JP2006226717A - Quantification method of nonionic surfactant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quantification method of a nonionic surfactant capable of quantifying the composition ratio of a sample including two or more kinds of nonionic surfactants. <P>SOLUTION: In this quantification method of the nonionic surfactant, a mass spectrum of the sample including two or more kinds of nonionic surfactants is measured by using mass spectrometry, and the composition ratio of the nonionic surfactants included in the sample is quantified from the intensity ratio of peaks of the nonionic surfactants included in the sample of the measured mass spectrum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for quantifying a nonionic surfactant.

  Some cosmetics such as detergents contain a nonionic surfactant, but quantifying the nonionic surfactant is also important for confirming the quality of the cosmetic.

  Conventionally, liquid chromatography, NMR, and the like have been used as methods for quantifying nonionic surfactants. However, liquid chromatography has a problem that the quantitativeness is lowered when a nonionic surfactant having no UV absorption is measured. Moreover, when NMR quantifies the composition ratio of a sample containing two or more kinds of nonionic surfactants, there is a problem that peaks may overlap and cannot be quantified.

Then, the method of quantifying a nonionic surfactant using matrix assistance laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) is known (refer nonpatent literature 1). However, Non-Patent Document 1 discloses a method for quantifying a nonionic surfactant by adding an internal standard substance to a composition containing a single nonionic surfactant. .
Rapid commun. Mass Spectrom. , (Rapid Communications in Mass Spectrometry), Volume: 13, Issue: 4, Page (s): 251-255 (1999).

  The present invention provides a method for quantifying a nonionic surfactant capable of quantifying the composition ratio of a sample containing two or more kinds of nonionic surfactants in view of the problems of the above-described conventional technology. For the purpose.

  The invention according to claim 1 is a method for measuring a nonionic surfactant by measuring a mass spectrum of a sample containing two or more kinds of nonionic surfactants using mass spectrometry, The composition ratio of the nonionic surfactant contained in the sample is quantified from the intensity ratio of the peak of the nonionic surfactant contained in the sample of the obtained mass spectrum.

  According to the first aspect of the present invention, a mass spectrum of a sample containing two or more kinds of nonionic surfactants is measured using mass spectrometry, and is included in the sample of the measured mass spectrum. Since the composition ratio of the nonionic surfactant contained in the sample is quantified from the intensity ratio of the peak of the nonionic surfactant, the composition ratio of the sample containing two or more types of nonionic surfactant is determined. A method of quantifying a nonionic surfactant that can be quantified can be provided.

  The invention according to claim 2 is the method for quantifying a nonionic surfactant according to claim 1, wherein the nonionic surfactant contained in the sample is at least one of a polyoxyethylene group and a polyoxypropylene group. It has one side.

  According to the invention described in claim 2, since the nonionic surfactant contained in the sample has at least one of a polyoxyethylene group and a polyoxypropylene group, two or more kinds of nonionic surfactants are used. The composition ratio of the sample containing can be quantified.

  The invention according to claim 3 is the method for quantifying a nonionic surfactant according to claim 1 or 2, wherein the molecular weight of the nonionic surfactant contained in the sample is 500 or more and 4000 or less. It is characterized by.

  According to the invention described in claim 3, since the molecular weight of the nonionic surfactant contained in the sample is 500 or more and 4000 or less, the composition of the sample containing two or more kinds of nonionic surfactants. The ratio can be quantified.

  The invention according to claim 4 is the method for quantifying a nonionic surfactant according to any one of claims 1 to 3, wherein the mass spectrometry is used to determine whether two types of nonionic surfactants are used. Measuring the mass spectra of a plurality of standard samples with known contents, the intensity ratio of the peaks of two types of nonionic surfactants contained in the standard sample of the mass spectra of the measured standard samples, The relationship between the composition ratio of two types of nonionic surfactants contained in a standard sample is obtained.

  According to the invention described in claim 4, mass spectrometry is used to measure mass spectra of a plurality of standard samples whose contents of two types of nonionic surfactants are known, and the measured standard Determine the relationship between the peak intensity ratio of the two types of nonionic surfactants contained in the standard sample and the composition ratio of the two types of nonionic surfactants contained in the standard sample in the sample mass spectrum. Therefore, the composition ratio of the sample containing two or more kinds of nonionic surfactants can be quantified.

