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GB/T 27741-2018 English PDF (GB/T27741-2018)
GB/T 27741-2018 English PDF (GB/T27741-2018)
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GB/T 27741-2018: Paper and board - Determination of migratable fluorescent whitening agents
Delivery: 9 seconds. Download (& Email) true-PDF + Invoice.
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GB/T 27741-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.010
Y 30
Replacing GB/T 27741-2011
Paper and board - Determination of migratable
fluorescent whitening agents
ISSUED ON: DECEMBER 28, 2018
IMPLEMENTED ON: JULY 01, 2019
Issued by: State Market Regulatory Administration;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Sampling and preparation of specimen ... 6
5 Qualitative determination ... 6
6 Quantitative determination ... 8
7 Detection limit and recovery rate ... 13
8 Precision ... 13
9 Test report ... 13
Appendix A (Normative) Information on the name and chemical structure of
fluorescent whitening agent ... 14
Appendix B (Informative) Liquid chromatogram of HPLC analysis of fluorescent
whitening agent standards ... 15
Paper and board - Determination of migratable
fluorescent whitening agents
Caution - Personnel using this standard shall have practical experience
in formal chemistry experiment work. This standard does not address all
safety issues; users are responsible for taking appropriate safety and
health measures and ensuring compliance with the relevant national
regulations.
1 Scope
This standard specifies qualitative and quantitative methods for the
determination of migratable fluorescent whitening agents in paper and board.
The qualitative analysis method of the migratable fluorescent whitening agent
in this standard is applicable to various paper and board; the UV-visible
spectrophotometry in the quantitative analysis method is suitable for the mobile
fluorescent whitening agent (in VBL) in paper and board. The high performance
liquid chromatography is suitable for the determination of the content of seven
fluorescent whitening agents (see Appendix A) in paper and board; other
fluorescent whitening agents can be tested with reference to it. The migratable
fluorescent whitening agent in the pulp can be tested by reference to qualitative
and quantitative methods in the standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 450 Paper and board - Sampling for testing and identification of
machine and cross direction, wire side and felt side
GB/T 6682 Water for analytical laboratory use. Specification and test
methods
3 Terms and definitions
The following terms and definitions apply to this document.
5.3.1 Conical flask: 250 mL.
5.3.2 Glass funnel: Glass core funnel with specification G1.
5.3.3 Glass watch glass.
5.3.4 Balance: The sensitivity is 0.1 g.
5.3.5 Constant temperature oscillating water bath: The temperature can be
controlled at (40 ± 2) °C.
5.3.6 UV lamp: A device with eye protection at a wavelength of 254 nm and a
wavelength of 365 nm.
5.3.7 pH meter: The reading is accurate to 0.01.
5.4 Test procedure
5.4.1 Extraction of specimen
Accurately weigh 2.0 g of the specimen and place it in a conical flask (5.3.1).
Add 100 mL of the extract (5.2.4) to the flask. Whilst slowing shaking the flask,
extract it at room temperature for 10 min. Then use a glass funnel (5.3.2) to
filter it. Use the hydrochloric acid solution (5.2.2) to adjust the pH of filtrate to
3.0 ~ 5.0. Immerse the gauze (5.2.1) in the filtrate. Heat it in a constant
temperature oscillating water bath (5.3.5) at a temperature of (40 ± 2) °C for 30
min. Use tweezers to take out the gauze. Then squeeze the filtrate dry and fold
it into 4 layers. Place it on the watch glass (5.3.3).
5.4.2 Blank test
Except for not adding specimen, follow the procedures of 5.4.1 to perform the
blank test.
5.4.3 Testing
Place the watch glass on which the specimen gauze (5.4.1) and the blank test
gauze (5.4.2) are placed at about 20 cm under the UV lamp (5.3.6) in the dark
room or dark box, to observe the gauze’s fluorescence phenomenon. Each
specimen is subjected two parallel determinations.
5.5 Determination of results
If the specimen gauze of two parallel tests is not significantly fluorescent
compared with the blank test gauze, it is judged that the specimen has no
migratable fluorescent whitening agent; if there is one blank test in the
specimen gauze of two parallel tests is significantly fluorescent than the blank
test gauze, perform two parallel tests again. If the re-tested specimen gauze
different working conditions of different instruments is different. The linearity of
the standard solution concentration range from 1 mg/L to 20 mg/L has been
proved to be satisfactory.
