Quantitative Determination Research Articles

Quantitative determination of the components of the mixture – ear drops “Melavet” by the method of high-performance liquid chromatography

The pharmaceutical industry is one of the most regulated industries in the world, and most medicines remain safe and effective. The level of impurity and degradation products in active pharmaceutical ingredients (APIs) must be strictly controlled and meet the specifications required by international bodies. for many years, chromatography has been the method of choice for assessing the chemical purity of medicinal substances and products and has a wide range of applications in the pharmaceutical industry, from research and development to laboratory quality control. The ability to integrate mass spectrometry into the chromatography workflow has been a real breakthrough in the science of separation, finding many inscriptions, especially in the field of pharmaceutical analysis. Therefore, the relevance of the research lies in finding the quantity of the composition of the created mixture – ear drops “Melavet” by the HPLC method with mass detection of the initial components. The purpose of the work is to create analytical methods for determining the active components of the mixture when they are present in the sample and interact with each other. Materials and methods: Chromato-mass-spectrometric studies, high-performance liquid chromatography (HPLC, LCMS). LCMS device: Agilent 1200 Quaternary DAD HPLC System (degasser, binary pump, autosampler, column thermostat, diode-matrix detector; single-quadrupole mass spectrometer Agilent 1100 LCMSD SL instrument; OpenLAB CDS Software. For the new combined veterinary test of ear drops “Melavet” 10 ml, containing various components, it is necessary to develop optimal methods of standardization. For this, 6 solutions of the external standard of each component were prepared. Based on the research, a method was developed for the simultaneous determination of the components in the model mixture ear drops “Melavet” 10 ml by the method of high-performance liquid chromatography using the same mobile and stationary phases, as well as similar chromatographic conditions, which were used during the study of individual samples of the external standard. When analyzing the chromatographic data, the presence of dioxidin in the mixture was fully consistent. In comparison with the external standards of each component, there are separate icons of substances on the chromatogram of the mixture, which contain information about the purity of the components and the interaction between them. During the research, a highly sensitive technique for the simultaneous determination of the components of the model mixture “Melavet” ear drops 10 ml by the method of high-performance liquid chromatography was developed. The optimal conditions for the simultaneous determination of the components of the mixture in one sample are selected. It was established that there is no interaction between the components of the mixture when they are simultaneously in the sample solution.

Design of a dual-mode ratiometric fluorescent probe via MOF-on-MOF strategy for Al (III) and pH detection

BackgroundThe construction of ratiometric fluorescent MOF sensors with integrated self-calibration and dual-channel detection can efficiently overcome the deficiencies of single-signal sensing. In this regard, the rational design of structurally functionalized MOFs is paramount for enhancing their performance in ratiometric fluorescent sensors. Lately, the concept of MOF-on-MOF design has garnered notable interest as a potential strategy for regulating the structural parameters of MOFs by integrating two or more distinct MOF types. Great efforts have been dedicated to exploring new MOF-on-MOF hybrids and developing their applications in diverse fields. Even so, these materials are still in the stage of advancement in the sensing field. ResultsHerein, a Zr-based metal-organic framework anchored on a rare-earth metal-organic framework (UiO-66(OH)2@Y-TCPP) was prepared for the ratiometric fluorescence detection toward Al (III) and pH. In this probe, the UiO-66(OH)2 featured hydroxyl active sites for Al (III), leading to a significant enhancement in fluorescence intensity upon the addition of Al (III), while the signal emitted by the red-emitting Y-TCPP, serving as the reference, remained constant. UiO-66(OH)2@Y-TCPP exhibited excellent selectivity for Al (III) sensing with a wider linear range of 0.1–1000 μM, and a lower detection limit of 0.06 μM. This probe has also been utilized for the quantitative determination of Al (III) in hydrotalcite chewable tablets with satisfactory results. In addition, the probe realized ratiometric pH sensing in the range of 7–13 using UiO-66(OH)2 as an interior reference. The paper-based probe strip was developed for visual pH sensing. By installing color recognition and processing software on a smartphone, real-time and convenient pH sensing could be achieved. SignificanceThis is the first ratiometric fluorescent sensor for Al (III) and pH detection based on a MOF-on-MOF composite probe, which yields two different response modes. The detection results of Al (III) in hydrotalcite chewable tables and smartphone imaging for pH test paper demonstrate the practicability of the probe. This work opens up a new outlook on constructing a multi-functional application platform with substantial potential for employment in environmental and biological analysis tasks.

