JPS6365345A - End point detector for separate-phase titration - Google Patents

Abstract

PURPOSE:To enable easy separate-phase titration by providing a detecting chamber which permits flow of an org. solvent phase through a porous film as well as a light emitting part having an optical path in the detecting chamber and light receiving part. CONSTITUTION:The detecting chamber 2 is provided with a notch at its base body 1 and is communicated with the outside through the porous film 3. The light generated in the light emitting part 4 arrives at the light receiving part 5 by passing the optical path (a). This device is immersed in a titration system at the time of the separate-phase titration. Since the porous film 3 allows the selective passage of only the org. solvent phase, the chamber 2 is filled with the org. solvent phase. No special force is required at the time of introducing the org. solvent phase in the titration system into the chamber 2 and the introduction depends only on the diffusion power from the porous film 3. The chamber 2 is, therefore, required to be of a small capacity. The porous film 3 which separates only the org. solvent phase from the titration system, allows the passage thereof and has the high passage rate thereof is preferable. Since the optical path (a) in the chamber 2 is increased without increasing the volume of the chamber 2 in the above-mentioned manner, the detection sensitivity improves.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an end point detection device for external phase titration of ionic surfactants.

[Conventional technology]

In phase separation titration, a heterogeneous system consisting of water and a water-insoluble organic solvent is used as a titrant, and titration is performed using an aqueous solution.

The titration end point is determined by observing the process in which the compound involved in the titration (phase separation indicator) is extracted into the organic phase and becomes colored or discolored, or conversely, the compound involved in the titration is dissolved into the aqueous phase and decolorized. Since the color tone of the phase separation indicator differs between the organic phase and the organic phase, skill is required to judge the end point. Also, is there one titrant for phase separation titration? Other titration methods require vigorous shaking of the titration cylinder with a stopper each time a drop is added, and it takes time for the two phases to separate due to emulsification, especially in the surfactant Kanakura system. Measurement requires more time and effort compared to

Therefore, from a titration system containing a test ionic surfactant and a phase separation titration indicator that forms a complex with the surfactant, the titration system is a heterogeneous system consisting of water and a water-insoluble organic solvent.
Only the organic solvent phase is extracted continuously through the entire porous thin membrane that can extract only the organic solvent phase, and its light absorption is measured.While circulating in the titration system, it is mixed with the ionic surfactant to be tested. When performing phase separation titration using a charged surfactant as a titrant, the organic solvent extraction part is discharged through the organic solvent extraction part arranged so that the perpendicular to the outer surface of the porous thin film is approximately horizontal. A method for measuring ionic surfactants characterized by the following was previously developed and reported (
4% Kaisho 57-106860).

[Problems to be solved by the present invention]

However, the above method requires a porous thin membrane and a pump in order to forcefully and continuously take out only the organic solvent phase9, and their durability has been problematic.

In addition, air was sucked in during the titration, and one titration session had to be interrupted. Furthermore, since the organic solvent phase in the titration system is sent to the detection device using a pipe,
There was also the problem of time lag, where the actual neutralization in the titration system and the judgment in the detection system were different.

Therefore, it has been desired to develop a method and an apparatus for easily performing phase separation titration.

[Means to solve the problem]

Under these circumstances, the present inventors have worked hard at their own expense to develop a phase separation titration method that can be applied to a wide variety of surfactants, has easy end point determination, is highly accurate, and can measure surfactants in a short time. As a result of research, it was discovered that this purpose could be achieved by using a porous membrane that can extract only the organic solvent phase from the emulsion system, a light emitting part and a light receiving part, under certain conditions. completed.

That is, the present invention provides an end point detection device for external phase titration, which includes a detection chamber in which an organic solvent phase can flow through a porous membrane, and a light emitting section and a light receiving section having an optical path in the detection chamber. .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An end point detection device for external phase titration (hereinafter referred to as "detection device") of the present invention will be described below with reference to drawings showing embodiments thereof.

FIGS. 1, 2, and 3 are cross-sectional views of one detection device of the present invention. In each figure, reference numeral 2 is a detection chamber, and a notch is provided in the base body 1'. This 2 communicates with the outside through a porous membrane 3. Also, 4 is the light emitting part, and 5 is the light receiving part.
The light generated at 4 passes through optical path a and reaches 5. During phase separation titration.

The detection device of the present invention is immersed in the titration system, and 3 selectively allows only the organic solvent phase to pass through, so that 2 is filled with the organic solvent phase.

In the present invention, when introducing the organic solvent phase into 2 in the titration system, no special force is used and it depends only on the diffusion force from 3. Therefore, 2 is preferably a small capacity, particularly preferably 2d or less. Also, 3
It is preferable that only the organic solvent phase is completely separated from the titration system in one pass, and that the passage speed is high. Specifically, a porous thin film made of a fluororesin such as a polyfluorinated ethylene resin or a polyfluorinated propylene resin is suitable. The hole diameter of holes 9 and 7 is l.
Appropriately, the diameter is 0 to 100μ, preferably 10 to 60μ, and the thickness is approximately 0.1 to 1m. Further, the light emitted in step 4 may be continuous light or monochromatic light, but the wavelength of the light used for detection is determined by the phase separation indicator used in phase separation titration.

The detection device of the present invention shown in FIG. 'e allows you to reach 5. According to this device.

Since the optical path a in 2 becomes longer without increasing the volume of 2,
Detection sensitivity can be improved.

The detection device of the present invention shown in FIG.
The glass fibers 6B and 5 are allowed to arrive as they are.

Note that the lens 7 is not essential in either of the detection devices shown in FIGS. 1 and 2, and can be omitted.

The detection device of the present invention shown in FIG. 3 uses a light emitting diode as 4 and a light receiving element as 5.

As the light receiving element, a photodiode, a phototransistor, etc. are used. In this detection device, the light emitting diode and the light receiving element are appropriately selected depending on the phase separation indicator used.

The end of the 1-minute phase titration is determined by the inclined detection device of the present invention based on the following principle.

That is, as mentioned above, the phase 2 is filled with the organic solvent phase from the titration system, but at the end point of the phase 1 titration, the phase separation indicator is extracted from the aqueous phase into the organic solvent phase, resulting in coloration or discoloration. Otherwise, the color tone of the entire organic solvent phase also changes because it is transferred from the organic solvent phase to the aqueous phase and decolorized. Therefore, the color tone of the organic solvent phase in 2 also changes, the light from 4 is also affected by this, and the change, ie, the end point of phase separation titration, is detected in 5.

Detection device of the present invention? The mechanism of the analytical method used will be explained in more detail as follows for all cases in which an anionic surfactant is analyzed using a phase separation titration indicator and a cationic surfactant as a titrant.

When an anionic surfactant (A11-) and an indicator (In'') are added to a titration liquid consisting of water and a water-insoluble organic solvent, a part of the anionic surfactant and the indicator form a complex.
form and enter the organic phase (organic phase coloration).

An-aq + Il”aq→(An-In+Jor
The anionic surfactant present in excess forms a complex with the cationic surfactant (Ct") supplied from the titrant and moves to the organic solvent phase, but this is colorless.0 An-a (1+ Ct” aq → (An −Ct) or
gThe cationic surfactant is further added, and near the end point, the complex between the anionic surfactant and indicator in the organic solvent phase is metathesized by the cationic surfactant, and the indicator is dissolved in the aqueous phase. Transsolve.

(An-In) org+ Ct+aq→(An-(
4] org + IH"aq At this point, the organic solvent phase is decolorized, so the end point can be determined by measuring the absorbance.

The absorbance may be determined by measuring visible absorption or ultraviolet absorption of the organic solvent phase depending on the type of indicator.

Detection device of the present invention? The ionic surfactants to which the analysis method is applied include anionic surfactants.

Includes cationic surfactants and amphoteric surfactants.

Anionic surfactants include fatty acid salts (soaps), carboxylic acid type surfactants such as polyoxyethylene alkyl ether carboxylate; alkylbenzene sulfonates (AB S, LA S), flucan sulfonates (
SAS or paraffin sulfonate), dialkyl sulfosuccinate, α-sulfo fatty acid salt, hydroxyalkane sulfonate.

Sulfonic acid type surfactants such as alkenesulfonates (AO8 or α-olefin sulfonates); sulfuric acid esters such as alkyl sulfate ester salts, polyoxyalkylene alkyl ether sulfate ester salts, and polyoxyalkylene alkyl phenyl ether sulfate ester salts Salt-type surfactants: Includes phosphate-type surfactants such as alkyl phosphate ester salts and polyoxyethylene alkyl ether phosphate ester salts.

Cationic surfactants include quaternary ammonium salts such as tetraalkylammonium salts and alkylpyridinium salts.

In addition, amphoteric surfactants include N, N, N-trialkyl-
N-carboxyalkylammonium betaine, N,N
, N-trialkyl-N-sulfoalkyl ammonium betaine (sulfobetaine), trialkylamine oxide, and the like.

A phase separation titration indicator that forms a complex with the ionic surfactant used in the present invention and becomes colored or changes color (q'+ includes methylene blue, methyl green, toluidine blue, fuchsin, neutral red, and botamine). First Trend BNL, Dimidium Bromide, Azole A, Bromphenol Blue, Methyl Orange, Erythrosi/, Bromthymol Blue, Bromcresol Verful, Orange ■, Dichlorofluorescein, Eosin, Erythrosin, Disulfine Blue, Tetrabromophenol Add phthalein ethyl ester potassium 11 salt, etc.

The water-insoluble organic solvent used as the titration liquid includes benzene,
Solvents with a specific gravity smaller than 1, such as toluene, xylene, and ethyl acetate, may be used, but chlorinated hydrocarbon solvents with a specific gravity larger than 1, such as chloroform, methine chloride, perchloroethylene, monochlorobenzene, and carbon tetrachloride, may be used. Preferably,
In particular, chloroform is the most preferred solvent because it dissolves the resulting complex well.