6.1.2.6 Microporous membrane: 0.45 μm.
6.1.3 Instruments
6.1.3.1 UV-visible spectrophotometer.
6.1.3.2 Balance: The sensitivities are 0.1 mg and 0.01 g, respectively.
6.1.3.3 Constant temperature oscillating water bath: The temperature can be
controlled at (80 ± 2) °C.
6.1.3.4 Flask with stopper: 250 mL.
6.1.4 Test procedure
6.1.4.1 Extraction of specimen
Weigh about 1.00 g of the specimen in a stoppered flask (6.1.3.4). Accurately
add 50 mL of the extract (6.1.2.2). Then shake it in a (80 ± 2) °C constant
temperature water bath (6.1.3.3) to extract it for 60 min. Cool to room
temperature in the dark. Use the microporous membrane (6.1.2.6) to filter it.
Retain the filtrate. Each specimen is subjected to parallel tests.
6.1.4.2 Blank test
Except for not adding the specimen, follow the procedures of 6.1.4.1 to perform
the blank test, to prepare the blank solution.
6.1.4.3 Determination
Adjust the wavelength of the UV-visible spectrophotometer to 348 nm.
Determine the absorbance of the fluorescent whitening agent VBL in the
standard working solution (6.1.2.5), the specimen solution (6.1.4.1), the blank
solution (6.1.4.2). Use the determination results of the standard working
solution to draw a standard curve. Calculate the mass concentration of the
migratable fluorescent whitening agent in the specimen filtrate and the blank
solution.
6.1.5 Calculation and representation of results
Calculate the content of the migratable fluorescent whitening agent w (in VBL)
in the specimen according to formula (1):
dissolve it. Make its volume reach to 100 mL.
Note: The standard stock solution is stored in the refrigerator at 2 °C ~ 4 °C in the dark,
valid for 6 months.
6.2.2.7 Fluorescent whitening agent standard working solution: Accurately
transfer a certain volume of standard stock solution (6.2.2.6) as needed. Use
the extract (6.2.2.5) to dilute it to the appropriate concentration of series
standard working solution. The standard working solution is prepared before
use. The linear range of the measurement under different working conditions of
different instruments is different. The linearity of the standard solution
concentration range of the seven fluorescent whitening agent from 0.1 mg/L to
10.0 mg/L has been proved to be satisfactory.
6.2.2.8 Microporous membrane: 0.45 μm.
6.2.3 Instruments
6.2.3.1 High performance liquid chromatograph, equipped with a fluorescence
detector (FLD).
6.2.3.2 Balance: The sensitivities are 0.1 g and 0.1 mg.
6.2.4 Test procedure
6.2.4.1 Extraction of specimen
It is performed according to 6.1.4.1.
6.2.4.2 Blank test
Except for not adding specimen, follow the procedures of 6.1.4.1 to carry out
the blank test.
6.2.4.3 Determination
6.2.4.3.1 HPLC analytical conditions
Since the test results depend on the instrument used, it is not possible to give
a general parameter for chromatographic analysis. The following parameters
have been proven to be suitable for testing.
a) Column: C18 column, 5.0 μm, 4.6 mm × 250 mm or equivalent;
b) Flow rate: 1.0 mL/min;
c) Column temperature: 40 °C;
d) Injection volume: 1 μL;
V - Volume of extract, in milliliters (mL);
m - The absolute dry mass of the specimen, in grams (g).
The calculation result is rounded off to one decimal place.
7 Detection limit and recovery rate
The detection limit of UV-visible spectrophotometry is 20.0 mg/kg. The
detection limit of high performance liquid chromatography is 1.0 mg/kg. Add an
appropriate amount of standard solution to the negative sample and analyze it
according to Chapter 6. The recovery of the fluorescent whitening agent is 80%
~ 120%.
8 Precision
In the same laboratory, the same operator uses the same equipment according
to the same test method to perform mutually independent tests for the same
tested object within a short period of time. The absolute difference between the
two independent test results obtained is not greater than 15% of the arithmetic
mean of the two measured values.
