CN102841175B - Method for identifying drainage oil based on detection of hydroxy valence - Google Patents
Method for identifying drainage oil based on detection of hydroxy valence Download PDFInfo
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Abstract
The invention provides a detection method for identifying drainage oil based on measurement of hydroxy valence of an oil sample. In the method, acetylation reaction is taken as a basis, and hydroxy content is indirectly characterized by the amount of acetic acid generated after hydroxy acetylation. The method comprises the steps of: acetylation and quantitative measurement of the oil sample, acid number measurement of the oil sample, and calculation of the hydroxy valence according to the acetylation and acid number experimental result. The method has the characteristics of simplicity in operation and low cost; and at the same time, the drainage oil detection method is based on the substance-diglyceride which is not easy to remove in the refining process of the drainage oil, so that the detection method has strong specificity and reliable results.
Description
Technical field
The present invention relates to a kind of method based on detecting hydroxyl valency discriminating waste oil, belong to food inspection field.
Background technology
Waste oil, all kinds of poor oils that general reference exists in life, mainly contain following three kinds of sources: the sense stricto oil reclaiming from trench, frying oil and animal fat inferior through repeatedly frying.If waste oil, through dealing carefully with, can be made the products such as soap, biodiesel, to reach the object turning waste into wealth.But some illegal manufacturer, in order to earn the golden eggs of this approach of waste oil backflow dining table, illegally reclaims refining waste oil.Owing to containing the strong carcinogens such as aflatoxin, palycyclic aromatic in waste oil, if people for a long time edible waste oil may cause cancer etc. various diseases, very harmful to human body, so the social cost that waste oil brings is high.
Since domestic there is the event of waste oil backflow dining table since, various circles of society are positive regard manage to solve waste oil problem all.State Council issues in time and administers the file < < reinforcement waste oil regulation of waste oil and the suggestion > > of kitchen castoff management.But severe gap of hitting is still being bored by illegal manufacturer, is producing waste oil, harm society.The method that the Ministry of Public Health was also once openly detected to whole society's collection waste oil for twice, want that from the approach of detection, stopping restaurant uses waste oil, but waste oil still lacks a kind of detection method simply accurately, therefore searching out a kind of suitable detection method has great social effect.
The call of the active response Ministry of Public Health of whole society collection waste oil, various circles of society have submitted hundreds of detection method altogether to, wherein mainly contain following several detection method:
1. survey electrical conductivity method: due to the severe contamination of the waste oil through using through edible-flavouring (salt) and sewer, wherein usually contain a large amount of metallic ions, the existence of these materials causes the conductivity of waste oil apparently higher than normal edible oil, it is foundation that electrical conductivity method be take the conductive capability of measuring oil samples, thereby differentiates waste oil.Mainly there is following technological deficiency in the method: waste oil can be removed substantially through the material of these electric conductivity of degree of depth refining, and the waste oil conductivity of degree of depth refining may be close with normal edible oil like this, causes judging.
2. cholesterol level diagnostic method: the discarded edible oil and fat that are separate sources mostly due to waste oil mix, so often contain animal fat in waste oil.Animal fat contains higher cholesterol with respect to vegetable oil, and cholesterol level diagnostic method detects the cholesterol level in oil samples, thereby differentiates waste oil.The major technique defect of this kind of method is: in not all waste oil, all contain animal fat composition, such as just containing the cholesterol of minute quantity in frying oil; In addition, in current domestic detection grease, the main method of cholesterol level is to utilize vapor-phase chromatography, and the sensitivity of the method is lower.Therefore the specificity of the method is not strong, easily causes erroneous judgement.
3. specific gene forms: owing to can containing animal fat in most of waste oils, according to molecular biology identified for genes method, identify the animal gene in grease, judge in edible oil, whether to contain animal derived materials.The major technique defect of the method is the same with cholesterol level diagnostic method: in not all waste oil, all contain animal fat composition.Therefore the specificity of the method is not strong.