The titrant solution is an aqueous solution of a surfactant having a charge opposite to that of the ionic surfactant to be tested. That is, when an anionic surfactant is analyzed, a cationic surfactant solution is used as the titration solution, and conversely, when a cationic surfactant is analyzed, an anionic surfactant solution is used as the titration solution. In this case, is the charge opposite to that of the ionic surfactant being tested? It is also possible to carry out so-called back titration, in which an excess amount of the ionic surfactant is added and the titration is performed with an active agent having the same charge as the ionic surfactant to be tested. Amphoteric surfactants behave as anionic surfactants or cationic surfactants depending on the difference in H, so for example, if an acid is added to lower the H, it becomes cationic. Surfactant?
This can be done in the same manner as when analyzing.

According to the present invention, it is possible to automate the phase separation titration of an ionic surfactant, which has conventionally been performed by shaking by hand, and to easily determine the end point, with high precision, and to perform it in a short time. It became possible to do so.

Further, since no pump or the like is used, problems such as the durability of the pump and the porous membrane, and the problems of air intrusion are solved.

Note that in the detection device of the present invention, the movement of the organic solvent phase through the porous membrane is rate-determining, so it is desirable to perform titration at a constant rate.

[Example] Next, the separation phase titration using the detection device tube for external phase titration of the present invention will be described with reference to Examples.

Example 1 (Quantitative determination of anionic surfactant) A. Reagent used fil 1/20 ON benzethonium chloride aqueous solution - Iami Y1622 (manufactured by Rohm & Hass, USA) 2.359 was weighed and water was added to make 1 liter. Note that the titer was determined using the primary standard sulfoconophosphate zo2-ethylhequinyl sodium.

121 Methylene blue solution methine/blue (JIS K8897 special grade) 0.03g
Add water to 6.8 g of concentrated sulfuric acid and 50 g of sodium sulfate (anhydrous) to make 1 liter.

(3) Chloroform Reagent special grade? use.

B. Equipment used (1) Detection device for external phase titration This is the same type of device as shown in Figure 1, and its detection chamber volume is 0. Fd. The porous membrane provided in this detection chamber is made of polyfluorinated ethylene (pore diameter 60 μ, thickness 0.3 m).
It is.

(2) Light-emitting section and light-receiving section PTA-118 manufactured by Kyoto Denshi Co., Ltd. was used as the light-emitting section and the light-receiving section. Just in case, the measurement wavelength is 63011.
81 de Ruru.

C6 Procedure: Precisely weigh a sample so that the amount of anionic surfactant is 0.3 to 0.4 g, dissolve in pure water, and make exactly 200 g. 10m of this solution? Take exactly 150 liters of beaker and add 2511 liters of methylene blue solution, 40 tJ of pure water and 25 liters of chloroform. Place a stirrer in the beaker and stir using a magnetic stirrer (1200 rpm).
Let's do it. The entire detection device for external phase titration is immersed in this beaker, and the light emitting part and light receiving part are adjusted to obtain the standard absorbance (absorbance =
0). Next, titration was performed using 1/200 N benzethonium chloride solution, which was added dropwise at a rate of 0.3 mJ/min. Is the end point the straight line centered on the inflection point in the titration curve recorded by absorbance? It is the intersection point extrapolated to the standard absorbance (absorbance -〇). The content of anionic surfactant was determined by the following formula.

Amount of sample collected (9) × Wataru MW: Average molecular weight of anionic surfactant f: Titrant titer Value measured when using all sodium dodecyl sulfate as an anionic surfactant and performing repeated quantitative analysis The first
Shown in the table.

Table 1 Example 2 (capacity of detection unit and analysis time) What are the accurate results when the capacity of the detection chamber is changed under the conditions shown in Example 1? The titration time required to obtain the desired amount was measured. The results are shown in Table 2.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a one-reflection type detection device of the present invention. FIG. 2 is a sectional view showing a passing type detection device of the present invention. FIG. 3 is a sectional view showing a detection device of the present invention using a light emitting diode as a light emitting part and a light receiving element as a light receiving part. Above, Article 2al1 7N Leap Day FF63 65345 (6) Figure 3 Procedural Amendment (Voluntary) October 8, 1985 1, Case Description 1985 Patent Application No. 209338 2, Title of Invention End Point for External Phase Titration Detection device 3, Relationship with the case of the person making the amendment Applicant address name (091) Kao Corporation 4, Agent 6, "Detailed description of the invention" column 7 of the specification to be amended, Contents of the amendment ( 1) In the specification, page 13, line 11 1'-6301
11j is corrected to 1'-63QnmJ.

Claims (1)

[Claims] 1. An end point detection device for external phase titration comprising a detection chamber 2 in which an organic solvent phase can flow through a porous membrane 3, and a light emitting section 4 and a light receiving section 5 each having an optical path in the detection chamber 2.