The influence of sample area on diclofenac sodium quantification by diffuse reflectance IR spectroscopy

Quantification and Classification of Diclofenac Sodium Content in Dispersed Commercially Available Tablets by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

A new methodology, based on Fourier transform infrared spectroscopy equipped with an attenuated total reflectance accessory (ATR FT-IR), was developed for the determination of diclofenac sodium (DS) in dispersed commercially available tablets using chemometric tools such as partial least squares (PLS) coupled with discriminant analysis (PLS-DA). The results of PLS-DA depicted a perfect classification of the tablets into three different groups based on their DS concentrations, while the developed model with PLS had a sufficiently low root mean square error (RMSE) for the prediction of the samples’ concentration (~5%) and therefore can be practically used for any tablet with an unknown concentration of DS. Comparison with ultraviolet/visible (UV/Vis) spectrophotometry as the reference method revealed no significant difference between the two methods. The proposed methodology exhibited satisfactory results in terms of both accuracy and precision while being rapid, simple and of low cost.

Self-associating cellulose-graft-poly(ε-caprolactone) to design nanoparticles for drug release

The growing interest in the use of polysaccharides nanoparticles for biomedical applications is related to the recent progresses on the synthesis of cellulose-based polymers with the specific functionalities. In particular, cellulose graft copolymers are emerging as amphiphilic materials suitable to fabricate smart nanoparticles for drug delivery applications. In this work, a cellulose-graft-poly(ε-caprolactone) (cell-g-PCL) was synthetized and characterized by FTIR, TGA and DSC in order to validate the synthesis process. We demonstrated that fast evaporation processes promoted cell-g-PCL self-assembly to form nanomicellar structures with hydrodynamic radius ranged from 30 to 60 nm as confirmed by TEM analysis. Moreover, the application of controlled electrostatic forces on solvent evaporation - namely electrospraying - allowed generating round-like nanoscaled particles, as confirmed by SEM supported via image analysis. We demonstrated also that sodium diclofenac (DS) drastically influenced the mechanism of particle formation, favoring the deposition of erythrocyte-like particles with highly concave surfaces, not penalizing the encapsulation efficiency of nanoparticles (>80%). The release profile showed a fast delivery of DS - about 60% during the first 24 h - followed by a sustained release - about 20% during the next 6 days - strictly related to the peculiar weak interactions among amphiphilic polymer segments and water molecules, thus suggesting a successful use of electrosprayed cell-g-PCL nanoparticles for therapeutic treatments in nanomedicine.

Quantitative analysis of solid samples using modified specular reflectance accessory

Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) is a fast, reliable and cost effective analytical method, requiring minimal or no sample preparation. It is commonly used in the course of qualitative and quantitative analysis of pharmaceutical ingredients and food. We demonstrate that simpler and cheaper specular reflectance (SR) accessory working in a DRIFTS like mode (SR-DL) can be an alternative for DIRFTS attachment. An application of a modified SR accessory for quantitative analysis of solids samples is presented. As a case study the concentration of cinnarizine in commercial tablets has been determined from DRIFTS and SR-DL infrared (IR) and near-infrared (NIR) spectra recorded using DTGS (deuterated triglicine sulphate) detector in the IR and NIR regions and InGaAs (indium-gallium arsenide) detector in the NIR range. Based on these spectra Partial Least Squares (PLS) models were constructed and relative standard errors of prediction (RSEP) were calculated for the calibration, validation and analysed data sets. They amounted to 2.4-2.5%, 2.1-2.7% and 2.0-2.6% for the DRIFTS attachment while 2.1-2.2%, 2.0-2.3% and 1.9-2.6%, respectively, for the modified SR accessory. Obtained error values indicate that modified SR accessory can be effectively used for quantification of solid pharmaceutical samples in the mid- and near-infrared regions.

Spectroscopic (FT-IR, FT-Raman and UV) investigation, NLO, NBO, molecular orbital and MESP analysis of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid

In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000-450cm(-1) and 4000-50cm(-1), respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (ΔH). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (η), chemical potential (μ), Electro negativity (χ) and electrophilicity values (ω) are calculated and reported. The oscillator's strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed.