Multivariate calibration techniques applied to the spectrophotometric analysis of one-to-four component systems

The UV spectrophotometric analysis of a multicomponent mixture containing paracetamol, caffeine, tripelenamine and salicylamide by using multivariate calibration methods, such as principal component regression (PCR) and partial least-squares regression (PLS), was described. The calibration set was based on 47 reference samples, consisting of quaternary, ternary, binary and single-component mixtures, with the aim to develop models able to predict the concentrations of unknown samples containing as many as one-to-four components. The calibration models were optimized by an appropriate selection of the number of factors as well as wavelength ranges to be used for building up the data matrix and excluding any information about the interfering excipients included in pharmaceutics. The PCR and PLS models were compared and their predictive performance was inferred by a successful application to the assays of synthetic mixtures and pharmaceutical formulations.     

Elimination De L'Interference Des Salicyles Dans Le Dosage U. V. Du Paracetamol Sanguin

Abstract

Authors propose a simple method for U. V. determination of blood paracetamol in emergency toxicology. First, diethy1-ether extraction allows salicylate elimination (especially salicylic acid which is the most frequently used in therapy). Secondly paracetamol is extracted by ethyl-acetate and measured by U. V. spectrophotometry at 244 nm. The method provides good repeta-bility (C V=3.3 %) and reproducibility (C V u 4.3 %) with a detection limit of 2 mg L^?1 in plasma.     

Synthesis, structure and luminescence properties of lanthanide complex with a new tetrapodal ligand featuring salicylamide arms

A new tetrapodal ligand 1,1,1-tetrakis{[(2′-(2-furfurylaminoformyl))phenoxyl]methyl}methane (L) has been prepared and their coordination chemistry with Ln^III ions has been investigated. The structure of {[Ln₄L₃(NO₃)₁₂]·H₂O}_∞ (Ln=Nd, Eu)] shows the binodal 4,3-connected three-dimensional interpenetration coordination polymers with topology of a (8⁶)₃(8³)₄ notation. [DyL(NO₃)₃(H₂O)₂]·0.5CH₃OH and [ErL(NO₃)₃(H₂O) (CH₃OH)]·CH₃COCH₃ is a 1:1 mononuclear complex with interesting supramolecular features. The structure of [NdL(H₂O)₆]·3ClO₄·3H₂O is a 2:1 mononuclear complex which further self-assembled through hydrogen bond to form a three-dimensional supramolecular structures. The result presented here indicates that both subtle variation of the terminal group and counter anions can be applied in the modulation of the overall molecular structures of lanthanide complex of salicylamide derivatives due to the structure specialties of this type of ligand. The luminescence properties of the Eu^III complex are also studied in detail.     

Structure variation and luminescence properties of lanthanide complexes with 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane

Using 1,9-salicylamide bissubstituted oxadecane ligand, 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane (L), two novel lanthanide complexes have been prepared and well characterized by means of elemental analysis, IR spectroscopy, UV-vis spectroscopy, TGA analysis and single-crystal X-ray diffraction. {[PrL(NO₃)₃(H₂O)₂]·CH₃OH}_n is a 1D zigzag polymer with three-dimensional supramolecular structure formed by hydrogen bonds, while [EuL(NO₃)₃(H₂O)]_n is a linear coordination polymer and present an interesting supramolecular double chain, which are very different from the structure of terbium complex reported before. The result reported herein demonstrated that steric crowding associated with the decreasing lanthanide ion radius causes changes of the conformation of the ligand as well as structures. Luminescence studies for the Eu(III) complexes demonstrated that the salicylamide ligand also exhibits a good antennae effect for the Eu(III) ion due to efficient intersystem crossing and ligand-to-metal energy transfer and the Eu(III) ion is well shielded from the surrounding environment.     

The intramolecular hydrogen bond in 2-hydroxy-benzamides

The two crystal structures of 5-chloro-2-hydroxy-benzamide and 2-hydroxy-N,N-diethyl-benzamide were determined by X-ray diffraction at 100 K. The intramolecular and intermolecular hydrogen bonds were found in these structurally similar 2-hydroxy-benzamides. Analysis of the hydrogen bonding was carried out on the basis of X-ray data, infrared spectra, and DFT calculations. Disruption of the intramolecular hydrogen bonding in the solid state by a steric effect is shown. Conformational analysis and potential energy calculations as functions of the turning angle around the C_aryl–C_alkyl bond were conducted. The values obtained for the HOMA index indicate mutual compensation of the amide and hydroxyl groups (due to the high degree aromaticity of the phenyl ring).     

Development of a potential carrageenan-based hard capsule as the alternative of conventional capsules by implementing the oligomerization reaction

Carrageenan-based (CRG) hard capsules have a slower disintegration rate compared to that of gelatin capsules. Therefore, there is an urgent need to optimize the performance of this material using the oligomerization process. The preparation was conducted by oligomerizing CRG, cross-linking it with maltodextrin (MD), and plasticizing it with sorbitol (SOR). Based on our research, we found that the capsule prepared with the code CRG(O)-MD/SOR had an ash content of 11.80% and a water content of 17.20 ± 1.20 %. No microbes or yeast were found in the capsule, and only negligible amounts of heavy metal traces were present. Scanning electron microscopy (SEM) morphology analysis of the capsule surface showed that no pores were observed, even at a magnification of 10,000 times. This result was supported by the BET-BJH analysis, which showed that the pores had an average diameter of 49.26 Ǻ. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the Tg of the prepared capsules was at 51.4 °C. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the presence of citric acid as the oligomerization agent had changed the chain composition of the carrageenan. Acute toxicity analysis showed that the capsule was safe even at a dose of 3,000 mg/bw. The Young's modulus of CRG(O)-MD/SOR was determined to be 1.500 ± 0.52 MPa. In vitro disintegration testing of CRG(O)-MD/SOR showed that the capsule required 20.01 ± 1.13 mins, 23.13 ± 1.14 mins, and more than 120 mins to disintegrate at pH 1.2, 4.5, and 6.8, respectively. Release kinetics analyses showed that the drugs paracetamol (PCT) and salicylamide (SCA) followed the zeroth-order model at pH 1.2 and 4.5, while they were best described by the Peppas-Sahlin model at pH 6.8. Finally, the maximum swelling degree of the CRG(O)-MD/SOR hard capsule was determined to be 708.88%, which was reached in 15.22 mins. This capsule has the potential to be used as an alternative to conventional hard capsules on a broader scale. Furthermore, this work supports Sustainable Development Goals (SDGs) point 3, good health and well-being, by providing a capsule made from biomaterial.