Parameter detection of dairy products

This standard specifies three methods for the determination of melamine in raw milk, dairy products, and dairy products, namely high-performance liquid chromatography (HPLC), Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS method) and gas chromatography-mass spectrometry (GC-MS method) [including gas chromatography-mass spectrometry (GC-MS method) and gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS method). This standard is applicable to the quantitative determination of melamine in raw milk, dairy products, and dairy products; liquid chromatography-mass spectrometry/mass spectrometry, gas chromatography-mass spectrometry (including gas chromatography-mass spectrometry/MS method) It is also suitable for qualitative confirmation of melamine in raw milk, dairy products, and dairy products. The quantitative limit of this standard is 2 mg/kg for high-performance liquid chromatography mass spectrometry, 0.01 mg/kg for liquid chromatography mass spectrometry, and 0.05 mg/kg for gas chromatography mass spectrometry (with 0.005 mg/kg for gas chromatography mass spectrometry). 2 Normative References: The clauses in the following documents become clauses of this standard through reference in this standard. For dated reference documents, all subsequent modification orders (excluding erroneous content) or revised versions do not apply to this standard. However, parties to agreements based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest version applies to this standard. GB/T 6682 Specification and Test Methods for Analytical Laboratory Water (GB/T 6682-2008. ISO 36961987, MOD) 3 First Method High Performance Liquid Chromatography (HPLC) 3.1 Principle Sample is extracted with trichloroacetic acid solution acetonitrile, purified by cation exchange solid-phase extraction column, determined by HPLC, and quantified by external standard method. 3.2 Reagents and Materials Unless otherwise specified, all reagents are analytical pure, and water is Grade 1 water as specified in GB/T 6682. 3.2.1 Methanol: Chromatically pure. 3.2.2 Acetonitrile: Chromatically pure. 3.2.3 Ammonia water: The content is 25%~28%. 3.2.4 Trichloroacetic acid. 3.2.5 Citric acid. 3.2.6 Sodium octane sulfonate; Chromatographic purity. 3.2.7 Methanol aqueous solution: Accurately measure 50 mL of methanol and 50 mL of water, mix well, and set aside. 3.2.8 Trichloroacetic acid solution (1%): Accurately weigh 10 g of trichloroacetic acid into a 1L volumetric flask, dissolve it in water and bring to volume to the mark. Mix and prepare for later use. 3.2.9 Ammoniated methanol solution (5%): Accurately measure 5 mL of ammonia water and 95 mL of methanol, mix well, and set aside. 3.2.10 Ion pair reagent buffer; Accurately weigh 2.10g of citric acid and 216g of sodium octanesulfonate, dissolve in approximately 980 mL of water, adjust the pH to 3.0, and bring to volume to 1L for later use. 3.2.11 Melamine standard: CAS 108-78-01. Purity greater than 99.0%. 3.2.12 Melamine standard stock solution: Accurately weigh 100 mg (accurate to 0.1 mg) of melamine standard into a 100 mL volumetric flask, dissolve it in methanol aqueous solution (3.2.7) and bring it to volume to the mark. Prepare a standard stock solution with a concentration of 1 mg/mL, and store it in dark at 4 ℃. 1

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