JPH0989857A - Method for analyzing polyvinylpyrrolidone - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a method for rapid and accurate quantitative analysis of polyvinylpyrrolidone present in low concentrations or trace amounts in compositions such as detergents and cosmetics. A method for analyzing polyvinylpyrrolidone present in a composition, comprising preparing a composition to be analyzed containing polyvinylpyrrolidone, and dissolving a predetermined amount of the composition to be analyzed in an organic solvent or an aqueous solution thereof. An analysis solution is prepared, and the solution to be analyzed is, if necessary, solid or sedimentary components are removed by a centrifugation method, and then pyrolyzed, and the obtained pyrolyzed components are separated by a gas chromatograph, and then by the gas chromatograph. A method comprising quantitatively analyzing the separated polyvinylpyrrolidone component by a thermal ion detection method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for analyzing polyvinylpyrrolidone, and more particularly to a method for quantitatively analyzing polyvinylpyrrolidone present in a detergent composition or a cosmetic composition at a low concentration or in a trace amount with high accuracy. It is a thing.

[0002]

2. Description of the Related Art In recent years, carboxymethylcellulose (CMC) and polyvinylpyrrolidone (hereinafter also referred to as PVP) have been added to detergent compositions as stain redeposition inhibitors. ing. Although PVP is more expensive than CMC, it has a higher recontamination preventing effect and a color transfer preventing effect. Therefore, PVP is blended as a composition component alone or in combination with CMC.

By the way, in a powder-form detergent composition, the composition is exposed to a relatively high temperature during its production process, so that the content of the compounded PVP is expected to change during the production process. It is necessary to accurately measure the amount of PVP in the final product for quality control.

Conventionally, methods such as size-exclusion chromatography and infrared spectroscopy have been applicable as methods for analyzing PVP having a relatively high concentration, but these methods are not more than 0.1% by weight. It is unsuitable as a method for analyzing PVP existing in low concentration or in a trace amount in terms of analysis accuracy, and in particular, a low concentration or trace amount of PVP present in a composition prepared by mixing a plurality of kinds of components such as detergents At present, no effective method for analysis is known. For example, when attempting to analyze PVP in a detergent composition by size exclusion chromatography or infrared spectroscopy, the presence of coexisting surfactants and other polymer components in the sample to be analyzed will interfere with the spectrum and analysis peaks. , It is necessary to completely remove these coexisting components. However, the removal of these coexisting components is extremely complicated, and the PVP may be removed at the same time in the process of removing these coexisting components, so that there is a problem in that the analysis accuracy is drastically reduced.

The present invention has been made in view of the above circumstances, and provides a method for rapid and accurate quantitative analysis of polyvinylpyrrolidone present in a low concentration or a trace amount in compositions such as detergents and cosmetics. The purpose is to do.

[0006]

The present invention is a method for analyzing polyvinylpyrrolidone present in a composition, which comprises preparing an analyte composition containing polyvinylpyrrolidone, and measuring a predetermined amount of the analyte composition. An analyte solution is prepared by dissolving it in an organic solvent or an aqueous solution thereof, and the analyte solution is
After removing solid or sedimentary components by centrifugation if necessary, pyrolysis, the resulting pyrolysis components are separated by gas chromatography, the polyvinylpyrrolidone components separated by the gas chromatograph by thermionic detection method. It is characterized by quantitative analysis.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION First, a sample to be analyzed which is an analyte is prepared, and a predetermined amount of the sample to be analyzed is dissolved in an organic solvent or an aqueous solution thereof to prepare a solution to be analyzed. Most of the coexisting surfactants precipitate at this time.

The solvent for dissolving the sample can be appropriately selected depending on the properties of the sample to be analyzed. In the case of a common detergent, methanol, ethanol, isopropyl alcohol, acetone and the like can be preferably used. Aqueous solutions can be used with particular preference. In the case of forming an aqueous solution, the compounding ratio of the organic solvent used is 5 to 50% by weight, preferably 5 to 20% by weight, more preferably 8 to
It is preferably in the range of 15% by weight.

Next, if necessary, a separation means such as a centrifugation method may be applied to the thus-obtained solution to be analyzed so as to remove solid components or sedimentation components from the solution in advance. preferable. Centrifugation in this case is performed at 3000 rpm or more, preferably 5000 rpm or more, and more preferably 9000 rpm or more.

