At present, there are many methods for detecting melamine. HPLC, liquid-mass and gas-mass spectrometry are more commonly used methods. This site collects some domestic related articles and arranges them as follows. Methods include: GC-MS, Spectra-Quad line detection, ultra high performance liquid chromatography_electrospray tandem mass spectrometry, reversed phase high performance liquid chromatography, high performance liquid chromatography-diode array method, high performance liquid chromatography (HPLC) , High performance liquid chromatography-quadrupole mass spectrometry, solid phase extraction and high performance liquid chromatography, liquid chromatography tandem mass spectrometry (LC-MS MS)
Liquid-mass and gas-mass detection for melamine
1.Ultra high performance liquid chromatography 2 Electrospray tandem mass spectrometry for the determination of melamine residues in feed. The feed sample was extracted with 1% trichloroacetic acid 2 dimethyl sulfoxide, purified by Wa te rs O as is MCX column, ultra high performance liquid chromatography Separated, and finally detected by electrospray tandem quadrupole mass spectrometry. The results showed that when the content of melamine in the feed ranged from 10 to 5 000 μg / kg, the linear relationship was good (r> 0199). The average recovery rate within the range of 10-100 μg / kg addition level was 83% -94%, and the relative standard deviation was 412% -615%. The detection limit of this method is 10μg / kg.
2. High performance liquid chromatography-quadrupole mass spectrometry for the determination of melamine content in feed. An automatic solid-phase extraction device was used to establish a suitable column passing procedure; Agilent HP1100 high-performance liquid chromatography-quadrupole mass spectrometry was used to optimize Mass spectrometry conditions to establish a method for the detection of melamine residues in feed. The linear range of the method is 0.010 ～ 0.500 μg / ml, the relative standard deviation is 3.2% ～ 7.7%, and the recovery rate is 72.4% ～ 91.2%, which has good accuracy and precision.
3. Liquid chromatography-tandem mass spectrometry (LC-MS / MS) analysis of melamine in pet foods Established a liquid chromatography-tandem mass spectrometry (LC-MS / MS) method for the detection of melamine in pet foods, and compared it with the United States The gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC) methods published by the Food and Drug Administration (US FDA) were compared, and it was found that the LC-MS / MS method has a simple pretreatment process and is a kind of Highly sensitive and highly selective analysis method.
4. Determination of melamine residues in feed by liquid chromatography 2 tandem mass spectrometry Determination of melamine residues in feed by liquid chromatography 2 tandem mass spectrometry The sample was extracted with V (acetonitrile): V (H2O) = 1: 1 solution, and after high-speed centrifugation, it was used for qualitative and quantitative analysis by liquid chromatography 2 tandem mass spectrometer. The mobile phase is a mixed solution of V (acetonitrile): V (H2O) = 80:20. Using electrospray ion source, the qualitative ion pair is 127.2 / 28.5.2 and 127.2 / 26.8.2. The quantitative ion pair is 127.2 / 28.5.2. When the melamine standard of 0.5 to 10.0 mg / kg was added, the recovery rate was 92.6% to 103.2%; the relative standard deviation (RSD) was 0.8% to 2.0%; inspection The limit is 0.2 mg / kg.
5. Solid phase extraction-liquid chromatography-tandem mass spectrometry detection of melamine samples in food is homogenized, extracted with 1% trichloroacetic acid solution, purified with OASIS MCX solid phase extraction cartridge, concentrated under reduced pressure and dissolved in methanol , With Waters BEH-C. Column separation, acetonitrile and water as mobile phase, detected by liquid chromatography-tandem mass spectrometry. The linear range of melamine is 0.1-100.0 mg / kg, the correlation coefficient r is 0.99999, the average recovery rate is 71% to 95%, and the relative standard deviation is 4.56% to 9.82% (n = 6) The detection limit of the method is 0.5 mg / kg.
Spectra-Quad online analysis of melamine content in the laboratory detection method of melamine content has a problem that the detection result is greatly affected by the nitrogen content of the protein molecule. This similarity will make the detection of melamine extremely difficult. The Spectra-Quad online composition analyzer provided by Thermo Fisher Scientific (Shanghai) Co., Ltd. can realize online real-time continuous detection of melamine content (see Figure 1), and can better solve the problem that the detection result is affected by protein content.
Spectra-Quad adopts near infrared absorption detection technology, which is a non-contact, non-damage and non-hazardous detection method. The sensor illuminates the sample with near-infrared rays of a specific wavelength and analyzes the reflected light. The light used by Spectra-Quad is very low in brightness and will not heat or damage the sample. For melamine, the higher the content, the less light is reflected. In the actual inspection, the inspector can fix the Spectra-Quad sensor to any existing conveyor. By using a powder sampler, the continuous detection of the melamine content in the pneumatic transmission products can be achieved, and the inspection data can be output to a process control system Or in the PC controller to ensure that the product is not contaminated by melamine.
HPLC detection of melamine
1. RP-HPLC determination of melamine in feed
2. Determination of melamine in high-protein foods by high-performance liquid chromatography-diode array method Establish a detection method for the determination of melamine in high-protein foods by high-performance liquid chromatography-diode array method. Use different pretreatment methods for different samples, and then use an Agilent TC2C18 4. 6 × 250 mm chromatographic column, the column temperature is 40 ℃, the mobile phase is 0.02 mol / L ammonium sulfate: methanol = 94: 6 (V: V ), The flow rate is 0.8 mL / min, the diode array detector is used for detection at a wavelength of 235 nm, and the qualitative is determined by the retention time and the similarity coefficient of the three-dimensional spectrum, and the external standard method is used for quantification. The recoveries of spiked samples from different samples ranged from 98.8% to 101.5%, and the RSD was less than 1.2%. The linear range of the method is 0.1 ～ 150μg / mL, the detection limit is 0.01μg / mL, and the correlation coefficient R = 0.9999.
3. Determination of melamine in feed by high-performance liquid chromatography (HPLC) This article established the HPLC determination method of melamine in feed. The method uses a Symmetry C18 column as the separation column and a diode array ultraviolet detector for sample detection (λmax = 236nm). The method is simple, fast, and reproducible.The average recovery rate is greater than 90%, the RSD is less than 3.0%, and the linear range is
1mg / L-100mg / L.
4. Determination of melamine in pet food by solid phase extraction and high performance liquid chromatography. The cation exchange 2 reverse phase extraction column was used to purify the sample extract.
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