a liquid sample 2 is placed in a sample container 1 and a standard solution having a known concentration is placed in a standard sample container 15. Accordingly, the liquid sample 2 of unknown concentration is sent to the sample nebulizer 5 and the standard solution 16 of known concentration is sent to the nebulizer 6 for standard solution, and the two are mixed in the spray chamber 7 as aerosol. Introduced to h8. Therefore, it is possible to prepare a calibration curve excluding the matrix effect by the standard addition method in which a known analysis element concentration is added to a liquid sample.

[0021]

The ICP analyzer of the present invention is configured as described above, and the nebulizer and the peristal pump have two liquid feed systems, so that the pressure pulsation in the spray chamber is eliminated and the emission intensity is reduced. The analysis accuracy can be stably improved. In addition, in order to feed the same amount of sample as compared with the case of one nebulizer, the rotation speeds of the two peristaltic pumps may be reduced to half, and clogging of the nebulizer hardly occurs. On the other hand, the carrier gas can flow twice, and the center temperature of the plasma can be further lowered, so that an analysis state suitable for analysis of an alkali element can be obtained.

Further, by using the apparatus of the present invention,
A calibration curve similar to the standard addition method can be prepared by dividing the two nebulizers into those for the liquid sample and those for the standard solution, so that the measurement can be automated more easily than in the case of one nebulizer of the conventional method.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an ICP analyzer of the present invention.

FIG. 2 is a diagram showing an example for creating a calibration curve using the ICP analyzer of the present invention.

FIG. 3 is a diagram showing a conventional ICP analyzer.

FIG. 4 is a front view of a peristaltic pump.

[Explanation of symbols]

 1 ... sample container 2 ... liquid sample 3 ... 4 peristaltic pump 5 6 ... nebulizer 7 ... spray chamber 8 ... ··· Plasma torch 9 ····· High frequency coil 10 ···· Control means 11 ··· Rotor 12 ··· Roller 13 ··· Press member 14 ····· Tube 15 ··· Standard sample container 16 ··· Standard solution

Claims (1)

[Claims] 1. A liquid sample is transferred to a nebulizer by a peristaltic pump which performs a liquid feeding operation while sequentially compressing a flexible tube, and a sample atomized by the nebulizer is passed through a spray chamber. Analyze by introducing into a plasma torch and exciting and emitting / ionizing I
In a CP analyzer, a plurality of nebulizers are arranged in the spray chamber, and a peristaltic pump is connected to each of the nebulizers.