CN103698328A - Reducing sugar direct titration method capable of improving titration accuracy - Google Patents
Reducing sugar direct titration method capable of improving titration accuracy Download PDFInfo
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Abstract
The invention belongs to the field of analytical chemistry, relates to a reducing sugar direct titration method capable of improving the titration accuracy, and further relates to a titration device for the method. The method comprises the following steps: A, adding equal amounts of a fehling liquid I and a fehling liquid II into a glass container to obtain a fehling solution; B, heating the fehling solution on a heating device to boil, keeping the boiling state, adding dropwise a reducing sugar solution of a calibrated or measured sample from a burette, adding dropwise the fehling solution until an indicator indicates the reaction endpoint, and the heating device is a magnetic stirring heater. The method combines the configuration of hardware and the optimization of operating conditions, so that the testing repeatability and the operability are greatly improved, the accuracy of the testing result is increased, the titration time is shortened, the titration environment is improved, and the endpoint is also judged easily. The investment cost for equipment is low, the method is simple and feasible and also convenient to operate, higher titration accuracy and working efficiency are achieved, and the reducing sugar direct titration method is widely applied to detecting the constant of a reducing sugar in foods like fruits.
Description
Technical field
The invention belongs to analytical chemistry field, relate to the detection of sugared content in food, be specifically related to adopt Fei Linshi direct titrimetric method to measure the method for content of reducing sugar in the fruit such as citrus.
Background technology
Reducing sugar is in molecule structure, to have the carbohydrate of the reductibility groups such as free aldehyde, hemiacetal hydroxyl or free carbonyl, as glucose, fructose, maltose, lactose, be distributed widely in the agricultural product such as fruit, grain, the direct sources of sweet taste, its content number be the important indicator that food quality is evaluated.
For the mensuration of reducing sugar, there are direct titrimetric method, phenol one sulfuric acid process, anthrone colourimetry, high performance liquid chromatography, standard addition method etc., all respectively there are its optimum range and detectability.As recorded a kind of direct titrimetric method of reducing sugar test in the mensuration > > of reducing sugar in GB < < GB/T5009.7-2008 food, its ultimate principle is: under boiling condition, with a certain amount of fehling reagent of reducing sugar solution titration, bivalent cupric ion in fehling reagent is reduced to monovalence copper, the methylene blue (being again methylene blue) of take is indicator, slightly excessive reducing sugar is reduced to colourless reduced form methylene blue by blue oxidized form methylene blue immediately, indication titration end-point.Non-reducing sugar is converted into after reducing sugar, also available the method test.In all methods of measuring in carbohydrate analysis, the advantage such as reducing sugar direct titrimetric method is easy, quick with it, stable reagent, instrument and equipment are simple and easy, is widely used in the test of soluble sugar, the reducing sugar in various food, the total reducing sugar in frozen, the lactose in dairy products and sucrose etc. in fruit, vegetables.
Yet, reducing sugar direct titrimetric method is in practical measurement process, be difficult to control, the factors such as operation is subject to application of sample amount, adds water volume, reacting liquid basicity, heat source strength, boiling time, hand shaken speed and strength, rate of titration, acid extraction affect, inevitably there are some problems, thereby cause testing result fluctuation large.Such as, < < GB 8210-1987 outlet fresh orange method of inspection > > P7-8 discloses a kind of assay method of reducing sugar, before titration, boil and want 2 minutes, titration process is wanted 3 minutes, one bottle of titration time-consuming about 5 minutes altogether.In whole titration process, tester must keep by electric furnace, and energy is concentrated, and shakes (manually) while dripping, time and effort consuming, and result is also not satisfactory; During heating by electric cooker, heating wire is aglow, affects the judgement of reaction end.In addition, in conical flask, solution is easily oxidized in air, becomes original blueness again, thus in titration process, must keep solution to be fluidized state, and shorten titration time as far as possible.Visible, the method titration time is restricted, and in order to prevent overtitration, rate of titration again can not be too fast, and these operations that mutually restrict contradiction are not only difficult to control, and directly affect last titration value, differ bigger than normal, and collimation is poor.
