FEBRUARY 99
RESIDUAL MONOMERS
410.1-99 RECOMMENDED TEST METHOD:
Superabsorbent materials- Polyacrylate superabsorbent powders -
DETERMINATION OF THE AMOUNT OF RESIDUAL MONOMERS
1 SCOPE
The method determines the sum of residual monomeric sodium acrylate and acrylic acid prent in pol
yacrylate (PA) superabsorbent powders as acrylic acid.
2 NORMATIVE REFERENCES
ISO 3696 Water for analytical laboratory u - Specification and test methods.
ISO 187 Paper, Board and pulps - Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples.
ISO 5725 Precision of test methods - Determination of repeatability and reproducibility for a standard test method by interlaboratory tests.
3DEFINITION
Amount of residual monomers is the sum of residual monomeric sodium acrylate and acrylic acid.
4 PRINCIPLE
Residual acrylic acid is extracted from the PA superabsorbent powders and amount of residual acrylic acid is determined by HPLC.
5 REAGENTS AND MATERIALS
All materials are analytical grade unless otherwi stated.
5.1 Ultrapure water (grade 1 according to ISO 3696).
5.2 Saline solution 0,9 %.
Preparation of saline solution:
(9 ± 0,1) g NaCl (analytical grade) is added to deionized water (grade 3, ISO 3696) to
give a total mass of (1000 ± 1) g and stirred until dissolved.
5.3 Phosphoric acid solution at 0,5 cm³.L-1 (0,0087 Mol.L-1). Dilute to volume from 85%
H3PO4 (HPLC grade or better).
5.4 Acetonitrile (HPLC grade or better).
5.5 Acrylic acid of >99,5% purity (e 12.5).
410.1-99FEBRUARY 99
6APPARATUS主卧装修效果图
6.1 Analytical balance capable of determining mass to an accuracy of 0,0001 g.
6.2 Analytical balance capable of determining mass to an accuracy of 0,001 g.
6.3 100 cm³ volumetric flasks (Grade A).
6.4 200 cm³ measuring cylinder, accurate to ±0,5%.
6.5 1, 2, 3, 4 and 10 cm³ volumetric pipettes (Grade A).
6.6 250 cm³ glass beakers or 250 cm³ Erlenmeyer flasks.
代赭石的功效与作用6.7 Magnetic followers (stirrer bars).
6.8 Magnetic stirrer to deliver 500 ± 50 rpm.
6.9 0,45 µm filters.
6.10 HPLC injection system to deliver 20-100 µl (± 1%) of analyte solution.
6.11 HPLC pump to deliver at the theoretical backpressure ±10%.
6.12 C18,5 µm particle size, 250 x 4,6 mm column with guard column.
6.13 HPLC UV detector able to measure at 210 nm.
7SAMPLING AND SAMPLES
Safety Caution: U respiratory protection, dust mask or fume hood, when handling sample amounts greater than 10 g.
In order to guarantee that a reprentative sample is taken from the bulk material, the top layer (approximately 20 cm) in a big bag or a silo truck is removed. The sample is taken with a scoop and filled into an airtight container within 3 minutes. The size of the container should be adequate for the size of the sample.
Laboratory samples must be kept in a clod container and allowed to equilibrate to the laboratory temperature before removing a test portion to run the test. The preferred test conditions are 23 ± 2°C
and 50 ± 10 % relative humidity. If the are not available, test at ambient conditions and report the temperature and relative humidity. The procedure for measurement of the laboratory conditions is specified in ISO 187.
The container is shaken 3-5 times in order to obtain a homogeneous product. Leave container at rest for 5 minutes before opening the lid and removing the sample portion.
All samples should be substantially free of lumps of size greater than 1 mm in diameter before proceeding with testing.
FEBRUARY 99410.1-99 8 PROCEDURE
8.1 Preparation of standard solutions for calibration
建筑风水学8.1.1Label 6 x 100 cm³ volumetric flasks S1 to S6.
8.1.2Weigh (0,1000 ± 0,0005) g acrylic acid (>99.5 % purity), and transfer to the
volumetric flask labelled S1. Make to the 100 cm³ mark using ultrapure water.
(S1⇑1000 mg.L-1). Prepare the following dilutions :
From S1: 10 cm³ to 100 cm³. (Flask S2⇑ 100 mg.L-1)
From S2: 1cm³ to 100 cm³. (Flask S3⇑ 1 mg.L-1)哪些蔬菜可以生吃
From S2: 2cm³ to 100 cm³. (Flask S4⇑ 2 mg.L-1)
From S2: 3cm³ to 100 cm³. (Flask S5⇑ 3 mg.L-1)
From S2: 4cm³ to 100 cm³. (Flask S6⇑ 4 mg.L-1)
8.2 Sample preparation
8.2.1Weigh (1,000 ± 0,005) g PA superabsorbent powders into a clean weighing boat and
record the weight (W).
8.2.2 Add this to the clean beaker or Erlenmeyer flask, ensuring that all of the sample is
transferred.
8.2.3 Measure 200 cm³ of 0,9% saline solution in the measuring cylinder and add it to the
beaker or flask.
8.2.4 Add a magnetic stirrer bar, al the beaker with Parafilm or stopper the flask.
8.2.5 Stir at (500 ± 50) rpm for 60 minutes.
8.2.6 After 60 minutes stop stirring.班级小游戏
8.2.7 Allow the polymer to ttle for 5 minutes.
8.2.8 Filter the supernatant through a 0,45 µm filter for HPLC analysis.
8.3 Separation and Detection
Injection:20-100 µl
Mobile pha:10% Acetonitrile : 90% Phosphoric acid solution
Analytical column:C18, 5 µm particle size, 250 x 4,6 mm
Guard column:C18, 5 µm particle size, 50 x 4,6 mm
Flow rate: 1 cm³.min-1
Detection:UV at 210 nm
The peak areas are obtained using an integrating recorder, data station, or computer.
