The Development Of Rapid Detection Of OTA Strip And Its Application In Grain Products

Ochratoxin A(OTA)is one of the most abundant food contaminating mycotoxins.And OTA distributed widely in fodder and feedstuff.After being feeded OTA,it will be accumulated inside the body of livestock and poultry in animals.It mainly harms the kidney of those animals,and then the Lung,liver,and the like.Nowdays it is said that OTA has become one of the important factors which arouse the nephropathy of animal.What more,animals get OTA poisoning incidents occur frequently in recent years.OTA has pose a threat to human health by the food chain.Therefore many countries have set the maximum residue limit to it,and established monitoring and inspection system.Compared with the traditional method for OTA detection,Immune colloidal gold technique is a kind of convenient and fast detection technology.It has been widely applied in many fields,such as clinical analysis,food safety,environmental testing,and the like.The technique is equipped with much merit,such as less time consuming,strong specificity,high sensitivity,and without too high demands for operators and so on.So it plays an important role in the field of modern food testing.OTA colloidal gold strip prepared in this experiment can be widely applied in the detection of grain feed.Appropriate condition of colloidal gold labeled is a vital step in preparation of strip products.Colloid gold was prepared with a reduction of chloroauric acid by sodium citrate.In the paper,several factors were explored that may affect the uniformity of coloidal gold particles.It is found that in the process of preparing colloidal gold,gold particles is more uniform when chloroauric acid and sodium citrate are added rapidly one after another after water is being boiling.When prestige antibody was preparing,the suitable centrifugal condition is 10000 r/min,20 min.The most suitable pH is 1 mL colloidal gold with 7 ?L,0.2mol/L K2CO3.The optimum labeling dosage of protein is 1 mL Colloidal gold with 7 ?g antibody.Antigen concentration in test line is 0.4 mg/mL,Anti-mouse antibody concentrations in quality control line is 0.4 mg/mL.The dissolving colloidal gold precipitation is pH 8.5,0.02mol/L Tris with 1% BSA,5% Sucrose.The sample pad conditioning fluid is pH 8.5,0.02 mol/L Tris with 1% BSA,1% Tween-20,0.5% Sucrose.The sensitivity of gold test strip is 15 ng/mL.Its cross reaction rate with other toxins(OTB,AFB1,DON,ZEN,T-2)is 0%.OTA gold test strip can be storaged for at least three months at room temperature.In the detection,the efficient extract of the sample is a critical step.This experiment choose a certain volume ratio of methanol solution containing a certain concentration of NaHCO3 as the extracting liquid.The experiment verified that 55%(v:v)methanol containing 3% NaHCO3 solution can achieve the ideal extraction in barley flour,buckwheat flour,oats and wheat bread.While in grain fodder,it is 70%(v:v)methanol containing 3% NaHCO3.For Barley flour and oats,the suitable ratio added to the sample are 1:2(m:v),then buckwheat flour,whole wheat bread and grain fodder are 1:3(m:v).Extracting time is 3-5 min.The sensitivity of gold test strip is 20 ng/mL in barley flour,buckwheat flour,oats and wheat bread.And in grain fodder,the sensitivity is 25 ng/g.The compliance rate of the test strip is more than 92% in three kinds of concentration spiked.The recoveries of OTA is 81.5%-104.0% by the extraction method.