JP3261288B2 - Dissolution supply device for sample used for ICP analysis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductively coupled high frequency plasma emission spectrometry.
red plasma atomic emissio
n spectrometry: hereinafter Dissolution supply device sample used when analyzing element in the sample by that ICP analysis).

[0002]

2. Description of the Related Art When a sample solution used for conventional ICP analysis is obtained by electrolysis, a so-called constant current method in which a constant current DC voltage is applied between a sample and a cathode is employed. This is because according to this constant current electrolysis method, the concentration of the main component between samples can be made constant (matrix matching) satisfactorily.

[0003]

However, when electrolysis of a metal sample containing Fe as a main component is performed by the above-mentioned constant current method, it is difficult to prepare a sample such as a carbide or nitride of Ti or Nb in the sample. When a soluble component is contained, there are the following inconveniences.

FIG. 3 shows a change in electrolysis voltage when a sample containing a hardly decomposable component is electrolyzed using a hydrochloric acid / nitric acid aqueous solution as an electrolytic acid solution by a constant current method. And Fe
And shows the temporal change of the ion concentration of Ti and Ti.
Melts quite smoothly as shown by curve A, but Ti
Does not dissolve after a considerable amount of time, as shown by curve B.

At some point, as shown by curve C,
The electrolytic voltage rises sharply, the dissolved amount of Fe that has been dissolved smoothly up to that time decreases, and the dissolved amount of Ti increases rapidly, but the electrolysis and dissolution of the metal sample stops.

Thus, a sample containing a hardly decomposable component is
In the conventional method of performing electrolysis by using a hydrochloric acid / nitric acid aqueous solution as an electrolytic acid solution by a constant current method, passivation of Fe occurs, so that a poorly soluble component such as Ti cannot be rapidly electrolyzed.

On the other hand, it is conceivable to perform electrolysis using a hydrochloric acid aqueous solution as an electrolytic acid solution by a galvanostatic method. Cannot be disassembled. In addition, it is conceivable to separately dissolve only the hardly soluble component,
In this case, the pre-processing of the ICP analysis is troublesome, and accordingly, the ICP analysis takes much time.

The present invention has been made in consideration of the above-mentioned problems, and has as its object to quickly and stably conduct electric power control over a wide range of components from a readily soluble component to a poorly soluble component contained in a metal sample. An object of the present invention is to provide a dissolving and supplying device for a sample that can be decomposed.

[0009]

In order to achieve the above object, according to the present invention, a sample is electrolyzed using an electrolytic acid solution, and a gas and a solution generated thereby are separated by a gas-liquid separation tube. In the sample dissolving / supplying apparatus used for ICP analysis in which the separated solution is sent to an ICP analyzer as a sample solution, when performing the electrolysis, a hydrochloric acid / nitric acid aqueous solution is used as an electrolytic acid solution, and the sample and the electrolytic acid are used. between the liquid, by applying a constant voltage in the range of 0.8V~2.8V
Along with the constant potential electrolysis,
Solution storage for temporarily storing the solution obtained by the electrolysis
A retaining part is provided .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus for dissolving and supplying a sample used for ICP analysis according to the present invention (hereinafter simply referred to as an apparatus for dissolving and supplying a sample).
In FIG. 1, reference numeral 1 denotes a cell for electrolyzing a metal sample 2; a metal sample 2 held down by a sample holding member 3; And the electrodes 4 are arranged so as to have an appropriate gap. A portion 3a of the tip side of the sample holding member 3 which presses the metal sample 2 is formed on an electrode.
The electrodes 4 are connected to a positive terminal 7P and a negative terminal 7N of a DC power supply 7 for electrolysis, as indicated by virtual lines 5 and 6, respectively. That is, the metal sample 2 is configured as a positive electrode, and the electrode 4 is configured as a negative electrode. In the cell 1 configured as described above, an electrolytic acid solution A described later is used.
When (or B) is supplied, electrolysis is performed, and gas G and solution L after electrolysis are generated.

Reference numerals 8 and 9 denote two flow paths connected to the upstream and downstream sides of the cell 1, respectively. First, the electrolytic acid solutions A and B are respectively supplied to the ends of the first flow path 8 on the upstream side. 2 accommodated
The two tanks 10 and 11 are connected via a first valve 12, and a first pump 14 is provided downstream of the first valve 12 (closer to the cell 1) via a separator 13. . The electrolytic acid solutions A and B are aqueous solutions of hydrochloric acid and nitric acid,
The concentrations are different from each other.

The first flow path 8 has a first pump 14
The second and third valves 15 and 16 are interposed in series with each other on the downstream side of the tank, and the second valve 15 is connected in series with a second pump 17 and a tank 18 containing cleaning water W. The washing water supply path 19 is connected, and a first drain flow path 21 having a drain pot 20 is connected to the third valve 16. Reference numerals 22 and 23 denote an internal liquid container and an electrode container connected to the liquid separator 13, respectively.
, The terminal 7C of the DC power supply 7
Is provided with a reference electrode 25 connected to the reference electrode 25.

