GB/T 38409-2019Leather - Chemical tests - Determination of N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP) content (English PDF)

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

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);

rhoS - 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;

......