scholarly journals New insights into the nature of the Cibacron brilliant red 3B-A – Chitosan interaction

2016 ◽  
Vol 88 (9) ◽  
pp. 891-904 ◽  
Author(s):  
Stefan Hoffmann ◽  
Juan Pablo Fuenzalida Werner ◽  
Ignacio Moreno-Villoslada ◽  
Francisco M. Goycoolea
Keyword(s):  
Fluorescence Emission ◽  
Pharmaceutical Formulations ◽  
Charge Ratio ◽  
Amino Groups ◽  
Linear Charge ◽  
Band Shift ◽  
Chiral Structure ◽  
Linear Charge Density ◽  
Emission Quenching ◽  
Absorbance Band

AbstractCibacron brilliant red 3B-A (CBR) has been introduced to determine chitosan (CS) concentrations in solution, and several studies applied it to measure chitosan content in pharmaceutical formulations. So far, studies have relied on the absorbance band shift to 570 nm to determine the extent of the CBR – CS interaction. In this study, we show that CBR forms micro- to nanometer sized aggregates with CS, depending on their charge ratio and that other photophysical changes in CBR are induced by this interaction. We found that, besides the bathochromic band shift, aggregation induces emission at 600 nm and emission quenching at 360 nm. We compared changes CS induced in absorbance and fluorescence emission of CBR with the CS monomer glucosamine and poly(allylamine) hydrochloride, which both contain amino groups, and found that similar but less intense photophysical changes also occur. Furthermore, CS-induced circular dichroism in CBR suggests a twisted, chiral structure of these aggregates that should match with the previously published in silico simulations of the structure of CS in solution. The low linear charge density of CS and its chiral conformation are considered responsible for the enhanced photophysical response of CBR interacting with the polycation.

scholarly journals Difference in the Dissolution Behaviors of Tablets Containing Polyvinylpolypyrrolidone (PVPP) Depending on Pharmaceutical Formulation After Storage Under High Temperature and Humid Conditions

2016 ◽  
Vol 19 (4) ◽  
pp. 511 ◽  
Author(s):  
Yoh Takekuma ◽  
Haruka Ishizaka ◽  
Masato Sumi ◽  
Yuki Sato ◽  
Mitsuru Sugawara
Keyword(s):  
High Temperature ◽  
Benzoic Acid ◽  
Dissolution Rate ◽  
Simple Structure ◽  
Pharmaceutical Formulations ◽  
Magnesium Stearate ◽  
Principal Agent ◽  
Amino Groups ◽  
Dissolution Tests ◽  
Rosuvastatin Calcium

PURPOSE. Storage under high temperature and humid conditions has been reported to decrease the dissolution rate for some kinds of tablets containing polyvinylpolypyrrolidone (PVPP) as a disintegrant. The aim of this study was to elucidate the properties of pharmaceutical formulations with PVPP that cause a decrease in the dissolution rate after storage under high temperature and humid conditions by using model tablets with a simple composition. METHODS. Model tablets, which consisted of rosuvastatin calcium or 5 simple structure compounds, salicylic acid, 2-aminodiphenylmethane, 2-aminobiphenyl, 2-(p-tolyl)benzoic acid or 4.4’-biphenol as principal agents, cellulose, lactose hydrate, PVPP and magnesium stearate as additives, were made by direct compression. The model tables were wrapped in paraffin papers and stored for 2 weeks at 40°C/75% relative humidity (RH). Dissolution tests were carried out by the paddle method in the Japanese Pharmacopoeia 16th edition. RESULTS. Model tablets with a simple composition were able to reproduce a decreased dissolution rate after storage at 40°C/75% RH. These tablets showed significantly decreased water absorption activities after storage. In the case of tablets without lactose hydrate by replacing with cellulose, a decreased dissolution rate was not observed. Carboxyl and amino groups in the structure of the principal agent were not directly involved in the decreased dissolution. 2-Benzylaniline tablets showed a remarkably decreased dissolution rate and 2-aminobiphenyl and 2-(p-tolyl)benzoic acid tablets showed slightly decreased dissolution rates, though 4,4’-biphenol tablets did not show a decrease dissolution rate. CONCLUSIONS. We demonstrated that additives and structure of the principal agent were involved in the decreased in dissolution rate for tablets with PVPP. The results suggested that one of the reasons for a decreased dissolution rate was the inclusion of lactose hydrate in tablets. The results also indicated that compounds as principal agents with low affinity for PVPP may be easily affected by airborne water under high temperature and humid conditions. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

scholarly journals Effect of chemical structure and linear density charge of sulfonate-containing aromatic polyamides on interaction with polycations in organic and water-organic media