9 Test report
The test report shall include at least the following:
a) The source and description of the sample;
b) The number of this standard and the method used;
c) The test results;
d) If the number of measurements is more than two, describe the number of
measurements;
e) Details on any deviation from this standard;
f) Any abnormal phenomena observed during the test;
g) Test date.
GB/T 27741-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.010
Y 30
Replacing GB/T 27741-2011
Paper and board - Determination of migratable
fluorescent whitening agents
ISSUED ON: DECEMBER 28, 2018
IMPLEMENTED ON: JULY 01, 2019
Issued by: State Market Regulatory Administration;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Sampling and preparation of specimen ... 6
5 Qualitative determination ... 6
6 Quantitative determination ... 8
7 Detection limit and recovery rate ... 13
8 Precision ... 13
9 Test report ... 13
Appendix A (Normative) Information on the name and chemical structure of
fluorescent whitening agent ... 14
Appendix B (Informative) Liquid chromatogram of HPLC analysis of fluorescent
whitening agent standards ... 15
Paper and board - Determination of migratable
fluorescent whitening agents
Caution - Personnel using this standard shall have practical experience
in formal chemistry experiment work. This standard does not address all
safety issues; users are responsible for taking appropriate safety and
health measures and ensuring compliance with the relevant national
regulations.
1 Scope
This standard specifies qualitative and quantitative methods for the
determination of migratable fluorescent whitening agents in paper and board.
The qualitative analysis method of the migratable fluorescent whitening agent
in this standard is applicable to various paper and board; the UV-visible
spectrophotometry in the quantitative analysis method is suitable for the mobile
fluorescent whitening agent (in VBL) in paper and board. The high performance
liquid chromatography is suitable for the determination of the content of seven
fluorescent whitening agents (see Appendix A) in paper and board; other
fluorescent whitening agents can be tested with reference to it. The migratable
fluorescent whitening agent in the pulp can be tested by reference to qualitative
and quantitative methods in the standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 450 Paper and board - Sampling for testing and identification of
machine and cross direction, wire side and felt side
GB/T 6682 Water for analytical laboratory use. Specification and test
methods
3 Terms and definitions
The following terms and definitions apply to this document.
5.3.1 Conical flask: 250 mL.
5.3.2 Glass funnel: Glass core funnel with specification G1.
5.3.3 Glass watch glass.
5.3.4 Balance: The sensitivity is 0.1 g.
5.3.5 Constant temperature oscillating water bath: The temperature can be
controlled at (40 ± 2) °C.
5.3.6 UV lamp: A device with eye protection at a wavelength of 254 nm and a
wavelength of 365 nm.
5.3.7 pH meter: The reading is accurate to 0.01.
5.4 Test procedure
5.4.1 Extraction of specimen
Accurately weigh 2.0 g of the specimen and place it in a conical flask (5.3.1).
Add 100 mL of the extract (5.2.4) to the flask. Whilst slowing shaking the flask,
extract it at room temperature for 10 min. Then use a glass funnel (5.3.2) to
filter it. Use the hydrochloric acid solution (5.2.2) to adjust the pH of filtrate to
3.0 ~ 5.0. Immerse the gauze (5.2.1) in the filtrate. Heat it in a constant
temperature oscillating water bath (5.3.5) at a temperature of (40 ± 2) °C for 30
min. Use tweezers to take out the gauze. Then squeeze the filtrate dry and fold
it into 4 layers. Place it on the watch glass (5.3.3).
5.4.2 Blank test
Except for not adding specimen, follow the procedures of 5.4.1 to perform the
blank test.
5.4.3 Testing
Place the watch glass on which the specimen gauze (5.4.1) and the blank test
gauze (5.4.2) are placed at about 20 cm under the UV lamp (5.3.6) in the dark
room or dark box, to observe the gauze’s fluorescence phenomenon. Each
specimen is subjected two parallel determinations.
5.5 Determination of results
If the specimen gauze of two parallel tests is not significantly fluorescent
compared with the blank test gauze, it is judged that the specimen has no
migratable fluorescent whitening agent; if there is one blank test in the
specimen gauze of two parallel tests is significantly fluorescent than the blank
test gauze, perform two parallel tests again. If the re-tested specimen gauze
different working conditions of different instrum...