For addressing the above problem, in " improvement of Fehling's reagent titration measuring reducing sugar method " (P9-11, No.3 2001 for Ye Haihui etc., tropical agriculture science), a kind of method of carrying out reducing sugar test under logical condition of nitrogen gas is disclosed.Compare with GB, although the numerical value relative deviation that this method records after improving has diminished, in its mensuration process, need special source nitrogen, environment is had to safety requirements, improved testing cost, should not promote the use of.
" in food, the assay method of carbohydrate is inquired into " (Ma Nailiang etc., modern food science and technology, P139-140, Vo1.22 No.1 2006) in a kind of improved titration apparatus is disclosed, the bottleneck at titration apparatus adds rubber plug jam-pack, to stop air to invade drop reaction system, affects test result.The improvement principle of the isolated air of the method and logical nitrogen is similar, but, in actual mechanical process, after vs boiling, jolting also needs to continue to splash into reducing sugar simultaneously, and this has not only been with inconvenience to operation, and plug requires to fit like a glove with conical flask bottleneck, the matching degree of claimed apparatus is high, has limited as the use of less (150ml) or large (250ml) conical flask, more inconvenient when particularly sample size is more.
The improvement of above two kinds of methods, all also exists and does not alleviate tester's working strength, hardware defectiveness, the problem that is not suitable for applying.The present invention is based on these technical matterss, prior art has been carried out improving invention.
Summary of the invention
In view of this, the invention provides a kind of reducing sugar direct titrimetric method that improves titration precision, the method utilizes Fei Linshi direct titrimetric method principle to carry out content of reducing sugar mensuration, has alleviated tester's working strength, and simple to operate and reproducible, test result precision is high.
For achieving the above object, technical scheme of the present invention is:
Reducing sugar direct titrimetric method, comprises the following steps:
A, Fehling first liquid and Fehling second liquid equivalent are added to glass container, obtain Fei Linshi solution; Add Fei Linshi liquor capacity 0.3-0.8 water doubly, obtain Fehling solution;
B, described Fehling solution are heated to boiling on heating arrangement, keep fluidized state, drip reducing sugar solution from buret, and titration Fehling solution is to indicator Indicator Reaction terminal;
Described heating arrangement is magnetic agitation well heater.
Said method adopts Fei Linshi direct titrimetric method principle to measure reducing sugar, unspecified operation steps can be with reference in the mensuration > > of reducing sugar in GB < < GB/T 5009.7-2008 food " first method direct titrimetric method ", " the sugar of citrus fruit, acid, Vitamin C assay method " (< < citrus science and technology communication > > 1973.5-6, P43-44) etc. the method described in is carried out.Described magnetic stirring apparatus (magnetic stirrer or claim magnetic mixer) is a kind ofly by magnetic force, to come stirrer in rotating liquid to have the laboratory equipment of heating function concurrently.Use this equipment to carry out titration operation, can require adjust solution stirring rate and heating power according to reaction, realize temperature adjustment, control speed, not only can accelerated reaction, improved controllability and the repeatability of operation; Avoid detection person to keep in other the scorching of electric furnace, and greatly alleviate tester's working strength.The present invention preferably heats the magnetic agitation well heater adjustable with stirring rate.
In described steps A, the preparation of Fehling first liquid and Fehling second liquid can be according to GB < < GB/T 8210-2011 outlet fresh orange method of inspection > >, < < GB 8210-1987 outlet fresh orange method of inspection > >, < < GB6194-86 fruit, method described in vegetables soluble sugar determination method > > etc. is carried out.Wherein, alkaline cupric tartrate first liquid, fehling reagent first, Fei Linshi liquid A in the corresponding standard of Fehling first liquid, alkaline cupric tartrate second liquid, fehling reagent second, Fei Linshi liquid B in the corresponding standard of Fehling second liquid.In this step, according to the concentration of testing sample, also can in Fei Linshi solution, add water, Fehling first liquid and second liquid are diluted, with final titration reducing sugar solution used and Fehling solution volume, be quite advisable; When described reducing sugar solution to be measured is rarer, can remove the step that adds water from, directly with reducing sugar solution, carry out titration.
