CN102768192A - Method for detecting polymerization indexes of fatty acids by utilizing spectral analysis - Google Patents
Method for detecting polymerization indexes of fatty acids by utilizing spectral analysis Download PDFInfo
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- CN102768192A CN102768192A CN2012102970126A CN201210297012A CN102768192A CN 102768192 A CN102768192 A CN 102768192A CN 2012102970126 A CN2012102970126 A CN 2012102970126A CN 201210297012 A CN201210297012 A CN 201210297012A CN 102768192 A CN102768192 A CN 102768192A
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Abstract
The invention discloses a method for detecting polymerization indexes of fatty acids by utilizing spectral analysis. The method comprises the steps of determining conjugate components and non-conjugate components in a fatty acid sample, namely, firstly determining the conjugate components by determining ultraviolet absorption of the fatty acid sample, secondly determining the non-conjugate components by converting the alkali isomerization into a conjugate isomer capable of absorbing ultraviolet light and determining ultraviolet absorption of the conjugate isomer, and finally calculating amount of various unsaturated fatty acids according to a modified calculation formula to obtain the polymerization indexes of the fatty acids. The method has the advantages that the ordinary spectral analysis is improved, ethylene glycol is replaced by glycerin which serves as solvent of a heterogeneous reaction to correct interference caused by the conjugate components undecomposed by the ethylene glycol, and the detection method is strong in specificity and easy to popularize and apply.
Description
Technical field
The present invention relates to the detection method of fatty acid polyglycol hop index, especially a kind of method that adopts spectrographic method to detect the index of polyphenol of fatty acid.
Background technology
The fatty acid soaps that will contain the few conjugated isomers acid of linolenic acid, leukotrienes, arachidonic acid and content is used for the emulsion polymerization of styrene-butadiene rubber, and the amount of its polymerization speed and linolenic acid adds that leukotrienes and arachidonic amount sum three times are linear.The fatty acid of this blending ingredients is divided into conjugation component and non-conjugated component; The conjugation component can directly be measured its content through measuring its uv absorption; And but non-conjugated component need be passed through the conjugated isomers that alkali isomerization is converted into absorbing ultraviolet light, measures its uv absorption again and records.Usually, when alkali isomerization, adopt monoethylene glycol, can non-conjugated component be converted into the conjugation component as the isomerization reaction solvent.Yet when in ethylene glycol solvent, carrying out isomerization reaction, undecomposed conjugation component is disturbed its measuring process easily in the sample, thereby influences testing result.
Summary of the invention
The object of the invention overcomes the defective that monoethylene glycol brings as the isomerization reaction solvent; Adopt glycerine to substitute the solvent of monoethylene glycol as isomerization reaction; The interference that the conjugation component causes when being solvent to proofread and correct monoethylene glycol provides a kind of method that detects the fatty acid polyglycol hop index with spectrographic method.
In order to solve the problems of the technologies described above, the technical scheme that the present invention adopts is following: a kind of method with spectrographic method detection fatty acid polyglycol hop index, comprise conjugation compound mensuration and non-conjugated compound mensuration in the fatty acid sample, and its characteristic may further comprise the steps:
(1) preparation of sample: accurate weighing 2g fatty acid sample, pour dissolving in the beaker that 75ml methyl alcohol is housed into, heating; Keeping temperature is 30-50 ℃; After the dissolving, change the volumetric flask of 100ml over to, be diluted to scale with methyl alcohol; Obtain 20g/l solution, again with the solution of methyl alcohol dilution until preparation 0.2g/l;
(2) mensuration of conjugation component: the solution dilution of step (1) preparation is different ratios, and the width of adjustment cuvette is contrast with methyl alcohol, and the wavelength that adopts automatic record photometer to be recorded in 220-340nm is measured solution absorbency;
(3) mensuration of non-conjugated component
A. potassium hydroxide glycerine mixed liquor preparation: the potassium hydroxide of 17.5g is dissolved in the glycerine of 100ml, feeds nitrogen mixing stirring, gas flow rate is set at 50-70ml/min, and heating mixed liquor to 200 ℃, removes excessive water;
B. alkali isomerization reaction: take by weighing the above-mentioned potassium hydroxide glycerine of 11g mixed liquor, pour in the test tube, this test tube is connected gas-tight sealing, feed nitrogen; Flow velocity is set at 50-70ml/min, and with 180 ℃ of oil bath heating, test tube immersion depth 11.4cm is when solution temperature rises to 180 ℃; Insulation 10min, and remove nitrogen gas seal equipment, take by weighing 0.1g fatty acid sample accurately, add test tube; Vigorous stirring 1min connects nitrogen gas seal equipment again, continues insulation 1min down at 180 ℃, and whether observe solution transparent; If transparent then the continuation is incubated, if saponification or not dissolving fully, then 2-3 back insulation of tube shaken, temperature retention time is 28-32min; After insulation finishes, take out test tube normal temperature and be cooled to 50 ℃, the methyl alcohol that adds 20ml stirs, and test tube is placed in 50 ℃ the hot water beaker and be incubated; Continue to stir and all to dissolve until dope, last, solution is transferred in the volumetric flask of 100ml and is diluted to scale;
C. blank test: the method according to step b describes, do not add like the fatty acid sample, handle the potassium hydroxide glycerite of back gained and test as blank;
D. detection method: non-conjugated sample obtains conjugated isomers solution after handling through step b, and the method that adopts step (2) to describe is determined at the wavelength solution absorbance of 220-340nm;
(4) with above-mentioned conjugation component that records and non-conjugated component absorbance, substitution formula, the index of polyphenol of calculating fatty acid.
