CN109541124A - The measuring method of lactic anhydride content in a kind of lactic acid - Google Patents
The measuring method of lactic anhydride content in a kind of lactic acid Download PDFInfo
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- CN109541124A CN109541124A CN201811425219.0A CN201811425219A CN109541124A CN 109541124 A CN109541124 A CN 109541124A CN 201811425219 A CN201811425219 A CN 201811425219A CN 109541124 A CN109541124 A CN 109541124A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
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Abstract
The invention discloses a kind of measuring methods of lactic anhydride content in lactic acid, and the measurement including a) total lactic acid: precision weighs m1The sample of g is simultaneously dissolved in water, and is subsequently added into excessive sodium hydroxide solution, is heated to reflux after a period of time plus instructions phenolphthalein solution 2~3 drips, be titrated to red disappearance with titration with hydrochloric acid liquid while hot, while doing blank test, total lactic acid content W1；B) measurement of free lactic acid: precision weighs m2The sample of g simultaneously adds neutral alcohol dissolution, adds instructions phenolphthalein solution 2~3 to drip, is titrated to pink, free lactic acid content W with ethanol hydrogen production potassium oxide titrating solution immediately2；C) calculating of lactic anhydride: the calculating formula of lactic anhydride content W is W=W1‑W2, by the measurement to lactic anhydride content, the hydrolysis degree of lactic acid is understood, to reach the complete reaction of lactic acid in production, to improve the stability of product content and product.
Description
[technical field]
The present invention relates to the technical field of the measurement of lactic anhydride content, the measurement of lactic anhydride content in especially a kind of lactic acid
The technical field of method.
[background technique]
Lactic acid, the entitled Lactic acid molecular formula of chemistry are C3H6O3.It is the carboxylic acid containing hydroxyl, therefore is one
A alpha-hydroxy acid (AHA).It is raw material that lactic acid, which is by starchiness such as corn, rice, sweet potatoes, is generated through everfermentation, in order to reduce
Storage and transportation cost, generally go through heating and are concentrated into 85% or more content, but heat under lactic acid normal pressure and be easy to decompose, and are concentrated into
When 50%, partially become lactic anhydride, therefore often contains a certain amount of lactic anhydride in product.Lactic acid is widely used in food, makeup
Product, agriculture farm in medicine production, due to more demanding in medicine production, need in production and application plus water hydrolyze again,
But hydrolysis rate is slow, and can be dehydrated generation lactic anhydride again, reaches a dynamic balance.The presence of lactic anhydride influences product
Quality and product stability, it is therefore necessary to the content for being strict controlled in lactic anhydride when production is extremely important.
[summary of the invention]
The object of the invention is to solve the problems of the prior art, a kind of measurement side of lactic anhydride content in lactic acid is proposed
Method understands the hydrolysis degree of lactic acid by the measurement to lactic anhydride content, to reach the complete reaction of lactic acid in production, with
Improve the stability of product content and product.
To achieve the above object, the invention proposes a kind of measuring methods of lactic anhydride content in lactic acid, including walk as follows
It is rapid:
A) measurement of total lactic acid: precision weighs m1The sample of g is simultaneously dissolved in water, and it is molten to be subsequently added into excessive sodium hydroxide
Liquid, was heated to reflux after a period of time plus instructions phenolphthalein solution 2~3 drips, and is titrated to red disappearance with titration with hydrochloric acid liquid while hot, records salt
Volume consumed by acidometric titration liquid is V1Ml, while blank test is done, recording volume consumed by titration with hydrochloric acid liquid is V0Ml, always
Lactic acid content W1Calculating formula be
Wherein, V0For the volume of titration with hydrochloric acid liquid consumed by titration blank solution, unit ml, V1It is molten for titration sample
The volume of titration with hydrochloric acid liquid consumed by liquid, unit ml, C1For the concentration of titration with hydrochloric acid liquid, unit mol/L, 90.08 are
The molal weight of lactic acid, unit g/mol, 1000 be mass conversion coefficient, m1For the quality of sample, unit g；
B) measurement of free lactic acid: precision weighs m2The sample of g simultaneously adds neutral alcohol dissolution, adds instructions phenolphthalein solution 2~3
Drop is titrated to pink with ethanol hydrogen production potassium oxide titrating solution immediately, records body consumed by ethanol hydrogen production potassium oxide titrating solution
Product is Vml, free lactic acid content W2Calculating formula be
Wherein, V is the volume for titrating ethanol hydrogen production potassium oxide titrating solution consumed by sample solution, unit ml, C2For
The concentration of ethanol hydrogen production potassium oxide titrating solution, unit mol/L, 90.08 be the molal weight of lactic acid, unit g/mol, 1000
For mass conversion coefficient, m2For the quality of sample, unit g；
C) calculating of lactic anhydride: the calculating formula of lactic anhydride content W is W=W1-W2。
Preferably, the concentration of the sodium hydroxide solution is 40g/L, the concentration of the titration with hydrochloric acid liquid is 1mol/L,
The concentration of the instructions phenolphthalein solution is 10g/L, and the concentration of the ethanol hydrogen production potassium oxide titrating solution is 0.5mol/l.