Further improvement as said method, in the Fei Linshi solution of described steps A, add Fehling first liquid and Fehling second liquid cumulative volume 0.3-0.8 water doubly, and add water in the titration process of described step B, obtain Fehling solution, maintain Fehling solution simultaneously and be fluidized state.Compared with prior art, to Fei Linshi solution, add the water ratio of 1～5 times of amount volume, the inventive method amount of water is few, can greatly shorten the time that solution boils.In addition, with glue head dropper, add water midway, on the one hand, can supply the moisture that loses of evaporation, avoid changing because evaporation water loss causes reacting liquid basicity, and then affect reaction end and judge inaccurate problem; On the other hand, reacting liquid temperature be can control, reactant liquor bumping or wall built-up prevented.Described water, preferably distilled water.
In described step B, reducing sugar solution, for demarcating the reducing sugar standard solution of fehling reagent, as glucose standard solution, fructose standard solution, lactose standard solution etc., or is sample solution to be determined.Preparing the method for sample solution can carry out with reference to GB, when in sample, concentration of reduced sugar is too high, and suitable dilute sample; When otherwise concentration of reduced sugar is too low in sample, can reduce timing signal Fehling solution cumulative volume, with the cumulative volume of final titration specimen in use solution and Fehling first liquid and Fehling second liquid, quite be advisable.Before official testing sample, generally first carry out pretest and consume the required sample solution volume of quantitative Fei Linshi solution to grasp, when formal titration, first directly to the sample solution that adds " required sample solution volume-1ml " in Fei Linshi solution, be heated to boil and slowly titration, add indicator, the preferred methylene blue of indicator (indicator also can add when fehling reagent is prepared) simultaneously.When using methylene blue to make indicator, for rarer Fei Linshi solution, solution is reaction end (referring to the mensuration > > of reducing sugar in GB < < GB/T 5009.7-2008 food) by blueness to blue disappearance; When the Fei Linshi solution of dense type formula, titration for reducing sugar in cedra fruits, solution by blueness disappear completely take on a red color bright for reaction end is (referring to " sugar of citrus fruit, acid, Vitamin C assay method " (< < citrus science and technology communication > > 1973.5-6, P43-44)), examine, its color exists by blue, green, yellow, orange, red progressive formation, so terminal is easy to control.
As the further improvement of said method, operating in 3 minutes of described step B completes.Compared with prior art, can shorten boil and seethe with excitement after titration time.Because indicator methylene blue is reduced after variable color, easily by airborne oxygen, be oxidized to original blueness again, so should keep solution to be boiling reaction state in titration process, avoid contacting with air as far as possible, and avoid titration time long.Adopt the method can shorten total titration time, and then improve the precision of test result.
As the further improvement of said method, in described step B, drip the speed of reducing sugar solution first quick and back slow, while closing on reaction end 1ml, rate of titration is no more than 2 drops/sec.Owing to having adopted magnetic agitation well heater, in titration process, controlled stirring rate can more effectively mix reaction, needn't as classic method, need to wait for the longer reaction time, therefore can accelerate rate of titration; On the other hand, due to the quickening of rate of titration, shorten total titration time, reduced the impact of the other factorses such as air on reaction result, can obtain titration results more accurately.Further, preferably rate of titration is 1-2 drop/sec.
As the further improvement of said method, in the titration process of described step B, the rotating speed of magnetic agitation well heater is 200-300 rev/min, and this rotating speed can better meet the mixing requirement of reactant liquor in test process.
As the further improvement of said method, in described glass container, be placed with for stirring the clip of Fehling solution.This clip replaces special rotor stirrer, and main rising mixes reactant liquor, and the effect of fast reaction speed, has avoided hand moving inconvenience, is difficult to the evenly problem of operation; Because be heating, reaction, boiling, titration, shake up etc. carried out simultaneously, also can play the effect of beaded glass, prevent from spilling reactant liquor because of local overheating bumping; Clip is easily got easily and is put, and can be recycled, and has reduced the total cost of experiment.