Further, the described wavelength of step (2) is 322 nm, 316 nm, 310 nm, 274 nm, 268 nm, 262 nm and 232nm.
Further, step a is described to remove excessive water, dewaters the back concentration of potassium hydroxide between 10.9-11.0%.
Further, the said test tube specification of step b is 15.2 * 2.5cm, and the temperature retention time after tube shaken 2-3 time is 30min.
Further, the described assay method of steps d, during to diluted sample, blank is also done corresponding dilution.
The invention has the advantages that: the spectroscopic methodology to common improves, and adopts glycerine to substitute the solvent of monoethylene glycol as isomerization reaction, the interference that undecomposed conjugation component causes when being solvent to proofread and correct monoethylene glycol, and this measuring method specificity is strong, popularization and application easily.
Embodiment
By on can know; Fatty acid is divided into conjugation component and non-conjugated component; The conjugation component can directly be measured its content through measuring its uv absorption; And but non-conjugated component need be passed through the conjugated isomers that alkali isomerization is converted into absorbing ultraviolet light, measures its uv absorption again and records, and the concrete computation process of its extinction ability is as follows:
The computing method of 1 conjugation component extinction ability
Calculate under the different absorbances, like 322 nm, 316 nm, 310 nm, 274 nm, 268 nm, 262 nm and 232nm, the extinction ability of sample can be obtained the extinction ability of same wavelength by following formula:
K=D/bc
c=w(100-m)/100v
In the formula, K is a sample extinction ability; The D indicated concentration is the absorbance of solution in the cuvette of b cm thickness of c g/L; B is the thickness of cuvette, cm; C is a solution concentration, g/l; W is the weight of sample, g; M is the % concentration of sample aqueous solution; V is the cumulative volume of solution, l.
In the following formula, 2,3 and 4 represent the double key number order.
1) conjugated diolefine acid
Through computes under the 232nm wavelength-the uv absorption ability of COOR, K
232Be sample actual measurement extinction ability:
K
2=K
232-0.03 (being suitable for fatty acid or soap sample)
K
2=K
232-0.07 (being suitable for grease and ester sample)
The percentage composition of conjugate linolenic acid is: C
2=100K
2/ 119.
2) conjugated triene acid
Through the receptivity of computes under the 268nm wavelength:
K
3=2.8｛K
268-1/2(K
262+K
274)｝
The percentage composition of conjugation three acid is: C
3=100K
3/ 214
If calculating K
3Value is zero or negative, then is designated as 0.000%.
3) conjugation tetraenoic acid
Through the receptivity under the computes 316nm wavelength:
K
4=2.5｛K
316-1/2(K
310+K
322)｝
The percentage composition of conjugation three acid is: C
4=100K
4/ 220
If calculating K
4Value is zero or negative, then is designated as 0.000%.
The computing method of 2 non-conjugated component extinction abilities
Calculating 322,310,274,268,262 and the 232nm wavelength under the receptivity K ' of non-conjugated component, calculate C with the method for calculating the conjugation component.
Owing to receive the influence of other component, pass through the receptivity under the computes 268nm:
K′
3=4.1｛K′
268-1/2(K′
262+?K′
274)｝
If calculating K '
3Value is zero or negative, then is designated as 0.000, and flax acid number is 0.000%.
Since the influence of other component, so pass through the receptivity under the computes 316nm:
K′
4=4.1｛K′
316-1/2(K′
310+?K′
322)｝
If calculating K '
4Value is zero or negative, then is designated as 0.000, and the arachidonic acid number is 0.000%.
For proofreading and correct the value of unborn conjugated diolefine acid in the undecomposed conjugate acid, so pass through the receptivity under the computes 232nm:
K '
2=K '
232-K
232(being suitable for fatty acid or soap sample)
K '
2=K '
232-K
232+ 0.04 (being suitable for grease and ester sample)
Here K '
232And K
232It is respectively the actual receptivity that records before and after the isomerization.
