Study On Rapid Detection Of Clenbuterol And Ractopamine Based On Microfluidic Technology

In recent years,vicious incidents of food safety have occurred repetitively,and food safety has become a critical issue.Therefore,rapid,sensitive and low-cost detection methods have attracted much attention.Clenbuterol(CLB)and ractopamine(RAC)are well known β-adrenergic agonists.When the dose exceeds 5 ? 10 times the standard dose,it can significantly promote the growth of animals,accelerate the decomposition and transformation of fat,and increase the lean meat rate.Because of large dose and long half-life time,β-adrenergic agonists are easy to accumulate in animal tissues.Long-term exposure of residual agonists in visceral tissues and muscles causes poisoning with symptoms of dizziness,chest tightness,palpitations,limb numbness and so on.Therefore,the detection of CLB and RAC in related samples is of great significance to human health.Nowadays,the widely used instrumental analysis methods,such as high-performance liquid chromatography(HPLC),gas chromatography-mass spectrometry(GC-MS)and liquid chromatography-mass spectrometry(LC-MS),which are used to detect the residues of β-adrenergic agonists in urine,animal tissues and feed.These methods have the advantages of high sensitivity,good accuracy and reproducibility.However,before chromatographic analysis,the samples need complex pretreatment.In addition,various techniques,such as fluorescent method,colorimetric method,electrochemical method,and electrochemiluminescent method,are available for the determination of trace residue of β-adrenergic agonists.Notably,most of them rely on high-tech instrumentations and professionals.Thus,a portable,easy-to-operate and low-cost method for veterinary drug residue detection is urgently needed,especially in resource-limited areas.We first introduce a microfluidics-based indirect competitive immunoassay(MICI)system that can sensitively detect residual CLB and RAC in pork,swine blood and swine urine.The rapid detection of multiple samples can be achieved in one chip,which greatly improves the detection efficiency.Compared with the traditional microplate method,this method greatly reduces the consumption of reagents and shortens the reaction time,while the sensitivity can still meet the needs of CLB and RAC detection.This method has good stability and reproducibility and the microfluidic chips are easy to manufacture.In order to construct a MICI method for detecting CLB and RAC simultaneously,we optimized multiple variables involved in the experiment.The linear ranges for CLB and RAC detection by MICI are 0.1 – 2.5 ng/m L and 0.1 – 5 ng/m L,and the limits of detection(LODs)are 0.094 ng/m L and 0.091 ng/m L,respectively.The developed MICI system is easily extended to other analytes by simple replacement of the corresponding antibody,showing great potential as a universal platform for sensitive,high-throughput and specific detection of pollutants in foods.On the basis of the "seven-channels" chip,we have developed a fully automatic portable microfluidic chip to achieve the automatic analysis of markers.The chip integrates functions such as reagent storage,fluid control,immune reaction,and waste collection.The on / off and signal acquisition of the chip valve are completed by a portable detector.Achieve "sample-to-answer",suitable for on-site detection of food contaminants.In the future work,we will control the assembly of the enzyme,and modify the surface of the chip to make it have a wider detection range and higher detection sensitivity.