1. Basis: GB/T 22388 — 2008
2. Principle: The sample is extracted with trichloroacetic acid solution - acetonitrile, purified by cation exchange solid phase extraction column, and determined by high performance liquid chromatography, and quantified by external standard method.
3. Reagents and materials: Unless otherwise stated, all reagents were of analytical grade and the water was the first grade water specified in GB/T 6682 .
3.1 methanol: chromatographically pure;
3.2 acetonitrile: chromatographically pure;
3.3 ammonia water: the content is 25 % ~ 28 %;
3.4 trichloroacetic acid;
3.5 citric acid.
3.6 sodium octane sulfonate: chromatographically pure;
3.7 Aqueous methanol solution: accurately measure 50 mL of methanol and 50 mL of water, mix and reserve;
3.8 Trichloroacetic acid solution ( 1 %): Accurately weigh 10 g of trichloroacetic acid in a 1 L volumetric flask, dissolve in water and dilute to volume, mix and set aside;
3.9 ammoniated methanol solution ( 5 %): accurately measure 5 mL of ammonia water and 95 mL of methanol, mix and reserve;
3.10 ion pair reagent buffer: Accurately weigh 2.10 g of citric acid and 2.16 g of sodium octane sulfonate, add about 980 mL of water to dissolve, adjust the pH to 3.0 , and dilute to 1 L for use .
3.11 melamine standard: CAS 108-78-01 , the purity is greater than 99.0% ;
3.12 melamine standard stock solution: Accurately weigh 100 mg (accurate to 0.1 mg ) melamine standard in a 100 mL volumetric flask, dissolve it with methanol aqueous solution ( 3.7 ) and dilute to volume to prepare a standard of 1 mg/mL . Store stock at 4 °C protected from light.
3.13 Cation Exchange SPE: Mixed cation-exchange solid phase extraction column, benzenesulfonic matrix is polystyrene - divinyl benzene polymer, 60 mg, 3 mL, or equivalent person.
3.14 qualitative filter paper.
3.15 microporous membrane: 0.2 μ m , organic phase.
3.16 Nitrogen: purity greater than or equal to 99.999 %
4. Instruments and equipment
4.1 High Performance Liquid Chromatography ( HPLC ): equipped with a UV detector or a diode array detector.
4.2 Analytical balance: The sensitivities are 0.00001 g and 0.01 g .
4.3 Centrifuge: The speed is not less than 10000 r/min .
4.4 Tianjin Hengao ultrasonic extractor. HS, HU series
4.5 Tianjin Hengao solid phase extraction device. HSE-12D
4.6 Tianjin Heng Ao Nitrogen Blowing Instrument. HGC, HSC series
4.7 Tianjin Hengao vortex oscillator. HMS-350
4.8 Tianjin Hengao vacuum pump. HPD-25
4.9 Tianjin Hengao precision gas steady flow regulating valve.
4.10 stoppered plastic centrifuge tube: 50 mL .
5. Sample processing
5.1 extraction
Weigh 2 g (accurate to 0.01 g ) sample in a 50 mL stoppered plastic centrifuge tube, add 15 mL of trichloroacetic acid solution ( 3.8 ) and 5 mL of acetonitrile. Ultrasonic extraction for 10 min , and then shaking for 10 min , centrifuged at not less than 10000 r/min for 30 min . After the supernatant was filtered through a filter paper moistened with trichloroacetic acid solution, the volume was adjusted to 25 mL with a trichloroacetic acid solution , 5 mL of the filtrate was removed , and 5 mL of water was added to mix and then to be purified.
Note: If the fat content of the sample is high, it can be degreased with the hexane liquid - liquid saturated with trichloroacetic acid solution and then purified by SPE column.
5.2 Activation
A cation exchange solid phase extraction column was activated ( 3,13 ) with 3 mL of methanol and 5 mL of water in that order . Precision gas steady flow control valve before rotating solid phase extraction device to make the washing liquid flow rate not exceed 1 mL/min
5.3 Loading
5.1 liquid to be purified is transferred to a solid phase extraction column (5.2) in.
5.4 rinse
Wash with 3 mL of water and 3 mL of methanol in turn, and draw to near dryness.
