Swill-cooked oil is extracted from the uneaten food. According to estimates, various restaurants in one city will produce at least 3000T swill-cooked oil every month. Swill-cooked oil can cause great harm to the society. Scientific test shows that rancidity and carbonyl group value have far beyond the national hygiene standard stipulated for edible oil. Rancidity will damage some enzyme system such as cytochrome oxidase; high oxidation of oil will produce AFT, which may cause several kinds of cancers. If animals eat spoil oil for long time, they will lose their weight and hurt their growth up. Toxicity of poisonous AFT is 100 times as much as arsenic----the strongest chemical carcinogen in the world. The test proves that animals take low doses of AFT for long time will 100% suffer from liver cancer; moreover, it will cause other cancers, such as sdenocarcinoma of stomach, renal carcinoma, rectal carcinoma, ovary, small intestine and other carcinomas.

    AFT is a group of compounds of similar chemical structure. At present, 12 kinds have been separated and identified as B1, B2, G1,G2, M1, M2, P1, Q, H1, GM, B2a and toxic alcohol. AFT is composed of difurrylpropane and cumarin. B1 is derived from dihydrofuran oxa-naphthyl-o-one that contains one bifuran and one oxa-naphthyl-o-one ( cumarin). The former one is toxic and the latter one relates to carcinogenic. M1 is derived metabolites after AFT B1 hydroxylation. B1 is the most toxic and carcinogenic substance. Compounds of the similar chemical structure are belonging to diffuryl cumarin. AFT is secondary metabolite produced by aspergillus flavus parasitized in a.parasiticus. In humid areas, AFT is usually found in food and feed.

二、Solutions

    The limit of AFT b1 has been clearly stipulated in relative food hygiene standards, where, corn, peanut kernel and peanut oil shall not contain b1 over 20ug/kg; rice and other edible oils shall not contain b1 over 10ug/kg; other foodstuff, beans and ferment food shall not contain more than 5ug/kg b1; food for baby shall not contain any b1.

    For the test of excessive AFT b1 and combined with relative standards, high-performance liquid chromatograph-fluorescence detector is developed to conduct the test, so as to ensure the healthy edible oil.

LC310 HPLC Configurations

P310 high-pressure delivery pump：2 sets
High-pressure static mixer（1.7ml）：1set
7725i manual injector：1 set
Post-column device：1 set
Fluorescence detector：1 set
Binary gradient kit：1 set
CT310 Chromatographic column: 1 set
LC310 Chromatographic data processing system：1 set
Chromatographic column：Kromasil C18 250*4.6mm，5um，100A or equivalent one: 1 pcs
Tray：1 set

Laboratory pre-treatment devices

Thermostat water bath: 1set
Filter ( with vacuum pump)1000ml ： 1 set
Homogenizer（18000r/min—22000r/min）：1 set
Aflatoxin Immuno-Affinity Column: 1 pcs
Glass fiber filter: Several
Glass injector: 10ml，20ml：several
Glass tube：Diameter in 12mm; length:75mm; without fluorescence: 2 pcs
Air-pressure pump：1 set
Ultra-sonic cleaner：1 set

Laboratory reagents

Acetonitrile: Chromatographic pure
Methyl: Chromatographic pure
Benzene: Chromatographic pure
Sodium Chloride: AR
Water: Ultra-pure water or redistilled water
Disodium Hydrogen Phosphate: AR
Monopotassium Phosphate: AR
Potassium Chlodire: AR
Tween-20: AR
Iodin: AR

Sample extraction:

Reference: GB/T18979-2003

Extract the sample through methanol alcohol-water; after the extracted solution is filtered and diluted, process the filtrate through the immunoaffinty chromatography purification of the aflatoxin antibody; remove the impurities on the immunoaffinty chromatographic column with water or polysorbate 20, elute immunoaffinty chromatographic column in methanol alcohol; test aflatoxin b1 content in eluent through post column iodine solution derivatization with High-efficiency Liquid Chromatograph, combined with fluorescence detector.

Chromatographic condition:

Mobile phase: methanol alcohol: water=45:55
Flow rate: 0.8ml/min
Post column derivatization system
Derivatives solution: 0.05% iodine solution
Derivatives solution flow rate: 0.2ml/min
Reaction tube temperature: 70℃
Reaction time: 1min

Descriptions:

Personnel with experience in chemical analytical instruments and related majors or operation of High-frequency Liquid Chromatograp