Rapid screening of 420 pesticide residues in fruits and vegetables using ultra high performance liquid chromatography combined with quadrupole-time of flight mass spectrometry

A new method for screening and identification 420 pesticide residues in fruits and vegetables by ultra-performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry(UPLC-Q-TOF/MS)were developed.The samples were extracted with acetonitrile/acetic acid(99:1,V/V),and clean-up by SinChERS-Nano(single-step,cheap,effective,rugged,safe,nano)column,determined by UPLC-Q-TOF/MS.The accurate mass database and MS/MS database which contains 420 pesticides were established,the automatic retrieval of detection results was carried on according to the accurate mass,retention time,isotope ratio,ion fragment information,and so on.Method verification was performed on leeks samples.The results showed that 420 pesticides had good linearity in the range of 0.1-100μg/L,and the correlation coeffificients(R2)was greater than 0.990.The limits of detections(LODs)and limits of quantifications(LOQs)of 420 pesticides were in range of 0.05-2.0 and 0.1-5.0μg/L,respectively.The average spike recoveries at 3 levels were 70.1%to 119.7%,and the relative standard deviations(RSD)were lower than 20%(n=6).With this method,a survey of pesticide residues was conducted for 110 samples of 10 different fruits and vegetables,which provided scientific data for ensuring pesticide residue safety of the fruits and vegetables consumed daily by the public.This method was simple,sensitive and accurate,and could be used for rapid screening of 420 pesticide residues in fruits and vegetables.

Adsorption characteristics of a novel ceramsite for heavy metal removal from stormwater runoff

Urban sediments have rapidly increased in recent years around the world,and their effective management has become an important problem.To remove heavy metals from stormwater runoff and use sediments as a resource,a novel ceramsite was developed using sewer pipe sediments(SPS),river bed sediments(RBS),urban water supply treatment sludge(WSTS),and wastewater treatment plant excess sludge(WWTS).The optimal composition was determined based on the Brunauer–Emmett–Teller specific surface area and an orthogonal test design.The adsorption characteristics of the novel ceramsite for dissolved heavy metals(Cu^(2+)and Cd^(2+)) were investigated through adsorption isotherms and kinetic experiments at(25±1)℃.Both Cu^(2+) and Cd^(2+) were effectively removed by the novel ceramsite,and their equilibrium adsorption was 4.96 mg·g^(-1) and 3.84 mg·g^(-1),respectively.Langmuir isotherms and a pseudo-first-order kinetic equation described the adsorption process better than other techniques.Characterization analysis of the ceramsite composition before and after heavy metal adsorption showed that the Cu^(2+) and Cd^(2+) contents in the ceramsite increased after adsorption.The results revealed that adsorption is both a physical and chemical process,and that ceramsite can be used as a bioretention medium to remove heavy metals from stormwater runoff while simultaneously converting problematic urban sediments into a resource.

“鱼”乐圈大揭秘

介绍了化学与生活中养鱼、卖鱼、吃鱼之间的关系,养鱼以鱼类生存环境入手解释鱼塘中的氮循环过程,卖鱼以“鱼浮灵”为切入口,让人们感受食品安全与化学的关联,吃鱼则从化学角度解释了鱼腥味的来源。对生活现象做出科学解释,加强人们的化学生活化意识,帮助人们树立正确的化学科学观,启发青少年学会综合利用所学知识解释生活现象,表明生活离不开化学,化学离不开生活。

A 1.2 V,3.1%3σ-accuracy thermal sensor analog front-end circuit in 12 nm CMOS process

This paper presents a 1.2 V high accuracy thermal sensor analog front-end circuit with 7 probes placed around the microprocessor chip.This analog front-end consists of a BGR(bandgap reference),a DEM(dynamic element matching)control,and probes.The BGR generates the voltages linear changed with temperature,which are followed by the data read out circuits.The superior accuracy of the BGR’s output voltage is a key factor for sensors fabricated via the FinFET digital process.Here,a 4-stage folded current bias structure is proposed,to increase DC accuracy and confer immunity against FinFET process variation due to limited device length and low current bias.At the same time,DEM is also adopted,so as to filter out current branch mismatches.Having been fabricated via a 12 nm FinFET CMOS process,200 chips were tested.The measurement results demonstrate that these analog front-end circuits can work steadily below 1.2 V,and a less than 3.1%3σ-accuracy level is achieved.Temperature stability is 0.088 mV/℃across a range from-40 to 130℃.