4. palycyclic aromatic method: edible oil experiences high temperature when culinary art, can generate palycyclic aromatic, can judge by detecting the content of palycyclic aromatic whether oil samples is waste oil.The major technique defect of the method is that, in waste oil carclazyte decoloration and deodorization process, the loose porous structure of carclazyte can adsorb to fall most of palycyclic aromatic, causes the content of palycyclic aromatic not necessarily to exceed standard.And only have oil through the frying of the degree of depth, and just having more palycyclic aromatic, most of waste oils are just through once being used, and polycyclic aromatic hydrocarbon content is wherein not necessarily very high.Therefore, utilize palycyclic aromatic to detect and easily cause erroneous judgement.
5. survey surfactant residual quantity method: because waste oil is the oil through using; usually can be polluted by pond and sewer; and these places often have washing agent; and in washing agent, contain surfactant; and the most frequently used surfactant-neopelex has fluorescent effect, can be used for accordingly detecting and in oil, whether contain surfactant and determine whether waste oil.The major technique defect of the method is: after the refining of the waste oil degree of depth, surfactant is removed in distillation deacidification, so the specificity of the method is not strong.
To sum up, all there is a problem in these existing methods: detect waste oil specificity not strong, can not accurately distinguish waste oil and normal edible oil.
The Major Difficulties that waste oil detects is waste oil wide material sources, contain impurity different, as shown in Figure 1, in addition, refining degree when each illegal manufacturer carries out waste oil processing is different, does not therefore have an extensive representational waste oil sample.This just causes can not only catching the singularity of part waste oil when design waste oil detection method, and should, from the total composition of waste oil, catch the one-tenth that is not easy to be removed in refining process to assign to design detection method.
Summary of the invention
The object of this invention is to provide a kind of method based on detecting hydroxyl valency discriminating waste oil, the present invention, by detecting the stronger detection index of a species specificity, can distinguish waste oil and normal edible oil exactly, thereby guarantees the public health of edible oil.
A kind of method based on detecting hydroxyl valency discriminating waste oil provided by the present invention, comprises the steps:
(1) taking quality is m
1oil samples to be identified;
(2) in oil samples described in step (1), add the mixed solution of pyridine and acetic anhydride, and mix;
(3) mixed solution step (2) being obtained adds hot reflux;
(4) in the mixed solution obtaining to step (3), add normal butyl alcohol, then add phenolphthalein indicator, and be titrated to and occur pale red terminal with potassium hydroxide-ethanol standard solution, write down the volume V of the potassium hydroxide-ethanol standard solution consuming while being titrated to terminal
2;
(5) do the blank assay that does not add described oil samples, repeat above-mentioned steps (2) ~ (4), write down the volume V of the described potassium hydroxide-ethanol standard solution consuming when blank assay is titrated to terminal
0;
(6) taking quality is m
2oil samples to be identified;
(7) to adding with described potassium hydroxide-ethanol standard solution in oil samples described in step (6), be titrated to neutral pyridine, shake up and dissolve this oil samples;
(8) in the mixed solution obtaining to step (7), add described phenolphthalein indicator, and be titrated to and occur pale red terminal with potassium hydroxide-ethanol standard solution, write down the volume V of the potassium hydroxide-ethanol standard solution consuming while being titrated to terminal
1;
Utilize following formula (1) to calculate the hydroxyl valency of oil samples to be detected:
If the value of the hydroxyl valency calculating is greater than 8mg (KOH) g
-1, in oil samples, contain waste oil.
In above-mentioned method, described m
1can be 4 ~ 5g, described m
2can be 9 ~ 11g.
In above-mentioned method, in step (2), described pyridine and acetic acid can the mixed solution of acid anhydride in, pyridine can be 3:1 with the volume parts ratio of acetic anhydride; The addition of the mixed solution of described pyridine and acetic anhydride can be 5mL.
In above-mentioned method, in step (3), described in add hot reflux time can be 1h, temperature can be 80 ℃; Described adding after hot reflux, also comprises and adds 10mL distilled water to continue to add the step of hot reflux 10min at 80 ℃.