5.5 elution
Elute with 6 mL of ammoniated methanol solution ( 3.9 ) and collect the eluate in a test tube. The flow rate of the whole solid phase extraction process does not exceed 1 mL/min . 5.6 Concentration
The eluate was dried with nitrogen at 50 ° C. The residue (corresponding to 0.4 g of sample) was made to volume with 1 mL of mobile phase, vortexed for 1 min , and passed through a microporous membrane for HPLC .
6. High performance liquid chromatography
HPLC reference conditions
a) Column: C8 column, 250 mm × 4.6 mm ( id ), 5 μ m , or equivalent;
C18 column, 250 mm × 4.6 mm ( id ), 5 μ m , or equivalent.
b) Mobile phase: C8 column, ion pair reagent buffer ( 3.2.10 ) - acetonitrile ( 85+15 , volume ratio), mix.
C18 column, ion pair reagent buffer ( 3.2.10 ) - acetonitrile ( 90+10 , volume ratio), mix.
c) Flow rate: 1.0 mL/min .
d) Column temperature: 40 °C.
e) Wavelength: 240 nm .
f) Injection volume: 20 μ L.
7. Analysis
With GB / T 22388 - 2008 standard test method for analysis of a sample measured using the device of constant Tianjin Otis recovery results were as follows:
Add level ( mg/Kg ) Recovery rate
blank
2 116%
4 108%
6 92%
8 96%
It can be seen from the above table that using Tianjin Hengao equipment to process samples can not only improve the speed of analyzing samples, but also obtain satisfactory recovery.
2. Principle: The sample is extracted with trichloroacetic acid solution - acetonitrile, purified by cation exchange solid phase extraction column, and determined by high performance liquid chromatography, and quantified by external standard method.
3. Reagents and materials: Unless otherwise stated, all reagents were of analytical grade and the water was the first grade water specified in GB/T 6682 .
3.1 methanol: chromatographically pure;
3.2 acetonitrile: chromatographically pure;
3.3 ammonia water: the content is 25 % ~ 28 %;
3.4 trichloroacetic acid;
3.5 citric acid.
3.6 sodium octane sulfonate: chromatographically pure;
3.7 Aqueous methanol solution: accurately measure 50 mL of methanol and 50 mL of water, mix and reserve;
3.8 Trichloroacetic acid solution ( 1 %): Accurately weigh 10 g of trichloroacetic acid in a 1 L volumetric flask, dissolve in water and dilute to volume, mix and set aside;
3.9 ammoniated methanol solution ( 5 %): accurately measure 5 mL of ammonia water and 95 mL of methanol, mix and reserve;
3.10 ion pair reagent buffer: Accurately weigh 2.10 g of citric acid and 2.16 g of sodium octane sulfonate, add about 980 mL of water to dissolve, adjust the pH to 3.0 , and dilute to 1 L for use .
3.11 melamine standard: CAS 108-78-01 , the purity is greater than 99.0% ;
3.12 melamine standard stock solution: Accurately weigh 100 mg (accurate to 0.1 mg ) melamine standard in a 100 mL volumetric flask, dissolve it with methanol aqueous solution ( 3.7 ) and dilute to volume to prepare a standard of 1 mg/mL . Store stock at 4 °C protected from light.
3.13 Cation Exchange SPE: Mixed cation-exchange solid phase extraction column, benzenesulfonic matrix is polystyrene - divinyl benzene polymer, 60 mg, 3 mL, or equivalent person.
3.14 qualitative filter paper.
3.15 microporous membrane: 0.2 μ m , organic phase.
3.16 Nitrogen: purity greater than or equal to 99.999 %
4. Instruments and equipment
4.1 High Performance Liquid Chromatography ( HPLC ): equipped with a UV detector or a diode array detector.
4.2 Analytical balance: The sensitivities are 0.00001 g and 0.01 g .
4.3 Centrifuge: The speed is not less than 10000 r/min .
4.4 Tianjin Hengao ultrasonic extractor. HS, HU series
4.5 Tianjin Hengao solid phase extraction device. HSE-12D
4.6 Tianjin Heng Ao Nitrogen Blowing Instrument. HGC, HSC series
4.7 Tianjin Hengao vortex oscillator. HMS-350
4.8 Tianjin Hengao vacuum pump. HPD-25
4.9 Tianjin Hengao precision gas steady flow regulating valve.
4.10 stoppered plastic centrifuge tube: 50 mL .
