CN103698328B - A kind of reduced sugar direct titrimetric method for improving titration precision - Google Patents
A kind of reduced sugar direct titrimetric method for improving titration precision Download PDFInfo
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Abstract
The invention belongs to analytical chemistry field, it is related to a kind of reduced sugar direct titrimetric method for improving titration precision, further relates to the titration outfit of this method, the method comprising the steps of：A, Fehling solution A and Fehling second liquid equivalent added into glass container, obtain Fei Linshi solution；B, the Fehling solution are heated to boiling on the heating, keep fluidized state, and demarcation is added dropwise from buret or test sample reduced sugar solution is treated, titration Fehling solution to indicator Indicator Reaction terminal；The heater is magnetic agitation heater.The configuration and the optimization of operating condition of this method synthesis hardware, greatly enhance the repeatability and operability of test, improve the accuracy of test result, shorten titration time, improve titration environment, terminal is easy to judgement.Equipment investment low cost, it is simple and easy to apply, be easy to manipulation, with higher titration precision and operating efficiency, it can be widely used for the constant detection of reduced sugar in the food such as fruit.
Description
Technical field
The invention belongs to analytical chemistry field, it is related to the detection of sugared content in food, and in particular to direct using Fei Linshi
The method of content of reducing sugar in the fruit such as titration measuring citrus.
Background technology
Reduced sugar is that have the reproducibility groups such as free aldehyde, hemiacetal hydroxyl or free carbonyl in molecule structure
Carbohydrate, such as glucose, fructose, maltose, lactose, are distributed widely in the agricultural product such as fruit, grain, are directly coming for sweet taste
Source, its content number be food quality evaluate important indicator.
For the measure of reduced sugar, have direct titrimetric method, the sulfuric acid process of phenol one, anthrone colorimetry, high performance liquid chromatography,
Standard addition method etc., all respectively there is its optimum range and detectability.Such as GB《Reduced sugar in GB/T5009.7-2008 food
Determine》In have recorded a kind of direct titrimetric method of reducing sugar test, its general principle is：It is molten with reduced sugar under the conditions of boiling
The fixed a certain amount of fehling reagent of drop, is reduced to monovalence copper, with methylene blue by the bivalent cupric ion in fehling reagent（It is called Asia
Methyl blue）For indicator, the oxidized form methylene blue of blueness is reduced to colourless reduced form by slightly excessive reduced sugar immediately
Methyl blue, indicates titration end-point.Non-reducing sugar is converted into after reduced sugar, it is also possible to which this method is tested.Determined in carbohydrate analysis
In all methods, reduced sugar direct titrimetric method is so that it is easy, quick, stable reagent, simple instrument and equipment the advantages of, be widely used in
Total reducing sugar in soluble sugar in water fruits and vegetables, the reduced sugar in various food, frozen, lactose and sugarcane in dairy products
The test of sugar etc..
However, reduced sugar direct titrimetric method is in practical measurement process, it is difficult to control, operation by sample-adding amount, the volume that adds water,
The factors such as reacting liquid basicity, heat source strength, boiling time, hand shaken speed and strength, rate of titration, acid extraction
Influence, is inevitably present some problems, so as to cause testing result fluctuation big.Such as,《GB 8210-1987 export citrus
The fresh fruit method of inspection》P7-8 discloses a kind of assay method of reduced sugar, is boiled before titration and wants 2 minutes, titration process wants 3 points
Clock, titrates one bottle time-consuming 5 minutes or so altogether.In whole titration process, tester must be kept by electric furnace, and energy is concentrated, side
Shake on drop side（Manually）, time and effort consuming is as a result also not satisfactory；Heating wire is aglow when electric furnace is heated, and influences the judgement of reaction end.
In addition, solution is easily oxidized in atmosphere in conical flask, becomes original blueness again, so must keep the solution to be in titration process
Fluidized state, and shorten titration time as far as possible.It can be seen that, this method titration time is restricted, and in order to prevent overtitration, titration
Speed again can not be too fast, and these operations for mutually restricting contradiction are not only difficult to control, and directly affect last titration value, difference
Bigger than normal, collimation is poor.