Next, a predetermined amount of the solution to be analyzed, preferably 10 μl or less, more preferably 5 μl or less, is sampled with a pipette or the like, and is used as a foil for pyrolysis (pyro foil).
Then, the sample is wrapped in a sample, set in a pyrolysis-gas chromatograph apparatus, and pyrolyzed and analyzed by a gas chromatograph. In this case, the analysis operation is carried out by a series of operations of thermal decomposition of the solution to be analyzed, separation of the obtained thermal decomposition component by gas chromatography, and quantitative analysis of the polyvinylpyrrolidone component separated by gas chromatography by thermionic detection method. Can be done on a regular basis.

First, the thermal decomposition of the sample solution can be carried out under a heating temperature condition of a temperature of 400 ° C. or higher, preferably 650 to 760 ° C. If the temperature is lower than 400 ° C, it is difficult to produce a quantifiable monomer, which is not preferable. Further, the thermal decomposition time is 2 seconds or more, preferably 5 seconds to 15 seconds.
It is desirable to carry out in the range of seconds for optimum production of the above-mentioned monomer. By this thermal decomposition treatment, the PVP to be analyzed is decomposed and a specific quantifiable monomer (N-vinyl-2-pyrrolidone) is produced as a decomposition component, which is subsequently introduced into the column of the gas chromatograph under predetermined conditions. Gas chromatographic analysis is performed at.

The thermal decomposition apparatus is controllable to the above-mentioned thermal decomposition conditions, and when the thermal decomposition product is introduced into the gas chromatograph, it maintains a gas having a vapor pressure above a certain limit at a set column temperature. It is not particularly limited as long as it is performed. Further, the gas chromatograph is not limited as long as the thermal decomposition products can be separated accurately and sufficiently.

Here, in the present invention, NPD is used as a detecting means to quantitatively analyze the components to be detected from the peak data of the monomers. This NPD (also called TID (thermo-ion detector)) detection method is a method known per se as a detection means of a gas chromatograph, and it lowers the response to coexisting organic compounds to reduce N (nitrogen) and P (phosphorus). ) Is a sensitive detection method that responds sensitively to a compound containing). An outline of this detection method is described, for example, in “Gas Chromatography Method” (edited by Tsugio Kojima et al., Edited by The Analytical Society of Japan, published by Kyoritsu Shuppan Co., Ltd.).

In the present invention, the quantification of the component to be detected is performed by using the peak area obtained by the NPD detector as
It can be carried out by plotting on a calibration curve prepared in advance with a standard substance.

As described above, in the present invention, thermal decomposition-
By using the gas chromatographic method and the detection with the NPD detector in combination, even when a large number of coexisting components such as a detergent composition are present, a small amount or a trace amount of PVP in the composition can be quantitatively analyzed quickly and with high accuracy. can do.

Furthermore, in the method of the present invention, the step of removing the coexisting interference components from the sample to be analyzed can be substantially omitted, so that the PVP in the analytical operation process can be omitted.
Is also advantageous in that the accuracy of analysis can be improved and quantitative analysis can be performed by a simplified operation.

[0017]

EXAMPLES The present invention will be described below based on actual analysis examples. Reagents The following reagents were used in this example.

Polyvinylpyrrolidone K25: Wako Pure Pharmaceutical Co., Ltd. (hereinafter abbreviated as PVPK25) Polyvinylpyrrolidone K15: Tokyo Chemical Industry polyvinylpyrrolidone K30: Tokyo Chemical Industry polyvinylpyrrolidone K60: Tokyo Chemical Industry polyvinylpyrrolidone K90: Tokyo Chemical Industry methanol ( Liquid Chromatograph): Wako Pure Pharmaceutical Distilled Water (for Liquid Chromatograph): Wako Pure Pharmaceutical Dichloromethane: Wako Pure Pharmaceutical Measuring Instruments The following measuring instruments were used.

