JPS5965256A - Measurement of sulfate ion in anionic surfactant - Google Patents

Abstract

PURPOSE:To perform the quantitative analysis of SO4<--> with good accuracy, by a method wherein an aqueous solution containing NaNO3 or NaClO4 is added to a specimen solution and the resulting mixture is injected into an anion exchange resin column while a nitric acid solution of ferric nitrate to the column passing liquid to measure ultraviolet absorption. CONSTITUTION:A solution specimen 2 of an anionic surfactant and 0.01-0.5M solution of NaNO3 or NaClO4 from a liquid feed part 1 are sent to a specimen introducing part 3 and, after mixing, the solution mixture is injected into an anion exchange resin column 4. To the eluted liquid of the column 4, a 0.01- 1.0M nitric acid solution containing 0.001-0.1M of ferric nitrate is sent from a liquid feed part 6 and both of them are mixed in a mixing part 5 to measure ultraviolet absorption generated by the complex formation of SO4<--> in the eluted liquid and FE<3+> by a fluidized photometer 7 while the measured value is compared with the calibration curve preliminarily obtained from known SO4<--> concn. to record and display the SO4<--> concn. by a recording apparatus 8. By this method, SO4<--> is automatically measured in good efficiency without receiving the the obstruction of the substance coexisting in the specimen solution.

Description

Detailed Description of the Invention (Technical Field to Which the Invention Pertains) The present invention relates to a method for measuring sulfate ions in an anionic surfactant in a liquid phase fluid system.In particular, a method for detecting and quantifying sulfate ions. Regarding.

[Description of prior art]

Conventionally, a method for measuring sulfate ions in a liquid phase flow system using a nitric acid solution containing ferric nitrate was published in Japanese Patent Publication No. 54-2.
6918. In this method, a sample solution is added to the nitric acid solution, passed through a separation column filled with anion exchange resin, and then the ultraviolet absorption of this solution is measured to measure sulfate ions. This is an excellent method for detecting and quantifying sulfate ions with simple operations without being affected by substances coexisting therein.

However, in the conventional measurement method described above, since the liquid passing through the separation column contains ferric ions, if an anionic surfactant with a concentration of about 10% coexists in the sample solution, ferric ions may be present. This method has the disadvantage that the reaction between iron ions and anionic surfactants causes precipitation, making it difficult to continuously measure sulfate ions.

[Purpose of the invention]

The present invention solves the above-mentioned drawbacks, and even if the sample solution contains a large amount of anionic surfactant, it can be used continuously without being affected by the anionic surfactant. An object of the present invention is to provide a method for measuring sulfate ions that can detect and quantify sulfate ions.

[Features of the invention]

In the present invention, a sample solution is added to a solution containing sodium nitrate or sodium perchlorate, and after passing through a minute δ1t column packed with an anion exchange resin, a nitric acid solution containing ferric nitrate is added, A patent characterized in that sulfate ions in a liquid phase flow system are detected and detected by measuring the ultraviolet absorption of the /8 liquid after addition.Hereinafter, the features of the present invention will be explained based on the drawings. .

FIG. 1 is a flowchart of the measurement process of the present invention. In FIG. 1, the liquid feeding section 1 is composed of a metering pump and the like, and delivers a 1-lium nitrate solution or a sodium perchlorate/8 solution. A sample introducing section 3 into which a fixed amount of sample solution 2 is added is connected to this liquid feeding section 1 . A separation force ram 4 filled with anion exchange resin is connected to this sample introduction section 3. A mixing section 5 is connected to this column 4. This mixing section 5 mixes the solution that has passed through the column 4 and the nitric acid solution containing ferric nitrate sent from the liquid sending section 6 .

This mixing section 5 is provided with a flow photometer 7 that measures the ultraviolet absorption of the mixed liquid. An automatic recording device 8 that automatically records the measured values of the photometer 7 is connected to the flow photometer 7 .

With such a configuration, the measurement method of the present invention will be explained.

After adding the sodium nitrate solution or sodium perchlorate solution sent from the liquid feeding section 1 to the sample solution in the sample introduction section 3, the added sample solution is injected into the separation force ram 4. If sulfate ions are present in the sample solution, the sulfate ions cause an ion exchange reaction with the anion exchange resin in the column 4.

Sulfate ions are eluted from column 4 after a certain period of time defined by this reaction has elapsed.

Next, the eluted sulfuric acid ions are mixed in the mixing section 5 with a nitric acid solution containing ferric nitrate, which is a coloring liquid and sent out from the liquid sending section 6, to form a complex with the ferric ions. This complex is introduced into the flow photometer 7, the ultraviolet absorption characteristic of the complex is measured, and the sulfate ion can be quantified using a calibration curve prepared in advance. By writing the measured values of the photometer 7 into the automatic recording device 8 and further inputting and storing them into a data processing device (not shown), an automated data processing system for sulfate ions can be realized.

According to the research of the present inventors, in the above measurement method, even if ions other than sulfate ions are contained in the nitric acid solution, or even if a large amount of anionic surfactant coexists with sulfate ions, sulfate ions and Since the ferric ions that react to form a complex are mixed with the sample solution after passing through the column, the time taken for the sulfate ions to pass through the column is not affected. This makes it possible to efficiently quantify sulfate ions even if coexisting substances are present in the sample solution.

