Chemiluminescence and Spectrofluorimetric Methods for Determination of Fluoroquinolones: A Review

Green and inventive fluorescence approach for levodropropizine determination in human plasma

A green, rapid and sensitive fluorimetric method to quantify levodropropizine (LVP) in human plasma was exploited for the first time. The proposed method adopts LVP's intrinsic fluorescence in distilled water at a detecting emission of 345 nm following excitation at 240 nm. LVP displayed linearity across concentrations ranging from 50 to 1000 ng mL-1, with a detection limit of 0.77 ng mL-1 and a quantification limit of 2.33 ng mL-1. Thorough validation confirmed its reliability, successfully determining LVP in tablets with an average recovery of 98.64 ± 1.07 %. Furthermore, the method's applicability extended to estimate the studied drug in spiked human plasma with excellent obtained percentage recoveries (98.68 ± 1.28-100.14 ± 1.23).

Moxifloxacin Metal Complexes: Synthesis, Characterisation, Antimicrobial and Antidiabetic Activities with Docking Studies

Six new metal complexes of Fe(III), Cu(II), and Hg(II) were synthesised, i.e., three (2, 4, and 5) with moxifloxacin (mono-ligand) and the other three (1, 3 and 6) with moxifloxacin and hydrazine (biligand). These were characterised through UV-Vis, FT-IR, elemental analysis (CHN), atomic absorption spectroscopy, TGA, scanning electron microscopy (SEM), and powder XRD studies. Further, all of these compounds were screened for their antimicrobial, cytotoxic, and antidiabetic potential. The study revealed that the synthesised metal complexes possess an excellent ability to become antifungal agents compared to moxifloxacin. Additionally, the cytotoxicity of compounds 1, 3, and 4 was in the acceptable range with much better antidiabetic potential as compared to the ligand moxifloxacin. Interestingly, the α-amylase inhibition activity of complexes 1 and 3 was found very close to the standard drug acarbose. Furthermore, the computational studies also authenticate the results of the antidiabetic potential of complexes 1, 3, and 4 by presenting the necessary interactions of these compounds with their respective binding sites. The overall results indicate that the antifungal and antidiabetic ability of moxifloxacin is enhanced significantly by complexation with the given metals and the secondary ligand, thereby making it a suitable lead compound for yet another avenue of an antifungal and antidiabetic agent in the field of drug discovery and development.

Quinolone Complexes with Lanthanide Ions: An Insight into their Analytical Applications and Biological Activity

Quinolones comprise a series of synthetic bactericidal agents with a broad spectrum of activity and good bioavailability. An important feature of these molecules is their capacity to bind metal ions in complexes with relevant biological and analytical applications. Interestingly, lanthanide ions possess extremely attractive properties that result from the behavior of the internal 4f electrons, behavior which is not lost upon ionization, nor after coordination. Subsequently, a more detailed discussion about metal complexes of quinolones with lanthanide ions in terms of chemical and biological properties is made. These complexes present a series of characteristics, such as narrow and highly structured emission bands; large gaps between absorption and emission wavelengths (Stokes shifts); and long excited-state lifetimes, which render them suitable for highly sensitive and selective analytical methods of quantitation. Moreover, quinolones have been widely prescribed in both human and animal treatments, which has led to an increase in their impact on the environment, and therefore to a growing interest in the development of new methods for their quantitative determination. Therefore, analytical applications for the quantitative determination of quinolones, lanthanide and miscellaneous ions and nucleic acids, along with other applications, are reviewed here.