Delivery: 9 seconds. Download (& Email) true-PDF + Invoice.
Get Quotation: Click GB/T 27741-2018 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 27741-2018
Preview True-PDF (Reload/Scroll-down if blank)
GB/T 27741-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.010
Y 30
Replacing GB/T 27741-2011
Paper and board - Determination of migratable
fluorescent whitening agents
ISSUED ON: DECEMBER 28, 2018
IMPLEMENTED ON: JULY 01, 2019
Issued by: State Market Regulatory Administration;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Sampling and preparation of specimen ... 6
5 Qualitative determination ... 6
6 Quantitative determination ... 8
7 Detection limit and recovery rate ... 13
8 Precision ... 13
9 Test report ... 13
Appendix A (Normative) Information on the name and chemical structure of
fluorescent whitening agent ... 14
Appendix B (Informative) Liquid chromatogram of HPLC analysis of fluorescent
whitening agent standards ... 15
Paper and board - Determination of migratable
fluorescent whitening agents
Caution - Personnel using this standard shall have practical experience
in formal chemistry experiment work. This standard does not address all
safety issues; users are responsible for taking appropriate safety and
health measures and ensuring compliance with the relevant national
regulations.
1 Scope
This standard specifies qualitative and quantitative methods for the
determination of migratable fluorescent whitening agents in paper and board.
The qualitative analysis method of the migratable fluorescent whitening agent
in this standard is applicable to various paper and board; the UV-visible
spectrophotometry in the quantitative analysis method is suitable for the mobile
fluorescent whitening agent (in VBL) in paper and board. The high performance
liquid chromatography is suitable for the determination of the content of seven
fluorescent whitening agents (see Appendix A) in paper and board; other
fluorescent whitening agents can be tested with reference to it. The migratable
fluorescent whitening agent in the pulp can be tested by reference to qualitative
and quantitative methods in the standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 450 Paper and board - Sampling for testing and identification of
machine and cross direction, wire side and felt side
GB/T 6682 Water for analytical laboratory use. Specification and test
methods
3 Terms and definitions
The following terms and definitions apply to this document.
5.3.1 Conical flask: 250 mL.
5.3.2 Glass funnel: Glass core funnel with specification G1.
5.3.3 Glass watch glass.
5.3.4 Balance: The sensitivity is 0.1 g.
5.3.5 Constant temperature oscillating water bath: The temperature can be
controlled at (40 ± 2) °C.
5.3.6 UV lamp: A device with eye protection at a wavelength of 254 nm and a
wavelength of 365 nm.
5.3.7 pH meter: The reading is accurate to 0.01.
5.4 Test procedure
5.4.1 Extraction of specimen
Accurately weigh 2.0 g of the specimen and place it in a conical flask (5.3.1).
Add 100 mL of the extract (5.2.4) to the flask. Whilst slowing shaking the flask,
extract it at room temperature for 10 min. Then use a glass funnel (5.3.2) to
filter it. Use the hydrochloric acid solution (5.2.2) to adjust the pH of filtrate to
3.0 ~ 5.0. Immerse the gauze (5.2.1) in the filtrate. Heat it in a constant
temperature oscillating water bath (5.3.5) at a temperature of (40 ± 2) °C for 30
min. Use tweezers to take out the gauze. Then squeeze the filtrate dry and fold
it into 4 layers. Place it on the watch glass (5.3.3).
5.4.2 Blank test
Except for not adding specimen, follow the procedures of 5.4.1 to perform the
blank test.
5.4.3 Testing
Place the watch glass on which the specimen gauze (5.4.1) and the blank test
gauze (5.4.2) are placed at about 20 cm under the UV lamp (5.3.6) in the dark
room or dark box, to observe the gauze’s fluorescence phenomenon. Each
specimen is subjected two parallel determinations.
5.5 Determination of results
If the specimen gauze of two parallel tests is not significantly fluorescent
compared with the blank test gauze, it is judged that the specimen has no
migratable fluorescent whitening agent; if there is one blank test in the
specimen gauze of two parallel tests is significantly fluorescent than the blank
test gauze, perform two parallel tests again. If the re-tested specimen gauze
different working conditions of different instruments is different. The linearity of
the standard solution concentration range from 1 mg/L to 20 mg/L has been
proved to be satisfactory.
