Dispersive solid-phase extraction followed by vortex-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet for the determination of benzoylurea insecticides in soil and sewage sludge.

A novel dispersive solid-phase extraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in soil and sewage sludge samples before high-performance liquid chromatography with ultraviolet detection. The analytes were first extracted from the soil and sludge samples into acetone under optimized pretreatment conditions. Clean-up of the extract was conducted by dispersive solid-phase extraction using activated carbon as the sorbent.

Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent.

Determination of 3,5,6-trichloro-2-pyridinol, phoxim and chlorpyrifos-methyl in water samples using a new pretreatment method coupled with high-performance liquid chromatography.

A novel low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with the solidification of floating organic droplet method coupled with high-performance liquid chromatography was developed for the determination of 3,5,6-trichloro-2-pyridinol, phoxim and chlorpyrifos-methyl in water samples. In this method, the addition of a surfactant could enhance the speed of the mass transfer from the sample solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous by the vortex process.

Vortex-assisted liquid-liquid microextraction using a low-toxicity solvent for the determination of five organophosphorus pesticides in water samples by high-performance liquid chromatography.

Vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with UV detection was applied to determine Isocarbophos, Parathion-methyl, Triazophos, Phoxim and Chlorpyrifos-methyl in water samples. 1-Bromobutane was used as the extraction solvent, which has a higher density than water and low toxicity. Centrifugation and disperser solvent were not required in this microextraction procedure.

Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution.

[Study of the epimers of dexamethasone sodium phosphate and betamethasone sodium phosphate by FTIR, FT-Raman and SERS].

Abstract Infrared spectroscopy (FTIR), normal Raman spectroscopy (NRS) of the solids and saturated solutions and surface-enhanced Raman spectroscopy (SERS) on the silver colloidal substrate were reported. The vibrational modes of each group were analyzed, and the enhanced peaks were assigned and compared. The results showed that the major differences between the epimers were the frequency of the CH3 asymmetric stretching vibration and symmetric in-plane deformation vibration of them.

A carbon dots-based fluorescence turn-on method for DNA determination.

In the present work, we found that methylene blue (MB) caused an efficient quenching of the fluorescence of carbon dots (CDots). However, as ct-DNA was added, the fluorescence of CDots was restored reversibly. Under the experimental conditions, CDots were excellent electron donors.

Study on the resonance Rayleigh scattering and resonance non-linear scattering spectra of ion-association complexes of [PdI4](2-)-protein systems and their analytical applications.

In an acid medium solution, proteins such as bovine serum albumin, human serum albumin, ovalbumin, hemoglobin, lysozyme, gamma-globulin, alpha-chymotrypsin and papain could react with [PdI(4)](2-) by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes. As a result, the resonance Rayleigh scattering (RRS) and resonance nonlinear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities were enhanced greatly and new scattering spectra appeared. The maximum scattering peaks of RRS, SOS and FDS were at 367, 720 and 370 nm, respectively.

A Novel Nonenzymatic Hydrogen Peroxide Sensor Based on a Polypyrrole Nanowire-Copper Nanocomposite Modified Gold Electrode.

A novel nonenzymatic hydrogen peroxide (H2O2) sensor has been fabricated by dispersing copper nanoparticles onto polypyrrole (PPy) nanowires by cyclic voltammetry (CV) to form PPy-copper nanocomposites on gold electrodes. Scanning electron microscopy (SEM) was used to characterize the morphologies of the PPy nanowires and the PPy-copper nanocomposite. The reactivity of the PPy-copper nanocomposite towards H2O2 was characterized by cyclic voltammetry and chronoamperometry.