As the further improvement of said method, described buret is bent-tube boiler acid buret, is more conducive to the titration operation under fluidized state.The conical flask of the preferred 150-250ml of described glass container, the bottle end, should not be too thick, and doleiform is as far as possible consistent.
Another object of the present invention is to provide a kind of titration apparatus of reducing sugar direct titrimetric method, this device has alleviated tester's working strength, weakened the impact on experimental result of environment and operation factors, the test result that unskilled operating personnel obtain also has very high precision, is applicable to applying.The technical scheme of this device is:
The titration apparatus of reducing sugar direct titrimetric method, this device utilizes Fei Linshi direct titrimetric method principle to carry out content of reducing sugar mensuration, comprise the buret of splendid attire reducing sugar solution, the glass container of splendid attire Fehling solution and the heating arrangement that Fehling solution is heated, described buret is bent-tube boiler acid buret, described heating arrangement is magnetic agitation well heater, and in described glass container, is placed with for stirring the clip of Fehling solution.
The present invention also provides a kind of method of utilizing the titration apparatus mensuration reducing sugar of reducing sugar direct titrimetric method, the method utilizes Fei Linshi direct titrimetric method principle to carry out content of reducing sugar mensuration, alleviated tester's working strength, simple to operate and repeated strong, test result precision is high.The technical scheme adopting is: the method for utilizing the titration apparatus mensuration reducing sugar of reducing sugar direct titrimetric method, described titration apparatus comprises the bent-tube boiler acid buret of splendid attire reducing sugar solution, the glass container of splendid attire Fehling solution and magnetic agitation well heater that Fehling solution is heated and mixed, and in described glass container, is placed with for stirring the clip of Fehling solution; Said method comprising the steps of:
A, Fehling first liquid and Fehling second liquid equivalent are added to glass container (conical flask), obtain Fei Linshi solution, and add Fehling first liquid and Fehling second liquid cumulative volume 0.3-0.8 water doubly, obtain Fehling solution;
B, described Fehling solution are heated to boiling on magnetic agitation well heater, keep fluidized state, from bent-tube boiler acid buret, drip reducing sugar solution, and in course of reaction, add water, maintain Fehling solution simultaneously and be fluidized state, titration Fehling solution is to indicator Indicator Reaction terminal; The operation of completing steps B in 3 minutes.
Operation steps described in aforementioned reducing sugar direct titrimetric method, reaction conditions, device parameter etc., be also applicable to the method that this part utilizes the titration apparatus mensuration reducing sugar of reducing sugar direct titrimetric method.
The above reducing sugar direct titrimetric method and device thereof are applicable to the mensuration of reducing sugar in numerous food, comprise the mensuration of soluble sugar, the reducing sugar in various food, the total reducing sugar in frozen, the lactose in dairy products and sucrose etc. in fruit, vegetables.As of the present invention preferred, described reducing sugar direct titrimetric method and device thereof are particluarly suitable for detection and the application of reducing sugar in the fruit such as citrus.
Useful technique effect of the present invention is:
Reducing sugar direct titrimetric method provided by the invention and titration apparatus thereof, adopted the device such as untapped magnetic agitation well heater, clip, bent-tube boiler acid buret in prior art, and add the factors such as water volume, stirring rate, heat time, rate of titration by changing in titration process, repeatability and the operability of test strengthen greatly, improved the precision of test result, the impact of tested person person's skilled operation degree is little, greatly alleviated tester's working strength, equipment investment cost is low, is applicable to being applied to the test of reducing sugar in numerous food.Concrete advantage also has: (1) has improved the parallel effect of titration numerical value, and general titration just can reach suitable accuracy requirement twice; (2) after method improvement, easy and simple to handle, controllability is strong, and terminal is easy to judgement, saving of work and time, and titration number of times reduces, and tests titration time at every turn and also shorten, and work efficiency improves greatly, is particularly useful for the more situation of sample size to be checked; (3) use reagent few (being beneficial to the screening agent of terminal point determining etc. as need not be added), supplementary material cheapness is easily got, and saves consumables cost.
