Food Additive Tert-butylhydroquinone

A.1 General provisions

The reagents and water used in this standard refer to the analytical reagents and the three kinds of water specified in GB/T 6682-2008, unless otherwise specified.

grade water. Standard titration solutions, standard solutions for impurity determination, preparations and products used in the test, unless other requirements are specified, are all

Prepared according to the provisions of GB/T 601, GB/T 602 and GB/T 603. When the solution used in the test is not indicated which solvent to prepare, it refers to

aqueous solution.

A.2 Identification test

Dissolve 4mg~8mg sample in 1 mL methanol, then add a few drops of 25% dimethylamine aqueous solution, the solution turns from light red to red

without being restored.

A.3 Determination of tert-butylhydroquinone, tert-butyl-p-benzoquinone, 2,5-di-tert-butylhydroquinone and hydroquinone

A.3.1 Reagents and materials

A.3.1.1 Acetone.

A.3.1.2 Standard hydroquinone. Known purity.

A.3.1.3 Tertiary butyl hydroquinone standard substance: purity ≥ 99%.

A.3.1.4 Tert-butyl-p-benzoquinone standard substance: purity ≥ 99%.

A.3.1.5 Standard substance of 2,5-di-tert-butylhydroquinone: purity ≥99%.

A.3.2 Instruments and equipment

Gas chromatograph: equipped with hydrogen flame ionization detector and automatic integrator.

A.3.3 Reference chromatographic conditions

A.3.3.1 Chromatographic column: HP-5 elastic quartz capillary column, column length 30 m, inner diameter 0.32 mm, coating thickness 0.25 μm; or others

efficient chromatographic column.

A.3.3.2 Air velocity: The carrier gas is high-purity nitrogen, and the linear velocity is 30 cm/s.

A.3.3.3 Temperature: column temperature 220 ℃, injection port 250 ℃, detector 300 ℃.

A.3.3.4 Split ratio: 20:1.

A.3.3.5 Injection volume: 1 μL.

A.3.4 Analysis steps

A.3.4.1 Preparation of standard solution

Weigh 10 mg standard substances of hydroquinone, tert-butylhydroquinone, tert-butyl-p-benzoquinone and 2,5-di-tert-butylhydroquinone respectively, dissolve them in acetone

solution, transferred to 10 mL volumetric flasks, dilute to volume, and shake well.

A.3.4.2 Preparation of sample solution

Weigh 0.2 g sample, dissolve it with acetone, transfer to a 10 mL volumetric flask, dilute to volume, and shake well.

A.3.4.3 Determination

Under the reference chromatographic conditions in A.3.3, carry out gas chromatographic analysis on each standard solution, determine the retention time of each standard, and then inject

1 μL of sample solution was used for chromatographic analysis.

A.3.5 Calculation of results

The contents of tert-butylhydroquinone, tert-butyl-p-benzoquinone, 2,5-di-tert-butylhydroquinone and hydroquinone were calculated by area normalization method.

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The experimental results are based on the arithmetic mean of the parallel determination results, and the relative deviation of the determination results of tertiary butyl hydroquinone is not more than 0.2

%, and the relative deviation of the determination results of other substances shall not exceed 2%.

A.4 Determination of toluene

A.4.1 Reagents and materials

A.4.1.1 Octanol.

A.4.1.2 Toluene.

A.4.2 Instruments and equipment

Gas chromatograph: equipped with a hydrogen flame ionization detector.

A.4.3 Reference chromatographic conditions

A.4.3.1 Chromatographic column: a packed column made of stainless steel, with a column length of 3.66m and an outer diameter of 3.18mm. The filler is SE-30 silicone resin and

Diatomite type insulation brick S (Diatoport S) (180μm~250μm), by weight, the ratio is 10:100; or other equivalent color

column.

A.4.3.2 The carrier gas is nitrogen, and the gas flow rate is 25 mL/min.

A.4.3.3 Temperature: column temperature 70 ℃, injection port 275 ℃, detector 300 ℃.

A.4.3.4 Split ratio: 50:1.

A.4.3.5 The injection volume is 1 μL.

A.4.4 Analysis steps

A.4.4.1 Preparation of sample solution

Weigh about 2 g of sample, accurate to 0.000 2 g, transfer to a 10 mL volumetric flask, dissolve with octanol, dilute to volume,

Shake well and count the exact concentration as cS.

A.4.4.2 Preparation of standard solution

Prepare an octanol solution containing 50 μg toluene per mL, and the exact concentration is cR.

A.4.4.3 Determination

Under the reference chromatographic conditions in A.4.3, carry out chromatographic analysis on the standard solution and the sample solution respectively. Measured on a chromatogram of a standard solution

The peak height (HR) of toluene, other peaks have no influence on the analysis. Similarly, measure the peak height (HS) of toluene on the chromatogram of the sample solution.

A.4.5 Calculation of results

The content of toluene is calculated as the mass fraction w of toluene, and the value is expressed in milligrams per kilogram (mg/kg), calculated according to the formula (A.1):

)/()/( SRRS ccHHw × = ……………………… (A.1)

In the formula:

HS - the value of the peak height of toluene in the chromatogram of the sample solution;

HR──Numerical value of toluene peak height in standard solution chromatogram;

cR──The numerical value of the concentration of toluene in the standard solution, the unit is microgram per milliliter (μg/mL).

cS - the value of the concentration of the sample solution, in grams per milliliter (g/mL).