Analytical Light Microscopy: Examples of Practical Problemsolving and Efficiency in Pharmaceutical Quality Control and Formulation

1998 ◽  
Vol 4 (S2) ◽  
pp. 474-475
Author(s):  
D. A. Stoney ◽  
W. C. McCrone

Five applications of analytical light microscopy to problem-solving in the pharmaceutical industry are described and illustrated by case examples. Problems included are (1) the caking of pharmaceutical products, (2) chemical incompatibility, (3) nucleation and precipitation, (4) recognition of hydrates and polymorphs, and (5) identification and sourcing of contaminant particles.Considerable effort goes into the sizing of solid pharmaceutical raw materials and products. In many instances, particle size is used to help control the rate and uniformity of dissolution, which in turn affects the kinetics of drug delivery. Caking is a macroscopic description of the change in a sample from a finely-divided powder to a single solid molded aggregate. Caking obviously has a severe impact on handling and dissolution characteristics.Caking of a powder is almost always caused by moisture through the cyclical dissolution and precipitation on the surfaces of the particles. When exposed to sufficient vapor pressure, often through changes in humidity or temperature,

2021 ◽  
Vol 6 ◽  
pp. 60-72
Author(s):  
R. I. Gulyaeva ◽  
◽  
A. M. Klyushnikov ◽  
S. A. Petrova ◽  
L. Yu. Udoeva ◽  
...  

The kinetics of low-temperature (900 – 1180 °C) reduction of iron tantalate (98.2 wt % FeTa2O6, 1.8 wt % Ta2O5, particle size < 0.1 mm) by excess aluminum (particle size < 0.14 mm) at the molar ratio Al:FeTa2O6 = 6 was studied. According to differential scanning calorimetry and X-ray powder diffraction, reduction is almost completed at 1180 °C, the metal products are TaFeAl, TaAl3, and Ta17Al12. Based on the results of thermokinetic calculations (Ozawa – Flynn – Wall and nonlinear regression methods), the formal mechanism of the process is represented by the Bna → CnC model, which includes two consecutive steps controlled by autocatalytically activated reactions. Kinetic parameters of the steps are: 1) Е1 = 429 kJ·mol–1, A1 = 1015.3 s–1; 2) Е2 = 176 kJ·mol–1, A2 = 103.9 s–1 (Ej is the activation energy, Aj is the preexponential factor). Prediction in the Bna → CnC model frames indicates the possibility of obtaining a reaction mixture containing ≥ 98 mol. % the final formal reduction product, with isothermal exposure in the temperature range of 1040 – 1120 °C during 1.5 – 5 minutes. The proposed model can be used to develop scientific foundations and substantiate technological modes for obtaining tantalum alloys from mineral and technogenic raw materials.


Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2236
Author(s):  
Igor Lomovskiy ◽  
Ekaterina Podgorbunskikh ◽  
Oleg Lomovsky

Enhancing the extraction rate is one of the key objectives in optimization of extraction of substances from biogenic raw materials. Ultra-fine grinding of plant raw materials (to achieve particle size less than 300 µm) is a very appealing method for increasing the extraction rate using relatively simple equipment. However, this approach often fails to yield the desired result. This study focuses on the kinetics of melanin extraction from two types of raw materials: fungus Ganoderma applanatum and buckwheat husk. Particle size is shown to be just one of the key factors. The degree of order of plant-based feedstock strongly affects the intraparticle diffusion constants and can be a parameter controlling the diffusion rate. It has been shown that there exist optimal degrees of disorder of the crystal structure of plant raw materials, which have a dome-shaped dependence pattern and allow one to increase the diffusion coefficient by several dozen times. The kinetics of melanin extraction was described by some kinetic models that include the first order equation, the Baker and Lonsdale model, the Axelrud equation, and the Ritger–Peppas model.


Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.


2020 ◽  
Vol 17 (1) ◽  
pp. 172-183
Author(s):  
Nandanwadkar Shrikrishna Madhukar Hema ◽  
Mastiholimath Vinayak Shivamurthy ◽  
Pulija Karunakar

