Test method for food additive gum base and its ingredients (3)

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The bulk sample was cut apart, and a piece of rubber with a thickness of 10 cm was cut from the bulk sample with a reciprocating motion of a multifunctional knif.

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Weigh 5 g of the prepared sample (accurate to 1 mg) and place it in a headspace via.

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1 Equilibrium temperature of sample: 135.

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2 Equilibrium heating time: 20mi.

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3 Oscillation frequency: 500r/mi.

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4 Reference gas chromatography conditions

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1 Chromatographic column: WCOT fused silica column, 25m×32mm, stationary phase is styrene-divinylbenzene porous polymer, film thickness 5um, 25m×32mm×5um, or equivalen.

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2 Carrier gas type: high-purity nitroge.

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3 Carrier gas flow: 5mL/mi.

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4 Injection method: no spli.

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5 Inlet temperature: 250.

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6 Detector temperature: 260.

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7 Column temperature program: the initial temperature is 50°C, rise to 250°C at 10°C/min, and hold for 25mi.

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5 Drawing of standard curve

Take each standard series solution to measure the response peak area of ​​the standard series solution according to the instrument conditions, take the response peak area as the ordinate and the concentration of the standard series solution as the abscissa, draw a standard curve, the correlation coefficient of the standard curve should not be less than 996.

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6 Qualitative analysis

According to the retention time of the standard sample of each component to be tested, qualitative determination is made with the retention time of the components in the sample to be teste.

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7 Quantitative analysis

The sample was measured according to the instrument conditions, and the quantitative analysis of the components was carried out by the external standard method according to the measured response peak are.

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6 Result calculation

The mass fraction w2 of residual monomers is calculated in milligrams per kilogram (mg/kg) according to formula (.
3):

where:

c ₁ — the calculated value of the monomer concentration in the solution, in milligrams per liter (mg/L);

V ₁ - the value of the volume of 1,2-dichlorobenzene, in milliliters (mL);

V ₂ ——the value of the sample volume, in milliliters (mL), through the mass m of the sample; obtained, and the density of the sample is set to 1;

m ₅ ——the value of the weight of the sample, in grams (g.

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7 Precision

The absolute difference between the results of two independent determinations obtained under repeated determination conditions shall not exceed 10% of the arithmetic mea.

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8 Confirmation test

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1 Confirmation of limit concentrations

If the residual monomer value exceeds the "confirmation limit" concentration, the measurement result is confirmed by gas-chromatography-mass spectromete.
The results determined by gas chromatography are the real value.
Confirm the limit concentration in Table .
1.

Table .
1 Confirmation limit concentration

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2 Validation procedures

Prepare a new sample solution as required for sample preparatio.
The sample solution was reanalyzed with an HS/GC system equipped with a mass spectromete.
Instrument conditions were identical to those described in the analytical procedur.
MS spectra were recorded between m/x=15 to m/z=160 throughout the gas chromatographic analysi.
The sample solution and standard solution were measured agai.
If there are peaks at the same retention time in the total ion chromatogram of the sample solution and the standard solution, confirm the monomer according to the characteristic m/z value of the qualitative io.

The ratio of characteristic proton number/charge number of each monomer mass spectrum in the database is shown in Table .
2.

Table .
2 Characteristic proton number/charge number ratio of monomer mass spectrum

Related link: Inspection method for food additive gum base and its ingredients (2)