Element analysis detection

This standard specifies the flame atomic absorption spectrometry, inductively coupled plasma emission spectrometry, inductively coupled plasma mass spectrometry, and disulfide gland colorimetric method for the determination of zinc content in food. This standard is applicable to the determination of zinc content in various foods. After sample digestion treatment, flame atomization was performed and the absorbance was measured at 213.9 nm. The absorbance value of zinc is directly proportional to the zinc content within a certain concentration range, and is quantitatively compared to the standard series. Unless otherwise specified, all reagents and materials used in this method are high-grade pure, and the water is Grade II water as specified in GB/T 6682. 3.1 Reagent 3.1.1: Nitric acid (HNO,). 3.1.2 Perchlorate acid (HCIO). 3.2 Reagent preparation 3.2.1 Nitric acid solution (5+95): Measure 50 mL of nitric acid, slowly add to 950 mL of water, and mix well. 3.2.2 Nitric acid solution (1+1): Measure 250 mL of nitric acid, slowly add to 250 mI of water, and mix well. 3.3 Standard zinc oxide (ZnO, CAS No. 1314-13-2): Purity ≥> 99.99%, or a certain concentration of zinc standard solution certified by the state and awarded with a standard substance certificate. 3.4 Preparation of standard solution 3.4.1 Zinc standard stock solution (1000 mg/L) Accurately weigh 1.244 7 g (accurate to 0.000 1 g) of zinc oxide, add a small amount of nitric acid solution (1+1), heat to dissolve, cool, transfer to a 1000 ml volumetric flask, add water to the mark, and mix well. 3.4.2 Zinc standard intermediate solution (10.0 mg/L): Accurately pipette 1.00 mL of zinc standard reserve solution (1000 mg/L.) into a 100 ml volumetric flask, add nitric acid solution (5+95) to the mark, and mix well

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