Influence of Supersaturation, Temperature and Rotational Speed on Induction Time of Calcium Sulfate Crystallization

Calcium sulfate is a very important product of precipitation reactions in various branches of industry. The most common applications include building materials, impression materials in dentistry, immobilizing casts and an inactive ingredient of tablet excipients. It is also used as a drying agent and color glaze. In this paper, influence of various conditions, i.e., substrates concentration (supersaturation), temperature and rotational speed on induction time was investigated. The range of investigated parameters was 0.15–0.35 M for concentration with step of 0.05 M, 298–323 K with step of 5 K for temperature, and 1.67–8.33 s−1 for rotational speed with change every 1.67 s−1. The experiments were performed using visual and turbidimetric methods. It was proven that increase in all three investigated parameters resulted in shorter induction time. The turbidimetric method was found to be more precise, but still insufficient for concentrations below 0.15 M. Moreover, as a result of data analysis, a simple method of induction time calculation was proposed when arbitrary measurements in various concentrations are known.

Free Immunoglobulin Light Chains in Patients with Tick-Borne Encephalitis: Before and after Treatment

Background: Tick-borne encephalitis (TBE) is inflammation of the central nervous system (CNS) caused by a viral infection which may be associated with increased synthesis of immunoglobulins. It can lead to inter alia, breakdown of the blood-brain barrier (BBB), or even death and, unfortunately, treatment is only symptomatic. Therefore, the aim of the present study was assessment of the concentrations of free light chains (FLC) kappa (κ) and lambda (λ in the cerebrospinal fluid (CSF) and serum of patients with TBE. Methods: A total of 58 cerebrospinal fluid and serum sample pairs were analyzed. Samples were collected from patients with TBE before and after treatment. FLC were measured using the turbidimetric method. The values of κIgG-index, λIgG-index, κFLC-index and λFLC-index were calculated using relevant formulas. Results: Pre-treatment serum λFLC concentrations were higher in comparison to post-treatment levels. Moreover, it was observed that CSF λFLC, TBEV IgM, TBEV IgG, and serum TBEV IgG, as well as the values of λFLC-index, κFLC-index, and λIgG-index were elevated after treatment. In the total study group, the concentrations of CSF κFLC and λFLC, and values of four indexes: κFLC-index, λFLC-index, κIgG-index, and λIgG-index correlated with each other and with CSF TBEV IgM and IgG antibodies. The CSF level of TBEV IgG was also associated with serum IgG TBEV and CSF IgM TBEV antibodies. Additionally, serum κFLC correlated with serum and CSF λFLC. Conclusion: This is the first study that demonstrates statistically significant differences in serum and CSF λFLC, as well as in the calculated values of three algorithms: λIgG-index, κFLC-index, and λIgG-index prior to and following treatment of TBE. Our findings may indicate that these differences reflect the intrathecal synthesis of immunoglobulins and increased permeability of BBB in patients with TBE. Moreover, it could provide the basis for developing new therapeutic strategies.

MINIATURIZED MICROBIOLOGICAL METHOD TO DETERMINE THE POTENCY OF RIFAXIMIN IN TABLETS

Background Rifaximin, a semi-synthetic antimicrobial, does not present microbiological method described in official compendia, and in the literature there is a lack for this topic. The quality control of antimicrobials is extremely important to evaluate the real potency of the pharmaceutical product. Objective A miniaturized turbidimetric method for determining the potency of rifaximin in tablets was developed and validated by turbidimetry, according to the international guidelines. Methods Escherichia coli ATCC 10536 IAL 2393, BHI broth, inoculum at 8%, rifaximin in purified water with 20% ethanol at 5, 10, and 20 μg/mL and 530 nm were used. Results The method was considered selective for rifaximin, as the adjuvants did not show activity; linear with correlation coefficients 0.9998 for standard and 0.9999 for sample; accurate with 99.73% recovery; precise with RSD less than 3%; and robust in the face of small variations in (i) rifaximin volume, (ii) proportion of ethanol, (iii) inoculum volume. Conclusion The method is considered adequate and safe to evaluate the potency of rifaximin in tablets, contemplating speed, low cost, low waste generation, and ease of operation. Highlights This work shows the current, sustainable, and green analytical chemistry and can be used in the routine analyzes of rifaximin by laboratories and the pharmaceutical industry around the world.

The Development of a Turbidimetric Method for the Quantitative Determination of Antibiotics of the Aminoglycoside Group in Medications

A method for the quantitative determination of streptomycin sulfate in medicines by the turbidimetric method has been developedand validated. Based on the results of the experiments, it was found that the metrological characteristics of such validation parameters of the method as linearity, precision, and correctness do not exceed the validation criteria. Linearity was noted in the range of streptomycin concentrations from 3.75 to 8.43 μg/ml. The results of validation tests of the method for the quantitative determination of streptomycin indicate the prospects and feasibility of introducing the turbidimetric method into the domestic system for standardization and quality assessment of aminoglycoside antibiotics.

Turbidimetric Method: A Multi-Advantageous Option for Assessing the Potency of Ceftriaxone Sodium in Powder for Injection

Background Ceftriaxone sodium, an antimicrobial used in parenteral form, does not have a microbiological method by turbidimetry described in the literature. For drugs from antimicrobial class, the existence of a microbiological method for assessing their potency is essential. Not only are the results from the physical-chemical methods enough, but microbiological analyzes are also necessary. Objective and Methods Thus, this paper reports the development and validation of an efficient, accurate, reproducible, fast, and low-cost microbiological assay by turbidimetry to quantify ceftriaxone sodium in powder for injection. Water was used as the diluent to prepare the ceftriaxone solutions. BHI broth as used as culture media for the growth of the S. aureus ATCC 6538 at 9%. Results The method was linear in the range of 100–196 µg/mL, selective against the sample adjuvants and the forced degradation test, precise (intraday RSD 4.53%, interday RSD 3.85% and between analysts tcalculated 0.14 < 2.23 tcritical), accurate with recovery of 100.33% and robust against minor changes in the volume of culture medium used, wavelength, incubation time, and inoculum concentration. Conclusions and Highlights The turbidimetric method developed in this paper is a convenient and valuable alternative to the routine quality control of ceftriaxone sodium in powder for injection, since it allows a reliable quantification and can be used to complement the physical-chemical analysis.

TURBIDIMETRIC DETERMINATION OF THE TURBIDITY INDEX OF SPENT PARAFFIN OIL

Проведены исследования по определению показателя мутности отработанного вазелинового (парафинового) масла, используемого в качестве растворителя при получении высокопрочных волокон из сверхвысокомолекулярного полиэтилена (СВМПЭ) методом гель-формования, турбидиметрическим методом по стандартным формазиновым растворам. Доказана возможность применения данного метода для оценки показателя мутности отработанного растворителя. The results of research on determining the turbidity index of spent Vaseline (paraffin) oil used as a solvent for the production of high-strength fibers from ultrahigh-molecular polyethylene (UHMWPE) by gel-spinning, turbidimetric method for standard formazine solutions are presented. The possibility of using this method to estimate the turbidity index of the spent solvent is proved.