GB 31604.39-2016National food safety standard - Food Contact Materials and Articles - Determination of Polychlorobiphenyls (PCBs) in Food Contact Paper (English PDF)

3.1 Reagents

3.1.1 N-hexane (C6H14). chromatographic pure.

3.1.2 Dichloromethane (CH2Cl2).

3.1.3 Acetonitrile (CH3CN). chromatographic pure.

3.1.4 Concentrated sulfuric acid (H2SO4). guarantee reagent.

3.2 Reagents preparation

3.2.1 N-hexane-dichloromethane mixed solution (1+1). weigh 100mL of n-hexane

and 100mL of dichloromethane; mxi evenly.

3.3 Standard substance

2, 2', 5-trichlorobiphenyl (PCB18); 2, 4, 4'- trichlorobiphenyl (PCB 28); 2, 2', 5, 5'-

tetrachlorobiphenyl (PCB 52); 2, 2', 4, 5, 5'-pentachlorobiphenyl (PCB 101); 2, 3', 4, 4',

5- pentachlorobiphenyl (PCB 118); 2, 2', 3, 4, 4', 5'-hexachlorobiphenyl (PCB 138); 2,

2', 4, 4', 5, 5'- hexachlorobiphenyl (PCB 153); 2, 2', 3, 4, 4', 5, 5'-heptachlorobiphenyl

(PCB 180); internal standard substance 2, 2', 3, 3', 4, 4', 5, 5', 6, 6'- decachlorobiphenyl

(PCB 209). purity of all standard substances is >=98%; or the standard substances that

are approved by the state or awarded standard substance certificate by the state.

Relevant information on the 8 polychlorobiphenyls (PCBs) and internal standard

substance can refer to Table A.1.

3.4 Preparation of standard solution

3.4.1 PCBs and internal standard substance standard stock solution. accurately

weigh appropriate amount of PCBs standard substances; use n-hexane to prepare into

the solution with concentration of 200mg/L, respectively; seal and store at -18°C; the

shelf life is 12 months.

3.4.2 Mixed standard working solution. separately and accurately pipette 8 PCBs

standard stock solutions; use n-hexane to gradually dilute into the 1.00mg/L mixed

standard working solution; seal and store at -18°C; the shelf life is 3 months.

3.4.3 Internal standard substance working solution. accurately pipette appropriate

amount of internal standard substance (PCB 209) standard stock solution; use n-

hexane to prepare into the solution with concentration of 1.00mg/L; seal and store at -

18°C; the shelf life is 3 months.

3.4.4 Mixed standard series solution. pipette appropriate amount of mixed standard

working solution and internal standard substance working solution; use n-hexane to

prepare into the mixed standard series solutions (the concentration of internal standard

substance is 0.050mg/L) with concentration of 0.0050mg/L, 0.010mg/L, 0.025mg/L,

0.050mg/L, 0.100mg/L and 0.200mg/L. It shall be prepared for current use.

3.5 Materials

3.5.1 Nylon filter. 0.22µm.

3.5.2 Diatomaceous earth carrier G. excellent grade; CAS No. of 68855-54-9; heat

for 4h in the 400°C muffle furnace before use, then prepare for later-use.

The Second Method of Gas Chromatography – Mass Spectrometry

10.1 Reagents

10.1.1 N-hexane (C6H14). chromatographic pure.

10.1.2 Dichloromethane (CH2Cl2).

10.1.3 Acetonitrile (C6H14) [here translator notes it shall be (CH3CN)].

chromatographic pure.

10.1.4 Concentrated sulfuric acid (H2SO4). guarantee reagent.

10.2 Preparation of specimen

10.2.1 N-hexane-dichloromethane mixed solution (1+1, volume ratio). weigh 100mL

of n-hexane and 100mL of dichloromethane, mix evenly.

10.3 Standard substance

2, 2', 5-trichlorobiphenyl (PCB 18); 2, 4, 4'-trichlorobiphenyl (PCB 28), 2, 2', 5, 5'-

tetrachlorobiphenyl (PCB52); 2, 2', 4, 5, 5'-pentachlorobiphenyl (PCB 101); 2, 3', 4, 4',

5-pentachlorobiphenyl (PCB 118); 2, 2', 3, 4, 4', 5' -hexachlorobiphenyl (PCB 138); 2,

2', 4, 4', 5, 5'-hexachlorobiphenyl (PCB 153); 2, 2', 3, 4, 4', 5, 5'-heptachlorobiphenyl

(PCB 180); internal standard substance (13C12-PCB 209). the purity of all standard

substances is >=98%, or the standard substances approved by the state or awarded

standard substance certificate by the state; relevant information on 8 PCBs and

internal standard substance can refer to Table A.1.

10.4 Preparation of standard solution

The operation is the same as 5.1.

12.2 Preparation of specimen

The operation is the same as 5.2.

12.3 Extraction

12.3.1 Water bath oscillation extraction (applicable to the monolayer food

contact paper)

Take about 2g (accurate to 0.01g) of sample into 50mL stopper glass centrifuge tube;

after adding 100µL of 13C12-PCB209 internal standard substance working solution

(1.00mg/L), the following operation is the same as 5.3.1.

12.3.2 Accelerated solvent extraction (applicable to the monolayer food

contact paper and composite food contact paper)

Take about 2g (accurate to 0.01g) of sample; after adding 100µL of 13C12-PCB209

internal standard substance working solution (1.00mg/L), the following operation is the

same as 5.3.2.

12.4 Purification

The operation is the same as 5.4.

12.5 Determination

12.5.1 Reference conditions of gas chromatography-mass spectrometry

a) Chromatographic column. 5% phenyl-methyl polysilane packing capillary column;

column length is 30m, inner diameter is 0.25mm, film thickness is 0.25µm.

b) Inlet temperature. 280°C.

c) Temperature-rise procedures. the starting temperature is 90°C; it rises to 200°C

at 15°C/min, maintain for 5min; then rise to 250°C at 2.5°C/min, maintain for

2min; finally rise to 290°C at 20°C/min, maintain for 5min.

d) Ion source temperature. 230°C.

e) Ion source voltage. 70 eV.

f) Carrier gas. high-purity nitrogen (purity>=99.999%), 1.0mL/min.

g) injecting volume. splitless mode, 1.0µL.

h) The characteristic ions of 8 PCBs and the internal standard substance (13C12-

PCB209) can refer to Table C.1.

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