In above-mentioned method, in step (4), the addition of described normal butyl alcohol can be 25mL;
Described phenolphthalein indicator is for obtaining in 95% ethanol that is dissolved in 100mL by 1.0g phenolphthalein;
The concentration of described potassium hydroxide-ethanol standard solution can be 0.5molL
-1.
In above-mentioned method, in step (7), the addition of described pyridine can be 10mL.
In above-mentioned method, in step (4) and (8), the addition of described phenolphthalein indicator can be 2 ~ 3, about 0.1ml.
Material-the diglyceride of the method for discriminating waste oil provided by the invention based on being difficult to remove in waste oil refining process, utilizes acetylization reaction to measure the hydroxyl valency in oil samples, have simple to operate, with low cost, differentiate the advantages such as accurate.
Accompanying drawing explanation
Fig. 1 is the situation of change of impurity in waste oil in the step of illegal manufacturer refining waste oil and process thereof.
Embodiment
The experimental technique using in following embodiment if no special instructions, is conventional method.
In following embodiment, material used, reagent etc., if no special instructions, all can obtain from commercial channels.
The present embodiment oil samples used is as follows:
1) soybean oil: good fortune is one-level soybean oil near the house, the date of manufacture: 2011.12.19;
2) peanut oil: good fortune is squeezed one-level peanut oil near the house, the date of manufacture: 2011.12.12;
3) dining room is through frying soybean oil: from Tsing-Hua University's DingXiangYuan dining room, obtain;
4) undressed waste oil: Jiangsu Jie Mei bioenergy company limited provides, is used for preparing the undressed waste oil crude oil of biodiesel;
5) waste oil of decoloration and deodorization: utilize voluntarily carclazyte to oil samples 4) carry out decoloration and deodorization and obtain;
6) refining waste oil: restaurant, Jiangsu provides.
Above-mentioned 6 kinds of oil samples are carried out to test experience, and the detecting step of each sample is as follows:
1) utilize poor heavy method with 100mL ground conical flask, to take the oil samples of 4 ~ 5g, claim standard to 0.0001g, be designated as m
1;
2) in the 100mL ground conical flask in step 1), with 5mL liquid-transfering gun, accurately add 5mL pyridine-acetic anhydride mixed solution, wherein the volume ratio of pyridine and acetic anhydride is 3:1, shakes and mixes gently;
3) by step 2) in 100mL ground conical flask as in water bath, connect bulb condensation recirculatory pipe, the temperature that water bath is set is 80 ℃, adds hot reflux 1h;
4) after step 3) adds hot reflux 1h and finishes, from condenser pipe upper end, gently add 10mL distilled water, and continue to add hot reflux 10min;
5) after step 4) finishes, from water bath, take out ground conical flask and bulb condensation recirculatory pipe, be cooled to room temperature;
6) utilize 25mL graduated cylinder to measure 25mL normal butyl alcohol, the normal butyl alcohol of half is added from spherical condensation tube upper end, then remove spherical condensation tube, with remaining normal butyl alcohol, clean the wall of ground conical flask;
7) in the 100mL conical flask in step 6), add 2 phenolphthalein indicators, wherein this phenolphthalein indicator is for obtaining in 95% ethanol that is dissolved in 100mL by 1.0g phenolphthalein; (concentration is 0.5molL to the potassium hydroxide-ethanol standard solution that utilization prepares
-1) be titrated to and occur pale red terminal, write down the volume V of the potassium hydroxide-ethanol standard solution consuming while being titrated to terminal
2;
8) do the blank test of non-refuelling sample simultaneously, repeat above-mentioned steps 1) to step 7), write down the volume V of the potassium hydroxide-ethanol standard solution consuming when blank assay is titrated to terminal
0;
9) with 250mL conical flask, take 9～11g oil samples, claim standard to 0.0001g, be designated as m
2;
10) in the 250mL conical flask in step 9), add 10mL to be titrated to neutral pyridine with potassium hydroxide-ethanol standard solution, shake up dissolved oil sample;
11) in the 250mL conical flask in step 10), add 2 phenolphthalein indicators, and be titrated to and occur pale red terminal with potassium hydroxide-ethanol standard solution, write down the volume V of the potassium hydroxide-ethanol standard solution of consumption
1.
