how to test the molecular weitht of cationic polyacrylamide? - CHINAFLOC
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how to test the molecular weitht of cationic polyacrylamide?
2019-02-22 10:33:22

how to test the molecular weitht of cationic polyacrylamide?

Cationic Polyacrylamide

Coution:The strong acid and strong base and organic solvent which using in this standard have corrosivity and poisonousness, When using, should avoid inhalation or touch with skin.Splashed on should rinse immediately with plenty of water, when serious should  go to a doctor immediately.


This standard stipulates the cationic polyacrylamide (abbreviations: CPAM) technical requirements, test methods, inspection rule, marks, packaging, transport and storage. 

This standard applies to cationic polyacrylamide。        

2  Normative reference files

The following documents for the application of this document is indispensable,Every document which note date reference ,only the version which note the date of apply to this document.Anyone which doesn't note date , the latest version (including all the modified single) apply to this document.GB/T 191-2008 packaging graphic symbol

GB/T 601-2002 Chemical reagent The preparation of standard titration solution

GB/T 603-2002 Chemical reagent the preparation of pharmaceutics in test methodGB/T 4946-2008  stipulation规定External notation外标法

GB/T 6003.1-1997  test sieve weave by wire

GB/T 6678-2003 sampling conditions of Chemical products

GB/T 6682-2008 water standards of analysis laboratory


3  Product      C  XXXX

model                        Types, and the molecular weight, ionic range


4  Technical requirements

4.1 appearance:White or light yellow powder

4.2  technical requirements


Chart 1 technical requirements





Solid content


Cation degree




Monomer (w/%)

Dissolution time


































































5  Test method

5.1  The testing of Appearance

Visual observation under natural light products with a white or light yellow powder.

5.2  The testing of Molecular weight


·                               Ubbelohde viscometer(Fisher  13-614 type);thermostatic waterbath(temperature control accuracy±0.1℃);stopwatchs(resolation 0.1s);precision electronic balance(sentitive 0.0001g);volumetric flask(100ml);pipette(50ml);beaker(150ml);Glass funnel sand core(G2type);graduated flask(50ml);Syringe; Latex tube; Wash ears ball, etc.; Magnetic stirrer.

5.2.2  reagent

1mol /L NaCl aqueous solution;

2mol /L NaCl aqueous solution;

Refer to GB601 preparation of standard solution used in hemical reagent titration analysis (volumetric analysis)

5.2.3  The preparation of the sample solution  According to 2.2  To measure the solid content of the sample firstly.  Measuring polymer samples 0.02~0.03g  Measuring 45 ml of distilled water in the middle of 150 ml beaker,Adjust the speed of agitator to form vortex of about 1 cm.  Pour the samples into the vortex,Stir for 1h till sample completely dissolved, then add 2 mol/L 2mol /L NaCl aqueous solution 50 ml, continue to stir for 30 minutes.  transfer solution into 100 ml volumetric flask and flush the beaker, solution constant volume to 100 ml scale.

5.2.4   Testing procedure  pour the solution which filter by glass sand core funnel into the Ubbelohde viscometer,put the solution Put the solution at 30 ℃in the constant temperature water bath for 10 minites. The flow time of the solution between viscosity meter calibration ,accurate to 0.1s.  Repeat test twice, test results are not more than 0.2 s, take the average  According to the above methods do blank test at the same time.

Note: all solution must be used with same viscosity meter and the same stopwatch test, measurement of sequence from low concentration to high concentration , and before each measurement, viscosity meter must be used for washing test solution 2-3 times.

5.2.5  Calculation of Molecular Weight.  To calculate the solution of Characteristic coefficient of viscosityηSP

ηSP =

   In  formula:T —The flow time of the solution between viscosity meter calibration s;

               T0 —The flow time of the blank samples between viscosity meter calibration s;

               C —The concentration of the sample solution,That is, 100 grams of polyacrylamide in g sample solution g。

               S —solid content of samples  Molecular weight calculation formula

 M =(ηSP/0.000373)1.515

     In  formula:M —molecular weight;

               0.000373 — empirical constant

 1.515 — empirical constant ;  Parallel test twice, the error must not exceed 0.5 s

5.3 Determination of solid content

5.3.1Instrument and equipment

Constant temperature oven (120 + 2 ℃), analytical balance (Precision:0.0001 g),Dryer (built-in silica gel),weighing bottle.