Analysis of active compounds and bioactivity of leaves extracts of Sonneratia species

AbstractThe present study focused on the quantitative determination of active compounds, antioxidant and antibacterial activities of leaf extracts of different Sonneratia species. The tested species including Sonneratia alba (SA), Sonneratia caseolaris (SC), and Sonneratia ovata Backer (SO) were collected from Can Gio Mangrove Forest, Vietnam. The methanol extract of SA leaves was found to contain the highest content of total flavonoids, total phenolics and gallic acid (4344.16 ± 51.78 μg/g dry mass). The highest luteolin‐7‐O‐glucoside and luteolin amounts (5963.28 ± 59.77 and 234.33 ± 10.41 μg/g dry mass, respectively) were found in the methanol extract of SC leaves according to HPLC‐DAD analysis. The methanol extracts of all three species exhibited strong DPPH radical scavenging activity while the ethanol extracts provided strong antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli. By fractionating the extracts over a SiO2 column using CHCl3: EA: MeOH gradients, the fractions containing high purity luteolin and luteolin‐7‐glucoside from SC and high purity luteolin from SO were collected. Moreover, all fractions demonstrated significant DPPH free radical scavenging ability but the fraction enriched in gallic acid showed the highest activity. These findings show that SA is a promising source of gallic acid while SC can be potentially used for the extraction and isolation of luteolin‐7‐glucoside.

Lanthanide MOFs based portable fluorescence sensing platform: Quantitative and visual detection of ciprofloxacin and Al3+

In the current context of water environmental monitoring and pollution control, there's a crucial need for rapid and simple methods to detect multi-pollutant. We herein report an easy one-step hydrothermal synthesis method to produce Eu-based metal-organic frameworks (Eu MOFs), which was used as a fluorescent probe to detect the aquatic environmental pollutants of ciprofloxacin (CIP) and aluminum ions (Al3+). This fluorescent sensor enabled the cascade detection of CIP and Al3+ through fluorescence enhancement and ratio fluorescence response, respectively. The introduction of CIP significantly turned on the characteristic fluorescence of Eu MOFs at 595 nm and 616 nm through the “antenna effect”. Based on this, the sensor enables quantitative detection of CIP within a linear range of 0–120 μM with a LOD as low as 50.421 nM. In the presence of Al3+, the fluorescence emission of Eu MOFs-CIP was sharply turned off due to strong Al3+ coordination with CIP, while the blue fluorescence emission of CIP was remarkably enhanced. And thus allowing ratio fluorescence quantitative detection of Al3+ (LOD = 2.681 μM). The introduction of CIP and Al3+ in cascade resulted in distinct fluorescence color changes from colorless to red and eventually to blue, exhibiting pronounced fluorescence characteristics. This observable phenomenon enables the visual detection of CIP and Al3+ in both aqueous phase and paper test strips. By combining the analysis of fluorescence chromaticity with the use of a smartphone, the fluorescence color of test papers allows for simple quantitative determination, which provides a convenient and accessible approach for quantifying CIP and Al3+ in water environments.

Quantitative Determination of Sulphur in Manikaran’s Water

As we know fresh water is a finite and limited resource on Earth and, increasingly is polluted, by both pathogenic microbes and chemical contaminants. Human demand for freshwater is increasing water is required to irrigate crops to feed the rapidly expanding human population. Our main focus during this work is to identify impurities present in Manikaran in terms of Analytical Chemistry which include Limit Tests of Heavy metals. Limit test is best method for detection of impurities present and determination of heavy metals. It is done for identify that the Manikaran water is safe for human use or not. After the completion of the work, it was found that use of water of these resources contains Sulphur as heavy metal.