Accompanying drawing explanation
Fig. 1 is the structural representation of the titration apparatus main composition part of reducing sugar direct titrimetric method of the present invention.
Embodiment
Hereinafter with reference to accompanying drawing, by embodiment and reference examples, describe the present invention, embodiment is the present invention, reference examples called after classic method, with reference to the " sugar of citrus fruit, acid, Vitamin C assay method " (< < citrus science and technology communication > > 1973.5-6, P43-44), in < < GB 8210-1987 outlet fresh orange method of inspection > > and < < GB/T 5009.7-2008 food, the mensuration > > of reducing sugar carries out.Not marked condition in embodiment, still carries out according to above-mentioned standard and method.
Preparatory work of experiment:
(1) preparation of reagent and sample
A, Fehling first liquid (fehling reagent A): analytical pure sulfuric acid copper (CuSO
45H
2o) 34.69g is soluble in water, is settled to 500ml, filters standby.
It is soluble in water that B, Fehling second liquid (fehling reagent B): 50g analyze pure cerium hydroxide sodium, adds and analyze pure sodium potassium tartrate tetrahydrate 173g, is settled to 500ml.
C, methylene blue indicator: 1g methylene blue is dissolved in 100ml water.
D, glucose standard solution: pure anhydrous dextrose is dried to constant weight in 105 ℃, accurately take 0.5g left and right, and water dissolves and is settled to 100ml.
E, reducing sugar sample solution: fruit crosscut, the filtration of squeezing the juice, draws Normal juice 10ml in 100ml volumetric flask, is settled to scale.
F, invert sugar sample solution: fruit crosscut, the filtration of squeezing the juice, draws Normal juice 10ml in 100ml volumetric flask, and adding distil water, to 50ml, adds concentrated hydrochloric acid 3ml and shakes up.Volumetric flask is placed in to water bath with thermostatic control to be transformed, make conversion fluid temperature reach 80 ℃ at 2-2.5 minute, and keep after 10 minutes at 80 ± 2 ℃, taking-up is put in circulating water and is cooled to rapidly 20 ℃, with 1～2 of phenolphthalein indicator, with 40% and 10% sodium hydroxide solution neutralization, as excessive neutral with 1:3 hydrochloric acid furnishing again, add water and be settled to scale.
(2) titration apparatus
Titration apparatus one: magnetic agitation well heater (German Heidolph magnetic stirring apparatus MR3001, major parameter: Ac 230/240v 50/60Hz 625w, temperature adjustment speed adjustable range: 0～350 ℃, 100～1250rpm), bent-tube boiler acid buret, clip, conical flask (200ml);
Titration apparatus two: adjustable electric furnace (band sheet asbestos), common acid buret, conical flask (250ml), beaded glass.
Embodiment the inventive method
Get above-mentioned solution and titration apparatus one, respectively the sample solution of summer orange, Pon mandarin orange and sweet orange is tested in the steps below, and test result is added up.As shown in Figure 1, wherein, 1 is magnetic agitation well heater to the structural representation of described titration apparatus main composition part, and 2 is bent-tube boiler acid buret, and 3 is clip, and 4 is conical flask.