  The invention according to claim 5 is the method for quantifying a nonionic surfactant according to claim 4, wherein the standard sample is different from two types of nonionic surfactants contained in the standard sample. It further comprises an ionic surfactant.

  According to the fifth aspect of the present invention, the standard sample further contains a nonionic surfactant different from the two types of nonionic surfactants contained in the standard sample. Different types of nonionic surfactants can be compatibilized.

  The invention according to claim 6 is the method for quantifying a nonionic surfactant according to any one of claims 1 to 5, wherein the mass spectrometry is performed by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry. It is a law.

  According to the invention described in claim 6, since the mass spectrometry is matrix-assisted laser desorption / ionization time-of-flight mass spectrometry, the composition ratio of the sample containing two or more kinds of nonionic surfactants Can be quantified.

  ADVANTAGE OF THE INVENTION According to this invention, the determination method of the nonionic surfactant which can quantify the composition ratio of the sample containing 2 or more types of nonionic surfactant can be provided.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  The nonionic surfactant quantification method of the present invention uses mass spectrometry to measure a mass spectrum of a sample containing two or more types of nonionic surfactants, and to determine the nonionic surfactant of the mass spectrum. The composition ratio of the nonionic surfactant is quantified from the intensity ratio of the peak of the agent.

  In the present invention, specific examples of the nonionic surfactant to be quantified include POE sorbitan fatty acid esters such as POE sorbitan monooleate, POE sorbitan monostearate, POE sorbitan diolate, and POE sorbitan tetraoleate. , POE sorbite monolaurate, POE sorbite monooleate, POE sorbite fatty acid esters such as POE sorbite monostearate, POE glycerin monostearate, POE glycerin monoisostearate, POE glycerin triisostearate POE glycerin fatty acid esters such as rate, POE monooleate, POE fatty acid esters such as POE distearate, POE lauryl ether, POE oleyl ether, POE alkyl ethers such as OE stearyl ether, POE behenyl ether, POE2-octyldodecyl ether, POE cholestanol ether, POE alkyl phenyl ethers such as POE octyl phenyl ether and POE nonyl phenyl ether, pluronic types such as brulon, POE -POE cetyl ether, POE / POP2-decyl tetradecyl ether, POE / POP monobutyl ether, POE / POP alkyl ethers such as POE / POP glycerin ether, Tetra POE / tetra POP ethylenediamine condensates such as Tetronic, POE castor Oil, POE hydrogenated castor oil, POE propylene glycol fatty acid ester, POE alkylamine, POE fatty acid amide and the like. Here, POE and POP are abbreviations for polyoxyethylene and polyoxypropylene, respectively. Thus, the nonionic surfactant which has at least one of a polyoxyethylene group and a polyoxypropylene group can be quantified.

  In the present invention, a nonionic surfactant having a molecular weight of 500 or more and 4000 or less can be quantified. If the molecular weight is smaller than 500, detection may not be possible, and if the molecular weight is larger than 4000, the quantitativeness is lowered.

  The mass spectrometry is a method of mainly analyzing the molecular weight of a sample using a mass spectrometer having a sample introduction unit, an ionization unit, a mass separation unit, and a detection unit. Specifically, the sample is ionized by the ionization unit, and the generated ions are separated by the mass separation unit according to the mass-to-charge ratio and detected by the detection unit. Since the inside of the mass spectrometer is maintained at a high vacuum by a turbo molecular pump or an oil diffusion pump, ions generated from the ionization unit are not scattered or fragmented by the interaction with other gas molecules. Then, the ion detection unit is reached. Ions that have reached the detector are amplified, converted into electrical signals, and processed as a spectrum.

  The method of ionizing the sample is not particularly limited, but the matrix-assisted laser desorption ionization (MALDI) method, laser desorption (LD) method, fast atom bombardment (FAB) method, liquid secondary ion mass spectrometry ( LSIMS) method, liquid ionization (LI), electrospray ionization (ESI) method, atmospheric pressure chemical ionization (APCI) method and the like. Among these, since the LD method does not use a matrix, it needs to absorb the laser light irradiated on the sample and be ionized. On the other hand, in the MALDI method, it is necessary to select a matrix in accordance with the wavelength of the laser light in order to absorb the laser light irradiated on the matrix. Therefore, if the matrix absorbs the laser beam, the sample does not need to absorb the laser beam, so that the sample that does not absorb the laser beam can be ionized. For this reason, it is preferable to use the MALDI method when the sample is ionized.