A filter 26 is provided in the second flow path 9 on the downstream side, and a gas-liquid separation pipe 27 is provided on the downstream side of the filter 26. At the inlet on the upstream side of the gas-liquid separation tube 27, a second flow path 9 through which a mixed fluid F of the gas G from the cell 1 and the solution L after electrolysis flows, and one end of the cleaning water supply path 19 at one end. 2 connected to the downstream side of the pump 17,
A washing water supply path 29 having a fourth valve 28 in the middle is connected. A flow path 31 provided with a fifth valve 30 is connected to an outlet on the downstream side of the gas-liquid separation pipe 27. Further, the drain discharge part 32 of the gas-liquid separation pipe 27 is connected to a drain flow path 33 connected to the drain pot 20 by a flow path 34.
Connected through.

The mixed fluid F supplied to the gas-liquid separation pipe 27 passes therethrough and is separated into a solution L and a drain, and the solution L is supplied to a solution storage section 35 through a flow path 31. Drain is supplied from a drain discharge section 32 to a drain flow path 33.
And is stored in the drain pot 20.

Reference numeral 35 denotes a solution storage section connected to the downstream side of the gas-liquid separation pipe 27, more specifically, to the downstream side of the flow path 31 connected to the downstream outlet of the gas-liquid separation pipe 27. In the part where the solution is slightly stagnant in the storage part, the ICP analyzer 36
The suction tube 37 of the nebulizer is inserted and connected. The outlet on the downstream side of the solution storage section 35 is connected to the drain flow path 33 through a sixth valve 38 composed of, for example, a two-way solenoid valve.
It is connected to the. Further, the flow path 3 of the solution storage section 35
A drain discharge section 39 is opened below the end of the first section and above the insertion end of the suction pipe 37, and the downstream side of the discharge section 39 is connected to the drain flow path 33.

The gas-liquid separation tube 27 and the solution storage section 35 are made of a material having excellent acid resistance and heat resistance (for example, Pyrex (trade name) glass).
20 ml. In addition, the first to third valves 12, 1
5 and 16 are formed of, for example, three-way solenoid valves, and the fourth to sixth valves 28, 30, and 38 are formed of, for example, two-way solenoid valves. In particular, the fifth and sixth solenoid valves 30 and 38 have valve portions made of a fluorine resin having excellent acid resistance. Also,
ON / OFF of the pumps 14 and 17 and the solenoid valves 1
Control of opening and closing of the valves 2, 15, 16, 28, 30, and 38 is appropriately sequence-controlled by a control unit (not shown).

The operation of the sample dissolving / supplying apparatus having the above configuration will be described. First, the cleaning water W and the electrolytic acid solution A (or B) are flowed in the direction of the cell 1 to clean the flow paths 8, 9 and the surface of the sample 2 (the portion facing the cell 1). At this time, the fifth
Valve 30 is Ri you open, not sixth valve 38 is closed
You. As a result, the solution storage section 35 has a drain discharge section 39
Usually, about 1 to 15 ml of the pre-cleaning liquid W accumulates up to the height, and this pre-cleaning liquid W is supplied to the ICP analyzer 36 via the suction pipe 37.

Next, the electrolytic acid solution A (or B)
A constant flow rate of about 10 to 10 ml / min is supplied, and the power supply 7 for electrolysis is turned on. The electrolysis power supply 7 has a constant voltage / constant current, and is determined by a preliminary experiment. At the timing when the fluid F after electrolysis reaches the gas-liquid separation tube 27, the fifth valve 30
Is closed. The solution L of the fluid F is separated from the gas G and stored in the gas-liquid separation tube 27. During this time, IC
The P analyzer 36 sucks the pre-cleaning liquid W in the solution storage 35.

Next, when the solution L required for the ICP analysis is accumulated, the sixth valve 38 is opened to discharge the pre-cleaning liquid W as drain.

After that, the sixth valve 38 is closed and the fifth valve 30 is opened to transfer the solution L stored in the gas-liquid separation tube 27 to the solution storage section 35. The solution L is stored in the solution storage unit 35, so that its ion concentration is averaged.

The solution L having the averaged concentration is sucked by the suction tube 37 of the nebulizer, sent to the ICP analyzer 36 as a sample solution, and subjected to a predetermined ICP analysis.

After that, the fifth valve 30 is closed, and the washing water W and the electrolytic acid solution A (or B) are flowed in the cell 1 direction,
The channels 8 and 9 and the surface of the sample 2 are washed, and the washing liquid W at this time is stored in the gas-liquid separation tube 27. By doing so, even if the cleaning liquid W flows into the gas-liquid separation tube 27 from the direction of the cell 1 during the ICP analysis, it flows into the solution storage unit 35 and mixes with the solution L having the averaged concentration. Is prevented. When the ICP analysis is completed, the sixth valve 38 is opened, and the solution storage unit 3 is opened.
The solution L remaining in 5 is discharged.

Then, the sixth valve 38 is closed, and the fifth valve 30 is opened to introduce the washing water W into the solution storage section 35 and wait for the next measurement.