5.3.2Weigh washed and dried weighing bottle (accurate to 0.0001g).

5.3.3 Add about 1g sample into weighing bottle(accurate to 0.0001g).

5.3.4In constant temperature oven drying samples for 2 hours to constant weight.

5.3.5Take the weighing bottle from the oven, and put it in the dryer which containing silica gel , cooling for 30 min, re-weighing (accurate to 0.0001 g).

5.3.6  Count


式中:w1 — weight of weighing bottle (g);

w2 — weight of samples and weighing bottle (g)

w3—weight of samples and weighing bottle after drying


5.3.7 Parallel determination of two samples, the diviation should not exceed 0.5%.


5.4 Determination of the degree of cation

5.4.1The principle of the method (colloidal titration)

    Colloidal titration:Under appropriate conditions,Polyelectrolyte can be fully ionized into charged poly ions and counter ions with small charge, and combining with polyion of positive and negative (i.e. polycation and polyanion) is in stoichiometric. After  polyanion neutralization,when points and tTraces of excess combine with indicator(toluidine blue) (T.B), The solution changed from blue to purple, indicating the endpoint


5.4.2 Analysis determination

Toluidine blue (T.B) as indicator, Poly-2-acrylamido-2-methylpropanesulfonic acid, potassium (PAMPSK)  as standard polyanion reagent titration cation test sample, after the equivalence point, then microscale residue combines with T.B, solution changed from blue to purple, indicates the end.


5.4.3Reagents and Instruments Reagents: Standard polyanion (PAMPSK),indicator: T.B (0.1%),benchmark reagents: cetylpyridinium bromide (CPB),cationic tested powder,double-distilled water. Instruments

Analytical balance (sense of volume 0.0001g),PH meter; 50ml burette,100ml graduated cylinder,250ml conical flask,5ml,10ml transferpipette,etc.


5.4.4Standard polyanion reagent(PAMPSK)preparation and calibration Preparation

Weigh accurately standard polyanion agent PAMPSK0.250-0.350g in a clean beaker, add about 500ml of double distilled water, stirred and dissolved at room temperature and transferred to 1000ml volumetric flask, dilute and set volumewith double distilled water. Calibration:

    Use weighing paper weigh crystallized purified cetylpyridinium bromide (CPB), m = 0.02-0.04g (accurate to 0.0001g) in 100ml volumetric flask, heated to dissolved with double-distilled water in a water bath, set the volume.


    Use transfer pipette transfers 10ml CPB solution in 250ml conical Erlenmeyer flask, add 60ml distilled water, T.B4 5 drops, use standard polyanion PAMPSK titrate, the solution changed from blue to purple, indicates the end.


Do at least three sets of parallel test, take the average of PAMPSK consumption volume as V, doing blank comparision at the same time, consumption PAMPSK volume as V0.


PAMPSK concentration is calculated as follows:



In formular:m - CPB weight g;

M - CPB (including crystal water) molecular weight: 402.46;

V - Titration CPB, PAMPSK consumption volume ml;

V0- Consumed PAMPSK blank titration volume ml. Determination steps

    Weigh accurately by weighing paper with cation powder tested samples m0= 0.3g (accurate to 0.0001g) (depending on molecular weight) in 500ml volumetric flask, use deoxy double distilled water, dissolve in a constant temperature water flume (20 ℃),constantly shake to dissolve completely,different point sampling10ml solution in 250ml conical flask(volume of the sample is based on pre-transfer and set by testing), add deoxy double distilled water 60ml, adjust the PH value of 3-5 with HCl, add T.B4 5 drops, shaking and determination by standard polyanion PAMPSK,then blue changed to purple, indicates the end.Do at least three sets parallel test,take the average of PAMPSK consumption volume as V, doing blank comparision at the same time, consumption PAMPSK volume as V0. Cation calculation:

In formula:

  193.67 -The molecular weight of cationic monomer (DAC),

  C-Standard mol concentration of polyanion PAMPSK mol/l,

  V-Titration consumption PAMPSK volume ml;

  V0-Blank consumption PAMPSK volume ml;

  m–Sample weight g;

  S-Solids content of the sample. actually cationic degree of the cationic powder is average value of Triplicate samples calculated


5.5 The determination of water insoluble substance


5.5.1. Equipment and reagents


500ml beaker, magnetic stirrer, drying oven, analytical balance (0.001 g of), the filter funnel (4cm in diameter, built in 200μm (80 mesh) stainless steel mirror), dryer, acylindrical container 250ml, timer, deionized water.


