Fluorescent kinetics combined with fourth-order calibration for the determination of diclofenac sodium in environmental water

Development of a 3D disposable device for the electrochemical determination of diclofenac in different matrices

In this work, the development of a disposable electrochemical device (US$ 0.02 per electrode) using a 3D printed support (3Ds) of acrylonitrile butadiene styrene (ABS) insulating filament with a composite material (CM) based on graphite and nail polish, immobilized on the support surface, was described for the electrochemical determination of diclofenac (DCF). The device was compared to the commercial glassy carbon electrode (GCE) and showed superior electroanalytical performance with approximately 1.8-fold higher current density. Additionally, an amperometric method for DCF determination in tap water, synthetic urine, and pharmaceutical formulation samples with the proposed electrode, using a flow injection analysis (FIA-AD) system, was developed. The optimized method presented excellent detectability (LOD = 0.47 µmol L^-1), with excellent precision and accuracy (relative standard deviation < 5.6%) and percent recovery from spiked samples ranging from 89 to 106%. In addition, the sensor showed optimal analytical frequency with approximately 108 injections per hour, which demonstrates the potential of this system using the proposed disposable electrode for implementation in routine analysis and quality control with good selectivity and sensitivity.

Sensitive Derivative Synchronous and Micellar Enhanced Ecofriendly Spectrofluorimetric Methods for the Determination of Atenolol, Diclofenac, and Triclosan in Drinking Tap Water

BACKGROUND

Nowadays, emergence of unexpected contaminants in drinking water is a challenging environmental problem facing humanity.

OBJECTIVE

Two eco-friendly spectrofluorimetric methods were proposed for the determination of three unexpected contaminants in drinking tap water.

METHODS

The first method is first derivative synchronous spectrofluorimetric method which was developed for simultaneous determination of atenolol (ATN) and diclofenac (DCF) without prior separation at Δλ = 70 nm and at Δλ = 80 nm for ATN and DCF, respectively. The second method was based on using sodium dodecyl sulfate (SDS) as fluorescent enhancer of triclosan (TCS) native fluorescence. TCS exhibits enhanced fluorescence at λ emission = 600 nm upon excitation at λ excitation = 299.4 nm. Solid phase extraction was carried out in both methods.

RESULTS

Linear calibration curves were obtained in concentration range of (4-3000 ng/mL) for ATN and (4-2000 ng/mL) for DCF, by measuring first derivative signal of fluorescence at 300 nm and 375.2 nm, respectively. TCS exhibits linear range (0.1-1 ng/mL) at 600 nm. Mean percentage recoveries were 101.04 ± 0.571, 99.66 ± 1.443, and 99.73 ± 0.566 for ATN, DCF, and TCS, respectively.

CONCLUSIONS

Validation of both methods were performed according to the International Conference on Harmonization guidelines. Results obtained were statistically compared with published methods and no significant differences were found. The proposed methods' greenness is evaluated using analytical Eco-scale and Green Analytical Procedure Index. A greenness comparison with previously published methods has been performed.

HIGHLIGHTS

Both methods were found to be eco-friendly and were successfully applied for the determination of the emerging contaminants in drinking tap water.

A capillary-based fluorimetric platform for the evaluation of glucose in blood using gold nanoclusters and glucose oxidase in the ZIF-8 matrix

A capillary-based fluorimetric analysis method was developed for probing glucose (Glu) in blood using Glu oxidase-anchored gold nanoclusters (GOD-AuNCs) and the ZIF-8 matrix. AuNCs were attached with GOD to be further encapsulated into the ZIF-8 matrix through the protein-mediated formation route. The resulting GOD-AuNCs@ZIF-8 nanocomposites could present the AuNC-improved catalysis of GOD and ZIF-8-improved environmental stability. The ZIF-8-enhanced fluorescence intensity of AuNCs could also be expected. Moreover, a capillary-based fluorometric platform was constructed for sensing Glu by coating the capillaries first with GOD-AuNCs and then the ZIF-8 matrix. Herein, Glu was introduced through the self-driven sampling to trigger the GOD-catalyzed production of hydrogen peroxide, which could induce the fluorescence quenching rationally depending on the Glu concentrations. The developed fluorimetric method could allow for the rapid and simple detection of Glu with the concentrations linearly ranging from 5.0 μM to 2.5 mM. Besides, the feasibility of practical applications was demonstrated by the evaluation of Glu in blood showing the recoveries of 96.2%-103.4%. Importantly, the proposed design of the capillary-based fluorimetric platform by the synergetic combination of catalysis-specific recognition and fluorescence signaling may open a new door toward extensive applications in the biological sensing, catalysis, and imaging fields.

Four- and five-way excitation-emission luminescence-based data acquisition and modeling for analytical applications. A review

The latest advances in both theory and experimental procedures on third-order/four-way and fourth-order/five-way calibration methods are discussed. This report is focused on excitation-emission (fluorescence and phosphorescence) matrices generation, employing different variables as the third data mode (time retention in chromatography, pH gradient, fluorescence/phosphorescence lifetime, kinetics, or other chemical treatments). Fully capitalizing on the second-order advantage, it has been possible to develop appealing analytical applications in spite of the complexity of the data. Extraction of the significant chemical information about the system under study as well as the individual abundance of the contributing constituents after proper higher-order data decomposition has allowed to analytical researchers performing quantitative analysis of complex samples. The experimental works reported up to the present are introduced and discussed in order to illustrate concepts. Throughout this work, the analytical benefits achieved by modeling third- and fourth-order data are exposed, attempting to contribute to the ongoing debate in the chemometric community regarding the existence and the true nature of the third-order advantage.