JPS5942434A - Apparatus for introducing sample of plasma emission spectrochemical analysis device - Google Patents

Abstract

PURPOSE:To obtain a sample introducing apparatus applicable to all solvents without impairing various characteristics of a heater, by providing a thin sheet of graphite on a tungsten heater to bring a sample solution out of direct contact with the heater. CONSTITUTION:A tungsten heater 3 is provided at the inside of a sample vaporizer 1 via titanium electrodes 2. Solvent vapor generated in the vaporizer 1 is evacuated by switching a four-way cock 4 and sample vapor is introduced into plasma 5a. The heater 3 is constituted by providing a thermally-decomposed graphite thin sheet 8 having 0.1mm. thickness to the bottom face of a dent 3a putting on the sample. Further, e.g. 5mul sample is added dropwise onto the thin sheet 8 and the solvent is vaporized by heating said sample at temperatures of 80-180 deg.C and then, is evacuated through the cock 4. The sample on the plate 8 is vaporized by switching the cock 4 and heating the heater 3 to 2,600 deg.C, and the sample vapor is introduced into the plasma 5a. Damage or consumption of the heater causing by a strong acid is eliminated because the direct contact between the heater 3 and the sample is prevented by the sheet 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sample introduction device for a plasma emission spectrometer, and in particular is a novel improvement for efficiently introducing a minute amount of sample into plasma.

A typical device of this kind that has been used in the past has been one in which a tungsten heater evaporates the sample and introduces it into plasma. These devices can effectively introduce samples for water samples, hydrochloric acid solutions, dilute nitric acid solutions, and organic solvent samples; however, for concentrated nitric acid solutions or hydrofluoric acid solutions, the tungsten heater The disadvantage was that it reacted with the acid. Since these acids react with almost all metals, heater materials other than graphite cannot overcome the above disadvantages.

When graphite is used as the heater material, it is difficult to achieve rapid temperature rise due to its larger heat capacity than tungsten.
b. Various chemical interferences occur on the heater.

The present invention provides an extremely effective means for quickly eliminating the above-mentioned drawbacks, and has a structure in which a thin graphite plate is provided on the tungsten heater to cut off direct contact between the sample solution and the heater. I'm taking it. The sample introduction device according to the present invention will be described in detail below with reference to the drawings.

The reference numeral 1 in FIG. 1 is a sample vaporizer, and a tungsten heater 3 having the shape shown in FIG. 2 is provided inside p1 with a titanium electrode 2 interposed therebetween. Reference numeral 4 is a four-way cock, and by switching it, the solvent vapor generated in the vaporizer 1 is exhausted and the sample vapor is introduced into the plasma 5a. 5 is a high frequency plasma torch, and 6.7 is a flow meter that controls the flow rate of Ar (argon) pHs (hydrogen). As shown in FIG. 3, the tungsten heater 3 has a structure in which a thin pyrolytic graphite plate 8 with a thickness of 0.1 mm is provided on the bottom surface of a recess 3a in which a sample is placed.

The case where the sample introduction device according to the present invention incorporating such a heater in the configuration shown in FIG. 1 is operated will be described below. 5 μl of the sample was dropped onto the graphite 8 of the heater 6 in the vaporizer 1 using a micropipette, and the temperature was increased from 80°C to 180°C.
Evaporate the solvent by heating at a temperature of °C. The heating temperature varies depending on the type of solvent. The evaporated solvent vapor is exhausted through the four-way cock 4. After changing the four-way cock to 4 gold, heating the heater 5' to 12,600℃, the sample on the graphite 8 is vaporized by conduction heat and radiant heat from the heater wall, and plasma 5 is heated.
introduced into a. Note that graphite here includes not only pyrolytic graphite but also tantalum-treated graphite, lanthanum-treated graphite, zirconium-treated graphite, and the like.

As described above, in the present invention, direct contact between the heater and the sample solution is prevented by the thin graphite plate, so there is no damage or wear and tear on the heater due to strong acid. In addition, since the sample seeps into these thin graphite plates at a depth of 60 μm or less from the surface, the thickness of the thin plate can be reduced to about 0.1+m, and the decrease in heating rate due to the difference in the amount of heat melt does not pose a major problem ( /''1゜The present invention does not impair the characteristics of conventional tungsten heaters,
This is a sample introduction system that can be applied to all solvents.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. FIG. 1 is a block diagram of a sample introduction device of the present invention. Figure 2 is a conceptual diagram of the heater used here, and Figure 3 is a conceptual diagram of the heater used here.
The figure is a sectional view. 1... Sample vaporizer 2... Titanium electrode 6... Tungsten heater 3a... Heater 4... Four-way cock 5... ...Plasma torch 5a...High frequency plasma 6.7...Flowmeter 8...Graphite thin plate or more Applicant Daini Seiko Go Co., Ltd.

Claims (1)

[Claims] a plasma torch section that emits plasma induced and excited by high frequency; a vaporizer for heating a sample to a high temperature and vaporizing it within a short time; and a four-way cock provided between the plasma torch and the vaporizer. , the vaporizer to the plasma) - a flow meter for controlling a carrier gas that carries the sample vapor from the vaporizer to the plasma),
A sample introduction device for a plasma emission spectrometer, characterized in that a graphite thin plate is provided on a tungsten heater provided in the vaporization device.