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GB/T 35953-2018 PDF in English


GB/T 35953-2018 (GB/T35953-2018, GBT 35953-2018, GBT35953-2018)
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GB/T 35953-2018: PDF in English (GBT 35953-2018)

GB/T 35953-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.100.70
Y 42
Determination of restricted dichloromethane and
1,1,1-trichloroethane in cosmetics - Headspace gas
chromatography
ISSUED ON. FEBRUARY 06, 2018
IMPLEMENTED ON. SEPTEMBER 01, 2018
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 and materials ... 5 
5 Instruments and equipment... 5 
6 Analytical procedures ... 5 
7 Calculation of result ... 7 
8 Recovery and precision ... 7 
9 Allowable difference ... 7 
Annex A (informative) CAS number, molecular formula, relative molecular mass
and structural formula of dichloromethane and 1,1,1-trichloroethane ... 9 
Annex B (informative) Gas chromatograms of dichloromethane and 1,1,1-
trichloroethane standard products ... 10 
Determination of restricted dichloromethane and
1,1,1-trichloroethane in cosmetics - Headspace gas
chromatography
1 Scope
This Standard specifies reagents and materials, instruments and equipment,
analytical procedures, calculation of results, recovery and precision, allowable
difference, etc. of headspace gas chromatography for dichloromethane and
1,1,1-trichloroethane in cosmetics.
This Standard is applicable to the determinations of dichloromethane and 1,1,1-
trichloroethane in cream, milk, liquid, water cosmetics.
The detection limits of this Standard for dichloromethane and 1,1,1-
trichloroethane are 0.070mg/kg and 0.0010mg/kg, respectively. The limits of
quantification are 0.25mg/kg and 0.0050mg/kg, respectively.
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
GB/T 6682, Water for analytical laboratory use - Specification and test
methods
3 Principle
The specimen is placed in a sealed headspace vial. At a certain temperature
and time equilibrium, the target compound in the specimen reaches dynamic
equilibrium in the gas-liquid two phases. At this time, the concentration of the
target compound in the gas phase is proportional to its concentration in the
liquid phase. By measuring the concentration of the target compound in the gas
phase, the concentration of the target compound in the specimen can be
calculated.
Weigh 10.00g of (to the nearest of 0.01g) sample directly into a 50mL volumetric
flask. Add methanol to the scale. Cover to seal. Vortex on a vortex shaker until
the sample is completely dissolved or evenly mixed. Pipette 10.0mL of sample
solution into the headspace vial. Take 1mL of upper gas after gas-liquid
equilibrium into gas chromatography for detection.
6.2 Headspace sampler conditions
The headspace sampler conditions are as follows.
a) Vaporization chamber temperature. 85°C; dosing tube temperature. 90°C;
transmission line temperature. 100°C;
b) Gas-liquid equilibrium time. 40min; injection time. 1min.
6.3 Gas chromatographic reference conditions
The gas chromatographic reference conditions are as follows.
a) Chromatographic column. HP-VOC, 30m × 0.2mm × 1.1μm, or the
equivalent;
b) Column temperature. keep at 40°C for 2 min, ramp to 120°C at a rate of
20°C/min (keep for 0min), and then ramp to 180°C at a rate of 10°C/min
(for 5min);
c) Inlet temperature. 250°C;
d) Split ratio. 1.5;
e) Detector temperature. 300°C;
f) Carrier gas. nitrogen;
g) Flow rate. 1.0mL/min.
6.4 Standard working curve drawing
Respectively pipette 10mL of standard working solution at each level in the
headspace bottle. Detect by 6.3 chromatographic conditions. Take the
concentrations of working solutions at various levels (dichloromethane
concentrations are 0.05μg/mL, 0.10μg/mL, 0.50μg/mL, 1.0μg/mL, 5.0μg/mL,
10μg/mL, the concentrations of 1,1,1-trichloroethane are 0.0010μg/mL,
0.0020μg/mL, 0.010μg/mL, 0.020μg/mL, 0.20μg/mL, 0.50μg/mL) as the
abscissa, corresponding peak areas as ordinate. Perform linear regression to
obtain standard curve equation.
For gas chromatograms of dichloromethane and 1,1,1-trichloroethane standard
products, see Figure B.1 in Annex B.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.