6.1.2.6 Microporous membrane: 0.45 μm.
6.1.3 Instruments
6.1.3.1 UV-visible spectrophotometer.
6.1.3.2 Balance: The sensitivities are 0.1 mg and 0.01 g, respectively.
6.1.3.3 Constant temperature oscillating water bath: The temperature can be
controlled at (80 ± 2) °C.
6.1.3.4 Flask with stopper: 250 mL.
6.1.4 Test procedure
6.1.4.1 Extraction of specimen
Weigh about 1.00 g of the specimen in a stoppered flask (6.1.3.4). Accurately
add 50 mL of the extract (6.1.2.2). Then shake it in a (80 ± 2) °C constant
temperature water bath (6.1.3.3) to extract it for 60 min. Cool to room
temperature in the dark. Use the microporous membrane (6.1.2.6) to filter it.
Retain the filtrate. Each specimen is subjected to parallel tests.
6.1.4.2 Blank test
Except for not adding the specimen, follow the procedures of 6.1.4.1 to perform
the blank test, to prepare the blank solution.
6.1.4.3 Determination
Adjust the wavelength of the UV-visible spectrophotometer to 348 nm.
Determine the absorbance of the fluorescent whitening agent VBL in the
standard working solution (6.1.2.5), the specimen solution (6.1.4.1), the blank
solution (6.1.4.2). Use the determination results of the standard working
solution to draw a standard curve. Calculate the mass concentration of the
migratable fluorescent whitening agent in the specimen filtrate and the blank
solution.
6.1.5 Calculation and representation of results
Calculate the content of the migratable fluorescent whitening agent w (in VBL)
in the specimen according to formula (1):
dissolve it. Make its volume reach to 100 mL.
Note: The standard stock solution is stored in the refrigerator at 2 °C ~ 4 °C in the dark,
valid for 6 months.
6.2.2.7 Fluorescent whitening agent standard working solution: Accurately
transfer a certain volume of standard stock solution (6.2.2.6) as needed. Use
the extract (6.2.2.5) to dilute it to the appropriate concentration of series
standard working solution. The standard working solution is prepared before
use. The linear range of the measurement under different working conditions of
different instruments is different. The linearity of the standard solution
concentration range of the seven fluorescent whitening agent from 0.1 mg/L to
10.0 mg/L has been proved to be satisfactory.
6.2.2.8 Microporous membrane: 0.45 μm.
6.2.3 Instruments
6.2.3.1 High performance liquid chromatograph, equipped with a fluorescence
detector (FLD).
6.2.3.2 Balance: The sensitivities are 0.1 g and 0.1 mg.
6.2.4 Test procedure
6.2.4.1 Extraction of specimen
It is performed according to 6.1.4.1.
6.2.4.2 Blank test
Except for not adding specimen, follow the procedures of 6.1.4.1 to carry out
the blank test.
6.2.4.3 Determination
6.2.4.3.1 HPLC analytical conditions
Since the test results depend on the instrument used, it is not possible to give
a general parameter for chromatographic analysis. The following parameters
have been proven to be suitable for testing.
a) Column: C18 column, 5.0 μm, 4.6 mm × 250 mm or equivalent;
b) Flow rate: 1.0 mL/min;
c) Column temperature: 40 °C;
d) Injection volume: 1 μL;
V - Volume of extract, in milliliters (mL);
m - The absolute dry mass of the specimen, in grams (g).
The calculation result is rounded off to one decimal place.
7 Detection limit and recovery rate
The detection limit of UV-visible spectrophotometry is 20.0 mg/kg. The
detection limit of high performance liquid chromatography is 1.0 mg/kg. Add an
appropriate amount of standard solution to the negative sample and analyze it
according to Chapter 6. The recovery of the fluorescent whitening agent is 80%
~ 120%.
8 Precision
In the same laboratory, the same operator uses the same equipment according
to the same test method to perform mutually independent tests for the same
tested object within a short period of time. The absolute difference between the
two independent test results obtained is not greater than 15% of the arithmetic
mean of the two measured values.
