Paraffin wax - Determination of polynuclear aromatics
This method is applicable to the inspection of polynuclear aromatics in paraffin wax for food, expressed by ultraviolet absorbance.
1 Method overview
The method uses dimethyl sulfoxide as a solvent to extract aromatics from paraffin wax, and then uses isooctane to back extract aromatics dissolved in dimethyl sulfoxide. Concentrate to a concentration equivalent to 1g of sample per milliliter of isooctane, and determine its ultraviolet absorbance. If the determined value exceeds the limit value, then treat with sodium borohydride and adsorb by magnesium oxide-celite to separate out polynuclear aromatics, and then determine the ultraviolet absorbance. If the determined value is still greater than the limit value, it shall be reported as not passing. If the first or second determined value is not greater than the limit value, it can be reported as passing.
2 Apparatus and materials
2.1 Separatory funnels: 250mL, 500mL, 1,000mL, and 2,000mL capacity, equipped with tetrafluoroethylene polymer stopcocks.
2.2 Container: 500mL capacity, equipped with a -18/30 taper male fitting at the bottom and a suitable ball-joint at the top for connecting to the nitrogen supply. The male fitting must be equipped with glass hooks upside. (see Figure 1).