For proofreading and correct undecomposed conjugated triene acid number, so pass through the receptivity under the computes 268nm:
K′′
3=K′
3-K
3
For proofreading and correct undecomposed conjugation tetraene acid number, so pass through the receptivity under the computes 316nm:
K′′
4=K′
4-K
4
With computes linolenic acid, leukotrienes, arachidonic percentage composition:
Linolenic acid %=X=1.125 K '
2-1.27 K ' '
3+ 0.04 K ' '
4
Leukotrienes %=Y=1.87 K ' '
3-4.43 K ' '
4
Arachidonic acid %=Z=4.43 K ' '
4
Annotate: as be animal tallow, hydrogenated oil and fat, soap, last can ignore the X equality, and following formula is represented the sour % in the whole sample, and the raw material for containing a small amount of how unsaturated component need not to convert to the sour % in the fatty acid, in experimental error.
The index of polyphenol computing formula is:
Index of polyphenol=X+3 (Y+Z)
Specific embodiment
(1) preparation of sample: accurate weighing 2.0894g fatty acid sample, pour dissolving in the beaker that 75ml methyl alcohol is housed into, heating; Keeping temperature is 30-50 ℃; After the dissolving, change the volumetric flask of 100ml over to, be diluted to scale with methyl alcohol; Obtain 20g/l solution, again with the solution of methyl alcohol dilution until preparation 0.2089g/l;
(2) mensuration of conjugation component: the solution dilution of step (1) preparation is different ratios; The width of adjustment cuvette; With methyl alcohol is contrast; Adopt and write down the wavelength mensuration solution absorbency that photometer is recorded in 322 nm, 316 nm, 310 nm, 274 nm, 268 nm, 262 nm and 232nm automatically, its result is as shown in table 1;
(3) mensuration of non-conjugated component
A. potassium hydroxide glycerine mixed liquor preparation: the potassium hydroxide of 17.5g is dissolved in the glycerine of 100ml; Feed nitrogen mixing stirring, gas flow rate is set at 50-70ml/min, and heating mixed liquor to 200 ℃; Remove excessive water, make concentration of potassium hydroxide between 10.9-11.0%;
B. alkali isomerization reaction: take by weighing the above-mentioned potassium hydroxide glycerine of 11g mixed liquor, pour in the test tube of 15.2 * 2.5cm, this test tube is connected gas-tight sealing, feed nitrogen; Flow velocity is set at 50-70ml/min, and with 180 ℃ of oil bath heating, test tube immersion depth 11.4cm is when solution temperature rises to 180 ℃; Insulation 10min, and remove nitrogen gas seal equipment, take by weighing 0.1165g fatty acid sample accurately, add test tube; Vigorous stirring 1min connects nitrogen gas seal equipment again, continues insulation 1min down at 180 ℃, and whether observe solution transparent; If transparent then the continuation is incubated, if saponification or not dissolving fully, then 2-3 back insulation of tube shaken, temperature retention time is 30min; After insulation finishes, take out test tube normal temperature and be cooled to 50 ℃, the methyl alcohol that adds 20ml stirs, and test tube is placed in 50 ℃ the hot water beaker and be incubated; Continue to stir and all to dissolve until dope, last, solution is transferred in the volumetric flask of 100ml and is diluted to scale;
C. blank test: the method according to step b describes, do not add like the fatty acid sample, the potassium hydroxide glycerite of handling the back gained is tested as blank;
D. detection method: non-conjugated sample obtains conjugated isomers solution after handling through step b, and the method that adopts step (2) to describe is determined at the wavelength solution absorbance of 220-340nm, and its determination data is as shown in table 2;
Table 1 conjugation compound mensuration data
The non-conjugated compound mensuration data of table 2
(4) according to the absorbance of conjugation component and non-conjugated component, calculating index of polyphenol according to above-mentioned formula is 0.97.