To solve the above problems, in " improvement of Fehling's reagent titration measuring reduced sugar method "（Ye Haihui etc., tropical agriculture
Industry science, P9-11, No.3 2001）In, disclose a kind of method that reduced sugar test is carried out under logical condition of nitrogen gas.With GB
Compare, although the numerical value relative deviation that measures diminishes after the method is improved, it is necessary to special source nitrogen in its continuous mode,
There is safety requirements to environment, improve testing cost, should not promote the use of.
" assay method of carbohydrate is inquired into food "（Ma Nailiang etc., modern food science and technology, P139-140, Vo1.22 No.1
2006）In disclose a kind of improved titration outfit, i.e., add rubber stopper to stopper in the bottleneck of titration outfit, to prevent air from invading
Drop reaction system influences test result.This method is similar with the improvement principle that logical nitrogen completely cuts off air, still, in practical operation
During, after liquid to be titrated seethes with excitement, shaking also needs to continue to instill reduced sugar simultaneously, and this not only gives the inconvenience of operation band, and
Plug requirement fits like a glove with conical flask bottleneck, it is desirable to which the matching degree of device is high, limits as smaller (150ml) or larger
The use of (250ml) conical flask, it is more inconvenient when particularly sample size is more.
The improvement of both the above method, all also exists and does not mitigate tester's working strength, hardware is defective, is not suitable for promoting
Using the problem of.The present invention is based on these technical problems, and prior art has been carried out to improve invention.
The content of the invention
In view of this, the present invention provides a kind of reduced sugar direct titrimetric method for improving titration precision, and this method utilizes Fehling
Family name's direct titrimetric method principle carries out content of reducing sugar measure, alleviates tester's working strength, simple to operate and reproducible, surveys
Test result high precision.
To achieve the above object, the technical scheme is that：
Reduced sugar direct titrimetric method, comprises the following steps：
A, Fehling solution A and Fehling second liquid equivalent added into glass container, obtain Fei Linshi solution；Add Fei Linshi solution bodies
The water of 0.3-0.8 times of product, obtains Fehling solution；
B, the Fehling solution are heated to boiling on the heating, keep fluidized state, and reduction is added dropwise from buret
Sugar juice, titration Fehling solution to indicator Indicator Reaction terminal；
The heater is magnetic agitation heater.
The above method is measured using Fei Linshi direct titrimetric method principles to reduced sugar, and unspecified operating procedure can join
According to GB《The measure of reduced sugar in GB/T 5009.7-2008 food》In " the first method direct titrimetric method ", " sugar of citrus fruit,
Acid, Vitamin C assay method "（《Citrus science and technology communication》1973.5-6, P43-44）Method Deng described in is carried out.The magnetic
Power agitator（Magnetic stirrer or magnetic mixer）Be it is a kind of by magnetic force come the stirring in rotating liquid
Son has the laboratory equipment of heating function concurrently.Titration operation is carried out using the equipment, adjustment solution stirring can be required according to reaction
Speed and heating power, realize temperature adjustment, rate controlling, can not only accelerate reaction, improve the controllability and repeatability of operation；Avoid inspection
Survey person keeps scorching by electric furnace, and mitigates the working strength of tester significantly.Preferred heating of the invention and mixing speed are adjustable
Magnetic agitation heater.
In the step A, the preparation of Fehling solution A and Fehling second liquid can be according to GB《GB/T 8210-2011 export citrus
The fresh fruit method of inspection》、《GB 8210-1987 export the fresh orange method of inspection》、《GB6194-86 water fruits and vegetables soluble sugars
Determination method》Method Deng described in is carried out.Wherein, in Fehling solution A correspondence standard alkaline cupric tartrate solution A, fehling reagent
Alkaline cupric tartrate second liquid, fehling reagent second in first, Fei Linshi liquid A, Fehling second liquid correspondence standard, Fei Linshi liquid B.In the step
In rapid, according to the concentration of testing sample, it can also add water, Fehling liquid A and liquid B is diluted, with most into Fei Linshi solution
Sugar juice is suitable with Fehling solution volume is advisable for titration reduction used eventually；When it is described it is to be measured reduction sugar juice it is diluter when, can remove from
The step of adding water, is directly titrated with reduction sugar juice.