5.5.2.Preparation of solution In room temperature, put 200ml water into the 500ml beaker. Add powder 1g when agitator is stiring (large rotor with diameter of about 5cm), speed 500r / min, stirred for two hours,weak cationic for 4 hours. The dissolved sample is poured into the filter funnel and drainage. After filtration funnel completely drained, use the flowing cold tap water, gently rinse the filter funnel (avoid using high-pressure water), rinse the funnel until no polymer ,depends on smoothness of the filte.


5.5.3. Evaluation Put the filter screen and the appended gel into the weighing dish, and bake at 120 ℃oven for 2 hours. Remove the dish from the oven and put it into the dryer to cool, weigh, record the weight (filter plus insoluble plus weighing dish). Wash filter screen with distilled water, bake at 120 ℃oven for 2 hours. remove the weighing dish and filter screen from the oven, cool in a desiccator, weigh, record the weight of the filter screen and weighing dish. Percentage of insolubles is calculated as follows:


Insolubles% = 100 [(filter plus insoluble plus weighing dish) Weight - (filter plus weighing dish) Weight]

5.6 Residual Monomer determination---- liquid chromatograph

5.6.1The principle of the method

    With the specified volume and concentration of acetone aqueous solution leaching of polyacrylamide samples to the leaching equilibrium. Using cation exchange resin as the stationary phase of chromatographic column, the liquid chromatography was used to separate the liquid from the liquid. The determination of the content of residual acrylamide by UV detector was used.


    In addition to other reagents, all reagents are analytically pure.(AR)  Acetone Mobile phase of liquid chromatography: Deionized water was treated by mixed bed  by cation-anion exchange resin.  Methanol

5.6.3(Equipment) Liquid chromatography constant-flux pump

     Requirement of constant-flux pump as following:

a)     Flow range:0.01 ml/min ~5 ml/min ;

b)     working pressure:2.5×107Pa ;

c)     pressure fluctuation:±1% ;

d)     Flow stability:±1% between 0.15-5 ml/min UV detector

     Requirement of UV detector as following:

a)      wave Length:190 nm ~700 nm ;

b)      Wavelength accuracy:±2 nm ;   six-way valve

    There are quantitative sampling tube, the volume is about 0.02ml.  chromatographic column    Column type: packed column  The characteristic requirements of the column are as follows:

a)  Material: titanium steel pipe

b)   Length : 250 mm

c)  internal diameter:4.6 mm

d)  Shape: straight  Stationary phase: Eighteen alkyl silane bonded silica gel Analytical balance. Accurate to 0.0001g  Others

      Laboratory conventional glass instruments

5.6.4 Preparation of samplesSolution 3g powder polyacrylamide sample accurate to 0.0001g, put them in a dry 50ml conical flask. Used to extract 10ml of volume ratio of soaked samples, 8:2 acetone solution ,shake gently, make it. After soaking for 6 h, interrupted 3 ~ 4 times, for 24 h to be determined (or ultrasonic ultrasonic instrument for 1 hours).

5.6.5operation step adjust instrument The temperature of chromatographic column:normal temperature speed of mobile phase:0.8 ml/min 。 Wavelenth of UV-detector210 nm 。 Setting up reasonable collection of software parameters according to actual situation calibration external standard method(ESTD)

According to stipulation of GB/T 4946-2008 The preparation of sample of acrylamide standard

    The samples of  Non-mark with color need to be secondary recrystallization by benzene The preparetion of standard solution of sample Pouring 0.1000g±0.0001g acrylamide into 10ml beaker,dissoving it by deionized water,Quantitative transfer into 100 ml volumetric flask and diluted with deionized water to the scale, it is 1 ml/mg acrylamide solution. Transfering above 5ml acrylamide solution into 50ml volumetric flask,diluted with deionized water to the scale, it is 0.1 ml/mg acrylamide solution. Pouring acrylamide 0.1ml、0.5ml、1.0ml、2.0ml、3.0ml into the volumetric flask,and diluted with deionized water to the scale.The solution are  0.001 mg/ml, 0.005 mg/ml, 0.01 mg/ml, 0.02 mg/ml, 0.03 mg/ml of acrylamide standard sample solution 0.1mg/ml Injection Inject samples solution into chromatographic column by Six-way valve,Get the chromatogram,Calculating the peak area. To abtain  external standard calibration curves by using hapmap of standart smples, AM concentration in the sample solution is obtained by check calibration curve

