JPS63210752A - Icp emission analyzer - Google Patents

Abstract

PURPOSE:To automate an analysis by a sequence controller by providing a means for detecting the formation of filamentary plasma and controlling on and off, etc., of a filamentary plasma inducing means by the detection signal thereof. CONSTITUTION:This instrument is so constituted that the formation of the filamentary plasma (f) is detected by an impedance detector D which detects said formation by a change in the input impedance of a coil C wound on a plasma torch P. A plasma flame F by a torch P is then formed by the sequence controller 12 and after the impedance is matched, a sample is dropped into a sample receiver 4 and the sample is dried by a heater 5. A Tesla coil T is thereafter operated to generate corona discharge from the receiver 4. Plasma (f) extends from the flame F and arrives at the receiver 4 when the formed ions arrive at the flame F. The plasma evaporates the sample at the tip of an electrode 3 and supplies the vapor thereof to the flame F. The formation of the plasma (f) is detected by the detector D and the operation of the coil T is stopped. Spectrophotometric measurement by a measurement circuit 11 is then executed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an ICP (high frequency inductively coupled plasma) emission spectrometer.

1. Prior Art 102 Emission spectrometry is suitable for analyzing samples in solution, and solid samples also need to be in solution. The solution sample is atomized in an atomizer and sent into the plasma flame in a flow of carrier gas. 102 Emission analysis uses an atomizer to introduce the sample, so a large amount of sample solution is required.
It cannot be applied to the analysis of trace samples or samples that are difficult to dissolve. It has also been proposed to use a graphite furnace for introducing solid samples and trace solution samples, but there is a problem in that it cannot be applied to samples that are difficult to volatile due to limitations due to the heat resistance of the furnace body.

Problems to be Solved by the Invention The present invention attempts to improve the problem that conventional ICP analyzers are unsuitable for analyzing solid samples or trace samples, and also aims to automate the operation of the apparatus.

21 Means for Solving Problems A sample setting means is provided in the center tube of the plasma torch, and this sample setting means is used as an electrode to extend filamentary plasma from the plasma flame inside the center tube toward the electrode. At the same time, a means for detecting the formation of filamentary plasma is provided, and a means for attracting the filamentary plasma from the plasma flame formed on the plasma torch toward the sample, for example, on/off of a Tesla coil is controlled by the detection signal. .

The plasma torch for ICP analysis has a triple tube structure, with the innermost tube being the center tube, the middle tube being the middle tube, and the outermost tube being the outer tube. The intermediate tube contains gas that forms a plasma flame,
Cooling gas is supplied to the outer tube, and gas is supplied to the central tube for blowing out a jet stream forming a low temperature region along the central axis of the plasma flame. Argon gas is used for all of these gases. In normal ICP analysis, a sample atomizer is connected to the central tube, a carrier gas is sent to the atomizer to atomize the sample, and this carrier gas is sent to the central tube. In the present invention, an atomizer is not connected to the central tube, but an electrode is inserted and a sample is held at the tip of the electrode. The same applies if the electrode itself is used as a sample. When the Tesla coil head is applied to this electrode, a brush discharge occurs from the electrode, and the generated ions ride the gas flow in the central tube and reach the plasma flame. extends towards the electrode and connects to it. Energy is supplied to the filamentary plasma from the coupling high-frequency coil of the plasma torch, and the filamentary plasma is maintained even after the Tesla coil is released. Since the filamentary plasma has a high temperature, when it reaches the electrode, the sample at the tip of the electrode is evaporated by the high temperature, moves up the central tube along with the flow of carrier gas, and is supplied to the plasma flame. Since the plasma directly heats the sample, it is not limited by the heat resistance of the sample holder.
This means that even non-volatile samples can be analyzed.

Since the device of the present invention operates as described above, the order of device operation is as follows, assuming that the plasma torch is already lit.
The sequence is as follows: introduction of the sample into the sample setting means, activation of the Tesla coil, confirmation of filamentary plasma formation, deactivation of the Tesla coil, start of spectroscopic measurement, and completion of - analysis operations, and these operations are performed by the sequence controller. In this case, confirmation of the formation of filamentary plasma is extremely important as it determines whether the sample is being supplied to the plasma flame or not. Automation becomes possible.

Embodiment The drawings show an embodiment of the present invention. A plasma torch P has a triple tube structure, and a sample introduction chamber 2 is connected to the lower end of a central tube 1. The sample introduction chamber is detachable and can be replaced with a sample atomization device used in normal ICP analysis.

