| Microfluidic chip indicats advantages in high efficiency and time saving,and thus becomes a hot topic in analytical researches.Due to urgent demands for high-throughput and automated analysis in biochemical applications.We tried to establish a microfluidic functional chip coupled with mass spectrometry.And based on this platform,three researches were taken as follows:1.Firstly,we employed photolithography to prepare an automated controlling electrospray microfluidic chip.The chip consist of five major functional areas,including drug gradient zone,reaction zone,microvalve controlling zone,waste outlet and electrospray.To evaluate the automated switching in the integrated microvalve,we used fluorescence chemical(RhB)and deionized water to observe fluorescent images under a microscope.The results showed that expected gradient concentration of solution was observed,and microvalve could control the fluid flow direction successfully within a flow rate rang(0-5 μL/min).In addition,ion intensity changes of solution were investigated online based on the proposed platform.The results showed that a series of samples with gradient concentrations could be detected in a single cycle(20 min),and their ion intensities increased in a stepwise manner(0、3.25×105、10.5×105、2.10×106).Preceding results showed that this analytical platform was relatively reliable,and with decent reproducibility and stability,which made it available in high-throughput automated drug evalution.2.Based on constructed platform,we evaluated inhibitory effects of 10 pesticides,including chlorpyrifos and DDD on acetylcholinesterase activity,and obtained median lethal concentration(LC50)correspondingly.In its analysis process,pesticide solutions with gradient dilutions were generated and then mixed with enzyme solution.Subsequently,pesticides inhbited enzyme,which react with substrate with microvalves,all mixed solutions were sequently injected and their ion intensity of product(TCh)was monitored by mass spectrometry.Based on the data,we found that seven organophosphorus pesticides such as chlorpyrifos had significantly inhibited AChE,and their LC50 range from 0.88 to 2.2×102 ppm;while other three nonorganophosphorus pesticide had little influence on AChE(LC50>500 ppm).3.Due to the low concentration of target analytes in related application,complex sample pretreatment are unavailable.Therefore,we developed an automated cycle extraction chip coupled with.In this analysis platform,flow direction of sample and eluent was controlled by microfluidic microvalve.Compared with traditional extraction methods,this analytical platform can achieve repeated enrichment and extraction(all 20 times)in 30 s.we evaluated its performance by enriching chemicals such as chlorantraniliprofen before and after extraction.The results showed that enrichment factor of sample(1μL)was 2.1 to 6.6,proving the feasibility of the constructed automated extraction methods for traces analytes.In addition,we also achieved actual sample analysis of quinacridone and detected its pesticide residues(0.68 ppm)in sorghum. |