The demarcation of A, fehling reagent mixed liquor
Draw 5.0ml fehling reagent A and 5.0ml fehling reagent B(and also fehling reagent A and fehling reagent B equivalent can be mixed to rear absorption 10.0ml) in 200ml conical flask, adding distil water 3～8ml, add 1 clip, from bent-tube boiler acid buret, drip about 9ml glucose standard solution.On magnetic agitation well heater, heat, be controlled in 2 minutes and be heated to boil, the rotating speed of magnetic agitation well heater is transferred to 200-300 rev/min, add 1～2 methylene blue indicator, with the speed of 1～2 drop/sec, continue to drip glucose standard solution again, in boiling reaction liquid, with a little glue head dropper, along wall, add appropriate distilled water simultaneously, prevent reactant liquor bumping or wall built-up, and maintain reactant liquor and be fluidized state, until solution blueness disappears completely and takes on a red color brightly for terminal, record the cumulative volume (T) of consumption of glucose standard solution.Parallel experiment more than twice, is got its mean value for the calculating of follow-up reducing sugar or invert sugar content.
The prediction of B, sample solution
Draw 5.0ml fehling reagent A and 5.0ml fehling reagent B, be placed in 200ml conical flask, adding distil water (addition refers to table 1-4), adds 1 clip.On magnetic agitation well heater, heat, be controlled in 2 minutes and be heated to boil, the rotating speed of magnetic agitation well heater is transferred to 200-300 rev/min, add 1～2 methylene blue indicator, with speed first quick and back slow, from bent-tube boiler acid buret, drip sample solution, and keep fluidized state, when solution blueness dies down, with the speed of 1-2 drop/sec, drip, in boiling reaction liquid, with a little glue head dropper, along wall, add appropriate distilled water simultaneously, prevent reactant liquor bumping or wall built-up, and maintain reactant liquor and be fluidized state, until solution blueness disappear completely take on a red color bright for terminal, record consumes the cumulative volume of sample solution.
C, sample solution are measured
Draw 5.0ml fehling reagent A and 5.0ml fehling reagent B, be placed in 200ml conical flask, adding distil water (addition refers to table 1-4), adds 1 clip, from bent-tube boiler acid buret, drips than the sample solution of the few 1ml of prediction volume.On magnetic agitation well heater, heat, be controlled in 2 minutes and be heated to boil, the rotating speed of magnetic agitation well heater is transferred to 200-300 rev/min, add 1～2 methylene blue indicator, then drip with the speed of 1-2 drop/sec, in boiling reaction liquid, with a little glue head dropper, along wall, add appropriate distilled water simultaneously, prevent reactant liquor bumping or wall built-up, and maintain reactant liquor and be fluidized state, until solution blueness disappears completely, to take on a red color bright be terminal, record consumes the cumulative volume (D) of sample solution.Parallel experiment more than twice, is calculated as follows respectively the content of reducing sugar or invert sugar: (demarcate with measure Fei Linshi solution phase used together and consumption equates)
In formula, G: glucose weigh (be about 0.5g);
T: the amount (ml) consuming during the titration of glucose standard solution;
W: glucose constant volume (100ml);
D: the amount consuming during sample solution titration (ml).
Test and statistics are in Table 1-table 4.
In table 1 summer orange, the detection of invert sugar and result are calculated (inventive method)
Note:
*during the preparation of glucose standard solution, the weight that takes glucose is 0.5460g;
In table 2 Pon mandarin orange, the detection of invert sugar and result are calculated (inventive method)
Note:
*during the preparation of glucose standard solution, the weight that takes glucose is 0.5286g; Other are the same.
In table 3 sweet orange, the detection of invert sugar and result are calculated (inventive method)
Note:
*during the preparation of glucose standard solution, the weight that takes glucose is 0.5103g; Other are the same.
In table 4 sweet orange, the detection of reducing sugar and result are calculated (inventive method)
Note:
*during the preparation of glucose standard solution, the weight that takes glucose is 0.5103g; Other are the same.
Reference examples classic method
Get above-mentioned solution and titration apparatus two, in the steps below the sample solution of tangerine orange is tested, and test result is added up.
The demarcation of A, fehling reagent mixed liquor
A. prepare titration: draw 5.0ml fehling reagent A and 5.0ml fehling reagent B(and also can will after fehling reagent A and fehling reagent B mixed in equal amounts, draw 10.0ml), be placed in conical flask, adding distil water (addition refers to table 5), drips part glucose standard solution in conical flask (A, B mixed liquor) from common acid buret in advance.On electric furnace, heat, make it in the boiling of 2min left and right, after boiling 1min, add 2 methylene blue indicator, again every 0.5min, the speed continuing under boiling with 4～5 per second drips glucose standard solution, until solution blueness disappears completely and presents brick-redly for terminal, from boiling to titration end-point, be no more than 3min.