5.6.6result presentations  Residual acrylamide (AM) show with mass fraction (W),numeric expressed in (%),According to the type (5) to computing

W(AM)= ……………………………………………… (5)

In above formula:

C—The numeric of actual concentration which abtain by external standard method.unit (mg/ml)

V— The volume of extractant ,unit :ml;

a—dilution ratio ;

m—The weight value unit :(g);

n—mass fraction of solid content.(%); Determination of the average of the results after delete two results,Results need to be revised to 3 decimal places.A single specimen measurements and arithmetic mean relative deviation is less than 5%, otherwise should resume sampling measurement.


5.7 The determination of dissolution time
5.7.1methods outline
With the continuous dissolution of sample, the conductance of the solution.All dissolved, conductivity keeps stable.A certain amount of samples dissolved in a certain water, the time required by conductance value reaches stable , is the dissolution time of sample.
5.7.2instruments and equipment conductivity meter: measuring range 0.01 mu mu s ~ 106 s, with a recorder, range of 4 mv. thermostat : temperature can be controlled 30 ℃ + / - 1 ℃. electromagnetic stirrer: with heating and temperature control device, and equipped with a length of 3 cm stirring.
5.7.3 analysis steps
Put the breaker ,which is filled with 100 ml water and stirring the 200 ml beaker in the thermostatic bath .insert the electrode conductivity meter into a beaker. The distance of conductivity meter and burning glass from 5 mm to 10 mm, with mixing distance is about 5 mm.To start the electromagnetic stirring, regulate the surface vortex depth about 20 mm.Open the heating device, make the thermostatic bath temperature 30 ℃ to + / - 1 ℃, temperature keep around 10 min ~ 15 min.Adjust the recording paper linear velocity, select the conductivity meter range.
Take 0.040 g + / - 0.002 g sample by vortex upper join into the beaker.
When the conductance of the recorder indicating no change within 3 minutes, stop the test.
5.7.4 analysis results
The time from adding sample to keep the conductivity  stable is the dissolving time..
The dissolution time of paper length conversion by the recorder expressed by min .
5.7.5 permissible error
Take the arithmetic mean as the determination results of parallel determination results.The absolute difference between the parallel determination results is not more than 5 min.

6 inspection rules
6.1 Sampling requirements: use sampler to each batch (not more than 30 t) 10% of the sack by Mi-zi type  to determine the sampling point (not less than 10 points) insertion depth of different sampling, sampling of not less than 20 g for each bag, after fully mixed, with four points method is divided into two copies, a reserved for inspection, a sealed for arbitration.
6.2 inspection should according to the appearance and the item requirement for full analysis in table 1, if there is an indicator does not meet the requirements, should be double sampling for the re-inspection.After the re-inspection if an indicator is not qualified,it is judged to be unqualified products.

7 approval method
7.1user sampling by sampling method, according to the provisions of this standard test method for inspection, if I found some indicators do not meet this standard, we should take the original sample and recheck it , in order to make sure the result is reliable.The re-inspection result does not meet this standard, is the unqualified products.If supplier and buyer both sides disputed, send arbitration unit test, the arbitration results shall prevail.
7.2 if users have any questions ,they should give feedback to the factory within 20 days after receiving the goods.


    8 marks, packaging, transport and storage
    8.1 marks
    Each one must have a clear and strong mark on the package, and indicate the following contents:
    a) the product name                   b) registered trademark
    c) standards No.                      d) net content
    e) producer name                     f) address
    g) Certificate of Approval (batch number, date and inspector)
    8.2  packaging
   Packing in the composite paper bag lined with plastic bag or paper barrel, has moisture-proof ICONS, each bag or a barrel has the net weight of 25 kg + / - 0.1 kg, every batch of products integrated error is more than zero or equal to zero.Each bag or barrel must be attached to the inspection certificate, every batch of goods must be attached to product inspection report.
    8.3 transportation and storage
During the transportation ,the product should be moisture-proof, dust-proof, avoid pollution and damage.Products according to the batch number should be stored in a clean, cool, dry warehouse, lining underneath a tray, stacking layer should not exceed 20 floors.