As the further improvement of the above method, in the Fei Linshi solution of the step A, Fehling solution A and Fehling second are added
The water of 0.3-0.8 times of liquid cumulative volume, and water is added in the titration process of the step B, Fehling solution is obtained, while maintaining Fehling
Solution is in fluidized state.Compared compared with the water that prior art adds 1~5 times of amount volume to Fei Linshi solution, the inventive method adds water
Amount is few, is substantially shorter the time that solution boils.In addition, water is added in midway with glue head dropper, on the one hand, evaporation can be supplied and lost
Moisture, it is to avoid cause reacting liquid basicity to change because of evaporation water loss, and then influence reaction end the problem of judge inaccurate；Separately
On the one hand, reacting liquid temperature is can control, reaction solution bumping or wall built-up is prevented.Described water, preferably distilled water.
In the step B, reduction sugar juice is demarcates the reduced sugar standard liquid of fehling reagent, and such as Glucose standards are molten
Liquid, fructose standard liquid, lactose standard liquid etc., or be sample solution to be determined.Preparing the method for sample solution can join
Carried out according to GB, can appropriate dilute sample when concentration of reduced sugar is too high in sample；Otherwise concentration of reduced sugar is too low in sample
When, Fehling solution cumulative volume when can reduce demarcation, finally to titrate the total of specimen in use solution and Fehling solution A and Fehling second liquid
Volume is quite advisable.Before official testing sample, typically first carry out pretest to grasp the sample needed for the quantitative Fei Linshi solution of consumption
Product liquor capacity, in formal titration, first directly adds the sample of " required sample solution volume -1ml " into Fei Linshi solution
Solution, is heated to boiling and slowly titrating, while adding indicator, the preferred methylene blue of indicator（Indicator can also be tried in Fehling
Agent is added when preparing）.When making indicator using methylene blue, for diluter Fei Linshi solution, solution is by blueness to blueness
Disappear for reaction end（Referring to GB《The measure of reduced sugar in GB/T 5009.7-2008 food》）；The Fehling being formulated when dense type
During family name's solution, for the titration of reduced sugar in cedra fruits, it is reaction end that solution, which is wholly absent by blueness and taken on a red color bright,
（Referring to " sugar of citrus fruit, acid, Vitamin C assay method "（《Citrus science and technology communication》1973.5-6, P43-44））, carefully
Observation, its color is present by blue, green, yellow, orange, red progressive formation, so terminal is easy to control.
As the further improvement of the above method, the operation of the step B was completed in 3 minutes.Compared with prior art,
The titration time after boiling and seething with excitement can be shortened.Because indicator methylene blue is reduced after discoloration, and easily by air
Oxygen is oxidized to original blueness, so it is in boiling reaction state that solution should be kept in titration process, avoids as far as possible and air contact,
And avoid titration time long.Total titration time can be shortened using this method, and then improve the precision of test result.
As the further improvement of the above method, in the step B, the speed that reduction sugar juice is added dropwise first quick and back slow, is faced
During proximal response terminal 1ml, rate of titration is no more than 2 drops/sec.It is controllable in titration process as a result of magnetic agitation heater
Mixing speed can more effectively mix reaction, it is not necessary to need to wait the longer reaction time as conventional method, therefore can be with
Accelerate rate of titration；On the other hand, due to the quickening of rate of titration, shorten total titration time, reduce air etc. it is other because
Influence of the element to reaction result, can obtain more accurately titration results.Further, preferably rate of titration is 1-2 drops/sec.
As the further improvement of the above method, in the titration process of the step B, the rotating speed of magnetic agitation heater is
200-300 revs/min, the rotating speed can better meet the mixing requirement of reaction solution in test process.
As the further improvement of the above method, the clip for stirring Fehling solution is placed with the glass container.
The clip replaces special rotor agitator, main rise mixes reaction solution, accelerate the effect of reaction speed, it is to avoid hand dynamic
Inconvenience, it is difficult to the problem of uniform operation；Because be heating, react, seethe with excitement, titrating, shaking up etc. and carry out simultaneously, glass may also function as
The effect of pearl, is prevented because hot-spot bumping spills reaction solution；Clip, which easily takes, easily to be put, and be can be recycled, is reduced experiment
Totle drilling cost.