Introduction: Capsaicin (8-methy-N-vanillyl-6-nonenamide), a potential analgesic derived from Capsicum annuum (Chili peppers), widely used from ancient times for its pharmacological activities such as anti-inflammatory, anti-oxidant and analgesic and provides relief from migraine and diabetes. But for obvious reasons, capsaicin cannot be administered directly. The present work was designed with a focus to comply with mandatory requirement in various pharmacopeias to know the actual content of API present in final formulations. The formulation (TS3) consisting of 3% lipid, with 4:6 ratio of the polymer and solvent, was found to be the optimized formulation, which gave the best evaluation with regard to the particle size (97.03±2.68) nm, polydispersity index (0.20±0.00), higher zeta potential (61.28±2.06) mv, morphological studies and highest drug entrapment efficiency (68.34±4.24)%. The prepared transferosome formulation was subjected to characterization by validated HP-TLC method consisting of N-Hexane: Tert- Iso-butyl-methyl ether in ratio (5:15) v/v. Linearity was performed in the range of 50-1500 ng/spot with LOD/LOQ 50 ng and 150 ng, with regression analysis (R) of 99.91%. Recovery analysis was performed at 3 different levels at 80, 100 and 120 with an average recovery of 106.97%, respectively. Till now, no analytical method has been reported, associated with the characterization of pharmaceutical nano-forms (Capsaicin), like transferosomes. Thus, the maiden validated HP-TLC method for concurrent analysis of capsaicin as API in nano-transferosome may be employed in process quality control of formulations containing the said API. Background: The irritability and adverse effects post application, leading to inflammation and neural pain at the site of administration of newly Capsaicin API and its chemical entities and marketed formulations are usually related to poor permeability, leading to drug complex reactions in the development phases or therapeutic failure along with the quantification of the same in blood plasma. However, advancement in drug formulations with the use of polymer: alcohol ratio and modernized analytical techniques for the quantification of Pharmaceutical APIs seems to be emerging and promising for overcoming pain and related inflammatory complications by formulating the APIs in Transferosome formulation with Validated HP-TLC technique being used as an effective economic and precise tool for quantitative analysis of APIs in their respective nano-forms. Objective: The study proposes a novel standardized method development and validation of pharmaceutical nanoforms with Capsaicin as API. Method: Capsaicin Transferosomes were formulated using Ultra probe sonication by utilizing different proportions of phospholipid 90G dissolved in a mixture of ethanol and propylene glycol. The formulation was subjected to Dynamic Light Scattering (DLS) technique for nano-particle analysis followed by characterization with respect to particle size, polydispersity index, zeta potential and entrapment efficiency. The morphological study of vesicles was determined using SEM and TEM. A Validated HP-TLC method for the identification and determination of Capsaicin in transferosomes formulation was performed as per the ICH guidelines. Results: The formulation gave the best evaluation for particle size (97.03±2.68) nm, polydispersity index (0.20±0.00), higher zeta potential (61.28±2.06) mv, morphological studies (SEM & TEM) and highest drug entrapment efficiency (68.34±4.24)%. DSC thermograms and FTIR spectral patterns confirmed no physical interaction by polymers with API. The prepared formulation was then characterized using HP-TLC method. The best resolution was found in NHexane: Tert-Isobutyl methyl ether in a ratio of 5:15 v/v. The Rf was found to be 0.3±0.03. Linearity was performed in a range of 50-1500 ng/spot, with regression analysis (R) of 99.91% Further, recovery analysis was done at 3 different levels as 80, 100 and 120 with an average recovery of 106.97%. The LOD/LOQ was found to be 50 and 150 ng, respectively. Precision was carried out in which % RSD was found to be precise and accurate. Conclusion: The outcomes of the present study suggested that the proposed novel formulation analyzed by Validated planar chromatographic technique (HP-TLC) for Capsaicin quantification in nanoforms may be employed as a routine quality control method for the said API in various other formulations.


2005 ◽  
Vol 155 (1) ◽  
pp. 85-91 ◽  
Author(s):  
N. Etxebarria ◽  
G. Arana ◽  
R. Antolín ◽  
E. Diez ◽  
G. Borge ◽  
...  

Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.


2021 ◽  
Vol 11 (14) ◽  
pp. 6265
Author(s):  
Alessandra Diotti ◽  
Giovanni Plizzari ◽  
Sabrina Sorlini

Construction and demolition wastes represent a primary source of new alternative materials which, if properly recovered, can be used to replace virgin raw materials partially or totally. The distrust of end-users in the use of recycled aggregates is mainly due to the environmental performance of these materials. In particular, the release of pollutants into the surrounding environment appears to be the aspect of greatest concern. This is because these materials are characterized by a strong heterogeneity which can sometimes lead to contaminant releases above the legal limits for recovery. In this context, an analysis of the leaching behaviour of both CDWs and RAs was conducted by applying a statistical analysis methodology. Subsequently, to evaluate the influence of the particle size and the volumetric reduction of the material on the release of contaminants, several experimental leaching tests were carried out according to the UNI EN 12457-2 and UNI EN 12457-4 standards. The results obtained show that chromium, mercury, and COD are the most critical parameters for both CDWs and RAs. Moreover, the material particle size generally affects the release of contaminants (i.e., finer particles showed higher releases), while the crushing process does not always involve higher releases than the sieving process.


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