B. formal titration: draw fehling reagent A, B liquid and distilled water in conical flask by preparation titration, upper heating by electric cooker, adds the glucose standard solution that approaches titer simultaneously in mixed liquor, makes the amount dripping after seething with excitement at 0.5～1ml, operates thereafter the same.Record the cumulative volume of consumption of glucose standard solution.With method with people parallel two to three times, get its mean value for the calculating of follow-up reducing sugar or invert sugar content.
The mensuration of B, sample solution
A. prepare titration: with the preparation titration of demarcating above.
B. formal titration: with the formal titration of demarcating above, parallel testing two to three times, the calculating formula of pressing respectively embodiment step C is calculated the amount of reducing sugar or invert sugar.
Test and statistics are in Table 5.
In table 5 tangerine orange, the detection of invert sugar and result are calculated (classic method)
Note: the mark after Fehling solution, represents that different glucose weighs:
When 1. glucose standard solution is prepared, the weight that takes glucose is 0.4938g;
When 2. glucose standard solution is prepared, the weight that takes glucose is 0.4887g;
When 3. glucose standard solution is prepared, the weight that takes glucose is 0.5011g.
During test, if titration twice, add up relative differences; If titration three times, add up relative average debiation.
The statistics of comparative example and reference examples is known:
(1) adopt the inventive method to carry out twice titration to same sample, the difference of the volume of vs that twice titration consumes is all in 0.1ml, and relative differences is all in 1%.Yet, adopt classic method to carry out titration to same sample, the difference maximum that consumes the volume of vs reaches 0.65ml(as table 5-sample 8), carried out the volume relative differences of vs that sample consumes of twice titration all more than 2%, the volume relative average debiation that has carried out the vs that sample consumes of three titration is all greater than 1.5%; Calculate the invert sugar of gained or the value of reducing sugar, the relative differences of the sugared content of same sample (or mean deviation) is greater than 1.5%, and mostly more than 2%, and sugared content results value relative differences of the present invention is all in 1%.Visible, the inventive method is compared with classic method, and degree of accuracy is significantly increased.
(2) from starting to be heated to titration, complete, the time of the each titration of the inventive method, classic method needed 3～5 minutes all in 3 minutes, and heating and titration are total consuming timely shortens closely half than classic method; And because the inventive method can obtain by twice titration the titration numerical value that degree of precision requires, reduced testing time, greatly improved work efficiency.
(3) in the inventive method, adopt the water supplementing method that adds in advance limit heating edge dropping distilled water in appropriate distilled water and course of reaction, two objects have been reached: one, make to treat that the reactant liquor volume total amount of test sample and standard sample is as far as possible suitable, improved the accuracy of test; Its two, in heating process, mend and splash into bumping and the wall built-up that water has been avoided reactant liquor, be more conducive to the judgement of terminal, thereby also reduced error.
To sum up, the inventive method can obtain by less test the measured value that degree of accuracy is higher, and the relative differences of titration value or relative average debiation are all much smaller than classic method; The relative differences of invert sugar or content of reducing sugar or relative average debiation are compared to classic method and have dwindled more than 60%, and data reappearance is strong, parallel effective.
The present invention's (method) has more than the mensuration that is limited to reducing sugar, is also applicable to the sugar of other kind as the detection of sucrose, and just other carbohydrate thing need carry out sample pre-treatments, through corresponding condition, changes into titratable reducing sugar.So the mensuration of the invert sugar of mentioning in literary composition is the mensuration of reducing sugar namely.
Finally explanation is, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can modify or be equal to replacement technical scheme of the present invention, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.