Development of an insulin-like growth factor-1 certified reference material by SI-traceable isotope-dilution mass spectrometry

In this study, an insulin-like growth factor-1 (IGF-1) certified reference material (CRM) was developed by the National Institute of Metrology (NIM), and two different principles for evaluating the IGF-1 CRM were established. After optimisation of the acid hydrolysis conditions (110 °C, 36 h), quantitative determination of peptide purity, and chromatographic separation and mass spectrometric detection, amino acid analysis-based high-performance liquid chromatography combined with isotope-dilution tandem mass spectrometry (AAA-HPLC-IDMS/MS) and peptide analysis-based HPLC-IDMS/MS (Peptide-HPLC-IDMS/MS) were used for certified value assignment; the results obtained were 136.28 and 135.01 μg/g, respectively, which were in good agreement. These results were subjected to the normal distribution test, outlier test, and method consistency test. The homogeneity and stability of the reference materials were also examined, and the uncertainty introduced in the experimental process was calculated. The final certified value was (136 ± 15) μg g−1 (k = 2). The CRM was found to be stable for at least six months when stored at −70 °C and for 7 d when stored at higher temperatures (−20 °C, 4 °C, 25 °C, or 40 °C). The CRM is expected to be used as a primary calibrator for quality control in biopharmaceutical production and clinical diagnostics.

Determination of palladium content in catalysts based on different carbon supports by inductively coupled plasma — atomic emission spectrometry (ICP-AES)

Catalytic processes and technologies are the structure-forming elements of modern chemical, petrochemical and pharmaceutical industries. Prospects of their development are strongly determined by continuous improvement of the existing catalysts and developing the advanced and more efficient ones. Among the available catalysts, an important place belongs to palladium catalysts with carbon supports. Palladium as an active component exhibits unique catalytic properties in various transformations of organic substances: hydrogenation, dehydrogenation, isomerization, dehydrocyclization, carbonylation, oxidation, etc. To control the content of the active component of a catalyst, precise and rapid physicochemical methods are used. ICP-AES shows a good performance in the analytical practice due to the rapidity, sensitivity, high accuracy and selectivity in determining various elements. The aim of the study was to develop a scientifically grounded methodological approach to estimate the palladium content in the catalysts synthesized on different carbon supports made of carbon black and Sibunit, which combines only the acidic decomposition of a sample and analysis by ICP-AES. A series of palladium catalysts synthesized on the carbon supports with different structural and textural characteristics was studied. An urgent goal is to control the content of the active component in the composition of catalysts. This characteristic affects the phase and electronic state of the metal, the structural and textural characteristics and thus determines the activity and selectivity of catalysts during operation. Therefore, quantitative chemical analysis is one of the main methods used to control the quality of catalysts. A method for quantitative determination of palladium concentration, which combines acidic decomposition of a sample and ICP-AES has been developed. The carbon support type was shown to exert no effect on the accuracy and reproducibility of data obtained by the analysis of supported palladium catalysts. The content of palladium in such catalysts can be measured using analytical lines 340.458 and 360.955 nm without lowering the measurement accuracy. The selected conditions of sample preparation make it possible to carry out a quantitative analysis of metal systems based on the carbon support with high accuracy. The relative error in determining the elements did not exceed 4%, the relative standard deviation was no more than 0.04. The results of this work can be used to analyze catalysts of similar chemical composition by ICP-AES.

Microbiological and Analytical Evaluation of Semi-Solid Formulations of Doxycycline Hyclate under Accelerated Stability Conditionsand analytical evaluation of semi-solid formulations of Doxycycline Hyclate under accelerated stability conditions

Doxycycline Hyclate (DOX) is a broad-spectrum antibiotic that belongs to the tetracycline family. It has been widely used in the treatment of several inflammatory diseases, and is considered the first-line therapy in the management of moderate to severe cases of acne. In this research, Doxycycline was formulated in four semi-solid formulations (F1and F2 as Gels, F3 and F4 as ointments), then these formulations were subjected to accelerated stability conditions for three months. The formulations were evaluated using microbiological and analytical methods after one and three months. Agar well diffusion method was used as a microbiological method to screen the antibacterial activity of semi-solid formulations against two types of bacteria, Staphylococcus Aureus and Pseudomonas Aeruginosa. HPLC was used as an analytical method for the quantitative and qualitative determination of these formulations. A comparison between a microbiological assay and analytical assay was achieved to evaluate the activity. The results showed that the ointment formulations were more stable than gel formulations since the percentages of drug were 91%, 93% at 25 ˚C after one month for formulations (F3, F4) against 90%,65% for formulations (F1, F2) respectively. Antibacterial activity results showed that formulation F4 had the highest zone of inhibition, which is 31mm for S.aurues and 26 mm for P. aeruginosa after storing it for three months at 25C°. The formulations were still effective despite the chemical degradation of doxycycline, this effectiveness returns to the fact that degradation products could still have active structural parts responsible for the antibacterial activity.