An electrode tube 3 is inserted into the sample introduction chamber 2, a sample receiver 4 is provided at the upper end of the electrode tube 3, and a heater 5 for drying the solution sample is inserted into the electrode tube 3. Further, a carrier gas inflow boat 6 is provided in the sample introduction chamber, and carrier gas is supplied to the central tube 1 through the sample introduction chamber. Furthermore, a microsyringe insertion boat 7 is installed in the sample introduction chamber.
is provided, and a drop of the solution sample is supplied onto the sample receiver 4 using the microsyringe 8. 9 is a sample automatic supply mechanism. If the sample is a powder, make it into a slurry with water or the like, apply it to the tip of the sample supply rod, insert it from the microsyringe insertion boat 7 and bring it into contact with the sample receiver 4, so that the slurry sample adheres to the sample receiver 4. .

The electrode tube 3 is connected to the Tesla coil T. C is a coil wound around the outer periphery of the upper end of the plasma torch P, and is connected to a high frequency power source H via an impedance matching box B by a coaxial cable K. D is an impedance detector that detects changes in the input impedance of the matching box B. Specifically, changes in the strength of reflected waves from the matching box are detected. 10 is a gas controller that adjusts the flow rate of carrier gas; 11 is a photometer of a spectrophotometer; and 12 is a sequence controller that controls the entire apparatus.

The operation of the device described above proceeds as follows. First, a plasma flame is formed in the plasma torch (lit), and the impedances of the coil C and the power source H are matched using the matching box B. This matching adjustment is performed by adjusting the variable capacitor in the matching box. From now on, leave the plasma torch lit. Next, the sample is injected into the sample introduction chamber 2 using the microsyringe 8. Injection here means dropping one drop of the sample solution onto the sample receiver 4. Next, the heater 5 is energized for a certain period of time to dry the sample. Then activate Tesla coil T. When the Tesla coil T is activated, a corona discharge is generated from the sample tray 4, and the generated ions ride the carrier gas flow and ascend the central tube 1, reaching the plasma flame F. In this way, when an ion path is created between the plasma flame F and the sample above the sample receiver, filamentary plasma f extends from the plasma flame F and reaches the sample receiver along this path. Once the filamentary plasma is formed, the Tesla coil becomes unnecessary, so the operation of the Tesla coil T is stopped.For this purpose, it is necessary to confirm that the filamentary plasma f has been formed, but in order to confirm this, the impedance A detector is provided. That is, since the matching box performs impedance matching between the coil C and the high frequency power source H while the plasma flame F is being formed, the input impedance of the matching box B is equal to the line impedance of the coaxial cable, The output impedance is equal to the input impedance of coil C. However, when the filamentary plasma f is formed, energy is supplied from the high frequency power source H to the filamentary plasma f, so that the coil C
input impedance changes. Therefore, impedance mismatch occurs between the matching box B and the coil C, and a reflected wave is returned from the output end of the matching box B. Therefore, by detecting the reflected waves, it is found that the impedance of the coil C has changed, and thereby it is confirmed that filamentary plasma has been formed.

When the formation of filamentary plasma is confirmed, the operation of the Tesla coil T is stopped, and the photometry circuit 11 performs spectrophotometric measurement. The filamentary plasma has an extremely high temperature, and this high temperature evaporates the sample. After a while, the sample on the sample receiver 4 completely evaporates, and the surface of the sample receiver 4 is exposed. When this state is reached, one analysis operation ends. If the filamentary plasma is applied to the sample receiver 4 even after the sample has run out, the sample receiver itself (made of carbon or tungsten) will evaporate and be damaged by fire. , the filamentary plasma f is immediately extinguished. To extinguish the filamentary plasma, the flow rate of the carrier gas to the central tube l is set to 0. Then, the next sample injection operation is performed, and the above-mentioned operation is repeated.

In the above embodiment, the filamentary plasma formation detection means is an impedance detection means, but it may be a means for detecting light of filamentary plasma.

G. Effects The ICP emission spectrometer of the present invention heats and evaporates the sample by filamentary plasma extending from the plasma flame of the plasma torch, so the sample may be in a small amount and may be solid. And since the operation is performed automatically, it is efficient.

[Brief explanation of the drawing]

The drawing is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention. P... Plasma torch, l... Center tube, 2... Sample introduction chamber, 3... Electrode, 4... Sample receiver, 5... Heater, 6... Carrier gas port, 8 ...Micro syringe, 9...Trial f4 controller, 10...Gas controller, 11...Photometry circuit, 12...Sequence controller, F...Plasma flame, f...Filamentary plasma, C... Coil, B... Impedance matching box, D... Impedance detector, K... Coaxial cable, H... High frequency power supply, T... Tesla coil.

Claims (1)

[Claims] A sample installation means is provided in the sample introduction chamber connected to the central tube of the plasma torch, and this sample installation means is connected as an electrode to a means for attracting filamentary plasma from the plasma flame, and the formation of filamentary plasma is detected. 1. An ICP emission spectrometer, characterized in that a means is provided, and the detection signal thereof controls turning on and off of the filamentary plasma attracting means and the start of measurement.