Figure 2 shows the measurement results when various coexisting substances were present in the sample solution. In FIG. 2, the vertical axis represents ion concentration and the horizontal axis represents time.

(al: sulfate ion only; bl: sulfate ion, chloride ion, and phosphate ion; C1: measurement result of a sample solution containing sulfate ion and long-chain sodium alkylbenzene sulfonate, respectively.

However, the concentration of C) long-chain sodium alkylbenzene sulfonate is 10%.

As is clear from FIG. 2, according to the present invention, sulfate ions can be determined without being affected by anionic surfactants or the like.

The concentration of sodium nitrate used in the present invention is 0.01 to 0.
．． The concentration of sodium perchlorate is in the range of 0.01 to 0.5M, the concentration of ferric nitrate is in the range of 0.001 to O.IM, and the concentration of nitric acid is in the range of 5M (molar concentration). The concentration is 0. It is preferable that it is in the range of 01 to 1.0M.

〔Effect of the invention〕

As described above, according to the present invention, since ferric ions that undergo a complex formation reaction with sulfate ions are mixed after passing through the column, even if the sample solution contains ions other than sulfate ions, Even if the anionic surfactant is contained at a concentration of about 10%, it has the excellent effect of being able to continuously detect and quantify sulfate ions without causing precipitation and with simple modifications.

Therefore, the present invention is effective for quantifying sulfate ions in anionic surfactants, which are industrial products.

[Explanation based on examples]

EXAMPLES In order to clarify the aspects of the present invention, the present invention will be described in more detail by way of examples, but the examples shown here are merely examples and do not limit the scope of the present invention.

(Example I) 0.06 M Gi'i ff5t sodium was delivered at 1.0 m12 per minute using a metering pump, to which 0.05%
After adding 20μβ of sodium sulfate water/8 solution as sample/8 solution and passing it through an anion exchange resin column (one column 4m++, length 150m5) packed with TSK Gel LS-222 (manufactured by Toyo Soda), It was mixed with a 0.2M nitric acid solution containing 0.01M ferric nitrate, and the ultraviolet absorption of the mixed t& was measured using a flow photometer. Table 1 shows the results of determining the content of sulfate ions from a calibration curve prepared in advance.

(Example ■) Accurately weigh 10 g of an anionic surfactant containing long-chain alkyl sulfate sodium salt, and add exactly 100 m of pure water.
β was used as a sample solution. Using 20 μρ of this sample solution, the content of sulfate ions was determined in the same manner as in Example I, and the content of sodium sulfate was calculated. The results are shown in Table 1.

(Comparative Example 1) A 0.1M nitric acid aqueous solution containing 0.01M ferric nitrate was pumped at 1.0 mjl/min using a metering pump! Send out, 2 for this
20 μβ of 0% 1-lium alkylhenzenesulfonate aqueous solution was added as a sample solution, and after passing through the same column as in Example I, the ultraviolet absorption was measured using a flow photometer.

In this measurement method, after repeating the measurement five times, the pressure in the separation column increased so dramatically that measurement became impossible.

On the other hand, when the sample solution of this comparative example was measured under the same conditions as in Example I, the column did not exhibit any abnormal pressure, and continuous measurements could be carried out 50 times or more.

Table 1

[Brief explanation of drawings]

FIG. 1 is a flowchart of the measurement process of the present invention. FIG. 2 is a characteristic diagram showing the measurement results. ■, 6...Liquid feeding part, 3...Sample introduction part, 4...Separation column, 5...Mixing part, 7...Flow photometer, 8...
...Automatic recording device. Patent applicant Kao Soap Co., Ltd. Agent Patent attorney Naotaka Ide Figure 1

[Minute] Time [Time] CG) (b) Figure 2 322-1 time [minutes] (C)

Claims (1)

[Claims] (11) A sample solution is added to a solution containing sodium nitrate or sodium perchlorate, and the solution to which the sample solution is added is injected into a separation column packed with an anion exchange resin. Anionic surfactant that measures sulfate ions in a liquid phase flow system by adding a nitric acid solution containing ferric nitrate to the solution that has passed through the column and measuring the ultraviolet absorption of the solution to which the nitric acid solution has been added. Method for measuring sulfate ions in the agent. (2) The concentration of 1-lium nitrate is 0.01 to 0.5M.
(Molar concentration) The method for measuring sulfate ions in an anionic surfactant according to claim 11. (3) Concentration of sodium perchlorate is 0.01-0.5M
(4) The method of measuring sulfate ions in an anionic surfactant according to claim 11. (4) The concentration of ferric nitrate is 0.001 to 0.1M. + How to measure sulfate ions in an anionic surfactant according to any one of Items 11 to 3)!
Law. (5) A method for measuring sulfate ions in an anionic surfactant according to any one of claims 11 to (4), wherein the concentration of nitric acid is 0.01 to 1.0 M. ( 6) Claim tl which measures ultraviolet absorption with a fluidized photometric needle and records the measured value with an automatic recording device.
A method for measuring sulfate ions in an anionic surfactant according to any one of items ) to (5).