As the further improvement of the above method, the buret is bent-tube boiler acid buret, more conducively fluidized state
Under titration operation.The conical flask of the preferred 150-250ml of glass container, bottom of bottle should not be too thick, and doleiform is tried one's best unanimously.
Another object of the present invention is to there is provided a kind of titration outfit of reduced sugar direct titrimetric method, the device is alleviated
Tester's working strength, weakens the influence of environment and operation factors to experimental result, the survey that unskilled operating personnel obtain
Test result also has very high precision, is adapted to popularization and application.The technical scheme of the device is：
The titration outfit of reduced sugar direct titrimetric method, the device carries out reduced sugar using Fei Linshi direct titrimetric methods principle and contained
It is fixed to measure, including contains the buret of reduction sugar juice, contains the glass container of Fehling solution and Fehling solution is heated
Heater, the buret is bent-tube boiler acid buret, and the heater is magnetic agitation heater, and described
The clip for stirring Fehling solution is placed with glass container.
The present invention also provides the method that a kind of titration outfit of utilization reduced sugar direct titrimetric method determines reduced sugar, this method
Content of reducing sugar measure is carried out using Fei Linshi direct titrimetric methods principle, tester's working strength is alleviated, it is simple to operate and again
Renaturation is strong, test result high precision.The technical scheme used for：Reduction is determined using the titration outfit of reduced sugar direct titrimetric method
The method of sugar, the titration outfit includes containing the bent-tube boiler acid buret of reduction sugar juice, contains the glass of Fehling solution
Container and the magnetic agitation heater for being heated and being mixed to Fehling solution, and be placed with the glass container for stirring
The clip of Fehling solution；It the described method comprises the following steps：
A, Fehling solution A and Fehling second liquid equivalent added into glass container（Conical flask）, Fei Linshi solution is obtained, and add striking
The water of 0.3-0.8 times of woods solution A and Fehling second liquid cumulative volume, obtains Fehling solution；
B, the Fehling solution are heated to boiling on magnetic agitation heater, fluidized state are kept, from bent-tube boiler acid
Reduction sugar juice is added dropwise in buret, and adds water during the course of the reaction, while it is in fluidized state to maintain Fehling solution, titrates striking
Woods solution is to indicator Indicator Reaction terminal；Step B operation was completed in 3 minutes.
Operating procedure, reaction condition, device parameter described in foregoing reduced sugar direct titrimetric method etc., are also applied for this part
The method for determining reduced sugar using the titration outfit of reduced sugar direct titrimetric method.
The measure of reduced sugar in the above reduced sugar direct titrimetric method and its suitable numerous food of device, including fruit,
Total reducing sugar in soluble sugar in vegetables, the reduced sugar in various food, frozen, the lactose in dairy products and sucrose etc.
Determine.As the preferred of the present invention, the reduced sugar direct titrimetric method and its device are particluarly suitable for reducing in the fruit such as citrus
The detection and application of sugar.
The method have the benefit that：
Reduced sugar direct titrimetric method and its titration outfit that the present invention is provided, employ untapped magnetic force in the prior art
The devices such as agitating heating device, clip, bent-tube boiler acid buret, and added water in titration process volume, stirring speed by changing
The factors such as degree, heat time, rate of titration, the repeatability and operability of test are greatly enhanced, and improve the essence of test result
Degree, the influence of test subject skilled operation degree is small, significantly reduces the working strength of tester, and equipment investment low cost is adapted to
It is applied to the test of reduced sugar in numerous food.Specific advantage also has：（1）Improve the paralleling effect of titration numerical value, one
As titrate twice with regard to suitable required precision can be reached；（2）Easy to operate after method is improved, controllability is strong, and terminal is easy to sentence
Disconnected, saving of work and time, titration number of times is reduced, and test titration time also shortens every time, and operating efficiency is greatly improved, especially suitable
In a fairly large number of situation of measuring samples；（3）It is few using reagent（The screening agent beneficial to terminal point determining need not such as be added）, it is supporting
Material inexpensively easily takes, and saves consumables cost.
Brief description of the drawings
Fig. 1 is the structural representation of the titration outfit main composition part of reduced sugar direct titrimetric method of the present invention.