Gas chromatograph: Model 5890 Series II Plus NPD detector data processor with Hewlett-Packard Company: Model 3365 Series II Chemistry Pyrolyzer with Hewlett-Packard Company: Model JHP-3S Pyrowheel Sampler manufactured by Japan Analytical Industry Co., Ltd. : Nippon Analytical Industry Co., Ltd. Model JPS-330 Flow Controller: Nippon Analytical Industry Co., Ltd. Model FWC-33 Pyrowheel: Nippon Analytical Industry Co., Ltd. Centrifuge: Kokusan Model H-1500F Tester Mixer: Advantech Toyo Model TME- 21 Micropipette: Nichiryu's Digital Micropipette Model 800 Glassware: Various measuring flasks, pipette GC analysis column: Supelco Wax 10 (membrane pressure 0.2 μm) coated with an inner diameter of 0.53 mm, length of 15 m Things. A column having an inner diameter of 0.53 mm and a length of 2 m which was not coated with the liquid phase was connected and used as a pre-column. Gas chromatographic analysis conditions Carrier gas: Helium Carrier gas flow rate: 7.8 ml / min Column head pressure: 18 kPa Injection part temperature: 250 ° C. Detector part temperature: 300 ° C. Column tank temperature: 90 ° C. Pyrolyzer analysis conditions Oven temperature: 250 ° C. Transfer line temperature: 250 ° C. Pyrolysis time: 10 seconds FIG. 1 shows the outline of the analysis system used in this example.

That is, the analysis sample is set in the sample tube 2 in the pyrolyzer (pyrolysis device) 1, is pyrolyzed under predetermined conditions, and is transferred from the inlet 5 of the gas chromatograph 4 to the column 6 via the transfer line 3. Was introduced in
Quantitative analysis is performed by the NPD detector 7. The carrier gas is supplied to the pyrolyzer from the helium gas cylinder 8 via the control device 9. (Preparation of Standard Solution (A)) PVPK25 was used after being dried at 105 ° C. for 2 hours and then left to cool in a desiccator. About 2
50 mg of PVPK25 was weighed accurately, dissolved in pure water, and then made up to a constant volume of 50 ml with pure water. (Preparation of Standard Solution (B)) From the standard solution (A), 5 ml was weighed into a 50 ml volumetric flask using a whole pipette, and the volume was made constant with pure water. (Preparation of Solution for Creating Calibration Curve) The standard station (A) was dispensed from the standard solution (B) into a 20 ml volume or 25 ml volumetric flask as described below, and the volume was made constant with pure water.

Concentration of PVP 25 Preparative amount Standard solution Constant volume (mg / ml) (ml) (A) or (B) (ml) 50 2 (B) 20 100 5 (B) 25 200 1 (A) 25 500 2.5 (A) 25 A calibration curve was prepared using the above 4 solutions and the standard solution (A) and the standard solution (B). Sample Preparation Sample preparation was performed according to the following procedure.

1. Accurately weigh about 1 g of laundry detergent into a centrifuge tube.

2.5 ml of methanol aqueous solution (10%)
Add well and mix well using a test tube mixer.

3. Centrifuge at 9000 rpm for 15 minutes.

4. Decant the supernatant and transfer to a sample vial.

5.5 ml of the methanol aqueous solution (10) is transferred to the sample vial in the separation tube and mixed.

6. Centrifuge at 9000 rpm for 15 minutes, transfer the supernatant to the above sample vial and mix.

7. 1 μl of this solution is placed in a pyrofoil and gently heated to evaporate and remove the methanol solution.

8. Place the pyrofoil in the pyrolyzer. Results and Discussion ( Study of linearity of calibration curve) The calibration curve solution was adjusted four times on different days to prepare a calibration curve. The calibration curve is shown below.

Day 1 Y = 1.77X ² + 9.04 × 10 ³ X-2.28 × 10 ⁵ (R = 0.999) Day ² Y = 1.07X ² + 4.84 × 10 ³ X− 8.92 × 10 ⁴ (R = 1.000) Day 3 Y = 1.07X ² + 5.04 × 10 ³ X-1.16 × 10 ⁵ (R = 0.999) Day 4 Y = 2. 97X ² + 1.23 × 10 ³ X-3.33 × 10 ⁵ (R = 1.000) All the calibration curves were quadratic curves and showed good correlation.

