Determination of phenacetin and salophen analgetics in solid binary mixtures with caffeine by infrared linear dichroic and Raman spectroscopy

Synchronous analysis of acetaminophen, codeine, and caffeine in human fluids employing graphite screen-printed electrodes

A facile electrochemical approach is proposed for the synchronous determination of acetaminophen (ACP), codeine (COD) and caffeine (CAF) utilizing unmodified screen-printed electrodes (SPEs). The determination of ACP, COD and CAF has been explored across different supporting electrolytes including sulfuric acid (H2SO4), hydrochloric acid (HCl), phosphoric acid (H3PO4) and Briton Robinson (B.R) buffer solutions. It was found that a 0.05 mol L-1 sulfuric acid solution is an optimal supporting electrolyte utilized for voltammetric analysis of ACP, COD, and CAF with improved sensitivity, stability, and reproducibility. The electro-analytical sensing of ACP, COD and CAF was investigated using SPEs within linear concentration ranges of 3.0-35.0 μmol L-1, 10-160 μmol L-1 and 10-160 μmol L-1 and revealed competitively low limits of detection (3S/N) of 0.9, 4.8 and 6.3 μmol L-1 for ACP, COD and CAF, respectively. The results indicated the possibility of such a simple and quick electroanalytical protocol for online monitoring of pharmaceutical formulations comprising ACP, COD, and CAF drugs in human fluids with satisfactory recovery.

Direct Quantification of Drug Loading Content in Polymeric Nanoparticles by Infrared Spectroscopy

Nanotechnology has enabled the development of novel therapeutic strategies such as targeted nanodrug delivery systems, control and stimulus-responsive release mechanisms, and the production of theranostic agents. As a prerequisite for the use of nanoparticles as drug delivery systems, the amount of loaded drug must be precisely quantified, a task for which two approaches are currently used. However, both approaches suffer from the inefficiencies of drug extraction and of the solid-liquid separation process, as well as from dilution errors. This work describes a new, reliable, and simple method for direct drug quantification in polymeric nanoparticles using attenuated total reflection Fourier transform infrared spectroscopy, which can be adapted for a wide variety of drug delivery systems. Silk fibroin nanoparticles and naringenin were used as model polymeric nanoparticle carrier and drug, respectively. The specificity, linearity, detection limit, precision, and accuracy of the spectroscopic approach were determined in order to validate the method. A good linear relation was observed within 0.00 to 7.89% of naringenin relative mass with an R2 of 0.973. The accuracy was determined by the spike and recovery method. The results showed an average 104% recovery. The limit of detection and limit of quantification of the drug loading content were determined to be 0.3 and 1.0%, respectively. The method's robustness is demonstrated by the notable similarities between the calibrations carried out using two different equipment setups at two different institutions.

Uranyl-water-containing complexes: solid-state UV-MALDI mass spectrometric and IR spectroscopic approach for selective quantitation

Since primary environmental concept for long storage of nuclear waste involved assessment of water in uranium complexes depending on migration processes, the paper emphasized solid-state matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) and IR spectroscopic determination of UO2(NO3)2·6H2O; UO2(NO3)2·3H2O, α-, β-, and γ-UO3 modifications; UO3·xH2O (x = 1 or 2); UO3·H2O, described chemically as UO2(OH)2, β- and γ-UO2(OH)2 modifications; and UO4·2H2O, respectively. Advantages and limitation of vibrational spectroscopic approach are discussed, comparing optical spectroscopic data and crystallographic ones. Structural similarities occurred in α-γ modifications of UO3, and UO2(OH)2 compositions are analyzed. Selective speciation achieved by solid-state mass spectrometry is discussed both in terms of its analytical contribution for environmental quality assurance and assessment of radionuclides, and fundamental methodological interest related the mechanistic complex water exchange of UO3·H2O forms in the gas phase. In addition to high selectivity and precision, UV-MALDI-MS, employing an Orbitrap analyzer, was a method that provided fast steps that limited sample pretreatment techniques for direct analysis including imaging. Therefore, random and systematic errors altering metrology and originating from the sample pretreatment stages in the widely implemented analytical protocols for environmental sampling determination of actinides are significantly reduced involving the UV-MALDI-Orbitrap-MS method. The method of quantum chemistry is utilized as well to predict reliably the thermodynamics and nature of U-O bonds in uranium species in gas and condensed phases.

Voltammetric determination of caffeine in beverage samples on bare boron-doped diamond electrode

A sensitive and selective electrochemical method for the caffeine determination using bare boron-doped diamond electrode was developed. It was found that caffeine provided highly reproducible and well-defined irreversible oxidation peak at very positive potential. The effects of supporting electrolyte, pH and scan rate on the voltammetric response of caffeine oxidation were studied to select the optimum experimental conditions. Linear response of peak current on the concentration in the range from 4×10(-7) to 2.5×10(-5)M, good repeatability (RSD of 2.1%) and detection limit of 1.5×10(-7)M without any chemical modifications and electrochemical surface pretreatment were evaluated. The effect of possible interferents appeared to be negligible which evidently proved very good selectivity. The proposed method was successfully applied for the caffeine determination in commercially available beverage samples, with results in a close statistical agreement to those declared by manufacturer and HPLC used as independent method.

Utilization of electrochemical methods in determination of trace elements in beverages

Electrochemical methods have many inherent advantages such as simplicity, low cost and amenability to miniaturization. A new, sensitive and selective electrochemical method for the caffeine determination using boron doped diamond electrode was developed. It was found by cyclic voltammetry that caffeine provided highly reproducible and well-defined irreversible oxidation peak, at very positive potential of +1.55 V vs. Ag/AgCl electrode. The effect of pH and scan rate on the voltammetric response of caffeine oxidation were studied to select the optimum experimental conditions. Linear response of peak current on the concentration in the range from 4 × 10-7to 2.5 × 10-5mol L-1, good repeatability (RSD of 2.1 %) and the detection limit of 1.5 × 10-7mol L-1without any chemical modifications and electrochemical surface pretreatment were observed by differential pulse voltammetry in 0.4 mol L-1perchloric acid. The effect of possible interfering compounds appeared to be negligible which evidently proved very good selectivity. The proposed method was successfully applied for the caffeine determination in commercially available beverage samples, with results in a close statistical agreement to these declared by manufacturer.