Validation of the Quantitative Determination Method of the active substance in Angiolin eye drops by spectrophotometry

Today, cataracts are the main cause of vision loss. Therefore, the creation of new ophthalmic medicines (drugs), namely eye drops, based on the active substance angiolin ((S)-2,6-diaminohexanoic acid 3-methyl-1,2,4-triazolyl-5-thioacetate) is an urgent task. Previously, we developed a method of standardization of the active substance – by the spectrophotometry. According to the requirements of the SPhU, the next step was the validation of the developed methods. That became the purpose of our work. Validation of the method of quantitative determination of active substances was carried out according to the following indicators: specificity, linearity, range of application, accuracy, correctness and robustness. In the course of the conducted studies, it was established that the method is characterized by sufficient convergence and correctness, as the criterion of insignificance of the systematic error of the method is fulfilled. The systematic error of the method satisfies the requirements of statistical and practical insignificance. The high value of the correlation coefficient r = 1.0000 and 0.99994 satisfies the requirements of the acceptance criterion (r = 0.9998) and confirms the linearity of the dependence between the amount of Angiolin taken and found in the range from 80% to 120%, according to its nominal content in the drug. The requirements for the linear dependence parameters (a, SD0/b, r) of the Angiolin determination method are met in the entire concentration range from 80% to 120% of the nominal value. Thus, the developed method of standardization of active substances in Angiolin eye drops is valid and can be introduced into the project of QCM (quality control methods).

Development and Validation of an HPLC-MS/MS Method for Quantification of Apixaban in Human Plasma

Introduction. Apixaban is an anticoagulant used in a number of thromboembolic diseases with an improved benefit-to-risk ratio, according to multiple clinical studies. Due to the prescription of apixaban as antithrombotic therapy in patients with COVID-19, an increase in its use has been observed. Thus, due to the widespread use of apixaban and the need to conduct pharmacokinetic and bioequivalence studies of the drug, it is important to develop and validate a simple and sensitive method for the quantitative determination of apixaban in human blood plasma.Aim. The aim of the study is to develop and validate a method for the determination of apixaban in human blood plasma using high-performance liquid chromatography with tandem mass selective detection (HPLC-MS/MS) for the subsequent bioanalytical study.Materials and methods. The determination of apixaban in human plasma was carried out by HPLC-MS/MS with rivaroxaban as an internal standard. The method of protein precipitation with acetonitrile was used as sample preparation. Mobile phase: 0.1 % solution of formic acid in water (eluent A); 0.1 % solution of formic acid in acetonitrile (eluent B). The total run time was 3.00 min. Column: Shim-pack Velox Biphenyl; 2.7 µm; 50 × 2.1 mm. Ionization source: electrospray with positive ionization mode. MRM transitions: 460.15 → 443.10 m/z (apixaban); 436.05 → 144.95 m/z (rivaroxaban).Results and discussion. The developed method was validated in accordance with the EAEU requirements for the following parameters: selectivity, calibration curve, accuracy and precision, lower limit of quantitation, suitability of standard samples, matrix effect, recovery, stability, carry-over, dilution effects. The parameters met the acceptance criteria.Conclusion. The confirmed analytical range of the developed and validated method was 1.00–300.00 ng/mL in blood plasma. The method for determining apixaban in blood plasma is simple and sensitive. This method was tested during the analytical part of the bioanalytical study and can be used to conduct other pharmacokinetic studies of apixaban drugs.

SPECTROPHOTOMETRIC DETERMINATION OF COPPER(II) IN SOIL IN THE FORM OF A PYROGALLOL RED COMPLEX IN THE PRESENCE OF SURFACTANTS

The spectrophotometric method of quantitative determination of copper(II) by reaction of complex formation with pyrogallol red (in the presence of cation and non-ionic surfactants is proposed. Optimal conditions for analysis have been determined. The method has been tested for the determination of copper(II) in the soil extractor sample. The metrological characteristics of the proposed methodology are evaluate: the detection limit is 0.12 mg/kg, relative standard deviation - less than 0.05.

