Spectrophotometric determination of fluoride in drinking water using aluminium complexes of triphenylmethane dyes

A sensitive spectrophotometric determination of fluoride in drinking water has been developed using aluminium complexes of triphenylmethane dyes (chrome azurol B and malachite green) as spectrophotometric reagents. The method allowed a reliable determination of fluoride in the range of 0.5–4.0 mg·l-1 for chrome azurol B and 0.0–2.0 mg·l-1 for malachite green. The molar absorptivity for the complexes of chrome azurol B at 582 nm and malachite green at 622 nm is 1.44 × 104 and 2.56 × 104 l·mol-1·cm-1, respectively. The sensitivity, detection limit, quantitation limit, and percentage recovery for 1.5 mg·l-1 fluoride for the method using chrome azurol B were found to be 0.125 ± 0.003 µg·ml-1, 0.2 mg·l-1, 0.5 mg·l-1, and 97.1 ± 4.2, respectively, and for malachite green were 0.143 ± 0.002 µg·ml-1, 0.1 mg·l-1, 0.3 mg·l-1, and 97.9 ± 4.1, respectively

Comparative analysis of co-processed starches prepared by three different methods

Co-processing is currently of interest in the generation of high-functionality excipients for tablet formulation. In the present study, comparative analysis of the powder and tableting properties of three co-processed starches prepared by three different methods was carried out. The co-processed excipients consisting of maize starch (90%), acacia gum (7.5%) and colloidal silicon dioxide (2.5%) were prepared by co-dispersion (SAS-CD), co-fusion (SAS-CF) and co-granulation (SAS-CG). Powder properties of each co-processed excipient were characterized by measuring particle size, flow indices, particle density, dilution potential and lubricant sensitivity ratio. Heckel and Walker models were used to evaluate the compaction behaviour of the three co-processed starches. Tablets were produced with paracetamol as the model drug by direct compression on an eccentric Tablet Press fitted with 12 mm flat-faced punches and compressed at 216 MPa. The tablets were stored at room temperature for 24 h prior to evaluation. The results revealed that co-granulated co-processed excipient (SAS-CG) gave relatively better properties in terms of flow, compressibility, dilution potential, deformation, disintegration, crushing strength and friability. This study has shown that the method of co-processing influences the powder and tableting properties of the co-processed excipient

Comparative analysis of co-processed starches prepared by three different methods

Co-processing is currently of interest in the generation of high-functionality excipients for tablet formulation. In the present study, comparative analysis of the powder and tableting properties of three co-processed starches prepared by three different methods was carried out. The co-processed excipients consisting of maize starch (90%), acacia gum (7.5%) and colloidal silicon dioxide (2.5%) were prepared by co-dispersion (SAS-CD), co-fusion (SAS-CF) and co-granulation (SAS-CG). Powder properties of each co-processed excipient were characterized by measuring particle size, flow indices, particle density, dilution potential and lubricant sensitivity ratio. Heckel and Walker models were used to evaluate the compaction behaviour of the three co-processed starches. Tablets were produced with paracetamol as the model drug by direct compression on an eccentric Tablet Press fitted with 12 mm flat-faced punches and compressed at 216 MPa. The tablets were stored at room temperature for 24 h prior to evaluation. The results revealed that co-granulated co-processed excipient (SAS-CG) gave relatively better properties in terms of flow, compressibility, dilution potential, deformation, disintegration, crushing strength and friability. This study has shown that the method of co-processing influences the powder and tableting properties of the co-processed excipient

Differences of Curing Effects between a Human and Veterinary Bone Cement

The goal of the study is to understand how the curing characteristics of a human bone cement (HBC) and veterinary bone cement (VBC) influence the mechanical behavior of each cement and cement bonding with an implant. This study hypothesizes that the curing temperature and time influence the mechanical properties of the cement adjacent to the implant, which resulted in the variability in bonding strength between the implant and cement. To test this hypothesis, this study measured the exothermic temperature, flexural strength, hardness, and morphology of a HBC and VBC at different curing times. In addition, this study measured shear strength at the interfaces of implant/HBC and implant/VBC samples during static and stepwise cyclic tests at different curing times. This study used Stryker Simplex P and BioMedtrix 3 poly methyl methacrylate (PMMA) as an HBC and VBC, respectively. This study cured HBC and VBC cement for 30 and 60 min and then conducted flexural, hardness, and interface fracture tests to evaluate the curing effect on mechanical behavior of each of the cements. This study found that the curing time significantly increases the values of flexure and hardness properties of each cement and shear strength of implant/HBC and implant/VBC (p < 0.05). This study observed a difference of curing time and temperature between HBC and VBC. This study also observed a significant difference of surface porosity at the interface of implant/HBC and implant/VBC interfaces. The variability of mechanical properties between HBC and VBC due to the differences of curing conditions may influence the bonding of cement with the implant

Novel inclusion complex of ibuprofen tromethamine with cyclodextrins: Physico-chemical characterization

Guest-host interactions of ibuprofen tromethamine salt (Ibu.T) with native and modified cyclodextrins (CyDs) have been investigated using several techniques, namely phase solubility diagrams (PSDs), proton nuclear magnetic resonance (H-1 NMR), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffractometry (XRPD). scanning-electron microscopy (SEM) and molecular mechanics (MM). From the analysis of PSD data (A(L)-type) it is concluded that the anionic tromethamine salt of ibuprofen (pK(a) = 4.55) forms 1: 1 soluble complexes with all CyDs investigated in buffered water at pH 7.0, while the neutral form of Ibu forms an insoluble complex with beta-CyD (B-S-type) in buffered water at pH 2.0. Ibu.T has a lower tendency to complex with beta-CyD (K-11 = 58 M-1 at pH 7.0) compared with the neutral Ibu (K-11 = 4200 M (1)) in water. Complex formation of Ibu.T with beta-CyD (Delta G degrees = -20.4 kJ/mol) is enthalpy driven (Delta H degrees = -22.9 kJ/mol) and is accompanied by a small unfavorable entropy (Delta S degrees = -8.4 J/mol K) change. H-1 NMR studies and MM computations revealed that, on complexation, the hydrophobic central benzene ring of lbu.T and part of the isobutyl group reside within the beta-CyD cavity leaving the peripheral groups (carboxylate, tromethamine and methyl groups) located near the hydroxyl group networks at either rim of beta-CyD. PSD, H-1 NMR, DSC, FT-IR, XRPD, SEM and MM studies confirmed the formation of Ibu.T/beta-CyD inclusion complex in solution and the solid state. (C) 2009 Elsevier B.V. All rights reserved