JPH10197448A - Icp emission spectrometric analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the introducing efficiency of a sample solution and to improve the sensitivity of quantitative analysis. SOLUTION: The main part 5a of an ultrasonic nebulizer is constituted of a peristaltic pump 11 which sucks up a sample solution 10, an atomizing section 13 which atomizes the sample solution sucked up by the pump 11, a heating section 14 which removes a solvent from the atomized sample 10 by heating the sample 10, and a cooling section 15 which cools the solvent-removed sample 10 and introduces the cooled sample to a nebulizer chamber 2. A nebulizer holder 3 fixes the nebulizer in a ultrasonic nebulizer leading-in section 5b and, in the atomization section 13, an ultrasonic vibrator 12 which generates ultrasonic vibrations is provided for accelerating the atomization. A plasma torch 4, on the other hand, is constituted of a cooling gas leading-on pipe 16, an auxiliary gas leading-in pipe 17, and a high-frequency induction coil 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ICP (Inductively Coupled Plasma) for quantitatively analyzing elements in a sample solution.
The present invention relates to an inductively coupled high frequency plasma) emission spectrometer.

[0002]

2. Description of the Related Art Conventionally, an ICP emission spectrometer has been used for quantitative analysis of elements in an aqueous solution in a water quality survey. This ICP emission spectrometer is excellent in terms of rapid measurement because it can measure multiple elements simultaneously. In addition, the sensitivity is high for most elements.

FIG. 5 is a cross-sectional view showing a schematic configuration near a coaxial nebulizer of a sample introduction device used in a conventional ICP emission spectrometer, and FIG. 6 is an enlarged view of the vicinity of a in FIG.

A sample solution 10 is sprayed into a spray chamber 2 together with a carrier gas by a coaxial nebulizer 1. The spray chamber 2 separates particles having a large particle diameter and discards them as drain,
A mist-like sample composed of only particles having a small particle diameter is introduced into the plasma torch 4. In the plasma torch 4, a cooling gas and an auxiliary gas are introduced separately from the atomized sample. Then, although not shown in FIG. 5, the plasma is generated by discharging by a high frequency induction coil attached to the upper part of the plasma torch. Then, the atomized sample sent into the plasma together with the carrier gas emits light. By measuring the luminescence intensity of this sample, the element can be quantitatively analyzed.

[0005]

In the conventional ICP emission spectrometer described above, for example, in the quantitative analysis of Na and K, the particle size of the mist introduced into the spray chamber is large, and most of the mist flows to the drain. Low sample introduction efficiency. For this reason, the lower limit of quantification is higher. Specifically, the lower limit of quantification is about 0.1 ppm for both Na and K, which is 10 to several tens times higher than other elements.
It can be seen that is not suitable for.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ICP emission spectroscopic analyzer which increases the efficiency of introducing a sample solution and enables highly sensitive quantitative analysis. Is to do.

[0007]

An ICP emission spectrometer according to the present invention is an ICP emission spectrometer which quantitatively analyzes elements in a sample solution by measuring an emission spectrum of a sample emitted in plasma. An atomizing unit that generates ultrasonic waves to atomize the sample solution, a heating unit that heats the sample atomized by the atomizing unit to remove the solvent, and cools the sample desolvated by the heating unit. And a plasma torch for introducing a sample sprayed in the spray chamber into plasma to emit light.

As a desirable mode of the present invention, the present apparatus is applied to the analysis of a sample solution of Na and K, and in this case, the flow rate of the carrier gas introduced into the atomizing section is 1.2 to 1.5 l / mi.
n, the high-frequency output of a high-frequency induction coil for generating plasma to 0.8 to 1.0 kW, and the distance between the upper end of a plasma torch for introducing a sample into the plasma from the spray chamber and the optical axis of the spectrometer. Set to ２３23 mm.

The ICP emission spectrometer according to the present invention has the following functions and effects. In the atomization section,
Ultrasonic waves are generated by ultrasonic generating means to atomize the sample solution. The atomized sample solution is sent to the heating unit, where it is heated and desolvated. This solvent removal increases the concentration of the sample solution per unit weight. Then, it is sent to the cooling unit to lower the temperature, and is sent to the spray chamber. Of the sample solution sent to the spray chamber, particles having a large particle diameter are sent to a drain, and particles having a small particle diameter are introduced into a plasma torch. In a plasma torch, plasma is generated by discharging a high-frequency induction coil. A mist sample is introduced into the plasma to emit light. The emission spectrum of this sample is quantitatively analyzed by a spectrometer.