  Examples of the matrix that absorbs the Nd-YAG fourth high frequency having a wavelength of 266 nm include nicotinic acid and 2-pyrazinecarboxylic acid. Further, as a matrix that absorbs a pulsed nitrogen laser having a wavelength of 337 nm and an Nd-YAG third high frequency having a wavelength of 355 nm, sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid) (SA), α -Cyano-4-hydroxycinnamic acid (CHCA), ferulic acid (FA), 3-hydroxypicolinic acid (HPA), 2,5-dihydroxybenzoic acid (DHB), 5-methoxysalicylic acid, diaminonaphthalene, 2- ( 4-hydroxyphenylazo) benzoic acid, disranol, 2,4,6-trihydroxyacetophenone (THAP) and the like. Furthermore, examples of the matrix that absorbs a carbon dioxide laser having a wavelength of 2.94 μm include succinic acid, 5- (trifluoromethyl) uracil, glycerin, and the like.

  As the laser, it is preferable to use a pulsed nitrogen laser having a wavelength of 337 nm. In order to rapidly heat the sample, it is possible to ionize while suppressing decomposition. Such pulse ionization is a kind of thermal ionization.

When the sample (M) is ionized using the MALDI method, generally, a pulse laser is irradiated to a crystal obtained by drying a solution in which a matrix and the sample are dissolved. Thereby, ions derived from the sample such as [M] ⁺ , [M + H] ⁺ , [M + Na] ⁺ , and [M + K] ⁺ and ions derived from the matrix are desorbed.

  In the mass separation unit, ions desorbed in the ionization unit are separated based on a difference in mass-to-charge ratio using electromagnetic interaction. As the mass separation unit, time-of-flight type (TOF), quadrupole ion trap time-of-flight type (QIT-TOF), quadrupole type, ion trap type, magnetic field type, Fourier transform ion cyclotron resonance type (FT-ICR) However, TOF is preferable.

  Time-of-flight mass spectrometry (TOFMS) is a method of performing mass analysis by utilizing the fact that the time of flight required for ions generated in the ionization section to pass through the vacuum analysis tube differs depending on the difference in mass-to-charge ratio of ions. .

  In the present invention, it is preferable to use matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOFMS) combining MALDI and TOFMS as mass spectrometry.

In the present invention, the sample is preferably mixed with a matrix and a sodium salt in order to measure a mass spectrum of the sample containing two or more kinds of nonionic surfactants using MALDI-TOFMS. Thereby, the ion derived from a sample can be made only into [M + Na] ⁺ , and quantitative property improves. Specifically, there is a method of drying a matrix, a sample, and a solution in which a sodium salt is dissolved. Thereby, the state in which the sample and the sodium salt are mixed in the crystal of the matrix can be formed. The S / N ratio can be improved by appropriately adjusting the crystal state of the matrix, the three-dimensional form, the sample and the sodium salt concentration.

  In the present invention, sodium salts include sodium chloride and sodium iodide.

  1, 2 and 3 show mass spectra of polyethylene glycol (PEG) measured using MALDI-TOFMS. 1, 2 and 3 are PEG mass spectra having number average molecular weights of 2000, 3000 and 4000, respectively. The mass-to-charge ratio at the peak is detected as a value added with sodium ions. Here, since each sample has a molecular weight distribution, a plurality of peaks appear. Further, the mass-to-charge ratio interval between peaks corresponds to a mass of 44.05 per mole of oxyethylene groups.

  In the present invention, the following procedure is exemplified as a method for quantifying the nonionic surfactant. First, a plurality of standard samples whose contents of two types of nonionic surfactants contained in the sample are known are prepared, and mass spectra are measured. From the obtained mass spectrum, the relationship (calibration curve) between the peak intensity ratio of the two types of nonionic surfactants and the composition ratio is determined. In addition, when there are three or more types of nonionic surfactants to be quantified, a standard sample in which a combination of two types of nonionic surfactants is changed is further prepared, as described above, Create a calibration curve. Next, the mass spectrum of the sample is measured, and the peak intensity ratio of the nonionic surfactant contained in the sample is obtained. Using the obtained peak intensity ratio and a calibration curve, the composition ratio of the nonionic surfactant is quantified. At this time, the peak of the mass spectrum used for quantification of the nonionic surfactant is not particularly limited, but it is preferable to use the peak having the maximum intensity. Thereby, quantitative property improves.

