The Research And Application Of Steroid Hormones Residue Detection In Milk

Steroid hormones are produced by a series of enzymatic reactions of cholesterol,which are lipophilic and have low molecular weight properties.The residues of these hormones in food products once taken though food chain by human could result in metabolic disorder,abnormal growth and even cause cancer.And it also make a bad influence on environmol/Lent and international trade.Several traditional method has been established to detect steroid hormones,such as HPLC,LC-MS/MS,GC-MS/MS and other chromatographic methods.However,these traditional methods are equipped with expensive instrument,professional operators,which can not meet the Chinese market’s need that high flux and on-site rapid detection.Electrochemical method and che miluminescence immunoassay method as rapid detection are same with chromatographic methods in high sensitivity,strong specificity and good stability,what’s more,they also have the advantage of low cost and sample operation,on-site monitoring,which make up for the traditional detection.In this paper,Estriol and hydrocortisone both belong to steroid hormones were used as the detection objects to construct electrochemical method and chemiluminescence immunoassay method respectively,at the same time,which were successfully applied to milk detection.The main research contents and result are as follows:（1）Application of nickel cobalt oxide nanoflakes for electrochemical sensing of estriol in milk.Nanostructured N i/Co oxide with controlled morphology was synthesized by a facile hydrothermal method.Results indicated that the porous hexagonal sheet-like N i/Co oxide exhibited excellent electrocatalytic activity toward estriol,with a low detection limit of 0.42nmol/L,and linear range from 1 nmol/L to 14 nmol/L.Good specificity,stability and reproducibility were also demonstrated.Recovery was determined from 92.7%to 103.7%for spiked milk samples.It compared the analytical characteristics of the developed sensors with other electrochemical devices reported in the recent literature.This revealed that the proposed sensor has the lowest detection limit and highest sensitivity,providing a promising platform for fast screening of estriol.（2）A magnetic particles-based chemiluminescence immunoassay for rapid detection of hydrocortisone in milk.The hydrocortisone was derived and coupled to carrier protein for antigen preparation.Then the rabbit polyclonal antibody was prepared by New Zealand white rabbit immunization.Magnetic nanoparticle as immobile phase was coated with second antibody.Competitive immunoassay mode was established;Hydrocortisoneand antigen labelled to acridinium esterbind competitively with polyclonal antibodyof hydrocortisonewhich have been made before.Hydrocortisone-antibodydocking complex or antigen-antibody docking complex could been binded to second antibodyand fixed on the magnetic particles,separated with others by the magnetic field,washed with pre-excitation and excitation liquid,and the RLU₀ was measured to determine the content ofhydrocortisone.The established MPs–C LIA method had a linear range from0.42 to 72.27ng/mL with a detection limit of 0.12 ng/mL.Recovery was determined from 84.3%to 102.3%for spiked milk samples.Good correlation between the results of the CLIA and LC-MS/MS wasobtained.The electrochemical sensor method and chemiluminescence immunoassay method for the detection of steroid hormones in milk have their own special advantages,which provide a reference for the establishment of other harmful substancesand provide the basis for strengthening the monitoring of steroid hormones in food.