Beneficial effects of the present invention: the present invention understands the hydrolysis degree of lactic acid by the measurement to lactic anhydride content, to reach
To the complete reaction of lactic acid in production, to improve the stability of product content and product.
[specific embodiment]
Use reagent:
Sodium hydroxide solution: concentration 40g/L takes sodium hydroxide 40g, be dissolved in water into 1000ml to get.
Titration with hydrochloric acid liquid: concentration 1mol/L takes hydrochloric acid 90ml, adds water to 1000ml, then demarcated to get.
Instructions phenolphthalein solution: concentration 10g/L takes phenolphthalein 10g, add ethyl alcohol 1000ml make dissolution to get.
Ethanol hydrogen production potassium oxide titrating solution: concentration 0.5mol/L takes potassium hydroxide 35g, sets in conical flask, adds no aldehyde second
Alcohol makes to dissolve and be diluted to 1000ml in right amount, is inclined take supernatant rapidly, set tool rubber stopper after being stood 24 hours with the close plug of rubber
Brown Glass Brown glass bottles and jars only in, then demarcated to get.
Neutral alcohol: taking dehydrated alcohol appropriate, adds instructions phenolphthalein solution 1 to drip, extremely with 0.1mol/L sodium hydroxide titration drop
Blush to get.
Use instrument:
General laboratory often with glassware and is heated to reflux device
Embodiment one carries out lactic anhydride content detection to two parts of lactic acid hydrolysis samples:
The measurement of total lactic acid:
Precision weighs two parts of samples 1 and two parts of samples 2, and the quality of sample 1 is respectively 1.1280g and 1.0895g, sample 2
Quality be respectively 1.2781g and 1.1985g, and be respectively placed in 250ml iodine flask, water 50ml added to dissolve, with pipette standard
40g/L sodium hydroxide solution 20ml is really added, is heated to reflux 5min, instructions phenolphthalein solution 2 is added to drip, uses 1mol/L titration with hydrochloric acid while hot
Liquid is titrated to red disappearance, and recording volume consumed by titration with hydrochloric acid liquid is V1Ml, while blank test is done, record titration with hydrochloric acid
Volume consumed by liquid is V0Ml obtains following experimental data:
Total Plasma lactate tables of data of 1 two parts of lactic acid hydrolysis samples of table
Wherein, total lactic acid content W1Calculating formula be
V0For the volume of titration with hydrochloric acid liquid consumed by titration blank solution, unit ml；
V1For the volume of titration with hydrochloric acid liquid consumed by titration sample solution, unit is ml '
C1For the concentration of titration with hydrochloric acid liquid, unit mol/L；
90.08 be the molal weight of lactic acid, unit g/mol；
1000 be mass conversion coefficient, m1For the quality of sample, unit g.
The measurement of free lactic acid:
Precision weighs two parts of samples 1 and two parts of samples 2, and the quality of sample 1 is respectively 0.3409g and 0.3895g, sample 2
Quality be respectively 0.2828g and 0.3676g, and set in the dry conical flask of 250ml respectively, neutral alcohol 50ml added to dissolve,
Add instructions phenolphthalein solution 2 to drip, be titrated to pink with 0.5mol/L ethanol hydrogen production potassium oxide titrating solution immediately, records ethanol hydrogen production oxygen
Changing volume consumed by potassium titrating solution is Vml, obtains following experimental data:
The free lactic acid determination data table of 2 two parts of lactic acid hydrolysis samples of table
Wherein, free lactic acid content W2Calculating formula be
V is the volume for titrating ethanol hydrogen production potassium oxide titrating solution consumed by sample solution, unit ml；
C2For the concentration of ethanol hydrogen production potassium oxide titrating solution, unit mol/L；
90.08 be the molal weight of lactic acid, unit g/mol；
1000 be mass conversion coefficient；
m2For the quality of sample, unit g.