After the metal sample 2 has been removed from the sample holding member 3, the washing water W is supplied to the washing water supply passage 19, the second pump 17, the washing water supply passage 29, and the fourth valve 29 for gas-liquid separation. It is supplied to tube 27.

As will be understood from the above description, the above test
According to the dissolving and supplying apparatus for the raw material, the solution L after electrolysis whose ion concentration changes with time is temporarily stored in the solution storage section 35 provided at the subsequent stage of the gas-liquid separation tube 27. As a result, a solution having an averaged ion concentration is obtained.

The inventor of the present invention has proposed that an aqueous solution of hydrochloric acid / nitric acid (hydrochloric acid, nitric acid and water be mixed at a volume ratio of For example, 1: 1: 2) is used, and a constant potential electrolysis method is used, and six samples a to f in which the amount of Ti contained in steel (Fe) is known are used.
The electrolytic voltage applied between the anode and the cathode 4 is varied (0.5 V,
When the solution L after the electrolysis was analyzed and measured while changing the voltage at 0.8 V, 2.8 V, and 3.0 V), the results shown in Table 1 below were obtained.

[0028]

[Table 1]

To give a brief explanation of the above Table 1, the numbers in parentheses in Samples a to f are known in advance by the amount (%) of Ti contained in Fe. Electrolysis voltage 0.5
V, 0.8 V, 2.8 V, and 3.0 V, the values obtained when the solution L after electrolysis was the same as those in FIG.
The results obtained when the ICP analysis was performed using the apparatus shown in FIG. 1 are specifically, [[L _Ti / L
_Fe ) × 100] (%).

From the above Table 1, it can be seen that the electrolysis voltage is 0.5V-2.
When the voltage is 8 V, it can be seen that normal Ti (%) can be obtained in any of the samples a to f.

FIG. 2 shows a temporal change of the potential and the current when the sample d among the samples a to f is electrolyzed at a constant potential of 0.8 V. Also, it can be seen that the current value hardly changes and electrolysis can be performed in a stable state.

From these facts, a hydrochloric acid / nitric acid aqueous solution was used as an electrolytic acid solution, and a potential of 0.8 to 0.8 was obtained by a potentiostatic electrolysis method.
By applying a constant electrolysis voltage in the range of 2.8 V (with respect to the AgCl reference electrode potential) between the sample 2 and the electrolytic acid solution, the components from the easily soluble component to the hardly soluble component can be subjected to the same electrolysis. can be analyzed by ICP by using a solution L, it is not necessary to separately dissolving process only sparingly soluble Ingredient.

[0033]

As described above, according to the apparatus for dissolving and supplying a sample of the present invention, it is possible to easily and stably dissolve easily soluble components contained in a sample as well as hardly soluble components. In particular, when the sample is steel, hardly soluble components such as Ti can be easily dissolved without causing passivation of Fe.

Therefore, the sample dissolution supply apparatus of the present invention is provided.
According to the device, from the easily soluble component to the hardly soluble component, ICP analysis can be performed using the same solution after electrolysis,
Since there is no need to separately dissolution treatment only sparingly soluble Ingredients,
The ICP analysis can easily and that the cell 's row in a short period of time.

[0035] The sample dissolution supply device of the present invention
In the latter stage of the gas-liquid separation tube,
Solution storage section for temporarily storing the solution
Of the solution after electrolysis where the ion concentration changes over time
The ion concentration can be averaged, and this ion concentration
Supply the averaged solution to the ICP analyzer as a sample solution
By doing so, the specified ICP analysis can be performed.
You.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing one configuration example of an apparatus for carrying out a sample dissolving method of the present invention.

FIG. 2 is a diagram showing an example of temporal changes in voltage and current when a sample is dissolved by the method for dissolving a sample.

FIG. 3 is a diagram for explaining a conventional technique.

[Explanation of symbols]

2 ... sample, 4 ... cathode, 27 ... gas-liquid separator, 35 ... solution storage
Retaining portion, A, B: electrolytic acid solution, G: gas, L: solution.

Continued on the front page (72) Inventor Takeshi Uemura 2nd Higashicho, Kichijoin-miya, Minami-ku, Kyoto, Kyoto Inside (72) Inventor Takaaki Minami 2nd Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto, Kyoto (56) References JP-A-2-216444 (JP, A) JP-A-63-151853 (JP, A) JP-A-8-122323 (JP, A) JP-A-8-233708 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 1/28 G01N 21/73

Claims (1)

(57) [Claims] 1. A sample is electrolyzed using an electrolytic acid solution, and a gas and a solution generated by the electrolysis are separated by a gas-liquid separation tube, and the separated solution is used as a sample solution in an ICP.
In the sample dissolution supply device used for ICP analysis, which is sent to an analyzer, when performing the electrolysis, a hydrochloric acid / nitric acid aqueous solution is used as an electrolytic acid solution, and 0.8 V to Apply a constant voltage in the range of 2.8V
Electrolysis, and at the subsequent stage of the gas-liquid separation tube,
Solution storage section for temporarily storing the solution obtained by gas decomposition
An apparatus for dissolving and supplying a sample used for ICP analysis, comprising: