ABSTRACT
The realistic implementation of electrochemistry into bacterial biosynthesis monitoring programs has always been a challenging task. In this study, two simple, rapid, selective, and sensitive potentiometric sensors were developed and optimized for quantitative analysis of the extremolyte / osmoprotector ectoine (ECT) in halophilic bacterial cultures and also in its related pharmaceutical products. The developed sensors were a Polyvinyl chloride membrane sensor (ECT-PVC) and a coated graphite sensor (ECT-CG). They were established based on the ion association complex of ectoine cation with phosphotungstic acid (ECT-PTA) counter anion as ion exchange site using dioctyl-phthalate (DOP) as a solvent mediator or plasticizer. The sensors exhibited fast, stable, selective, and linear Nernstian responses over a broad range of concentrations ranging from 1 × 10-5 to 1 × 10-2 M of the studied drug. The developed sensors were optimized and cross-validated with a proposed HPLC method according to ICH guidelines. The proposed methods were successfully employed to quantify the studied drug in three different types of halophilic bacterial cultures and in an ectoine nasal spray pharmaceutical product. The selected bacteria species were Chromohalobacter salexigens, Halobacillus halophilus, and Halomonas elongata. The proposed methods were statistically compared with the reported methods, demonstrating no significant difference with respect to accuracy and precision. Greenness and environmental impact were also evaluated for the proposed procedures, verifying that they were excellent green and eco-friendly analytical methods.
Subject(s)
Amino Acids, Diamino , Pharmaceutical Preparations , Polyvinyl Chloride/chemistry , Potentiometry/methodsABSTRACT
Three eco-friendly and cost-effective analytical methods were developed and optimized for quantitative analysis of some veterinary drug residues in production wastewater samples. The studied drugs were ivermectin, rafoxanide and sulfadimidine. A solid-phase extraction procedure was employed using Bond Elut C18 cartridges, prior to analysis. The first method was a chemometric approach called multivariate curve resolution - alternating least squares (MCR-ALS). A calibration model was developed and several figures of merit (RMSEP, SEP, bias, RE%) were calculated. The second method was a thin layer chromatography followed by densitometric measurements at 245 nm. The separation was performed using silica gel 60 F254 plates and ethyl acetate : acetonitrile : toluene : ammonia (20 : 3 : 2 : 1, by volume) as a developing system. The third method was a high performance liquid chromatographic separation on HiQsil C18 HS column with UV detection at 245 nm. The mobile phase consisted of acetonitrile : methanol : water (60 : 25 : 15, by volume), with a flow rate of 1.5 mL min-1. The proposed methods were validated according to ICH guidelines. The described procedures were applied to quantify the studied drug residues in synthetic and real industrial wastewater samples. The proposed methods were statistically compared with the official and the reported methods, showing no significant difference with respect to accuracy and precision at P = 0.05.
ABSTRACT
The present study investigates a synergistic adsorption/photodegradation technique catalyzed by a pectin/chitosan/zinc oxide (Pec/CS/ZnO) nanocomposite for the removal of carbamazepine (CBZ) in aqueous solutions under direct sunlight. The Pec/CS/ZnO nanocomposite was prepared by an inotropic gelation method and was characterized using different techniques. The adsorption/photocatalytic activity of the Pec/CS/ZnO nanocomposite for the remediation of CBZ was optimized using Box-Behnken design under response surface methodology. The examined parameters included the amount of Pec/CS/ZnO nanocomposite (0.25-0.75 g L-1), pH (4-10), and run time for adsorption/photo-irradiation (1-5 hours). The efficiency of CBZ degradation was calculated in terms of changes in CBZ concentration using a validated chromatographic assay. The optimum conditions for the remediation of CBZ were 0.5 g L-1 Pec/CS/ZnO nanocomposite, pH 4, and 3 hour run time. Under such conditions, the degradation efficiency of 10 mg L-1 CBZ was found to be 69.5% with a rate constant (k) of 0.00737 min-1 and half-life time of 94 min. The efficiency of the Pec/CS/ZnO nanocomposite for CBZ remediation was found to be stable and consistent after three cycles of reuse. The presence of other pharmaceutical contaminants such as acetaminophen in wastewater samples was also investigated. The efficiency of CBZ degradation was not significantly affected by the addition of acetaminophen in a 0-15 mg L-1 concentration range which confirmed the selectivity and efficiency of the proposed method for CBZ degradation and removal.