Since the sensitivity of the used GC detector NPD has a large daily variation, a calibration curve should be prepared on the same day as the sample analysis. (Study of PVP Extraction Rate) The PVP extraction rate was examined in the sample preparation method used in this study. 4 samples, 3 each
The extraction operation was performed 12 times in total. The minimum extraction rate is 95.
2%, maximum pouring rate is 98.6%, average pouring rate is 97.4
%, And the standard deviation was 0.9%. PVP was satisfactorily extracted by the sample preparation method used in this study. (Pyrofoil cleaning) Fig. 2 shows a pyrogram of standard PVK25. FIG. 3 shows a pyrogram of only unwashed pyrofoils, and FIG. 4 shows a pyrogram of the pyrofoils after washing with dichloromethane. An unknown peak is observed around the retention time of vinylpyrrolidone in FIG. 3, but disappears in FIG. In the following, the pyrofoil washed with dichloromethane was used for the study. (Study of Pyrolysis Temperature) The following table shows the results of pyrolysis at each temperature. At 650 ° C, the amount of generated monomer was the maximum, and the variation in the amount of generated was the minimum. In this study, the pyrolysis temperature was 650 ° C.

Sample: Standard polyvinylpyrrolidone solution (504ug / mL) Thermal decomposition temperature 764 ° C 650 ° C 590 ° C 445 ° C 333 ° C 235 ° C N-vinyl 1096570 1817936 477493 221067 ND ND-2-pyro 1772069 1973556 434422 719361 ND ND 1355984 1926572 308737 907308 ND ND peak area 1310841 1966684 592399 968395 ND ND 2060535 311294 1012205 2140429 504033 443899 2295861 585427 997096 Mean 1383866.0 2025939.0 459115.0 752761.6 Standard amount 282459.8 156288.7 116296.4 310007.7 Variation coefficient 2248 Effect on Pyrolysis) The effect of the difference in the molecular weight of PVP on the pyrolysis was examined. As shown in FIG. 5, it was found that the amount of produced monomer was not influenced by the molecular weight. PV in this study
PK25 was used as a standard. (Examination of influence on analysis of coexisting substances) JISK3362
The index detergent shown in -1990 7.1.4 (2) was prepared and used as a blank sample. To this, a known amount of polyvinylpyrrolidone was added and prepared according to the procedure of the sample preparation section, and the influence of coexisting substances on the analysis was examined.

As shown below, sufficient recovery was shown at any concentration, and the effect of coexisting substances was negligible in this method.

(1) 0.02% level in PVP product Repeat recovery rate 1st day 102.5% 2nd day 98.8% 3rd day 104.0% 4th day 101.5% Average 101.7% (2) 0.10% level in PVP product Repeated recovery rate 1st day 99.6% 2nd day 96.4% 3rd day 100.3% 4th day 96.3% Average 98.5% (3) 0.25% level in PVP products Repeated recovery 1st day 104.2% 2nd day 99.9% 3rd day 102.5% 4th day 104.9% Average 102.9% (4) In PVP product 1.00% level Repeated recovery rate 1st day 95.5% 2nd day 95.4% 3rd day 96.8% 4th day 104.0% Average 97.9%

[Brief description of drawings]

FIG. 1 is a schematic diagram of an analysis system used in an example of the present invention.

FIG. 2 is a pyrogram obtained in an example of the present invention.

FIG. 3 is a pyrogram obtained in an example of the present invention.

FIG. 4 is a pyrogram obtained in an example of the present invention.

FIG. 5 is a graph showing the influence of the molecular weight of PVP on the amount of monomers generated in Examples of the present invention.

[Explanation of symbols]

 1 Pyrolyzer 2 Sample tube 4 Gas chromatograph 6 Column 7 NPD detector 8 Helium gas cylinder

Claims (4)

[Claims] 1. A composition to be analyzed containing polyvinylpyrrolidone is prepared, and a predetermined amount of the composition to be analyzed is dissolved in an organic solvent or an aqueous solution thereof to prepare a solution to be analyzed. According to the method, the solid or sedimentary components are removed by centrifugation, and then pyrolyzed, the resulting pyrolyzed components are separated by a gas chromatograph, and the polyvinylpyrrolidone component separated by the gas chromatograph is quantified by a thermal ion detection method. A method for analyzing polyvinylpyrrolidone present in a composition, characterized by analyzing. 2. The thermal decomposition is performed under a temperature condition of 400 ° C. or higher,
The method according to claim 1, which is preferably carried out under a temperature condition of 650 to 760 ° C. 3. The method according to claim 1, wherein the organic solvent comprises at least one selected from the group consisting of methanol, ethanol, isopropyl alcohol and acetone. 4. The method according to claim 1, wherein the solvent in which the composition to be analyzed is dissolved comprises an aqueous solution containing 5 to 50% by weight of an organic solvent.