β- Carotene detection

This standard specifies the graphite furnace atomic absorption spectrometry, inductively coupled plasma mass spectrometry, flame atomic absorption spectrometry, and dithizone colorimetric method for the determination of lead content in food. This standard is applicable to the determination of lead content in various types of food. After sample digestion treatment, the absorbance was measured at 283.3 nm after graphite furnace atomization. The absorbance value of lead within a certain concentration range is directly proportional to the lead content. Compare with the standard series for quantification. 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 High Amino Acid (HClO1). 3.1.3 Ammonium dihydrogen phosphate (NH, H: PO). 3.1.1.4 Palladium nitrate [Pd (NO3);]. 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+9): Measure 50 mL of nitric acid, slowly add to 450 mL of water, and mix well. 3.2.3 Ammonium dihydrogen phosphate palladium nitrate solution: Weigh 0.02 g of palladium nitrate. Dissolve in a small amount of nitric acid solution (1+9), then add 2 g of ammonium dihydrogen phosphate. Dissolve and dilute to 100 mL with nitric acid solution (5+95). Mix well. 3.3 Standard lead nitrate [Pb (NO,);. CAS number: 10099-74-8]: Purity> 999% or a certain concentration of lead standard solution certified by the state and awarded with a standard substance certificate. 3.4 Preparation of standard solution 3.4.1 Lead standard stock solution (1000 mg/L): Accurately weigh 1.598 5 g (accurate to 0.000 1 g) of lead nitrate, dissolve with a small amount of nitric acid solution (1+9), transfer to a 1000 mL volumetric flask, add water to the mark, and mix well

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