Identifying potential Q-markers for quality evaluation of Zhenyuan capsule by integrating chemical analysis, network pharmacology, molecular docking, and molecular dynamics simulations

Quality markers (Q-markers) are of great significance for quality evaluation of herbal medicines. Zhenyuan Capsule (ZYC) is a kind of Chinese patent medicine used to treat cardiovascular diseases. However, reliable and effective Q-markers for ZYC are still lacking. Herein, a UHPLC-Q/Orbitrap-MS/MS was performed to characterise the preliminary chemical profile of ZYC. A total of 86 components were characterised among which 20 constituents were unambiguously identified by reference compounds. Based on network pharmacology, seven major ginsenosides with great importance in the network were identified as Q-markers among which ginsenoside Re with the highest betweenness was screened to inhibit the development of coronary heart disease (CHD) by binding with vascular endothelial growth factor A (VEGFA). Docking and molecular dynamics simulation studies suggested that ginsenoside Re stably bound to VEGFA. Quantitative determination and chemical fingerprinting analysis were performed using HPLC-DAD. The results showed that ginsenosides screened might function as potential Q-markers for ZYC.

Multiresponsive luminescent metal–organic framework for cooking oil adulteration detection and gallium(III) sensing

A new 3D metal–organic framework {[Cd16(tr2btd)10(dcdps)16(H2O)3(EtOH)]∙15DMF}n (MOF 1, tr2btd = 4,7-di(1,2,4-triazol-1-yl)benzo-2,1,3-thiadiazole, H2dcdps = 4,4′-sulfonyldibenzoic acid) was obtained and its luminescent properties were studied. MOF 1 exhibited bright blue-green luminescence with a high quantum yield of 74 % and luminescence quenching response to a toxic natural polyphenol gossypol and luminescence enhancement response to some trivalent metal cations (Fe3+, Cr3+, Al3+ and Ga3+). The limit of gossypol detection was 0.20 µM and the determination was not interfered by the components of the cottonseed oil. The limit of detection of gallium(III) was 1.1 µM. It was demonstrated that MOF 1 may be used for distinguishing between the genuine sunflower oil and oil adulterated by crude cottonseed oil through qualitative luminescent and quantitative visual gossypol determination.

New Tritopic Terpyridine‐based Fluorescent Probe for the Efficient Determination of Th4+, Zn2+ and F− Ions

AbstractThe present work demonstrates the determination of thorium (Th4+), zinc (Zn2+) and fluoride (F−) ions by employing a substituted tripodal terpyridine (TP) as a fluorescence sensor. The distinct fluorescence intensities of the free TP and TP‐M complexes (M=Zn2+or Th4+) with the same emission wavelength at 468 nm were observed in steady‐state photoluminescence (PL) spectra at pH 7.0 with a 1 : 3 ratio of metal to the ligand. A ratiometric dual fluorescence signals for Zn2+ and Th4+ were displayed by the probe TP at varied concentrations. Furthermore, the quantitative determination of F− ions was achieved through the addition of F− to the tripod‐terpyridine‐zinc complex (TP‐Zn2+) where the fluorescence intensity decreases gradually. Notably, the present work facilitates the LOD (limit of detection) as 1.1×10−10 M, 1.01×10−8 M and 3.18×10−10 M and further LOQ (limit of quantification) as 0.37×10−9 M, 0.33×10−7 M and 5.26×10−9 M for Zn2+, Th4+ and F− ions, respectively. The predicted absorption spectra of TP show HOMO to LUMO+2 electronic excitation at 358 nm whereas the complex TP‐Th4+ exhibits HOMO to LUMO+1 electronic excitation at 568 nm.

Single-centre prospective evaluation of the first 5 years of cystic fibrosis newborn screening in Germany.

In 2016, nationwide cystic fibrosis newborn screening (CFNS) was newly implemented in Germany, using an immunoreactive trypsin/pancreatitis-associated protein/DNA screening algorithm that differs from most other nationwide screening programmes. We analysed real-life feasibility of the confirmation process with respect to our pre-specified procedural objectives. These included overall accuracy through false-negative and false-positive results, effectiveness of the Bavarian tracking system, and accuracy of Macroduct and Nanoduct sweat conductivity compared with quantitative chloride determination. All consecutive CFNS-positive newborns assigned to our CF centre and born between 1 September 2016 and 31 August 2021 (n=162) were included. The German CFNS was feasible at our CF centre as all procedural objectives were met. The positive predictive value (PPV) of positive CFNS was low (0.23) and two initially negatively screened children were later diagnosed with CF. The tracking system was highly efficient with a 100% tracking rate. The Macroduct and Nanoduct systems had comparable success rates (93.2% versus 95.9%). Importantly, conductivity via Macroduct was more accurate than via Nanoduct (zero and four false-positive newborns, respectively). CF confirmation diagnostics of neonates in a certified regional CF centre was well managed in daily routine. The PPV of the German CFNS needs to be improved, e.g. by extending the DNA analysis within the screening algorithm and by increasing the number of variants tested. The Bavarian tracking system can serve as a successful model for other tracking systems. We preferred the Macroduct system because of its more accurate sweat conductivity readings.