9 Test report
The test report shall include at least the following:
a) The source and description of the sample;
b) The number of this standard and the method used;
c) The test results;
d) If the number of measurements is more than two, describe the number of
measurements;
e) Details on any deviation from this standard;
f) Any abnormal phenomena observed during the test;
g) Test date.
GB/T 27741-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.010
Y 30
Replacing GB/T 27741-2011
Paper and board - Determination of migratable
fluorescent whitening agents
ISSUED ON: DECEMBER 28, 2018
IMPLEMENTED ON: JULY 01, 2019
Issued by: State Market Regulatory Administration;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Sampling and preparation of specimen ... 6
5 Qualitative determination ... 6
6 Quantitative determination ... 8
7 Detection limit and recovery rate ... 13
8 Precision ... 13
9 Test report ... 13
Appendix A (Normative) Information on the name and chemical structure of
fluorescent whitening agent ... 14
Appendix B (Informative) Liquid chromatogram of HPLC analysis of fluorescent
whitening agent standards ... 15
Paper and board - Determination of migratable
fluorescent whitening agents
Caution - Personnel using this standard shall have practical experience
in formal chemistry experiment work. This standard does not address all
safety issues; users are responsible for taking appropriate safety and
health measures and ensuring compliance with the relevant national
regulations.
1 Scope
This standard specifies qualitative and quantitative methods for the
determination of migratable fluorescent whitening agents in paper and board.
The qualitative analysis method of the migratable fluorescent whitening agent
in this standard is applicable to various paper and board; the UV-visible
spectrophotometry in the quantitative analysis method is suitable for the mobile
fluorescent whitening agent (in VBL) in paper and board. The high performance
liquid chromatography is suitable for the determination of the content of seven
fluorescent whitening agents (see Appendix A) in paper and board; other
fluorescent whitening agents can be tested with reference to it. The migratable
fluorescent whitening agent in the pulp can be tested by reference to qualitative
and quantitative methods in the standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 450 Paper and board - Sampling for testing and identification of
machine and cross direction, wire side and felt side
GB/T 6682 Water for analytical laboratory use. Specification and test
methods
3 Terms and definitions
The following terms and definitions apply to this document.
5.3.1 Conical flask: 250 mL.
5.3.2 Glass funnel: Glass core funnel with specification G1.
5.3.3 Glass watch glass.
5.3.4 Balance: The sensitivity is 0.1 g.
5.3.5 Constant temperature oscillating water bath: The temperature can be
controlled at (40 ± 2) °C.
5.3.6 UV lamp: A device with eye protection at a wavelength of 254 nm and a
wavelength of 365 nm.
5.3.7 pH meter: The reading is accurate to 0.01.
5.4 Test procedure
5.4.1 Extraction of specimen
Accurately weigh 2.0 g of the specimen and place it in a conical flask (5.3.1).
Add 100 mL of the extract (5.2.4) to the flask. Whilst slowing shaking the flask,
extract it at room temperature for 10 min. Then use a glass funnel (5.3.2) to
filter it. Use the hydrochloric acid solution (5.2.2) to adjust the pH of filtrate to
3.0 ~ 5.0. Immerse the gauze (5.2.1) in the filtrate. Heat it in a constant
temperature oscillating water bath (5.3.5) at a temperature of (40 ± 2) °C for 30
min. Use tweezers to take out the gauze. Then squeeze the filtrate dry and fold
it into 4 layers. Place it on the watch glass (5.3.3).
5.4.2 Blank test
Except for not adding specimen, follow the procedures of 5.4.1 to perform the
blank test.
5.4.3 Testing
Place the watch glass on which the specimen gauze (5.4.1) and the blank test
gauze (5.4.2) are placed at about 20 cm under the UV lamp (5.3.6) in the dark
room or dark box, to observe the gauze’s fluorescence phenomenon. Each
specimen is subjected two parallel determinations.
5.5 Determination of results
If the specimen gauze of two parallel tests is not significantly fluorescent
compared with the blank test gauze, it is judged that the specimen has no
migratable fluorescent whitening agent; if there is one blank test in the
specimen gauze of two parallel tests is significantly fluorescent than the blank
test gauze, perform two parallel tests again. If the re-tested specimen gauze
different working conditions of different instrum...
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