5. Sample processing
5.1 extraction
Weigh 2 g (accurate to 0.01 g ) sample in a 50 mL stoppered plastic centrifuge tube, add 15 mL of trichloroacetic acid solution ( 3.8 ) and 5 mL of acetonitrile. Ultrasonic extraction for 10 min , and then shaking for 10 min , centrifuged at not less than 10000 r/min for 30 min . After the supernatant was filtered through a filter paper moistened with trichloroacetic acid solution, the volume was adjusted to 25 mL with a trichloroacetic acid solution , 5 mL of the filtrate was removed , and 5 mL of water was added to mix and then to be purified.
Note: If the fat content of the sample is high, it can be degreased with the hexane liquid - liquid saturated with trichloroacetic acid solution and then purified by SPE column.
5.2 Activation
A cation exchange solid phase extraction column was activated ( 3,13 ) with 3 mL of methanol and 5 mL of water in that order . Precision gas steady flow control valve before rotating solid phase extraction device to make the washing liquid flow rate not exceed 1 mL/min
5.3 Loading
5.1 liquid to be purified is transferred to a solid phase extraction column (5.2) in.
5.4 rinse
Wash with 3 mL of water and 3 mL of methanol in turn, and draw to near dryness.
5.5 elution
Elute with 6 mL of ammoniated methanol solution ( 3.9 ) and collect the eluate in a test tube. The flow rate of the whole solid phase extraction process does not exceed 1 mL/min . 5.6 Concentration
The eluate was dried with nitrogen at 50 ° C. The residue (corresponding to 0.4 g of sample) was made to volume with 1 mL of mobile phase, vortexed for 1 min , and passed through a microporous membrane for HPLC .
6. High performance liquid chromatography
HPLC reference conditions
a) Column: C8 column, 250 mm × 4.6 mm ( id ), 5 μ m , or equivalent;
C18 column, 250 mm × 4.6 mm ( id ), 5 μ m , or equivalent.
b) Mobile phase: C8 column, ion pair reagent buffer ( 3.2.10 ) - acetonitrile ( 85+15 , volume ratio), mix.
C18 column, ion pair reagent buffer ( 3.2.10 ) - acetonitrile ( 90+10 , volume ratio), mix.
c) Flow rate: 1.0 mL/min .
d) Column temperature: 40 °C.
e) Wavelength: 240 nm .
f) Injection volume: 20 μ L.
7. Analysis
With GB / T 22388 - 2008 standard test method for analysis of a sample measured using the device of constant Tianjin Otis recovery results were as follows:
Add level ( mg/Kg ) Recovery rate
blank
2 116%
4 108%
6 92%
8 96%
It can be seen from the above table that using Tianjin Hengao equipment to process samples can not only improve the speed of analyzing samples, but also obtain satisfactory recovery.
Milk Cooling Tank / milk chilling machine for dairy farm
Introduction of Leo milk cooling tank / milk chiller:
Milk cooling tank composed of refrigeration units and tank body as two major parts. Tank body made of high quality AISI stainless steel (food grade); insulation layer use polyurethane foam one time forming; compressor unit using the most advanced U.S. Copeland flexible scroll compressor; optional device including automatic cleaning devices, electronic metering device and heat recovery system; independent computer control system makes our milk cooling tank in intelligent automatic working condition. Our milk cooling tank features are:quick cooling speed, high efficiency and insulation ability , low noise, reliable, simple operation, no maintenance and on-site installation, long service life. Capacity from 500L to 12000L to meet the different needs of various customer groups.
Features and benefits of Leo milk cooling tank/ milk chiller :
- Compact design;
- Rapid and efficient cooling,( from +32ºC To +4ºC within 2 hours);
- Low energy and operation costs;
- High quality materials and quality craftsmanship;
- Microprocessor driven cooling and cleaning controls;
- Available in wide range of capacities.
Milk Cooling Tank
Milk Cooling Tank,Cow Milk Cooling Tank,Horizontal Milk Cooling Tanks,Farm Milk Cooling Tank
Henan Leo Husbandry Equipment Science and Technology Co.ltd , https://www.chinaleodairy.com