Single And Multi-analyte Lateral Flow Immunoassay For Detection Of Four Pesticides

As the characteristic of organophosphorus and chloronicotinyl insecticides,fenitrorhion,ehlorpyrifos-methyl,imidaeloprid and isocarbophos cause harms on human,animal and environment while bring economic benefit on agriculture.To date,instrumental methods(e.g.,HPLC,GC/MS)can detect these insecticides with high sensitivity and specificity but with requirements of large advanced instrunents.They can not meet demands for high-throughput on-line screening.Therefore,it is very important to present a novel lateral flow immunoassay for the simultaneous detection of the pesticides.Organophosphorus and chloronicotinyl insecticides are commonly used in China.Fenitrorhion,chlorpyrifos-methyl and isocarbophos are organophosphorus insecticides.The fenitrorhion,named O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate,has special effects to the larva of C.medinalis,Chilo suppressalis and T.incertulas as well as to the coleopera and the hemiptera insects.Chlorpyrifos-methyl,O,O-dimethyl-O-3,5,6-trichloro-2-pyridyl phosphorodithioate,used to control the insects in stored grain and public health during the poison effects of inner absorber,touch-kill and stomach poison,with the characteristics such as high efficiency,low toxicity and broad insecticidal spectrum.Isocarbophos,Isopropyl 2-[(aminomethoxyphosphinothioyl)oxy]benzoate,has two poison effects of touch-kill and stomach poison.It is used to control the insects in cereals,cotton and vegetables,and has special effects on anti-mite and ovicidal actions.Imidacloprid,1-(6-chloro-3-pyridylmethyl)-N-nitromidazolidin-2-ylideneanine,is the typical example of chloronicotinyl insecticides.It has multiple functions such as touch-kill,stomach poison,and systemic action.Imidacloprid has well mobility in phanerogamic xylem and atability in soil,which aims at homoptera insects like aphid,leafhopper,planthopper and thysanoptera insects(such as thrip).As the characteristic of organophosphorus and chloronicotinyl insecticides,fenitrorhion,chlorpyrifos-methyl,imidacloprid and isocarbophos cause harms on human,animal and environment while bring economic benefit on agriculture.To date,instrumental methods(e.g.,HPLC,GC/MS)can detect these insecticides with high sensitivity and specificity but with requirements of large advanced instruments.They can not meet demands for high-throughput on-line screening.Therefore,it is very important to present a novel lateral flow immunoassay for the simultaneous detection of the pesticides.In this study,we developed a simple and rapid immunochromatography assay(ICA)for detection of fenitrorhion,and also a lateral flow immunoassay(LFIA)for the simultaneous detection of three pesticides(including imidacloprid,chlorpyrifos-methyl and isocarbophos),both of them were based on competitive immunoreactions.On the optimized condition,detection limit of this ICA is 300 ?g/L and the visual examination is 6.25 ?g/L for fenitrorhion.In contrast to previously reported LFIAs,our LFIA was based on the use of four strips.Each strip has three red channels(used to dispense different capture reagent)to detect imidacloprid,chlorpyrifos-methyl and isocarbophos respectively.Different channels on each strip were the key to multi-detection,and needed for visualand semiquantitative read-outs.Under optimized conditions,the LFIA was applied to the determination of three pesticides.The detection time was within 7 min and the detection limit of imidacloprid is 0-50 ?g/L(negative samples),and 50-200 ?g/L,200-500 ?g/L,500-2000 ?g/L and>2000 ?g/L(positive samples),the detection limits of chlorpyrifos-methyl and isocarbophos both were 0-100 ?g/L(negative samples),and 100-600 ?g/L,600-2000 ?g/L,2000-6000 ?g/L and>6000 ?h/L respectively.Furthermore,the LFIA was applied to the analysis of spiked Chinese cabbage and soil samples,validated by HPLC.