Separation of acrylic acid is normally achieved within 5-6 minutes.
410.1-99FEBRUARY 99
9 CALCULATION
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9.1 Calibration Solutions S 3-S 6 are analyd in duplicate, and an average peak area obtained for each level.
Take the average of the 2 values, provided that the difference between them is not greater than 5% of their mean value.
If the difference exceeds 5%, the determination shall be repeated in duplicate.
Plot acrylic acid concentration (C) against average peak area (Y). Linear regression analysis is ud
to calculate the correlation coefficient, and the equation for the concentration-area relationship. For a linear calibration curve, this is:
C = aY + b (mg.L -1)
where:
C = concentration of analyte
Y = peak area of analyte
a = slope of the line
b = intercept on the Y axis.
The correlation coefficient obtained should be greater than 0,99.
9.2 Calculation
The sample concentration is calculated from the above expression, where Y is the peak area obtained for the sample.
The concentration of acrylic acid in PA superabsorbent powders should take into account the mass of polymer taken (W), and the volume of extraction solution (200cm³).Residual acrylate =1
kg . mg W
200 C −10PRECISION
The data for the repeatability and reproducibility limit of this method are the result of interlaboratory tests carried out in 1997 by EDANA, and are given in annex (e 12). The evaluation of the laboratory test was carried out according to ISO 5725.
Samples for the Round Robin test have been mainly lected for testing the accuracy of the method. They are not reprentative of the products on the market (e.g. sample A coming from a batch produced in the past).
FEBRUARY 99410.1-99 The absolute difference between two single test results obtained under repeatability test conditions according to ISO 5725-2 shall not be greater than 55 units, with a probability of 95%.
The absolute difference between two single test results obtained under reproducibility test conditions
according to ISO 5725-2 shall not be greater than 416 units, with a probability of 95%.
The high reproducibility limit stems probably from calibration problems due to ageing of acrylic acid (e 12.5).
If the repeatability and reproducibility test criteria are not met, the test shall be repeated twice, each in duplicate, after ensuring that the original sample is thoroughly mixed. If it still fails to satisfy the criteria report as unusual.
11TEST REPORT
The test report shall include the following information:
a) Type of PA superabsorbent powders tested.
b) Reference to this ERT.
c) Amount of residual acrylate monomer in ppm (mg.kg-1) to one unit accuracy.
d) Any deviation from the standard procedure.
12 INFORMATIVE ANNEXE
12.1 Precision
Figures for the repeatability and reproducibility of this method are the result of
collaborative studies carried out in 1997 by EDANA, with the following data:
SAMPLE A B C
No. of participating laboratories:101010
No. of non-eliminated laboratories:999
No. of single values of the non-eliminated laboratories:363636
Average (ppm):716356400
Standard deviation of repeatability,s r:18,5813,9519,52
Coefficient of repeatability,CV r:2,603,924,88
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Repeatability limit, r (2,8 x s r):52,0339,0754,66
Standard deviation of reproducibility, s R:148,5183,9884,76
Coefficient of reproducibility, CV R:20,7723,5821,19
Reproducibility limit, R (2,8 xs R):415,83235,15237,32
410.1-99FEBRUARY 99
瑜伽有什么好处12.2 Reference
The procedure is a modified version of that published by Neyer, J.M. et al .
Reference:
J.M. Neyer, A. Vigouroux, Ch. Vamvakaris and H. Mandery. High-Performance Liquid
Chromatographic Determination of Monomeric Sodium Acrylate and Acrylic Acid in
Polyacrylic Gelling Agents. Chromatographia vol. 25, 10 (1988).
The linear range of this method is 0,01–10 mg.L-1 acrylic acid, equivalent to 2–2000
mg.kg-1 of residual monomers in PA superabsorbent powders. The limit of detection
is 0,01 mg.L-1 of acrylic acid.
12.3 Chromatography
Deviations from the chon chromatographic mode are acceptable. The level of
precision and accuracy in both peak paration and quantitation must be equal to, or
better than that recommended here. For example:
•Any equivalent rever pha chromatography column may be ud.
•The mobile pha organic modifier can be omitted if high purity, pH stable rever pha columns are the sample chromatogram was achieved without
organic modifier.
Warning : C18 phas are subject to "Hydrophilic Collap" in the abnce of organic
modifier in the mobile pha. This can result in shifts in retention time. Column
performance should be verified under such circumstances.
•Ion exclusion chromatography columns may be ud in place of rever pha chromatography columns, 0,005 M sulphuric acid is recommended as the mobile
pha.
•Chromatography columns of different dimensions may be ud as long as analyte paration is achieved, e.g. the sample chromatogram was achieved using a 100
x 4.6 mm column, with a 50 x 4,6 mm guard column.
•Filtration aids may be added at the end of the 1 hour stirring H3PO4 1ml.
12.4 Sample chromatograph
100 x 4,6 mm C18 column, 5 µm particle size, 0,0087 Mol.L-1 H3PO4 mobile
pha, 1 cm³.min-1, UV detection at 210 nm.
12.5 Acrylic acid purity
It is well known that acrylic acid degrades over time. It is therefore important to
measure the purity of acrylic acid ud to calibrate the HPLC.