2019 ◽  
Vol 60 (11) ◽  
pp. 40-47
Author(s):  
Natalya N. Smirnova ◽  
Keyword(s):  
Chemical Structure ◽  
Phase State ◽  
Linear Charge ◽  
Linear Charge Density ◽  
Sodium Sulfonate ◽  
Interpolyelectrolyte Complexes ◽  
Composition And Structure ◽  
Average Size ◽  
Organic Solutions ◽  
Acrylonitrile Copolymers

The interaction of sulfonate-containing aromatic poly- and copolyamides with acrylonitrile copolymers with N,N-dimethyl-N,N-diallylammonium chloride (DMDAAC) and N,N-diethylaminoethylmethacrylate (DEAEM) in organic and water-organic solutions was studied. It was shown that as a result of macromolecular reactions interpolyelectrolyte complexes (IPEC) forms. They are stabilized mainly by electrostatic forces. To characterize the interpolyelectrolyte complexes composition the φ parameter was used, that defines as the ratio of corresponding functional groups molar concentrations of interacting polyelectrolytes. The transformation degree in interpolymer reactions θ was calculated as the ratio of the salt bonds number between polyions to their maximum possible number. It was shown that the main factors determining the composition and structure of forming interpolyelectrolyte complexes are linear charge density of polyelectrolytes, the nature and composition of the solvent in which interpolymer reactions occurs. It is possible to obtain IPEC, the composition of which for the same polycation will vary from φ = 2.5 to φ = 1.0, changing these factors. It was found that at the complexation process is not accompanied by a change in the phase state of the interpolymer system, when the concentration of units with sulfonate groups in the macromolecular polyamide chain 5 mol.%. It was found that the introduction of polycation leads to the formation of IPEC structures in the form of particles with an average size of ~217.7 nm for poly-4,4'-(2-sodium sulfonate) – diphenylaminisophthalamide and ~248.1 nm in the case of poly-4,4'-(2-sodium sulfonate) -diphenylaminterephthalamide. It was shown that the decrease in the polymer content of units with sulfonate groups is accompanied by a decrease in the transformation degree from 0.65-0.66 to 0.18. It was found that the studied complexes can be transferred to the solution by increasing its ionic strength. The result obtained during this work can serve as a base for the development of for the manufacturing technology of film and membrane materials based on sulfonate-containing aromatic poly- and copolyamides.

TEMPO-Mediated Oxidation of Pullulan and Influence of Ionic Strength and Linear Charge Density on the Dimensions of the Obtained Polyelectrolyte Chains

1996 ◽  
Vol 29 (20) ◽  
pp. 6541-6547 ◽  
Author(s):  
A. E. J. de Nooy ◽  
A. C. Besemer ◽  
H. van Bekkum ◽  
J. A. P. P. van Dijk ◽  
J. A. M. Smit
Keyword(s):  
Ionic Strength ◽  
Charge Density ◽  
Linear Charge ◽  
Linear Charge Density ◽  
Mediated Oxidation

Study on Optimization of Blasting Parameters and its Effect on Anchoring Rock Beam of a Underground Workshop

2011 ◽  
Vol 90-93 ◽  
pp. 2045-2052 ◽  
Author(s):  
Cheng Liang Zhang ◽  
Xin Ping Li
Keyword(s):  
Rock Mass ◽  
Protective Layer ◽  
Surrounding Rock ◽  
Linear Charge ◽  
Linear Charge Density ◽  
Joint Development ◽  
The Neural Networks ◽  
Optimum Model ◽  
Smooth Blasting ◽  
Rock Beam

