GB/T 7979-2005 English PDF (GBT7979-2005)

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GB/T 7979-2005: Pulps -- Determination of dichloromethane soluble matter
GB/T 7979-2005
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.040
Y 30
Replacing GB/T 7979-1987
Pulps - Determination of
dichloromethane soluble matter
ISSUED ON. SEPTEMBER 26, 2005
IMPLEMENTED ON. APRIL 1, 2006
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope .. 4 
2 Normative references ... 4 
3 Principle ... 4 
4 Reagents .. 4 
5 Instruments ... 5 
6 Sample preparation ... 5 
7 Test procedure .. 5 
8 Result representation ... 6 
9 Test report ... 6 
Appendix A ... 8 
Foreword
This Standard is the revision to GB/T 7979-1987 “Pulps - Determination of
dichloromethane soluble matter”.
This Standard replaces GB/T 7979-1987.
Compared with GB/T 7979-1987, the main changes are as follows.
- Add the contents of the scope (see Chapter 1);
- Add the contents of normative references (see Chapter 2);
- Modify the contents of the test procedure (see Chapter 7);
- Add the contents of the test report (see Chapter 9).
Appendix A of this Standard is informative.
This Standard was proposed by China National Light Industry Council.
This Standard shall be under the jurisdiction of the National Standardization Technical
Committee of Paper-making Industry (SAC/TC141).
This Standard was drafted by Tianjin Paper-Making Technology Research Institute of Light
Industry.
Main drafters of this Standard. Nie Junhong.
This Standard replaces the previous version as follows.
- GB/T 7979-1987.
This Standard shall be responsibly interpreted by National Standardization Technical
Committee of the National Paper Industry.
Pulps - Determination of
dichloromethane soluble matter
1 Scope
This Standard specifies the method for the determination of the components which can
be dissolved in dichloromethane in pulp.
This method is applicable to various chemical pulp and semi-chemical pulp.
2 Normative references
The following documents contain the provisions which, through reference in this
Standard, become the provisions of this Standard. For the dated references, their
subsequent amendments (excluding corrections) or revisions do not apply to this
Standard. However, the parties who enter into agreement based on this Standard are
encouraged to investigate whether the latest versions of these documents are
applicable. For undated reference documents, the latest versions apply to this
Standard.
GB/T 740 Pulps - Sampling for testing (GB/T 740-2003, ISO 7213.1991, IDT)
GB/T 741 Pulps - Determination of moisture content (GB/T 741-2003, ISO 638.1989,
MOD)
3 Principle
In the Soxhlet extractor, extract the sample of the pulp with dichloromethane. After at
least 24 cycles of extraction, evaporate the solvent; and under the temperature of
105°C ± 2°C, dry and extract the residue for no more than 16 hours; and then weigh it.
Through the ratio OF mass of the dichloromethane soluble matter AND absolute-dry
mass of the sample, obtain the content of the dichloromethane soluble matter.
Warning! The dichloromethane extraction method is better than diethyl-ether
extraction method. Because, if diethyl-ether is acted as the solvent, there exists
the danger of fire or explosion.
4 Reagents
Analytical reagents shall be used in the analysis unless otherwise stated.
Dichloromethane. content is 98% ~ 100%; dry and solid matters shall be less than
5mg/L; boiling point shall be 39°C ~ 41°C.
If adopting the general commercial product, it shall be redistilled; collect the distillate
between 38°C ~ 41°C; and store it in the brown glass bottle. This distillate shall be
neutral.
Warning! Due to the toxic nature of this solvent, therefore, appropriate
ventilation shall be paid attention to.
5 Instruments
General laboratory equipment and
a) Soxhlet extractor. it is made entirely of glass; it is consisted of the ground
condenser, the ground extractor and ground flat-bottomed flask. The capacity of
the flat-bottomed flask should be 150mL; the capacity of the extractor should be
60mL ~ 120mL;
b) Drying oven. it can maintain the air temperature at 105°C ± 2°C, and it can be
properly ventilated;
c) Balance. the sensitivity is 0.0001g;
d) Constant-temperature water bath.
6 Sample preparation
Perform sampling according to GB/T 740; tear the pulp sample into the sample which
is less than 15mm × 15mm; and place the sample in the ground wild-mouth bottle for
standby application.
7 Test procedure
Weigh two-portion samples of about 10g (The accuracy is 0.0001g) to perform parallel
determination; at the same time, determine the moisture content according to GB/T
741.
Firstly, PUT a small mass of absorbent cotton which has been previously extracted
with the dichloromethane solvent INTO the drain pipe of the Soxhlet extractor; then
place the sample in the extractor; CONNECT the flat-bottomed flask which has been
dried at 105°C ± 2°C and cooled to constant weight TO the extractor; then PLACE the
dichloromethane of which the volume is equal to 1.5 times volume of the extractor IN
the flat-bottomed flask; connect the condenser and start to extract.