In situ photochemical synthesis of fluorescent carbon dots for optical sensing of hydrogen peroxide and antioxidants.

A new synthesis approach for obtaining fluorescent carbon dots (CDs) based on UV irradiation of carbohydrates was developed. The photochemical synthesis pathway allows the formation of water soluble CDs of analytical usefulness within one min. CDs obtained by photochemical treatment from the sucrose/NaOH/poly(ethylene glycol) system are monodisperse with an average size of 8 nm as determined by transmission electron microscopy.

Facile preparation of an immobilized surfactant-free palladium nanocatalyst for metal hydride trapping: a novel sensing platform for TXRF analysis.

In this work, a simple route for the synthesis of surfactant-free immobilized palladium nanoparticles (Pd NPs) and their use as effective nanocatalysts for metal hydride decomposition is described. A mixture of ethanol : water was used as the reducing agent. Ethanol was added in a large excess to reduce the ionic Pd and stabilize the obtained Pd NPs.

In situ building of a nanoprobe based on fluorescent carbon dots for methylmercury detection.

A new fluorescent assay based on in situ ultrasound-assisted synthesis of carbon dots (CDs) as optical nanoprobes for the detection of methylmercury has been developed. Application of high-intensity sonication allows simultaneous performance of the synthesis of fluorescent CDs within the analytical time scale and the selective recognition of the target analyte. Microvolume fluorospectrometry is applied for measurement of the fluorescence quenching caused by methylmercury.

Solid-state chemiluminescence assay for ultrasensitive detection of antimony using on-vial immobilization of CdSe quantum dots combined with liquid-liquid-liquid microextraction.

On-vial immobilized CdSe quantum dots (QDs) are applied for the first time as chemiluminescent probes for the detection of trace metal ions. Among 17 metal ions tested, inhibition of the chemiluminescence when CdSe QDs are oxidized by H2O2 was observed for Sb, Se and Cu. Liquid-liquid-liquid microextraction was implemented in order to improve the selectivity and sensitivity of the chemiluminescent assay.

Quantum dots confined in an organic drop as luminescent probes for detection of selenium by microfluorospectrometry after hydridation: study of the quenching mechanism and analytical performance.

Following a preliminary work (Costas-Mora, I.; Romero, V.; Pena-Pereira, F.

Rapid screening of polycyclic aromatic hydrocarbons (PAHs) in waters by directly suspended droplet microextraction-microvolume fluorospectrometry.

A rapid and simple screening method for polycyclic aromatic hydrocarbons (PAHs) in water samples is proposed. The method is based on the combination of a miniaturized sample preparation approach, namely, directly suspended droplet microextraction (DSDME), and microvolume fluorospectrometry. Benzo[a]pyrene (BaP) was used as the model compound for screening purposes.

Ion pair-based liquid-phase microextraction combined with cuvetteless UV-vis micro-spectrophotometry as a miniaturized assay for monitoring ammonia in waters.

A miniaturized method based on liquid-phase microextraction (LPME) in combination with microvolume UV-vis spectrophotometry for monitoring ammonia in waters is proposed. The methodology is based on the extraction of the ion pair formed between the blue indophenol obtained according to the Berthelot reaction and a quaternary ammonium salt into a microvolume of organic solvent. Experimental parameters affecting the LPME performance such as type and concentration of the quaternary ammonium ion salt required to form the ion pair, type and volume of extractant solvent, effect of disperser solvent, ionic strength and extraction time, were optimized.

Quantum dot-based headspace single-drop microextraction technique for optical sensing of volatile species.

Core-shell CdSe/ZnS quantum dots (QDs) dispersed in a droplet of organic solvent have been applied for the first time as luminescent probes for the selective detection of volatile species. Luminescence quenching caused by volatile species was examined after their trapping onto a drop using the headspace single-drop microextraction (HS-SDME) approach along with microvolume fluorospectrometry. The novel method is characterized by low reagent and sample consumption, especially regarding QDs, a reduction about 500-fold for each analysis being attained in comparison with luminescent probing in aqueous phase using conventional luminescence spectrometers with 1 cm quartz cells for measurement.