Flow method based on cloud point extraction for fluorometric determination of epinephrine in human urine

Highly selective detection of epinephrine by a "turn-off" fluorescent sensor based on N-doped carbon quantum dots

Epinephrine (EP) is a catecholamine hormone with a variety of physiological activities. Monitoring the concentration of EP in drugs, food, biological samples and cosmetics is of great significance for their quality control. Herein, a novel fluorescence sensing method was designed for the high-specificity detection of EP based on N-doped carbon quantum dots (N-CDs). The EP could interact with the fluorescent senor of N-CDs which emits blue fluorescence to produce concentration- dependent fluorescence quenching through the photo-induced electron transfer (PET). The established sensing method has good linearity in the range of 0.5-10 μM with the LOD of 0.15 μM. More importantly, it is highly selective because similar components with phenolic hydroxyl groups or primary amino groups, even norepinephrine (NEP), could not interfere with the detection. This method can provide a low-cost, rapid and simple new way for the detection of EP, and has a good application prospect in point-of-care assay and in situ test.

Promotion Effect of Palladium on BiVO4 Sensing Material for Epinephrine Detection

In this study, the Pd/BiVO4 composite was prepared by hydrothermal method as an electrochemical sensing material for epinephrine. X-ray diffraction, scanning electron microscopy, and a transmission electron microscope were used to characterize the samples. In the electrochemical detection system, cyclic voltammetry and differential pulse voltammetry were applied to measure the concentration of the epinephrine solution (0.9–27.5 µM) with the Pd/BiVO4-coated glassy carbon electrode. As a result, the oxidation peak current of Pd/BiVO4/GCE demonstrated good linearity with the epinephrine concentration. The detection limit of the epinephrine concentration by cyclic voltammetry and differential pulse voltammetry were 0.262 µM and 0.154 µM, respectively. Additionally, the proposed sensing material exhibited good reproducibility, stability, and selectivity. A plausible sensing mechanism was proposed.

Selective determination of epinephrine using electrochemical sensor based on ordered mesoporous carbon / nickel oxide nanocomposite

A nanocomposite of ordered mesoporous carbon/nickel oxide (OMC-NiO) was synthesized by hard-templating method. The nanocomposite remained ordered mesostructure and high surface area with the NiO nanocrystals embedded in the wall of the OMC. A sensitive sensor for electrochemical detection of epinephrine (EP) was developed with GCE modified by OMC-NiO nanocomposite. Cyclic voltammogram (CV) and differential pulse voltammetry (DPV) were used as the techniques to explore the electrochemical behavior of EP on OMC-NiO/GCE surface. The result showed that the electrode demonstrated better electrocatalytic performance to EP compared to that seen at OMC/GCE. Under the optimum condition, DPV measurements of the electrode response displayed a linear detection range for 8.0 × 10^-7 to 5.0 × 10^-5 M with a detection limit of 8.5 × 10^-8 M (S/N = 3). It is worth noting that the electrocatalytic redox mechanism of EP on the electrode have studied through experiments and calculations (cyclic voltammetry and molecular electrostatic potential distribution). Moreover, the electrocatalytic behavior for the oxidation of EP and uric acid (UA) on OMC-NiO/GCE surface was investigated. The result showed that the sensor can be used to selectively determinate EP in the presence of an excesses of UA. Finally, the developed sensor was successfully applied to the determination of EP in spiked human blood serum and EP injection with satisfactory results.

The Automation Technique Lab-In-Syringe: A Practical Guide

About eight years ago, a new automation approach and flow technique called "Lab-In-Syringe" was proposed. It was derived from previous flow techniques, all based on handling reagent and sample solutions in a flow manifold. To date Lab-In-Syringe has evidently gained the interest of researchers in many countries, with new modifications, operation modes, and technical improvements still popping up. It has proven to be a versatile tool for the automation of sample preparation, particularly, liquid-phase microextraction approaches. This article aims to assist newcomers to this technique in system planning and setup by overviewing the different options for configurations, limitations, and feasible operations. This includes syringe orientation, in-syringe stirring modes, in-syringe detection, additional inlets, and addable features. The authors give also a chronological overview of technical milestones and a critical explanation on the potentials and shortcomings of this technique, calculations of characteristics, and tips and tricks on method development. Moreover, a comprehensive overview of the different operation modes of Lab-In-Syringe automated sample pretreatment is given focusing on the technical aspects and challenges of the related operations. We further deal with possibilities on how to fabricate required or useful system components, in particular by 3D printing technology, with over 20 different elements exemplarily shown. Finally, a short discussion on shortcomings and required improvements is given.