Embodiment
Hereinafter with reference to accompanying drawing, by embodiment and reference examples, the present invention will be described in detail, and embodiment is the present invention；
Reference examples are named as conventional method, i.e., with reference to " sugar of citrus fruit, acid, Vitamin C assay method "（《Citrus science and technology communication》
1973.5-6, P43-44）、《GB 8210-1987 export the fresh orange method of inspection》With《In GB/T 5009.7-2008 food
The measure of reduced sugar》Carry out.Unreceipted condition in embodiment, is still carried out according to above-mentioned standard and method.
Preparatory work of experiment：
（1）The preparation of reagent and sample
A, Fehling solution A（Fehling reagent A）：Analytical pure sulfuric acid copper（CuSO4·5H2O）34.69g is soluble in water, is settled to
500ml, is filtered standby.
B, Fehling second liquid（Fehling reagent B）：50g analysis pure cerium hydroxide sodium is soluble in water, adds the pure sodium potassium tartrate tetrahydrate of analysis
173g, is settled to 500ml.
C, methylene blue indicator：1g methylene blues are dissolved in 100ml water.
D, glucose standards solution：Pure DEXTROSE ANHYDROUS, to constant weight, accurately weighs 0.5g or so, uses water in 105 DEG C of drying
Dissolve and be settled to 100ml.
E, reduced sugar sample solution：Fruit is crosscutting, filtering of squeezing the juice, and draws Normal juice 10ml in 100ml volumetric flasks, is settled to
Scale.
F, inverted sugar sample solution：Fruit is crosscutting, filtering of squeezing the juice, and draws Normal juice 10ml in 100ml volumetric flasks, plus distillation
Water is shaken up to 50ml, enriching hydrochloric acid 3ml.Volumetric flask is placed in water bath with thermostatic control and converted, conversion fluid temperature was reached at 2-2.5 minutes
80 DEG C, and after 80 ± 2 DEG C are kept for 10 minutes, is put in taking-up be rapidly cooled in circulating water 20 DEG C, plus phenolphthalein indicator 1~2 drips,
Neutralized with 40% and 10% sodium hydroxide solution, it is such as excessive again with 1:3 hydrochloric acid are tuned into neutrality, add water and are settled to scale.
（2）Titration outfit
Titration outfit one：Magnetic agitation heater（German Heidolph magnetic stirring apparatus MR3001, major parameter：Ac
230/240v 50/60Hz 625w, temperature adjustment speed adjustable range：0~350 DEG C, 100~1250rpm）, bent-tube boiler acid buret, return
Shape pin, conical flask（200ml）；
Titration outfit two：Adjustable electric furnace（Band asbestos board）, common acid buret, conical flask（250ml）, bead.
Embodiment the inventive method
Above-mentioned solution and titration outfit one are taken, the sample solution of summer orange, Ponkan and sweet orange is carried out respectively in the steps below
Test, and test result is counted.The structural representation of the titration outfit main composition part as shown in figure 1, wherein,
1 is magnetic agitation heater, and 2 be bent-tube boiler acid buret, and 3 be clip, and 4 be conical flask.
A, fehling reagent mixed liquor demarcation
Draw 5.0ml fehling reagent A and 5.0ml fehling reagents B（Also fehling reagent A and fehling reagent B equivalent can be mixed
After draw 10.0ml）In 200ml conical flasks, plus 3~8ml of distilled water, 1 clip is added, from bent-tube boiler acid buret
Middle dropwise addition about 9ml glucose standards solutions.Heated on magnetic agitation heater, control was heated to boiling in 2 minutes, by magnetic force
The rotating speed of agitating heating device is transferred to 200-300 revs/min, adds 1~2 and drips methylene blue indicator, then with 1~2 drop/sec of speed
Degree continues that glucose standards solution is added dropwise, while appropriate distilled water is added along wall with a small glue head dropper in boiling reaction liquid,
Reaction solution bumping or wall built-up are prevented, and maintenance reaction liquid is in fluidized state, until solution blueness is wholly absent to take on a red color bright is
Terminal, records the cumulative volume of consumption of glucose standard liquid（T）.Parallel test more than twice, takes its average value to be used to subsequently go back
Raw sugar or the calculating for converting sugared content.