By above-mentioned steps, can be obtained acid value and the hydroxyl valency of 6 kinds of sample oil:
The acid value of table 1 sample and hydroxyl valency testing result
From testing result, can find, the hydroxyl valency of soybean oil is 5.23mg (KOH) g
-1, the hydroxyl valency of peanut oil is 4.43mg (KOH) g
-1all be less than 8mg (KOH) g
-1, therefore judge that the two is normal edible oil; And through the acid value of frying soybean oil, untreated waste oil, decoloration and deodorization waste oil and refining waste oil all higher than 8mg (KOH) g
-1, can judge the oil that contains waste oil or process use in these oil.
Claims (7)
1. the method based on detecting hydroxyl valency discriminating waste oil, comprises the steps:
(1) taking quality is m
1oil samples to be identified;
(2) in oil samples described in step (1), add the mixed solution of pyridine and acetic anhydride, and mix;
(3) mixed solution step (2) being obtained adds hot reflux; Describedly also comprise the step that adds 10mL distilled water to continue to add hot reflux 10min after adding hot reflux;
(4) in the mixed solution obtaining to step (3), add normal butyl alcohol, then add phenolphthalein indicator, and be titrated to and occur pale red terminal with potassium hydroxide-ethanol standard solution, write down the volume V of the potassium hydroxide-ethanol standard solution consuming while being titrated to terminal
2;
(5) do the blank assay that does not add described oil samples, repeat above-mentioned steps (2)～(4), write down the volume V of the described potassium hydroxide-ethanol standard solution consuming when blank assay is titrated to terminal
0;
(6) taking quality is m
2oil samples to be identified;
(7) to adding with described potassium hydroxide-ethanol standard solution in oil samples described in step (6), be titrated to neutral pyridine, shake up and dissolve this oil samples;
(8) in the mixed solution obtaining to step (7), add described phenolphthalein indicator, and be titrated to and occur pale red terminal with potassium hydroxide-ethanol standard solution, write down the volume V of the potassium hydroxide-ethanol standard solution consuming while being titrated to terminal
1; Utilize following formula (1) to calculate the hydroxyl valency of oil samples to be detected:
If the value of the hydroxyl valency calculating is greater than 8mg KOHg
-1, in oil samples, contain waste oil.
2. method according to claim 1, is characterized in that: described m
1be 4～5g, described m
2be 9～11g.
3. method according to claim 1 and 2, is characterized in that: in step (2), in the mixed solution of described pyridine and acetic anhydride, pyridine is 3:1 with the volume parts ratio of acetic anhydride; The addition of the mixed solution of described pyridine and acetic anhydride is 5mL.
4. method according to claim 3, is characterized in that: in step (3), described in add hot reflux time be 1h, temperature is 80 ℃.
5. method according to claim 4, is characterized in that: in step (4), the addition of described normal butyl alcohol is 25mL;
Described phenolphthalein indicator is for obtaining in 95% ethanol that is dissolved in 100mL by 1.0g phenolphthalein;
The concentration of described potassium hydroxide-ethanol standard solution is 0.5molL
-1.
6. method according to claim 5, is characterized in that: in step (7), the addition of described pyridine is 10mL.
7. method according to claim 6, is characterized in that: in step (4) and (8), the addition of described phenolphthalein indicator is 2～3.
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|---|---|---|---|
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| CN103592412A (en) * | 2013-11-01 | 2014-02-19 | 惠州市长润发涂料有限公司 | Hydroxyl value detection method |
| CN106442502A (en) * | 2016-09-29 | 2017-02-22 | 扬州晨化新材料股份有限公司 | Determination method for molecular weight of polyether amine |
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| JP2009150664A (en) * | 2007-12-18 | 2009-07-09 | Idea Consultants Inc | Total concentration prediction method of compound in prediction object by statistical technique |
| CN102435640A (en) * | 2010-09-29 | 2012-05-02 | 湖南城市学院 | Hotwash oil inspection method |
| CN102393426A (en) * | 2011-10-28 | 2012-03-28 | 李涛 | Identification method for illegal cooking oil |
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