The calculating of lactic anhydride:
Sample 1:W=W1-W2=46.6%-40.8%=5.8%
Sample 2:W=W1-W2=46.6%-44.5%=2.1%
Embodiment 2 carries out lactic anhydride content detection to a lactic raw material sample:
The measurement of total lactic acid:
Precision weighs two parts of samples, and the quality of sample is respectively 1.0196g and 1.0234g, other are as in the first embodiment, obtain
Following experimental data:
Total Plasma lactate tables of data of a lactic raw material of table 3
The measurement of free lactic acid:
Precision weighs two parts of samples, and the quality of sample is respectively 0.2872g and 0.3044g, other are as in the first embodiment, obtain
Following experimental data:
A lactic raw material of table 4 dissociates total Plasma lactate tables of data
The calculating of lactic anhydride:
W=W1-W2=85.7%-71.2%=14.5%
Above-described embodiment is the description of the invention, is not limitation of the invention, after any pair of simple transformation of the present invention
Scheme all belong to the scope of protection of the present invention.
Claims (2)
1. the measuring method of lactic anhydride content in a kind of lactic acid, it is characterised in that include the following steps:
A) measurement of total lactic acid: precision weighs m1The sample of g is simultaneously dissolved in water, and is subsequently added into excessive sodium hydroxide solution, heating
After reflux a period of time plus instructions phenolphthalein solution 2~3 drips, and is titrated to red disappearance with titration with hydrochloric acid liquid while hot, records titration with hydrochloric acid
Volume consumed by liquid is V1Ml, while blank test is done, recording volume consumed by titration with hydrochloric acid liquid is V0Ml, total lactic acid contain
Measure W1Calculating formula be
Wherein, V0For the volume of titration with hydrochloric acid liquid consumed by titration blank solution, unit ml, V1To titrate sample solution institute
The volume of the titration with hydrochloric acid liquid of consumption, unit ml, C1For the concentration of titration with hydrochloric acid liquid, unit mol/L, 90.08 be lactic acid
Molal weight, unit g/mol, 1000 be mass conversion coefficient, m1For the quality of sample, unit g；
B) measurement of free lactic acid: precision weighs m2The sample of g simultaneously adds neutral alcohol dissolution, adds instructions phenolphthalein solution 2~3 to drip, immediately
It is titrated to pink with ethanol hydrogen production potassium oxide titrating solution, recording volume consumed by ethanol hydrogen production potassium oxide titrating solution is Vml,
Free lactic acid content W2Calculating formula be
Wherein, V is the volume for titrating ethanol hydrogen production potassium oxide titrating solution consumed by sample solution, unit ml, C2For ethyl alcohol system
The concentration of potassium hydroxide titrating solution, unit mol/L, 90.08 be the molal weight of lactic acid, and unit g/mol, 1000 be quality
Conversion coefficient, m2For the quality of sample, unit g；
C) calculating of lactic anhydride: the calculating formula of lactic anhydride content W is W=W1-W2。
2. the measuring method of lactic anhydride content in a kind of lactic acid as described in claim 1, it is characterised in that: the sodium hydroxide
The concentration of solution is 40g/L, and the concentration of the titration with hydrochloric acid liquid is 1mol/L, and the concentration of the instructions phenolphthalein solution is 10g/L, institute
The concentration for stating ethanol hydrogen production potassium oxide titrating solution is 0.5mol/l.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112782341A (en) * | 2020-12-25 | 2021-05-11 | 广东先导稀材股份有限公司 | Method for determining content of free lactic acid in bismuth lactate sample |
| CN114414674A (en) * | 2021-12-16 | 2022-04-29 | 健帆生物科技集团股份有限公司 | Method for detecting active ingredients in citric acid disinfectant |
-
2018
- 2018-11-27 CN CN201811425219.0A patent/CN109541124A/en active Pending
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112782341A (en) * | 2020-12-25 | 2021-05-11 | 广东先导稀材股份有限公司 | Method for determining content of free lactic acid in bismuth lactate sample |
| CN114414674A (en) * | 2021-12-16 | 2022-04-29 | 健帆生物科技集团股份有限公司 | Method for detecting active ingredients in citric acid disinfectant |
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