  In addition, when the compatibility of the two types of nonionic surfactants contained in the standard sample is low, the distribution of the two types of nonionic surfactants in the standard sample will be non-uniform, so a good calibration curve will be obtained. It may be difficult to prepare a nonionic surfactant. For this reason, it is preferable to add a third nonionic surfactant in order to make the two types of nonionic surfactants compatible. The third nonionic surfactant is not particularly limited as long as it compatibilizes two types of nonionic surfactants, but two types of nonionic surfactants whose mass spectrum peaks are quantified It is preferable that the peak does not overlap.

  When measuring the mass spectrum of the sample, the absolute amount of the nonionic surfactant can be determined by adding an internal standard substance. The internal standard is not particularly limited, but it is preferable that the peak of the mass spectrum does not overlap with the peak of the nonionic surfactant to be quantified. Examples of the internal standard substance include polyethylene glycol.

  As nonionic surfactants, polyoxyethylene-6 (capryl / capric acid) glyceryl (hereinafter referred to as surfactant 1), polyoxyethylene-20 glyceryl isostearate (hereinafter referred to as surfactant 2) and polyoxy A method for quantifying a sample in which the weight ratio of ethylene-10 methyl glucoside (hereinafter referred to as “surfactant 3”) is 6: 9: 4 is shown below. Note that the mass-to-charge ratios of the peaks in the mass spectrum used for quantification of the surfactant 1, the surfactant 2, and the surfactant 3 are 622, 1311, and 614, respectively.

  Surfactant solution 1 containing 10 mg / ml of surfactant 1, surfactant solution 2 containing 10 mg / ml of surfactant 2 and surfactant using a water / methanol mixed solvent with a volume ratio of 1: 1 A surfactant solution 3 containing 3 at 3 mg / ml was prepared.

A matrix solution containing 10 mg / ml of CHCA was prepared using a water / acetonitrile mixed solvent having a volume ratio of 1: 1.
(Create a calibration curve)
Surfactant solution 1 and surfactant solution 2 are mixed at a volume ratio of 1: 9, 2: 8, 3: 7, 4: 6, 5: 5, 6: 4, 7: 3, 8: 2 and 9: The standard sample solutions 1, 2, 3, 4, 5, 6, 7, 8 and 9 were prepared. Standard sample measurement solutions 1-9 were prepared by adding 50 μl of matrix solution 50 μl and 5.85 mg / ml sodium chloride aqueous solution 10 μl to 50 μl of standard sample solutions 1-9. After 1 μl of standard sample measurement solutions 1 to 9 were dropped on the sample stage and dried, the mass spectrum was measured using KOMPACT MALDI IV (manufactured by Shimadzu Corporation), and a calibration curve 1 was created (see FIG. 4). . 4 is the ratio of the weight of the surfactant 1 to the sum of the weights of the surfactant 1 and the surfactant 2, and the peak intensity ratio is the peak of the surfactant 1 and the surfactant 2. The ratio of the peak intensity of the surfactant 1 to the sum of the intensity.

  Surfactant solution 1 and surfactant solution 3 were mixed so that the volume ratios were 2: 8, 5: 5, and 8: 2, and standard sample solutions 10, 11, and 12 were prepared. Standard sample measurement solutions 10-12 were prepared by adding 50 μl of matrix solution 50 μl and 5.85 mg / ml aqueous sodium chloride solution 10 μl to 50 μl of standard sample solutions 10-12. After dropping 1 μl of the standard sample measurement solutions 10 to 12 onto the sample stage and drying, a mass spectrum was measured using KOMPACT MALDI IV to create a calibration curve 2 (see FIG. 5). The weight ratio in FIG. 5 is the ratio of the weight of the surfactant 1 to the sum of the weights of the surfactant 1 and the surfactant 3, and the peak intensity ratio is the peak of the surfactant 1 and the surfactant 3. The ratio of the peak intensity of the surfactant 1 to the sum of the intensity.