Claims (9)
1. reducing sugar direct titrimetric method, comprises the following steps:
A, Fehling first liquid and Fehling second liquid equivalent are added to glass container, obtain Fei Linshi solution; Add Fei Linshi liquor capacity 0.3-0.8 water doubly, obtain Fehling solution;
B, described Fehling solution are heated to boiling on heating arrangement, keep fluidized state, drip reducing sugar solution from buret, and titration Fehling solution is to indicator Indicator Reaction terminal;
It is characterized in that: described heating arrangement is magnetic agitation well heater.
2. reducing sugar direct titrimetric method according to claim 1, it is characterized in that: in the Fei Linshi solution of described steps A, add Fehling first liquid and Fehling second liquid cumulative volume 0.3-0.8 water doubly, obtain Fehling solution, and add water in the titration process of described step B, maintain Fehling solution simultaneously and be fluidized state.
3. reducing sugar direct titrimetric method according to claim 1, is characterized in that: operating in 3 minutes of described step B completes.
4. reducing sugar direct titrimetric method according to claim 1, is characterized in that: in described step B, drip the speed of reducing sugar solution first quick and back slow, while closing on reaction end 1ml, rate of titration is no more than 2 drops/sec.
5. reducing sugar direct titrimetric method according to claim 1, is characterized in that: in the titration process of described step B, the rotating speed of magnetic agitation well heater is 200-300 rev/min.
6. reducing sugar direct titrimetric method according to claim 1, is characterized in that: in described glass container, be placed with for stirring the clip of Fehling solution; Described buret is bent-tube boiler acid buret.
7. the titration apparatus of reducing sugar direct titrimetric method, this device utilizes Fei Linshi direct titrimetric method principle to carry out content of reducing sugar mensuration, comprise the buret of splendid attire reducing sugar solution, the glass container of splendid attire Fehling solution and the heating arrangement that Fehling solution is heated, it is characterized in that: described buret is bent-tube boiler acid buret (2), described heating arrangement is magnetic agitation well heater (1), and in described glass container, is placed with the clip (3) for stirring Fehling solution.
8. utilize the method for the titration apparatus mensuration reducing sugar of reducing sugar direct titrimetric method, it is characterized in that: described titration apparatus comprises the bent-tube boiler acid buret (2) of splendid attire reducing sugar solution, the glass container of splendid attire Fehling solution and magnetic agitation well heater (1) that Fehling solution is heated and mixed, and in described glass container, is placed with the clip (3) for stirring Fehling solution; Said method comprising the steps of:
A, Fehling first liquid and Fehling second liquid equivalent are added to glass container, obtain Fei Linshi solution, and add Fehling first liquid and Fehling second liquid cumulative volume 0.3-0.8 water doubly, obtain Fehling solution;
B, described Fehling solution are heated to boiling on magnetic agitation well heater (1), keep fluidized state, from bent-tube boiler acid buret (2), drip reducing sugar solution, and in course of reaction, add water, maintain Fehling solution simultaneously and be fluidized state, titration Fehling solution is to indicator Indicator Reaction terminal; The operation of completing steps B in 3 minutes.
9. the application of the reducing sugar in measuring citrus of the reducing sugar direct titrimetric method described in claim 1 to 6 any one.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105572114A (en) * | 2015-11-19 | 2016-05-11 | 英格尔检测技术服务（上海）有限公司 | Method for determining reducing sugar in food |
| 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 |
| CN113504336A (en) * | 2021-06-30 | 2021-10-15 | 青岛市食品药品检验研究院（青岛市药品不良反应监测中心、青岛市实验动物和动物实验中心） | Reducing sugar titration device and method |
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Cited By (5)
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| CN105572114A (en) * | 2015-11-19 | 2016-05-11 | 英格尔检测技术服务（上海）有限公司 | Method for determining reducing sugar in food |
| 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 |
| CN113504336A (en) * | 2021-06-30 | 2021-10-15 | 青岛市食品药品检验研究院（青岛市药品不良反应监测中心、青岛市实验动物和动物实验中心） | Reducing sugar titration device and method |
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