GB/T 38409-2019 English PDF (GBT38409-2019)

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GB/T 38409-2019: Leather -- Chemical tests -- Determination of N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP) content
GB/T 38409-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather - Chemical tests - Determination of N-methyl-
2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP)
content
[ISO 19070:2016, Leather - Chemical determination of N-methyl-2-pyrrolidone
(NMP) in leather, MOD]
ISSUED ON: DECEMBER 31, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Principles ... 5 
4 Reagents and materials ... 5 
5 Apparatus and equipment ... 6 
6 Test procedure ... 6 
7 Calculation and presentation of results ... 8 
8 Test report ... 8 
Appendix A (Informative) Structural changes of this standard compared with
ISO 19070:2016 ... 10 
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard uses the redrafting method to modify and adopt ISO 19070:2016
"Leather - Chemical determination of N-methyl-2-pyrrolidone (NMP) in leather".
Compared with ISO 19070:2016, this standard has many adjustments in
structure. Appendix A gives a list of comparisons of clause numbers between
this standard and ISO 19070:2016.
Compared with ISO 19070:2016, this standard has made the following technical
modifications:
- Regarding normative references, this standard has adjusted the technical
differences; the adjustments are collectively reflected in Chapter 2
"Normative references". The specific adjustments are as follows:
● ADD the reference to GB/T 6682;
● USE the QB/T 2716 which modifies and adopts international standard
to replace ISO 4044;
● DELETE the ISO 2418.
- ADJUST the expression of "3 Principles" in ISO 19070:2016, which is more
in line with China's habits.
- ADJUST the "5.4 Micropipette" in ISO 19070:2016 to "5.4 Appropriate
Pipette", for easy operation.
- ADJUST and MODIFY the "6.1.1 NMP standard stock solution" in ISO
19070:2016 to "4.5 NMP and NEP mixed standard stock solution (1000
μg/mL)". At the same time, ADD the storage requirements and validity
period of the stock solution, for easy understanding and use.
- In "6.1 Drawing the standard working curve", ADD the standard solution,
which has a concentration of 0.5 μg/mL, to make the concentration range
covered by the standard curve more reasonable.
- In ISO 19070:2016 "6.3 Extraction procedure", DELETE the repeated
provision that "the test of filtrate shall be finished within 24 hours", MODIFY
the extraction time from "(1.0 ± 0.1) h" to "(60 ± 2) min"; MODIFY the
refrigerator's temperature from "(4 ± 2) °C " to "0 °C ~ 4 °C", which is
consistent with similar standards in China.
- ADJUST the "Appendix A Chromatographic analysis" in ISO 19070:2016
Leather - Chemical tests - Determination of N-methyl-
2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP)
content
1 Scope
This standard specifies the determination method of N-methyl-2-pyrrolidone
(NMP) and N-ethyl-2-pyrrolidone (NEP) content in leather and its products.
This standard is applicable to the determination of NMP and NEP in various
leather and its products.
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 6682 Water for analytical laboratory use - Specification and test
methods (GB/T 6682-2008, ISO 3696:1987, MOD)
QB/T 2716 Leather - Preparation of chemical test samples (QB/T 2716-2018,
ISO 4044:2008, MOD)
3 Principles
Under specified conditions, the sample is ultrasonically extracted by acetone.
The obtained extract is analyzed by gas chromatography-mass spectrometry
(GC-MS); it is quantified by external standard method.
4 Reagents and materials
4.1 General requirements: Unless otherwise specified, all reagents used are of
analytical grade; the test water shall meet the requirements of Grade 3 water in
GB/T 6682.
4.2 Acetone, chromatographically pure.
then increase to 300 °C at 30 °C/min; hold for 1 min.
6.4.2 Mass spectrometry conditions
Ionization method: EI.
Ionization energy: 70 eV.
Detection method (SIM/SCAN mode): SIM: m/z = 99 (NMP), m/z = 98 (NEP).
Ion source's temperature: 230 °C.
Temperature at interface of chromatography-mass spectrometry: 280 °C.
Solvent delay: 2.5 min.
7 Calculation and presentation of results
According to formula (1), calculate the content of NMP and NEP in the
specimen:
Where:
w - The content of NMP or NEP in the specimen, in milligrams per kilogram
(mg/kg), (accurate to 0.1 mg/kg);
ρS - The mass concentration of NMP or NEP, which is read from the standard
curve, in micrograms per milliliter (μg/mL);
V - Extraction volume (V = 10 mL under standard conditions), in milliliter (mL);
m - The mass of the specimen, in grams (g).
The detection limit of this method is 5 mg/kg.
8 Test report
The test report shall include the following:
a) Number of this standard;
b) The name, number, type, manufacturer (or trademark) of specimen;
c) The content of NMP and NEP as extracted from the specimen, mg/kg;