GB 5009.271-2016National food safety standard - Determination of phthalates in food (English PDF)

3.1 Reagents

3.1.1 n-Hexane (C6H14).

3.2 Standard substance

3.2.1 The 16 phthalate standard substances

The mixed liquid standard substance of Dimethyl phthalate (DMP), Diethyl

phthalate (DEP), Diisobutyl phthalate (DIBP), Dibutyl phthalate (DBP), Bis (2-

methoxyethyl) phthalate (DMEP), Bis(4-methyl-2-pentyl) phthalate (BMPP),

Bis(2-ethoxyethyl) phthalate (DEEP), Dipentyl phthalate (DPP), Dihexyl

phthalate (DHXP), Benzylbutyl phthalate (BBP), Bis (2-n-butoxyethyl) phthalate

(DBEP), Dicyclohexyl phthalate (DCHP),

3.3 Standard solution preparation

3.3.1 The 16 phthalate standard intermediate solutions (10 µg/mL). accurately

PIPETTE 1 mL of phthalate standard substance (1000 µg/mL) into a 100 mL

volumetric flask, USE the n-hexane to make its volume reach to the mark.

3.3.2 Phthalate internal standard solution of 16 deuterated isotopes (100

µg/mL).

4.5 Ultrasonic generator.

4.6 Centrifuge. Speed >= 4000 r/min.

4.7 Crusher.

4.8 Solid phase extraction (SPE) device.

4.9 Solid phase extraction column. PSA/Silica composite packed glass column

(1000 mg, 6 mL).

5.1 Specimen preparation

5.2 Specimen processing

5.2.1 Liquid specimen

5.2.1.1 Liquid specimen A. liquid milk, beverage, soy sauce, vinegar, liquor,

honey, etc.

5.2.1.2 Liquid specimen B. vegetable oil, etc.

MIX the liquid fat uniformly, accurately WEIGH 0.5 g (accurate to 0.0001 g) in

a 10 mL centrifuge tube, ADD 25 µL of isotope internal standard solution, ADD

5.2.2 Semi-solid specimen

5.2.2.1 Semi-solid specimen A. jelly, sweet sauce, etc.

Accurately WEIGH 0.5 g (accurate to 0.0001 g) of the uniformly mixed

specimen in a 25 mL stoppered centrifuge tube, ADD 125 µL of isotope internal

standard solution, ADD 2 mL ~ 5 mL of distilled water, VORTEX it uniformly,

then accurately ADD 10 mL of n-hexane, VORTEX it for 1 min, vigorously

SHAKE it for 1 min, PERFORM ultrasonic extraction for 30 min, CENTRIFUGE

it at 1000 r/min for 5 min, TAKE the supernatant to prepare for GC-MS analysis.

5.2.3 Solid specimen

5.3 SPE purification

ADD 5 mL of dichloromethane and 5 mL of acetonitrile for activation, DISCARD

the effluent; ADD the liquid to be purified to the SPE column, COLLECT the

effluent; then ADD 5 mL of acetonitrile, COLLECT the effluent, COMBINE the

two collected effluent, ADD 1mL of acetone, USE 40 °C nitrogen to blow it

almost dry, USE the n-hexane to make its volume reach to 2 mL, VORTEX it

uniformly to prepare for GC-MS analysis.

5.4 Blank test

Except that no specimen is added, the determination procedures are carried

out in accordance with 5.2 and 5.3.

Note. It shall avoid contact with plastic products throughout the operation.

5.5 Instrument reference conditions

5.5.1 Gas chromatography reference conditions

5.5.2 Mass spectrometry reference conditions

5.5.2.1 Ionization mode. electron bombardment ionization source (EI);

5.5.2.2 Ionization energy. 70 eV;

5.6 Production of standard curve

Respectively INJECT the standard series working fluids into the gas

chromatography-mass spectrometer, USE the peak area ratios of the phthalate

components and their corresponding deuterated isotope internal standard as

the ordinate, USE the ratio of the content of each component of the series

standard solution (µg/mL) to the content of the corresponding deuterated

isotope internal standard content (µg/mL) as the abscissa, to draw a standard

curve.

5.7 Determination of specimen solution

INJECT the specimen solution into a gas chromatography-mass spectrometer,

USE the ratio of each component of the phthalate in the specimen to its internal

standard peak area for quantitative calculation, to obtain the ratio of the content

of each component in the specimen solution (µg/mL) to the corresponding

internal isotope internal standard content (µg/mL).

5.8 Qualitative confirmation

Under 5.5 instrument conditions, the target compound of the specimen test

solution and the phthalate standard appear at the same retention time (±0.5%),

and the mass-to-charge ratio of the corresponding mass spectrometry ion is

consistent to the mass spectrum of the standard substance, the comparison of

its abundance ratio with that of the standard substance shall comply with Table

1, which can be used to characterize the target compound.