Inverse design of chiral functional films by a robotic AI-guided system.

Artificial chiral materials and nanostructures with strong and tuneable chiroptical activities, including sign, magnitude, and wavelength distribution, are useful owing to their potential applications in chiral sensing, enantioselective catalysis, and chiroptical devices. Thus, the inverse design and customized manufacturing of these materials is highly desirable. Here, we use an artificial intelligence (AI) guided robotic chemist to accurately predict chiroptical activities from the experimental absorption spectra and structure/process parameters, and generate chiral films with targeted chiroptical activities across the full visible spectrum. The robotic AI-chemist carries out the entire process, including chiral film construction, characterization, and testing. A machine learned reverse design model using spectrum embedded descriptors is developed to predict optimal structure/process parameters for any targeted chiroptical property. A series of chiral films with a dissymmetry factor as high as 1.9 (gabs ~ 1.9) are identified out of more than 100 million possible structures, and their feasible application in circular polarization-selective color filters for multiplex laser display and switchable circularly polarized (CP) luminescence is demonstrated. Our findings not only provide chiral films with the highest reported chiroptical activity, but also have great fundamental value for the inverse design of chiroptical materials.

Determination of in a sequential injection lab-on-valve system with voltammetric detection using a modified electrode.

A stripping voltammetric assay using a morin modified electrode in a sequential injection lab-on-valve system was developed for the determination of trace amounts of cadmium. The sample and reagent arrangements were achieved by a syringe pump. The target metal ions were accumulated on the morin modified glassy carbon electrode surface, and the quantification step was performed by subsequent anodic stripping voltammetry. The key experimental variables relevant to the voltammetric measurement procedure were optimized. For a 100 s preconcentration time, a linear calibration curve was obtained for a concentration range of 1 to 125 µg L-1 with a detection limit of 0.41 µg L-1. The analytical use of the established method was assessed by applying it to the determination of cadmium in real samples and carrying out recovery experiments. The method was subsequently validated by comparing the results with those given by ICP-OES.

Determination of cadmium with a sequential injection lab-on-valve by anodic stripping voltammetry using a nafion coated bismuth film electrode.

This work exploited a sequential injection lab-on-valve (LOV) system for the determination of cadmium by anodic stripping voltammetry (ASV). A miniaturized electrochemical flow cell (EFC) was fabricated in LOV, in which a nafion coated bismuth film electrode was used as working electrode. The cadmium was electrodeposited on the electrode surface in bismuth solution, and measured with the subsequential stripping scan. Under optimal conditions, the proposed system responded linearly to cadmium concentrations in a range 2.0-100.0 microg L(-1). The detection limit of this method was found to be 0.88 microg L(-1). By loading a sample volume of 800 microL, a sampling frequency of 22 determinations h(-1) was achieved. The repeatability expressed as relative standard derivation (R.S.D.) was 3.65% for 20 microg L(-1) cadmium (n=11). The established method was applied to analysis of trace cadmium in environmental water samples and the spiked recoveries were satisfactory.

An electrochemical assay for the determination of Se (IV) in a sequential injection lab-on-valve system.

A sequential injection lab-on-valve (LOV) unit, integrating a miniaturized electrochemical flow cell (EFC), has been constructed for the determination of trace amounts of Se (IV) by employing cathodic stripping voltammetry (CSV) technique. The procedure is carried out on a mercury film coated glassy carbon electrode. The analyte solution and electrolyte solution were continuously aspirated and merged in the holding coil (HC) by using a single syringe pump, which were afterwards pushed into the EFC, where the peak current was generated during the subsequent deposition/stripping procedure and measured as the basis of quantification. Assay parameters were optimized in order to achieve the best analytical performance, including mercury film preparation, supporting electrolyte composition, deposition potential and deposition time, and flow variables in the LOV. By loading a sample volume of 500 microL, a linear calibration graph was derived within 1-600 microg L(-1), and a detection limit (3b) of 0.11 microgL(-1) was achieved along with a sampling frequency of 20 h(-1). By integrating the EFC into the LOV unit, the assembling system not only minimized the sample/reagent consumption and waste generation, but also enhanced the sampling frequency. The work itself extended the applications of electrochemical detection techniques and provided a good platform for Se (IV) electrochemical analysis.

On-line coupling of sequential injection lab-on-valve to differential pulse anodic stripping voltammetry for determination of Pb in water samples.

Sequential injection lab-on-valve (LOV) was first proposed for analyzing ultra-trace amounts of Pb using differential pulse anodic stripping voltammetry (DPASV) with a miniaturized electrochemical flow cell fabricated in the LOV unit. Deposition and stripping processes took place between the renewable mercury film carbon paste electrode and sample solution, the peak current was employed as the basis of quantification. The mercury film displayed a long-term stability and reproducibility for at least 50 cycles before next renewal, the properties of integrated miniature LOV unit not only enhanced the automation of the analysis procedure but also declined sample/reagent consumption. Potential factors that affect the present procedure were investigated in detail, i.e., deposition potential, deposition time, electrode renewable procedure and the volume of sample solution. The practical applicability of the present procedure was demonstrated by determination of Pb in environmental water samples.