GB 5009.231-2016Determination of volatile phenolic compounds residues in fishery products Spectrophotometric method (English PDF)

3.1 Reagents

3.1.1 Trichloromethane (CHCl 3).

3.1.2 Ammonia solution (NH 3·H 2 O).

3.1.3 Sulfuric acid (H 2 SO4).

3.1.4 Sodium hydroxide (NaOH).

3.1.5 Potassium ferricyanide (K 3[Fe(CN)6].

3.1.6 Copper sulfate (CuSO4·5H 2O).

3.1.7 Methyl orange (C 14H 15N 3NaO 3S).

3.1.8 Ammonium chloride (NH 4Cl).

3.4.2 Standard working solution: take an appropriate amount of phenol standard

solution; use phenol-free water to dilute to 1.00 µg of phenol per millimeter; use it within 2 hours after preparation.

4.1 Water vapor distiller or 500 mL glass water-vapor distilling apparatus (see

Appendix A).

4.2 Balance: the sensitivity is 0.1mg and 0.01g.

4.3 500 mL (pear-shaped) separatory funnel.

4.4 Magnetic stirrer.

4.5 Spectrophotometer.

4.6 Constant-temperature electric furnace or thermostat electric heating sleeve.

4.7 Tissue masher.

5.1 Sample preparation and storage

Use the tissue masher to homogenate the edible part of the aquatic products; stir the mixture uniformly; package; seal and refrigerate or freeze to store.

5.2 Sample processing

5.2.1 Distillation extraction

Weigh 10 g ~ 20 g of pretreated sample (accurate to 0.01g, and do a blank test at the same time) into the beaker; add 75 mL of sodium hydroxide solution; use a magnetic stirrer to stir for 10 min. Then, add 3 ~ 5 drops of methyl orange solution; use sulfuric acid solution to adjust the pH <= 4 (the solution is orange-red); add 5 mL of copper sulphate solution; mix; then put it in a water-vapor distiller or a 500 mL distilling flask;

use a small amount of phenol-free water to wash the flask; merge the washing liquid into a water-vapor distilling apparatus or a distilling flask, and add several glass beads.

Use the glass water-vapor distilling apparatus (or water-vapor distiller) to perform distillation - the water-vapor distilling apparatus shall be connected well to ensure strict gas leakage; take a 250 mL conical flask to receive the distillate; distillate at medium speed for 60 min ~ 90 min; until the distillate is about 240 mL, stop the distillation, and use 10 mL of phenol-free water to wash the condenser; merge the washing liquid into the distillate (which remains acidic during the distillation). The distillate shall be