B, sample solution prediction
5.0ml fehling reagent A and 5.0ml fehling reagent B are drawn, are placed in 200ml conical flasks, plus distilled water（Addition
Refer to table 1-4）, add 1 clip.Heated on magnetic agitation heater, control was heated to boiling in 2 minutes, by magnetic force
The rotating speed of agitating heating device is transferred to 200-300 revs/min, adds 1~2 and drips methylene blue indicator, with speed first quick and back slow,
Sample solution is added dropwise from bent-tube boiler acid buret, and keeps fluidized state, when solution blueness dies down, with 1-2 drops/
The speed of second is added dropwise, while adding appropriate distilled water along wall with a small glue head dropper in boiling reaction liquid, prevents that reaction solution is quick-fried
Boiling or wall built-up, and maintenance reaction liquid be in fluidized state, until solution blueness be wholly absent take on a red color it is bright be terminal, record consumption
The cumulative volume of sample solution.
C, sample solution are determined
5.0ml fehling reagent A and 5.0ml fehling reagent B are drawn, are placed in 200ml conical flasks, plus distilled water（Addition
Refer to table 1-4）, 1 clip is added, the sample solution than predicting the few 1ml of volume is added dropwise from bent-tube boiler acid buret.In magnetic
On power agitating heating device heat, control be heated in 2 minutes boiling, by the rotating speed of magnetic agitation heater be transferred to 200-300 turn/
Minute, add 1~2 and drip methylene blue indicator, then be added dropwise with 1-2 drops/sec of speed, while small with one in boiling reaction liquid
Glue head dropper adds appropriate distilled water along wall, prevents reaction solution bumping or wall built-up, and maintenance reaction liquid is in fluidized state, until molten
It is terminal, the cumulative volume of record consumption sample solution that liquid blueness, which is wholly absent and taken on a red color bright,（D）.Parallel test more than twice,
The content of reduced sugar or inverted sugar is calculated as follows respectively：（Demarcation is with determining Fei Linshi solutions used together and consumption is equal）
In formula, G：Glucose is weighed（That is 0.5g or so）；
T：The amount that glucose standards solution is consumed when titrating（ml）；
W：Glucose constant volume（100ml）；
D：The amount that sample solution is consumed when titrating（ml）.
Test and statistics are shown in Table 1-table 4.
The detection of inverted sugar is calculated with result in the summer orange of table 1（Inventive method）
Note：*When glucose standards solution is prepared, the weight for weighing glucose is 0.5460g；
X in formula1----individual event measurement result.
The detection of inverted sugar is calculated with result in the Ponkan of table 2（Inventive method）
Note：*When glucose standards solution is prepared, the weight for weighing glucose is 0.5286g；Other are ibid.
The detection of inverted sugar is calculated with result in the sweet orange of table 3（Inventive method）
Note：*When glucose standards solution is prepared, the weight for weighing glucose is 0.5103g；Other are ibid.
The detection of reduced sugar is calculated with result in the sweet orange of table 4（Inventive method）
Note：*When glucose standards solution is prepared, the weight for weighing glucose is 0.5103g；Other are ibid.
Reference examples conventional method
Above-mentioned solution and titration outfit two are taken, the sample solution of tangerine orange is tested in the steps below, and test is tied
Fruit is counted.
A, fehling reagent mixed liquor demarcation
A. preparation titration：Draw 5.0ml fehling reagent A and 5.0ml fehling reagents B（Also fehling reagent A and Fehling can be tried
10.0ml is drawn after agent B mixed in equal amounts）, it is placed in conical flask, plus distilled water（Addition refers to table 5）, in advance from common acid
Part glucose standard liquid is added dropwise in conical flask in buret（A, B mixed liquor）In.Heated on electric furnace, make it in 2min or so
Boiling, boils and added after 1min 2 drop methylene blue indicator, and every 0.5min, continue at the boil with the speed of per second 4~5 drops
Glucose standards solution is added dropwise in degree, until it is terminal that solution blueness, which is wholly absent presentation brick-red, from boiling to titration end-point not
More than 3min.
B. formal titration：Fehling reagent A, B liquid and distilled water are drawn in conical flask by preparation titration, upper electric furnace heating,
Glucose standards solution close to titer is added into mixed liquor simultaneously, makes the amount that is added dropwise after boiling in 0.5~1ml, thereafter
Operation is ibid.Record the cumulative volume of consumption of glucose standard liquid.With method parallel two to three times with people, after taking its average value to be used for
Continuous reduced sugar or the calculating for converting sugared content.
