GB 5009.254-2016National Standard for Food Safety - Determination of Polydimethylsiloxane in Animal and Vegetable Fats and Oils (English PDF)

3.1 Reagents

3.1.1 1# Aviation kerosene (or it can be considered as organic solvents that can be directly injected into inductively coupled plasma atomic emission spectrometer and dissolve polydimethylsiloxane).

3.1.2 Hydrochloric acid (HCl).

3.1.3 Hydrochloric acid solution (1.37 mol/L). weigh-take 114 mL of hydrochloric acid;

add water to dilute to 1,000 mL.

3.2 Standards

1.37 mol/L hydrochloric acid, and mix it thoroughly. Start static stratification in water bath, then, take 10 mL of supernatant and reserve it in 15 mL plastic centrifuge tube.

Simultaneously start reagent blank test. Easily solidified grease shall be placed in water bath at 70°C, and immediately measured after being taken out.

5.2 Instrument Reference Conditions

Please refer to Table A.1.

5.3 Formulation of Standard Curve Lines

Inhale the standard series of working fluid into inductively coupled plasma atomic emission spectrometer; determine the intensity of emission. Take the density of polydimethylsiloxane in the standard working fluid as the x-coordinate, and the value of emission intensity as the y-coordinate. Draw the standard curve line.

5.4 Determination of Sample Solution

Inhale the blank and sample solution into inductively coupled plasma atomic emission spectrometer; determine the intensity of emission. Obtain the density (µg/mL) of polydimethylsiloxane in the test solution in accordance with the standard curve line.

10.3.2 Standard working fluid of polydimethylsiloxane. weigh-take 4 g (accurate to

0.01 g) of vegetable oil or animal oil or hydrate vegetable oil blank grease (blank grease is a kind of grease that doesn’t include polydimethylsiloxane in the market), then, place it in 10 mL volumetric flask. Place what’s need to be dissolved into water bath kettle at 70°C; add 2 mL~3 mL of 4-methyl-2-pentanone to dilute. Respectively transfer and take 0 µL, 40 µL, 100 µL, 200 µL, 300 µL and 500 µL of standard stock solution of polydimethylsiloxane. Add 4-methyl-2-pentanone to dilute to the constant volume, and shake it well. Obtain 0 µg/mL, 4 µg/mL, 10 µg/mL, 20 µg/mL, 30 µg/mL and 50 µg/mL of standard working fluid of polydimethylsiloxane based on the vegetable oil or animal oil or hydrate vegetable oil. Easily solidified grease shall be placed in water bath at 70°C, and immediately measured after being taken out.

11.1 Atomic absorption spectrometer. silicon-attached hollow cathode lamp; nitrous

oxide-acetylene gas system (pressure reducing valve with heating device);

combustion head exclusive for nitrous oxide-acetylene gas system.

11.2 Balance. division value is 0.1 mg.

11.3 Water bath kettle. with temperature-regulating device.

11.4 Volumetric flask. 10 mL, 100 mL.

12.1 Preparation of Samples

Vegetable oil or animal oil or hydrate vegetable oil. weigh-take 4 g (accurate to 0.01 g) and place it in 10 mL volumetric flask. Place what’s need to be dissolved into water bath kettle at 70°C; add 4-methyl-2-pentanone to dilute to the constant volume, then, shake it well. Simultaneously start reagent blank test.

12.2 Instrument Reference Conditions

12.2.1 Wavelength. 251.6 nm.

12.2.2 Spectral passband. 0.2 nm.

12.2.3 Lamp current. 10 mA.

12.2.4 Acetylene flow. 4.0 L/min.

12.2.5 Nitrous oxide flow. 6.0 L/min.

12.3 Formulation of Standard Curve Lines

......