Claims (5)
1. the method with spectrographic method detection fatty acid polyglycol hop index comprises conjugation compound mensuration and non-conjugated compound mensuration in the fatty acid sample, and its characteristic may further comprise the steps:
(1) preparation of sample: accurate weighing 2g fatty acid sample, pour dissolving in the beaker that 75ml methyl alcohol is housed into, heating; Keeping temperature is 30-50 ℃; After the dissolving, change the volumetric flask of 100ml over to, be diluted to scale with methyl alcohol; Obtain 20g/l solution, again with the solution of methyl alcohol dilution until preparation 0.2g/l;
(2) mensuration of conjugation component: the solution dilution of step (1) preparation is different ratios, and the width of adjustment cuvette is contrast with methyl alcohol, and the wavelength that adopts automatic record photometer to be recorded in 220-340nm is measured solution absorbency;
(3) mensuration of non-conjugated component
A. potassium hydroxide glycerine mixed liquor preparation: the potassium hydroxide of 17.5g is dissolved in the glycerine of 100ml, feeds nitrogen mixing stirring, gas flow rate is set at 50-70ml/min, and heating mixed liquor to 200 ℃, removes excessive water;
B. alkali isomerization reaction: take by weighing the above-mentioned potassium hydroxide glycerine of 11g mixed liquor, pour in the test tube, this test tube is connected gas-tight sealing, feed nitrogen; Flow velocity is set at 50-70ml/min, and with 180 ℃ of oil bath heating, test tube immersion depth 11.4cm is when solution temperature rises to 180 ℃; Insulation 10min, and remove nitrogen gas seal equipment, take by weighing 0.1g fatty acid sample accurately, add test tube; Vigorous stirring 1min connects nitrogen gas seal equipment again, continues insulation 1min down at 180 ℃, and whether observe solution transparent; If transparent then the continuation is incubated, if saponification or not dissolving fully, then 2-3 back insulation of tube shaken, temperature retention time is 28-32min; After insulation finishes, take out test tube normal temperature and be cooled to 50 ℃, the methyl alcohol that adds 20ml stirs, and test tube is placed in 50 ℃ the hot water beaker and be incubated; Continue to stir and all to dissolve until dope, last, solution is transferred in the volumetric flask of 100ml and is diluted to scale;
C. blank test: the method according to step b describes, do not add like the fatty acid sample, handle the potassium hydroxide glycerite of back gained and test as blank;
D. detection method: non-conjugated sample obtains conjugated isomers solution after handling through step b, and the method that adopts step (2) to describe is determined at the wavelength solution absorbance of 220-340nm;
(4) with above-mentioned conjugation component that records and non-conjugated component absorbance, substitution formula, the index of polyphenol of calculating fatty acid.
2. a kind of method with spectrographic method detection fatty acid polyglycol hop index according to claim 1, it is characterized in that: the described wavelength of step (2) is 322 nm, 316 nm, 310 nm, 274 nm, 268 nm, 262 nm and 232nm.
3. according to claim 1ly a kind ofly detect the method for fatty acid polyglycol hop index with spectrographic method, it is characterized in that: step a is described to remove excessive water, dewaters the back concentration of potassium hydroxide between 10.9-11.0%.
4. according to claim 1ly a kind ofly detect the method for fatty acid polyglycol hop index with spectrographic method, it is characterized in that: the said test tube specification of step b is 15.2 * 2.5cm, and the temperature retention time after tube shaken 2-3 time is 30min.
5. a kind of method with spectrographic method detection fatty acid polyglycol hop index according to claim 1, it is characterized in that: the described assay method of steps d, during to diluted sample, blank is also done corresponding dilution.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5958714A (en) * | 1996-10-02 | 1999-09-28 | Safety Associates, Inc. | Test kits for determining at least two specific analytes in foods and other complex matrices |
| CN1715909A (en) * | 2005-08-11 | 2006-01-04 | 中国农业科学院畜牧研究所 | The method of a kind of fast detecting milk conjugated linoleic acid (CLA) composition and content |
| CN102288695A (en) * | 2011-07-02 | 2011-12-21 | 明一（福建）婴幼儿营养品有限公司 | Method for detecting four common unsaturated fatty acids in infant milk powder |
-
2012
- 2012-08-21 CN CN2012102970126A patent/CN102768192A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5958714A (en) * | 1996-10-02 | 1999-09-28 | Safety Associates, Inc. | Test kits for determining at least two specific analytes in foods and other complex matrices |
| CN1715909A (en) * | 2005-08-11 | 2006-01-04 | 中国农业科学院畜牧研究所 | The method of a kind of fast detecting milk conjugated linoleic acid (CLA) composition and content |
| CN102288695A (en) * | 2011-07-02 | 2011-12-21 | 明一（福建）婴幼儿营养品有限公司 | Method for detecting four common unsaturated fatty acids in infant milk powder |
Non-Patent Citations (3)
| Title |
|---|
| 林玉宙等: "婴幼儿奶粉中亚麻酸、亚油酸、花生四烯酸和二十二碳六烯酸的测定", 《食品研究与开发》 * |
| 桑卫国等: "异构化菜油中共轭亚油酸的紫外分光光度法的定量", 《浙江工业大学学报》 * |
| 薛秀恒等: "牛奶中共轭亚油酸含量的紫外分光光度测定方法", 《食品工业科技》 * |
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Application publication date: 20121107 |