Hollow-fiber liquid-phase microextraction for the direct determination of flumequine in urban wastewaters by flow-injection analysis with terbium-sensitized chemiluminescence

A flow-injection analysis chemiluminescence method based on the enhancement effect of the flumequine-Tb(III) complex on the weak native emission of the Ce(IV)-Na2SO3 system has been developed for the determination of flumequine. The method includes a cleanup and preconcentration stage (750-fold) of the sample by hollow-fiber liquid-phase microextraction using an Accurel(®) Q 3/2 polypropylene hollow fiber impregnated with 1-octanol as the supported liquid membrane. The obtained 50 μL acceptor phase was injected in a 1 mM Tb(III) + 4 mM Ce(IV) in 5% v/v H2 SO4 stream and mixed with a 2 mM Na2 SO3 stream before its introduction into the flow cell. The chemiluminescence signal was linear in the 0.3-15 ng/mL range, with detection and quantitation limits of 0.1 and 0.3 ng/mL, respectively. The method allows the selective extraction and determination of flumequine in wastewater samples, using simpler and lower-cost instrumentation and with shorter extraction and analysis times than traditional high-performance liquid chromatography analysis.

Chemiluminescence detector based on a single planar transparent digital microfluidic device

We report on a compact and portable prototype of chemiluminescence detector based on a single planar single polar transparent electrowetting-on-dielectrics (EWOD) device. The coupling ground model was proposed to build the EWOD device, which could be driven under a single polar voltage. Such a design not only simplified the chip construction and control circuit, but also had the potential for the ball-like droplet to focus the fluorescence and enhance the detection sensitivity. Simulations and experiments both confirmed that the greater the contact angle, the stronger the detected optical signal, and thus the higher the sensitivity. The sensitivity of the prototype detector to H2O2 was 5.45 mV (mmol L(-1))(-1) and the detection limit was 0.01 mmol L(-1) when the contact angle of the EWOD surface was 120°. To further increase the sensitivity and decrease the detection limit, the contact angle of the EWOD device could be increased and the dark current of the photomultiplier decreased. The prototype shows potential applications as highly sensitive, cost effective and portable immuno-detectors, especially as a blood glucose monitor.

Electromembrane extraction (EME)--an easy, novel and rapid extraction procedure for the HPLC determination of fluoroquinolones in wastewater samples

For the first time, an electromembrane extraction combined with a HPLC procedure using diode array and fluorescence detection has been developed for the determination of seven widely used fluoroquinolones (FQs): marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, gatifloxacin and grepafloxacin. The drugs were extracted from acid aqueous sample solutions (pH 5), through a supported liquid membrane consisting of 1-octanol impregnated in the walls of a S6/2 Accurel® polypropylene hollow fiber, to an acid (pH 2) aqueous acceptor solution inside the lumen of the hollow fiber. The main operational parameters were optimized, and extractions were carried out in 15 min using a potential of 50 V. Enrichment factors of 40-85 have been obtained using only 15 min of extraction time versus 330 min used in a previously proposed hollow-fiber liquid-phase microextraction procedure. The procedure allows low detection and quantitation limits of 0.005-0.07 and 0.007-0.15 μg L(-1), respectively. The proposed method was successfully applied to the FQs analysis in urban wastewaters.

Highly sensitive synchronous fluorescence measurement of danofloxacin in pharmaceutical and milk samples using aluminium (III) enhanced fluorescence

A simple, rapid and sensitive constant wavelength synchronous fluorescence method is developed for the determination of danofloxacin (DAN) in pharmaceutical formulations and its residue in milk based on Al(III) enhanced fluorescence. The synchronous fluorescence intensity of the system is measured at 435 nm using ∆ λ = 80 nm and an excitation wavelength of 280 nm. A good linear relationship between enhanced fluorescence intensity and DAN concentration is obtained in the range of 3-100 ng mL(-1)(r (2) = 0.9991). The limit of detection (LOD, S/N = 3) of the present method is 0.9 ng mL(-1). The proposed method can be successfully applied to the determination of DAN in pharmaceutical formulations and in milk without serious interferences from common excipients, metal ions and other co-existing substances. The method can be used as a rapid screening to judge whether the DAN residues in milk exceed Maximum Residue Limits (MRLs) or not.