Since surfactant 2 and surfactant 3 have low compatibility, surfactant 1 was added to prepare a calibration curve. Specifically, the surfactant solution 2, the surfactant solution 3, and the surfactant solution 1 are mixed so that the volume ratios are 2: 8: 8, 5: 5: 5, and 8: 2: 2. Standard sample solutions 13, 14 and 15 were prepared. Standard sample measurement solutions 13 to 15 were prepared by adding 50 μl of matrix solution and 10 μl of 5.85 mg / ml sodium chloride aqueous solution to 50 μl of standard sample solutions 13 to 15. After dropping 1 μl of the standard sample measurement solutions 13 to 15 on the sample stage and drying, the mass spectrum was measured using KOMPACT MALDI IV to prepare a calibration curve 3 (see FIG. 6). 6 is the ratio of the weight of the surfactant 2 to the sum of the weights of the surfactant 2 and the surfactant 3, and the peak intensity ratio is the peak of the surfactant 2 and the surfactant 3. This is the ratio of the peak intensity of the surfactant 2 to the sum of the intensity.
(Quantification of nonionic surfactant)
Surfactant solution 1, surfactant solution 2 and surfactant solution 3 were mixed so that the volume ratio was 6: 9: 4 to prepare a sample solution. A sample measurement solution was prepared by adding 50 μl of the matrix solution and 10 μl of the 5.85 mg / ml aqueous sodium chloride solution to 50 μl of the sample solution. 1 μl of the sample measurement solution was dropped on the sample stage and dried, and then the mass spectrum was measured using KOMPACT MALDI IV (see FIG. 7). Accordingly, the ratio of the peak intensity of the surfactant 1 to the sum of the peak intensity of the surfactant 1 and the surfactant 2 is 0.54, and the ratio of the peak intensity of the surfactant 1 and the surfactant 3 is The ratio of the peak intensity of the surfactant 1 was 0.51, and the ratio of the peak intensity of the surfactant 2 to the sum of the peak intensity of the surfactant 2 and the surfactant 3 was 0.39. From the calibration curve 1, the ratio of the weight of the surfactant 1 to the sum of the weights of the surfactant 1 and the surfactant 2 is 0.40, and from the calibration curve 2, the surfactant 1 and the surfactant 3 The ratio of the weight of the surfactant 1 to the sum of the weights is 0.57. From the calibration curve 3, the ratio of the weight of the surfactant 2 to the sum of the weights of the surfactant 2 and the surfactant 3 is 0. .69. This shows that the weight ratio of surfactant 1, surfactant 2 and surfactant 3 is 6: 9: 4, indicating that the nonionic surfactant could be quantified.

It is a figure which shows the mass spectrum of PEG whose number average molecular weight is 2000. It is a figure which shows the mass spectrum of PEG whose number average molecular weight is 3000. It is a figure which shows the mass spectrum of PEG whose number average molecular weight is 4000. It is a figure which shows the analytical curve 1 of an Example. It is a figure which shows the analytical curve 2 of an Example. It is a figure which shows the analytical curve 3 of an Example. It is a figure which shows the mass spectrum of the sample of an Example.

Claims (6)

Using mass spectrometry, measure the mass spectrum of a sample containing two or more nonionic surfactants,
A nonionic interface characterized by quantifying the composition ratio of the nonionic surfactant contained in the sample from the intensity ratio of the peak of the nonionic surfactant contained in the sample of the measured mass spectrum Quantitative method of activator.   The method for quantifying a nonionic surfactant according to claim 1, wherein the nonionic surfactant contained in the sample has at least one of a polyoxyethylene group and a polyoxypropylene group.   The method of quantifying a nonionic surfactant according to claim 1 or 2, wherein the molecular weight of the nonionic surfactant contained in the sample is 500 or more and 4000 or less. Using mass spectrometry, measure the mass spectra of multiple standard samples with known contents of two types of nonionic surfactants,
The intensity ratio of the peaks of the two types of nonionic surfactants contained in the standard sample in the mass spectrum of the measured standard sample and the composition ratio of the two types of nonionic surfactants contained in the standard sample The method for quantifying a nonionic surfactant according to any one of claims 1 to 3, wherein a relationship with the ionic surfactant is obtained.   The nonionic surfactant according to claim 4, wherein the standard sample further contains a nonionic surfactant different from the two types of nonionic surfactants contained in the standard sample. Quantitation method.   The method for quantifying a nonionic surfactant according to any one of claims 1 to 5, wherein the mass spectrometry is matrix-assisted laser desorption / ionization time-of-flight mass spectrometry.

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