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       L-carnitine (L- carnitine), also known as carnitine, is a water-soluble amino acids, derived from lysine. The molecular structure of L-γ- trimethylamine β- hydroxybutyrate, formula C7H16NO3, a molecular weight of 161.2. It is like B vitamins, has been known as vitamin BT. Its molecular structure containing a fatty acid ester of a hydroxyl group for its unsaturated bond and a polar functional group has good water solubility and hygroscopic, it is still above 200 ℃ stable, can be placed in a solution of PH3 ~ 6 in more than one year not bad. In 1998 the Ministry of Health approved the L- carnitine food additives, nutritional supplements included in the class.
Branch Xiao Instruments With the new high-performance liquid chromatograph LC-10B, by the practice in feed detection L- carnitine content, the result is accurate and reliable, good detection limits for dietary L- carnitine the determination of reference for the majority of users.
The following is a detailed feed detection method L- carnitine.
1 instruments and reagents
1.1 Instrument
LC-10B high-performance liquid chromatography
Vertex column C18 250mm × 4.6mm × 5μm
Common laboratory equipment
Ultrasonic bath
Analytical balance (sense of volume 0.001g)
0.45μm aqueous filter
1.2 Reagents
Isopropanol, chromatography.
Methanol, HPLC grade.
Acetonitrile, HPLC grade.
Disodium hydrogen phosphate.
Potassium dihydrogen phosphate.
Triethanolamine.
Citric acid.
Silver oxide.
Carnitine derivative agent.
2 measurement principle
The samples were extracted with ethanol ultrasound, then added carnitine derivative agent, will reverse phase column derivative injected into the HPLC separation, in quantitative determination of 210nm wavelength UV detector.
Preparation of sample solution 3
Weigh 5g sample into 100ml beaker, add 30ml ethanol, dissolved and transferred to a 100ml volumetric flask, washed with ethanol three times 10ml wash beaker sample was transferred to a 100ml volumetric flask, ultrasonic extraction 10min after with anhydrous ethanol to volume, mix after 4000r / min centrifugal 5min. Supernatant 2ml, carnitine derivatizing agent is added 0.25ml (Preparation method derivatizing agent: 40 mg P- benzyl bromide was dissolved in 1.0 ml of acetonitrile, was added 40% tetrabutylammonium hydroxide 50 μl), mixed at 60 ℃ constant temperature box 120 min, draw 20 μl sample analysis.
4 chromatographic conditions
Column: Vertex C18 column 250mm × 4.6mm × 5μm;
Mobile phase: methanol: phosphate = five ninety-five
Flow rate: 1.0mL / min;
Temperature: room temperature;
Injection volume: 20μL;
Detection wavelength: 210nm.