B, sample solution measure
A. preparation titration：With the preparation titration demarcated above.
B. formal titration：With the formal titration demarcated above, parallel testing two to three times, respectively by embodiment step C's
Calculating formula calculates the amount of reduced sugar or inverted sugar.
Test and statistics are shown in Table 5.
The detection of inverted sugar is calculated with result in the tangerine orange of table 5（Conventional method）
Note：Mark after Fehling solution, represents different glucose and weighs：
1. when glucose standards solution is prepared, the weight for weighing glucose is 0.4938g；
2. when glucose standards solution is prepared, the weight for weighing glucose is 0.4887g；
3. when glucose standards solution is prepared, the weight for weighing glucose is 0.5011g.
During test, if having titrated twice, relative differences are counted；If having titrated three times, relative average debiation is counted.
In formula：X1----individual event measurement result；The average value of secondary measurement result；dIt is average----average deviation；dIt is average=(|d1|
+|d2|+....|dn|)/n；dn----individual event measurement result and the absolute deviation of average value, dn=|Xn-x|；N---- testing times.
The statistics of comparative example and reference examples is understood：
（1）Same sample is titrated twice using the inventive method, titration twice consumes the difference of the volume of titrating solution
Within 0.1ml, relative differences are within 1%.However, being titrated using conventional method to same sample, consumption titration
The difference maximum of the volume of liquid reaches 0.65ml（Such as table 5- samples 8）, the sample titrated twice consumes the volume phase of titrating solution
To difference more than 2%, the sample titrate for three times consumes the volume relative average debiation of titrating solution and is all higher than 1.5%；
The value of inverted sugar or reduced sugar obtained by calculating, the relative differences of the sugared content of same sample（Or average deviation）More than 1.5%,
And mostly more than 2%, and the sugared content end value relative differences of the present invention are within 1%.It can be seen that, the inventive method is more traditional
Method, accuracy is significantly increased.
（2）The completion from beginning to warm up to titrating, the time that the inventive method is titrated every time is and traditional within 3 minutes
Method is then needed 3~5 minutes, and heating and titration total time-consuming ratio conventional method shorten nearly half；And because the inventive method passes through two
Secondary titration can obtain the titration numerical value of degree of precision requirement, reduce testing time, substantially increase operating efficiency.
（3）Using the benefit for adding appropriate distilled water in advance with distilled water being added dropwise in course of reaction in heating in the inventive method
Water mode, has reached two purposes：First, making the reaction solution volume total amount for treating test sample and standard sample try one's best quite, survey is improved
The accuracy of examination；Second, being mended in heating process and instilling water avoid the bumping and wall built-up of reaction solution, more conducively terminal is sentenced
It is disconnected, so as to also reduce error.
To sum up, the inventive method can obtain the higher measured value of accuracy by less time test, titration value it is relative
Difference or relative average debiation are much smaller than conventional method；The relative differences or relative average debiation of inverted sugar or content of reducing sugar
It is compared to conventional method and reduces more than 60%, and data reappearance is strong, paralleling effect is good.
The present invention（Method）It is not only limited in the measure of reduced sugar, is also applied for the detection of the sugar such as sucrose of other species,
Simply other carbohydrate things need to carry out sample pre-treatments, and titratable reduced sugar is changed into by corresponding condition.So in text
I.e. the measure of the measure reduced sugar for the inverted sugar mentioned.
Finally illustrate, the above embodiments are merely illustrative of the technical solutions of the present invention and it is unrestricted, although with reference to compared with
The present invention is described in detail good embodiment, it will be understood by those within the art that, can be to skill of the invention
Art scheme is modified or equivalent, and without departing from the objective and scope of technical solution of the present invention, it all should cover at this
Among the right of invention.
