-
Categories
-
Pharmaceutical Intermediates
-
Active Pharmaceutical Ingredients
-
Food Additives
- Industrial Coatings
- Agrochemicals
- Dyes and Pigments
- Surfactant
- Flavors and Fragrances
- Chemical Reagents
- Catalyst and Auxiliary
- Natural Products
- Inorganic Chemistry
-
Organic Chemistry
-
Biochemical Engineering
- Analytical Chemistry
- Cosmetic Ingredient
-
Pharmaceutical Intermediates
Promotion
ECHEMI Mall
Wholesale
Weekly Price
Exhibition
News
-
Trade Service
Coloring agent, also known as food coloring, is a type of food additive that can color food and improve the color of food
.
According to its source, it can be divided into two types: edible natural pigments and edible synthetic pigments
(1) Principle The artificial synthetic colorant in food is extracted by polyamide adsorption method or liquid-liquid partition method, made into aqueous solution, injected into high performance liquid chromatograph, separated by reverse phase chromatography, qualitatively based on retention time and comparison with peak area Quantitative
.
Calculate as follows:
In the formula, X——the content of colorant in the sample, mg/g
m 1 ——the quality of the colorant in the sample solution, ug
V 2 ——Injection volume, mL
V 1 ——Total volume of sample dilution, mL
m 2 ——the mass of the sample, g
(2) Chromatographic reference conditions
Chromatographic column: YWG-C 18 , 10um stainless steel column, 4.
6mm(id.
)×250mm
.
Mobile phase: methanol - ammonium acetate solution (pH=4, 0.
02mol/L)
.
Gradient elution: methanol: 20%~35%, 3%/min; 35%~98%, 9%/min; after 98%, continue for 6 minutes
.
Flow rate: 1mL/min.
Ultraviolet detector: 254nm wavelength
.
(3) The main points suggest that the minimum detection amount of this method: 5ng for new red, 4ng for lemon yellow, 6ng for amaranth , 8ng for carmine , 7ng for sunset yellow , 18ng for erythrosin, and 26ng for brilliant blue
.
5.
Determination of antioxidants in food
Antioxidants are a type of food additives that can prevent or delay the oxidative deterioration of food ingredients, improve food stability and prolong the storage period
.
According to its solubility, it can be divided into oil-soluble antioxidants and water-soluble antioxidants
Antioxidants are mainly used in fats and high-fat foods.
The mechanism of their action is to prevent the oxygen in the air from reacting with the -C=C- in the fat to form a peroxide chain, thereby preventing the fat from oxidizing rancidity
.
There are 14 kinds of antioxidants currently allowed in our country, including BHA and BHT
.
There are three national standard methods for the determination of BHA and BHT: gas chromatography, thin layer chromatography and colorimetry
(1) Principle The tert-butyl hydroxyanisole (BHA) and 2,6-di-tert-butyl-p-cresol (BHT) in the sample are extracted with petroleum ether , and the BHA and BHT are purified through a chromatography column.
After concentration, After being separated by gas chromatography, it is detected by a hydrogen flame ionization detector and quantified according to the peak height of the sample and the standard peak height
.
(2) Reagent
① Petroleum ether (boiling range 30~60℃)
.
② Dichloromethane (analytical grade)
.
③Carbon disulfide (analytical pure)
.
④ Anhydrous sodium sulfate (analytical grade)
.
⑤Silica gel G (activate at 120°C for 4 hours on 60-80 days and put it in the dryer for later use)
.
⑥ Florisil (60-80 mesh activated at 120°C for 4 hours and placed in a desiccator for later use)
.
⑦BHA and BHT mixed standard stock solution: accurately weigh 0.
1g each of BHA and BHT (purity 99.
9%), dissolve with carbon disulfide after mixing , and dilute to a 100mL volumetric flask.
This solution contains 1.
0mg BHA per 1mL.
BHT
.
Store in the refrigerator
⑧BHA and BHT mixed standard use solution: Pipette 4.
0mL of standard stock solution into a 100mL volumetric flask, and dilute to 100mL with carbon disulfide .
This solution contains 0.
040mg BHA and BHT per 1mL respectively
.
Store in the refrigerator
(3) Instruments
①Gas chromatograph: with FID detector
②Evaporator: 200mL in volume
③Oscillator
④Chromatography column: 1cm×30cm glass column with piston
⑤Gas Chromatography Column: A glass column with a length of 1.