Technology for Isolation Essential Oil from the Buds of Populus balsamifera L.

The article presents the results of the development of technology for isolating essential oil from the buds of Populus balsamifera L. and a medicinal substance based on it. For the first time, a technology has been developed for the quantitative isolation of essential oil from the buds of Populus balsamifera L. by the barothermal method at a temperature of 140 ºC, under a vacuum of 1333‒2000 Pa. The main components of the essential oil of Populus balsamifera L. buds, isolated by the barothermal method, were determined to be α-bisabolol, β-eudesmol, and 2-phenylethyl-2-methylbutanoate. A technological scheme for the production of essential oil substance from Populus balsamifera L. buds has been developed, including 2 stages of the main technological process and 2 stages of auxiliary work, and its pilot industrial regulations. The control points during the isolation and preparative production of the essential oil substance from the Populus balsamifera L. buds are the major components α-bisabolol and β-eudesmol. The main critical points in the production of a substance based on the essential oil of Populus balsamifera L. buds are pressure, temperature, and duration of isolation. The stages of production of the substance are controlled using a standard sample of α-bisabolol (1). A quantitative determination of 108 components of essential oil from Populus balsamifera L. buds was carried out, as well as standardization for organoleptic properties and major components. A comparative analysis of essential oil from Populus balsamifera L. buds collected in the vicinity of Karaganda and the North Kazakhstan region was carried out. A substance based on essential oil from Populus balsamifera L. buds has antimicrobial, wound-healing, and antitumor activities with relatively low toxicity.

The Effect of Clopidogrel and Ticagrelor on Human Adipose Mesenchymal Stem Cell Osteogenic Differentiation Potential: In Vitro Comparative Study.

Ticagrelor (TICA) and clopidogrel (CLP) are extensively used antiplatelet drugs that act by antagonizing the P2Y12 receptors that are found on platelets in addition to bone cells. Aim. The purpose of this study was to investigate the effect of clopidogrel and ticagrelor on stem cells osteogenic differentiation in vitro. Methods. Human adipose-derived mesenchymal stem cells (hAd-MSCs) were divided into (1) control group, (2) osteogenic group (osteo group), (3) clopidogrel group (CLP group), and (4) ticagrelor group (TICA group). The osteogenic differentiation potential was determined by mineralization nodule formation using Alizarin Red S staining, measuring ALP enzyme activity by alkaline phosphatase assay. Quantitative determination for osteogenic markers included osteocalcin (OC); runt-related transcription factor 2 (RUNX2) performed using western blot; osteoprotegerin (OPG) using enzyme-linked immunosorbent assay (ELISA) and inflammatory markers; and tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) measured using real-time polymerase chain reaction quantitative (RT-PCR) and ELISA. Results. In comparison to all study groups, the TICA group showed significant increase in the mineralized extracellular matrix, ALP enzyme activity, and bone markers expression as RUNX2 (P < 0.0001), OC, and OPG (P < 0.05). The expression of IL-6 and TNF-α was determined by RT-qPCR and ELISA techniques. TICA and CLP significantly decreased both markers compared to the control group. The TICA group showed statistically significant lower levels of both markers (P < 0.0001) than the CLP and control groups via the ELISA technique. Conclusion. TICA may possess a positive effect on hAd-MSCs osteogenic differentiation compared to CLP.

Linearity and bias of proton density fat fraction across the full dynamic range of 0-100%: a multiplatform, multivendor phantom study using 1.5T and 3T MRI at two sites.