The optimum model for blasting parameters of anchoring rock beam is established and its blasting parameters are optimized by making use of a strong mapped function of the neural networks technology with the typical samples of other practical smooth blasting parameters. The explosive types, the extent of joint development of rock mass, the diameter of bore-hole, the depth of bore-hole, the linear charge density, the burden line of least resistance and the spacing of bore-hole are considered as the primary effective factors in the excavation of anchoring rock beam. In the meantime, the experimental blasting parameters for anchoring rock beam are determined by the in-site blasting experiments of the protective layer and platform of rock mass in similar conditions. The results show that the in-site experimental blasting parameters are preferably identical to those of the optimum design. The acoustic wave examination for the blasting of the protective layer and platform of rock mass indicates that the blasting effect is satisfied and its smaller loose ring of surrounding rock mass is obtained.

scholarly journals Validated Analytical Spectrofluorimetric Method for Quantitation of Diphenhydramine HCl in Commercial Dosage Forms

2018 ◽  
Vol 1 (4) ◽  
pp. 12-26
Author(s):  
Syed Najmul Hejaz Azmi ◽  
Aisha Al-Mahroqi ◽  
Khoula Al-Mamari ◽  
Shaima Al-Shukaili
Keyword(s):  
Dynamic Range ◽  
Fluorescence Emission ◽  
Reference Method ◽  
Pharmaceutical Formulations ◽  
Ion Pair ◽  
Ratio Method ◽  
Eosin Y ◽  
Stoichiometric Ratio ◽  
Buffer Solution

Diphenhydramine HClis a weakly fluorescent drug having tertiary amine group forming ion pair complex with eosin Y in dichloromethane at pH 5 in disodium hydrogen phosphate-citric acid buffer solution. The complex formation was the basis for the development of new analytical method for determination of active diphenhydramine in pharmaceutical formulations. The stoichiometric ratio between diphenhydramine and eosin Y was studied by mole ratio method and found to be 2:1. The ion-pair complex showed maximum fluorescence emission intensity at 554 nm with excitation at 259 nm. The linear dynamic range was obtained in the concentration range of 2-22 µg mL-1 with a linear equation of FI = 0.361 + 13.675 C. The apparent Gibb’s free energy (ΔGº) was calculated and found to be -80.783 KJ mol-1, confirmed the feasibility of the reaction. The proposed method was successfully applied to the determination of diphenhydramine HCl in pharmaceutical formulations and in good agreement with the reference method.

scholarly journals Spectrophotometric Assay of some Nitrogen Containing Drugs in Pharmaceutical Formulations using p-Chloranilic Acid Reagent

2013 ◽  
Vol 9 (1) ◽  
pp. 1798-1809 ◽  
Author(s):  
Theia’a N. Al-Sabha ◽  
Mahmood A. Hasan ◽  
Huda A. Ibrahim
Keyword(s):  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Charge Transfer Complexes ◽  
Amino Groups ◽  
Chloranilic Acid ◽  
Terbutaline Sulfate ◽  
Acid Reagent ◽  
Sulfacetamide Sodium ◽  
Better Than

A spectrophotometric method is developed for the determination of some drugs containing amino groups (sulfacetamide sodium, lidocaine and terbutaline sulfate) based on their reaction with p-chloranilic acid reagent in an organic medium forming colored charge transfer complexes. The complexes have maximum absorptions at 530 and 527 nm for sulfacetamide sodium and lidocaine respectively, but terbutaline sulfate gave two maximum absorptions at 529 and 319 nm. Beers law is obeyed over the concentration range of 10-60 µg.ml-1 for sulfacetamide sodium and lidocaine and 5-70 µg.ml-1 for terbutaline sulfate. The molar absorptivity values are 0.940×103, 0.913×103 L.mol-1.cm-1 for sulfacetamide sodium and lidocaine respectively while terbutaline sulfate gave 0.987×103 L.mol-1.cm-1 at 529 nm and 7.407×103 L.mol-1.cm-1 at 319 nm with accuracy range between 100.20% and 101.42% and RSD better than 3.15% for all drugs. The method is applied successfully for determination of these drugs in pharmaceutical formulations and compared favorably with British Pharmacopeia standard methods. F and t tests are less than the tabulated values at 95% confidence level.

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