GB/T 40189-2021 PDF English
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GB/T 40189-2021: Determination of metronidazole and norfloxacin in toothpaste - High performance liquid chromatography method
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GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 71.040.40 Y 43 Determination of metronidazole and norfloxacin in toothpaste - High performance liquid chromatography method ISSUED ON: MAY 21, 2021 IMPLEMENTED ON: DECEMBER 01, 2021 Issued by: State Administration for Market Regulation; Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3 1 Scope ... 4 2 Normative references ... 4 3 Principle ... 4 4 Reagents and standard materials ... 4 5 Instruments ... 5 6 Specimen preparation ... 5 7 Determination by high performance liquid chromatography ... 6 8 Result calculation ... 7 9 Precision ... 7 10 Identification of positive samples ... 7 Annex A (informative) Liquid chromatogram of metronidazole and norfloxacin mixed standard sample ... 8 Determination of metronidazole and norfloxacin in toothpaste - High performance liquid chromatography method1 Scope
This Standard specifies high performance liquid chromatography (HPLC) method for the content of forbidden antibiotic drugs - metronidazole and norfloxacin - in toothpaste. This Standard is applicable to the determination of the content of forbidden antibiotic drugs - metronidazole and norfloxacin - in toothpaste. The method detection limit of this Standard is 1mg/kg.2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 6682-2008, Water for analytical laboratory use - Specification and test methods3 Principle
The sample is extracted by the extraction solution. The supernatant is filtered through a 0.45μm filter membrane. Use high performance liquid chromatography-ultraviolet detection method to determine. Use retention time to characterize. Use external standard peak area method to quantify.4 Reagents and standard materials
Unless otherwise specified, all reagents used are analytically-pure AND water is grade one water specified in GB/T 6682-2008. 4.1 Extraction solution: 0.1% (volume fraction) formic acid aqueous solution: acetonitrile (95:5, volume ratio).7 Determination by high performance liquid
chromatography 7.1 Reference conditions of liquid chromatography The reference conditions of liquid chromatography are as follows: a) Chromatographic column: C18 stainless steel column (250mm×4.6mm×5μm). b) Detection wavelength: 290nm. c) Mobile phase: use triethylamine to adjust the pH value of 0.1% (volume fraction) phosphoric acid aqueous solution: acetonitrile (83:17, volume ratio) to 2.5~3.0. d) Flow rate: 1.0mL/min. e) Column temperature: 30°C. f) Injection volume: 10μL. 7.2 Preparation of standard working solution Use mobile phase solution to gradually dilute 100mg/L mixed standard stock solution (4.7). Prepare into 50mg/L, 20mg/L, 10mg/L, 5mg/L standard working solutions. Use 0.45μm filter membrane to filter for future use. Under the set chromatographic conditions, respectively take 10μL for analysis. Take the mass concentration of the standard series of solutions as the abscissa (mg/L), the peak area of the reference substance as the ordinate to draw the calibration curve (linear correlation coefficient R ≥0.9990). Refer to Figure A.1 in Annex A for the liquid chromatogram of metronidazole and norfloxacin mixed standard sample. 7.3 Determination steps After the sample is processed according to the steps in Chapter 6, perform on- board testing according to the instrument conditions of 7.1. The response values of metronidazole and norfloxacin in the test sample solution shall be within the linear range of the standard curve. If it exceeds the linear range, it shall be diluted before injection for determination. 7.4 Blank test Except for not adding specimen, the test is carried out according to the processing steps in Chapter 6 and the instrument conditions in 7.1. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