Performance assessments of quantitative determinations of proton density fat fraction (PDFF) have largely focused on the range between 0 and 50%. We evaluate PDFF in a two-site phantom study across the full 0-100% PDFF range. We used commercially available 3D chemical-shift-encoded water-fat MRI sequences from three MRI system vendors at 1.5T and 3T and conducted the study across two sites. A spherical phantom housing 18 vials spanning the full 0-100% PDFF range was used. Data at each site were acquired using default parameters to determine same-day and different-day intra-scanner repeatability, and inter-system and inter-site reproducibility, in addition to linear regression between reference and measured PDFF values. Across all systems, results demonstrated strong linearity and minimal bias. For 1.5T systems, a pooled slope of 0.99 with a 95% confidence interval (CI) of 0.981-0.997 and a pooled intercept of 0.61% PDFF with a 95% CI of 0.17-1.04 were obtained. Results for pooled 3T data included a slope of 1.00 (95% CI 0.995-1.005) and an intercept of 0.69% PDFF (95% CI 0.39-0.97). Inter-site and inter-system reproducibility coefficients ranged from 2.9 to 6.2 (in units of PDFF), while intra-scanner same-day and different-day repeatability ranged from 0.6 to 7.8. PDFF across the 0-100% range can be reliably estimated using current commercial offerings at 1.5T and 3T.

Quantification of Riboflavin and Thiamine in GI (Geographical Indication) Branded Yogurts Collected from Bogura, Bangladesh Using HPLC Equipped with a Fluorescence Detector

Thiamine (vitamin B1) and riboflavin (vitamin B2) are both essential vitamins for human health. Thiamine (vitamin B1) is essential for energy metabolism, nervous system function, carbohydrate metabolism, cardiovascular health, digestion, muscle function, etc. On the other hand, Riboflavin (vitamin B2), which acts as an antioxidant, is essential for energy production, healthy skin, hair and nails, eye health, red blood cell production, nervous system function, etc. Due to its specialty, Bogura's famous yogurt was recognized as a Geographical Indication (GI) on June 26, 2023 by the Directorate of Patents, Designs, and Trademarks (DPDT) under the Ministry of Industry, the Government of the People’s Republic of Bangladesh (Prothom Alo, 2023). The purpose of the study was the quantitative determination of two water-soluble vitamins, thiamine and riboflavin, in the GI branded yogurt and whey (Ghol), collected from Bogura, Bangladesh to ensure health benefits. The methods employed for the quantitative analysis of these vitamins were reversed-phase high performance liquid chromatography (RP-HPLC) equipped with a fluorescence detector. The extraction process involved acid hydrolysis followed by enzymatic hydrolysis with takadiastase enzyme. Chromatographic separation was achieved with a Shimadzu Prominence HPLC system using isocratic elution mode on a C18 column (4.6 mm × 250 mm, 5 μm). The correlation coefficients for thiamine and riboflavin were 0.9975 and 0.9974, respectively. The recovery rates for thiamine and riboflavin were found as 97.70% and 105.40%, respectively. Twenty-two samples were analyzed. Thiamine and riboflavin were found in the range of 0.0647 to 0.1396 mg/100 g and 0.0227 to 0.3749 mg/100 g, respectively. It can be concluded that these yogurts were rich in thiamine and riboflavin. Therefore, these yogurts are beneficial for health. Bangladesh Pharmaceutical Journal 27(1): 59-66, 2024 (January)

Quantitative determination of dopamine in the presence of interfering substances supported by machine learning tools

In the field of neuroscience as well as in the clinical setting, the neurotransmitter dopamine (DA) is an analyte which is important for research as well as medical purposes. There are plenty of methods available to measure dopamine quantitatively, with voltammetric ones such as differential pulse voltammetry (DPV) being among the most convenient and simple ones. However, dopamine often occurs, either naturally or because of the requirements of involved enzymatic systems, alongside substances that can influence the signal it produces upon electrochemical conversion. An example for such substances is the magnesium ion, which itself is not electrochemically active in the potential range needed for DA oxidation, but influences the dopamine signal. We have characterized the properties of DPV signals subject to the interaction between DA and Mg2+ and show that, although these properties are changing in a nonlinear fashion when both concentrations are varying, relatively simple linear mathematical models can be used to determine dopamine concentrations quantitatively in the presence of magnesium ions. The focus of this study is thus, the mathematical treatment of experimental data in order to overcome an analytical problem and not the investigation of the chemical background of DA-Mg2+ interaction.