Claims (7)
1. reduced sugar direct titrimetric method, it is characterised in that comprise the following steps：
A, Fehling solution A and Fehling second liquid equivalent added into glass container, obtain Fei Linshi solution；Add Fei Linshi liquor capacities
0.3-0.8 times of water, obtains Fehling solution；
B, the Fehling solution are heated to boiling on the heating, keep fluidized state, reduced sugar are added dropwise from buret molten
Liquid, titration Fehling solution to indicator Indicator Reaction terminal；
The heater is magnetic agitation heater, and the clip for stirring Fehling solution is placed with the glass container；
Water is added in the titration process of the step B, while it is in fluidized state to maintain Fehling solution；
The Fehling solution A is the aqueous solution of copper sulphate；The Fehling second liquid is formulated by sodium potassium tartrate tetrahydrate with NaOH,
The mass ratio of the Fehling second liquid mesotartaric acid potassium sodium and NaOH is 173:50；
The concentration of the indicator is 1g/100ml；
The Fehling solution is heated to after boiling the indicator on the heating in stepb, is added dropwise also from buret
Indicator is added during raw sugar solution, reaction solution is titrated to and changes colour again as terminal.
2. reduced sugar direct titrimetric method according to claim 1, it is characterised in that：The operation of the step B is in 3 minutes
Complete.
3. reduced sugar direct titrimetric method according to claim 1, it is characterised in that：In the step B, reduced sugar is added dropwise molten
First quick and back slow, when closing on reaction end 1ml, rate of titration is no more than 2 drops/sec to the speed of liquid.
4. reduced sugar direct titrimetric method according to claim 1, it is characterised in that：In the titration process of the step B, magnetic
The rotating speed of power agitating heating device is 200-300 revs/min.
5. reduced sugar direct titrimetric method according to claim 1, it is characterised in that：It is placed with the glass container for stirring
Mix the clip of Fehling solution；The buret is bent-tube boiler acid buret.
6. the method for determining reduced sugar using the titration outfit of reduced sugar direct titrimetric method, it is characterised in that：The titration outfit
The bent-tube boiler acid buret (2) of sugar juice is reduced including containing, the glass container of Fehling solution is contained and Fehling solution is entered
Row heating and the magnetic agitation heater (1) of mixing, and be placed with the glass container for stirring the back-shaped of Fehling solution
Pin (3)；It the described method comprises the following steps：
A, Fehling solution A and Fehling second liquid equivalent added into glass container, obtain Fei Linshi solution, and it is overall to add Fei Linshi solution
The water of 0.3-0.8 times of product, obtains Fehling solution；
B, the Fehling solution are heated to boiling on magnetic agitation heater (1), keep fluidized state, from bent-tube boiler acid drop
Reduction sugar juice is added dropwise in fixed tube (2), and adds water during the course of the reaction, while it is in fluidized state, titration to maintain Fehling solution
Fehling solution is to indicator Indicator Reaction terminal；Step B operation was completed in 3 minutes；
The Fehling solution A is the aqueous solution of copper sulphate；The Fehling second liquid is formulated by sodium potassium tartrate tetrahydrate with NaOH,
The mass ratio of the Fehling second liquid mesotartaric acid potassium sodium and NaOH is 173:50；
The concentration of the indicator is 1g/100ml；
The Fehling solution is heated to after boiling indicator on the heating in stepb, and reduced sugar is added dropwise from buret
Indicator is added during solution, reaction solution is titrated to and changes colour again as terminal.
7. the application of reduced sugar direct titrimetric method reduced sugar in citrus is determined described in any one of claim 1 to 5.
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| CN110133179A (en) * | 2019-06-20 | 2019-08-16 | 邹文海 | A kind of reduced sugar Test paper and its application method |
| CN110702846A (en) * | 2019-10-17 | 2020-01-17 | 四川鑫统领新材料有限公司 | Method for determining total sugar in Fehling solution and molasses |
| CN111879891A (en) * | 2020-06-30 | 2020-11-03 | 武汉钢铁有限公司 | Method for rapidly determining content of sulfite in industrial sulfuric acid |
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| CN103399009A (en) * | 2013-08-12 | 2013-11-20 | 四川郎酒集团有限责任公司 | Method for detecting contents of glucose and starch in fermented grains |
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| CN1474183A (en) * | 2003-08-01 | 2004-02-11 | 莱阳农学院 | Method for detecting starch content in ash tree flower polysaccharide |
| CN103399009A (en) * | 2013-08-12 | 2013-11-20 | 四川郎酒集团有限责任公司 | Method for detecting contents of glucose and starch in fermented grains |
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