THE STUDY ON NOVEL MICROELECTRODE ARRAY CHIPS FOR THE DETECTION OF HEAVY METALS IN WATER POLLUTION

Qualitative and quantitative analysis of trace heavy metals in aqueous environment are rapidly assuming significance along with the rapid development of industry.In this paper,gold microelectrode array(MEA)plated with mercury film was used for simultaneous voltammetric detection of zinc,cadmium,lead and copper ions in water.The electrochemical behavior and the actual surface area of the MEA were investigated by cyclic voltammetry in K_(3)[Fe(CN)_(6)].Electrochemical impedance spectrum(EIS)was utilized to examine the deposition of mercury on the electrode surface.Based on anodic stripping voltammetry,mercury film
Au MEA was applied to the detection of heavy metals in artificial analyte,where good calibrate linearity was obtained for cadmium,lead and copper ions,but with zinc exhibiting poor linearity.

Detection and quantification of Pb and Cr in oysters using laser-induced breakdown spectroscopy

The quantitative determination of heavy metals in aquatic products is of great importance for food security issues.Laser-induced breakdown spectroscopy(LIBS)has been used in a variety of foodstuff analysis,but is still limited by its low sensitivity when targeting trace heavy metals.In this work,we compare three sample enrichment methods,namely drying,carbonization,and ashing,for increasing detection sensitivity by LIBS analysis for Pb and Cr in oyster samples.The results demonstrate that carbonization can remove a significant amount of the contributions of organic elements C,H,N and O;meanwhile,the signals of the metallic elements such as Cu,Pb,Sr,Ca,Cr and Mg are enhanced by3–6 times after carbonization,and further enhanced by 5–9 times after ashing.Such enhancement is not only due to the more concentrated metallic elements in the sample compared to the dried ones,but also the unifying of the matter in carbonized and ashed samples from which higher plasma temperature and electron density are observed.This condition favors the detection of trace elements.According to the calibration curves with univariate and multivariate analysis,the ashing method is considered to be the best choice.The limits of detection of the ashing method are 0.52 mg kg-1 for Pb and0.08 mg kg-1 for Cr,which can detect the presence of heavy metals in the oysters exceeding the maximum limits of Pb and Cr required by the Chinese national standard.This method provides a promising application for the heavy metal contamination monitoring in the aquatic product industry.

Sign Response Mechanism of TCA Self-assembled Fluorescence Probe for Cu^2＋ Detection： FRET Evidence by DFT

A new type of self-assembled molecule ON-OFF fluorescence probe for toxic transition metal ions, made up of thiacalix[4]arene, micelle and fluorescence group, has been studied by DFT/TDDFT method combined with experiment spectra. Since the mechanism of the optical quenching signal response of such self-assembled micelle probe has always been a controversial issue of uncertainty, the spatial construction and geometric structures of the functional units of probe in the Cu2＋ ion detecting process were calculated and the mechanism was investigated by the molecular transition orbital pairs method to explore the origination of ON-OFF fluorescence sign response. The results presented that the signal response mechanism of the micelle probe is ascribed to F？rster resonance energy transfer（FRET） which provides new sights different from most of the conclusions by the related research work reported.

Fluorogenic detection of mercury ion in aqueous environment using hydrogel-based AIE sensing films

A“turn-on”fluorescent sensing strategy was developed for ultrasensitive detection of heavy metal mercury ion(Hg2+)directly in water.It utilized an aqueous soluble aggregation-induced emission(AIE)-active probe,named 1,1,2,2-tetrakis(4-(1Htetrazol-5-yl)phenyl)ethene(TPE-4TA),composing of a luminescent tetraphenylene core and multiple anionic tetrazolate spawns.The probe retained dark when molecularly dissolved in water.However,mercury ions can ligate with multiple tetrazolate groups to form infinite coordination polymer particles spontaneously,thus inducing a fluorogenic AIE response for in situ analysis.Moreover,by embedding this AIE sensing molecules in a hydrophilic polyvinyl alcohol substrate,the resulting hydrogel film allowed in situ detection of Hg^(2+)on a laser-induced fluorescence analysis setup in aqueous environment.This strategy worked effectively in common aqueous environments with pH from 4 to 7.5 and showed high sensitivity(limit of detection down to 0.38 ppb/1.9 nM),good selectivity and a wide linearity range for quantification.This work may lead to a reliable and promising platform for on-site environmental water analysis.