[0010] As described above, since the sample solution is atomized by ultrasonic energy before being introduced into the spray chamber,
The particle size of the mist is small, and the ratio of the sample sent to the drain can be reduced. Therefore, since the efficiency of introducing the sample solution into the plasma can be increased, highly accurate measurement is possible even for a small amount of sample.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view illustrating the overall configuration of an ICP emission spectrometer according to an embodiment of the present invention. As shown in FIG. 1, the present apparatus is roughly divided into an ultrasonic nebulizer 5 that sucks up a sample solution 10 and atomizes the sample solution 10 (in FIG. 1, including an ultrasonic nebulizer main part 5 a to an ultrasonic nebulizer introduction part 5 b). The spray chamber 2 introduces the sample sprayed by the ultrasonic nebulizer 5 into the plasma together with the carrier gas, and the sample introduced from the spray chamber 2 is decomposed and excited in the generated plasma to emit light. Plasma torch 4, spectroscope (not shown)
Consists of The configuration after 6 in the sample introduction direction in FIG. 1 is a sample introduction system of the main body of the ICP emission spectrometer.

The main part 5a of the ultrasonic nebulizer is provided with a peristaltic pump 1 for sucking up a sample solution 10.
1. An atomizing section 13 for atomizing the sample solution sucked up by the pump 11 by inflow of a carrier gas, a heating section 14 for heating the atomized sample 10 in the atomizing section 13 and removing the solvent, and a heating section 14 for removing the solvent. The cooling unit 15 is configured to cool the sample 10 in which the solvent has been cooled and introduce the cooled sample 10 into the spray chamber 2. Reference numeral 3 denotes a nebulizer holder for fixing the nebulizer in the ultrasonic nebulizer introduction part 5b.

The ultrasonic vibrator 12 is installed in the atomizing section 13 to promote atomization.
Numeral 2 generates ultrasonic waves. In addition, since the carrier gas inflow section and the sample solution inflow section are provided separately, the carrier gas flow rate and the amount of mist generated are independent, and the optimum value of the carrier gas flow rate is used regardless of the amount of mist generated. be able to. On the other hand, the plasma torch 4
It is composed of a cooling gas introduction pipe 16, an auxiliary gas introduction pipe 17, and a high frequency induction coil 18.

In the ICP emission spectrometer described above, the atomizing unit 13, the heating unit 14, and the spray chamber 2
The sample not introduced into the plasma is discarded as drain. The operation of the above embodiment will be described.

The peristaltic pump 11 sucks up the sample solution 10 and introduces it into the atomization unit 13. Atomization unit 13
The ultrasonic vibrator 12 installed in the device generates ultrasonic waves.
The introduced sample solution 10 is atomized by the ultrasonic waves, and moves to the heating unit 14 by the flowing carrier gas. The heating unit 14 removes the solvent from the atomized sample by heating and concentrates the sample. This desolvation increases the concentration of solute per unit weight contained in the sample, and can reduce the amount of sample discarded as drain. The desolvated sample is introduced into the cooling unit 15. Cooling unit 15
Cools the sample to room temperature and sends it to the spray chamber 2 through the inlet tube.

In the introduced sample, particles having a large particle size are separated in the spray chamber 2 having a double structure. Here, when the spray chamber 2 is introduced, the particle size of the mist is reduced by the ultrasonic vibrator 12, so that the ratio of the sample to be drained is reduced. The thus obtained particles having a small particle diameter go up the plasma torch 4 and reach the vicinity of the high-frequency induction coil 18 mounted on the upper part of the plasma torch 4. on the other hand,
The high-frequency induction coil 18 is discharged by a carrier gas or the like and generates plasma. Here, the introduced sample is
It is decomposed and excited in the generated plasma and emits light. Quantitative analysis is possible by measuring the emission intensity with a spectroscope or the like (not shown).

As a verification of the effectiveness of the above embodiment, N
According to the working conditions shown in Table 1 where a and K were sample solutions,
An experiment was performed. Here, an IC using a conventional coaxial nebulizer performed in comparison with the implementation conditions according to the present embodiment
Table 1 also shows the experimental conditions using the P emission spectrometer.

[0018]

[Table 1] Table 2 shows the respective vacuum wavelengths of Na and K to be measured.

[0019]

[Table 2]

In this embodiment, since the structure is different from that of the sample introduction device using the coaxial nebulizer, the flow rate of the carrier gas, the high frequency output of the high frequency induction coil 18, the observation height of the torch of the plasma torch 4, that is, the plasma torch 4,
The distance between the beam and the optical axis of the spectroscope was optimized by the S / B ratio.
That is, the use of the ultrasonic nebulizer 5 changes the optimum carrier gas flow rate. In addition, by optimizing the high frequency output, the temperature of the plasma is adjusted to the temperature at which Na and K are easily excited in the plasma, that is, the temperature at which plasma is easily emitted, thereby improving the luminous efficiency of the sample. Is optimized, it is possible to contribute to the improvement of the detection efficiency of the emission spectrum in accordance with the maximum point of the emission depending on the position of the plasma.

Here, the S / B ratio is defined as (sample strength−
The blank strength is represented by (blank strength) / blank strength, and the blank strength is the strength of noise due to background or the like. The S / B ratio is a value that is an index of how large a required signal is compared to unnecessary noise and the like.
The larger the value, the better the sensitivity. Therefore,
One method is to select a condition that maximizes the S / B ratio at the stage of condition examination. These carrier gas flow rates,
FIGS. 2 to 4 show the relationship between the high-frequency output, the torch observation height and the S / B ratio. The horizontal axis shows each experimental parameter, and the vertical axis shows the S / B ratio. From FIG. 2 to FIG. 4, the optimum values of the respective parameters are as follows.
2 to 1.5 (l / min), high frequency output 0.8 to 1.0
(KW), and the torch observation height is 16 to 23 (mm).

Table 3 shows the lower limit of quantification of Na and K determined based on the above-mentioned optimum value of the S / B ratio, together with the experimental results obtained by an ICP emission spectrometer using a conventional coaxial nebulizer.

[0023]

[Table 3]

As is clear from Table 3, the ICP of the present invention
According to the emission spectrometer, the lower limit of quantification of Na and K can be drastically improved to about 1/20 as compared with the result obtained under the conventional conditions, thereby greatly improving the sensitivity of Na and K to 20 times. You can see what you can do.

As described above, since the sample solution is atomized before introduction into the spray chamber 2 by using the ultrasonic energy by the ultrasonic vibrator 12, the particle size of the mist is small at the time of introduction into the spray chamber 2, and The introduction efficiency can be kept high. Further, since the sample atomized in the atomization unit 13 is desolvated by the heating unit 14, the concentration of Na and K per unit weight increases,
The introduction efficiency is higher. Further, by optimizing the carrier gas flow rate, the high-frequency output, and the torch observation height based on the S / B ratio, the detection efficiency of the emission spectrum and the luminous efficiency of the sample are improved, and more accurate measurement becomes possible.

In this embodiment, the ICP emission spectroscopy apparatus applied to the water quality survey is shown.
Of course, the present invention can be applied to the investigation of incinerators and other causes when corrosion has occurred, the investigation of the degree of contamination of lubricating oil in diesel engines, etc., and the investigation of scale adhesion in incinerators and the like.

[0027]

As described above, according to the present invention, since the sample solution is atomized by the ultrasonic wave generating means before being introduced into the spray chamber, the particle size of the mist is reduced when the sample solution is introduced into the spray chamber. It is small, and the sample introduction efficiency is improved, and the luminous efficiency in plasma can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an ICP emission spectrometer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a high-frequency output and an S / B ratio in the embodiment.

FIG. 3 shows carrier gas flow rate and S / B in the present embodiment.
The figure which shows the relationship with a ratio.

FIG. 4 is a diagram showing a relationship between a torch observation height and an S / B ratio in the embodiment.

FIG. 5 is a sectional view showing a schematic configuration of a conventional ICP emission spectroscopy analyzer.

FIG. 6 is an enlarged cross-sectional view near the coaxial nebulizer of the ICP emission spectrometer in FIG.

[Explanation of symbols]

 Reference Signs List 2 spraying chamber 3 nebulizer holder 4 plasma torch 5a main part of ultrasonic nebulizer 5b ultrasonic nebulizer introduction part 10 sample solution 11 peristaltic pump 12 ultrasonic oscillator 13 atomization part 14 heating part 15 cooling part 16 cooling gas introduction pipe 17 auxiliary Gas inlet tube 18 High frequency induction coil

Claims (1)

[Claims] An ICP emission spectrometer for quantitatively analyzing an element in a sample solution by measuring an emission spectrum of the sample emitted in plasma to generate an ultrasonic wave to atomize the sample solution. A heating unit for heating the sample atomized by the atomization unit to remove the solvent, a cooling unit for cooling the sample desolvated by the heating unit and introducing the sample into the spray chamber, and the spray chamber. And a plasma torch for introducing the sample sprayed into the plasma into the plasma to emit light.