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Spectrophotometric estimation

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https://www.readbyqxmd.com/read/29310215/exploiting-multivariate-calibration-for-compensation-of-iron-interference-in-the-spectrophotometric-flow-based-catalytic-determination-of-molybdenum
#1
Eliezer Oliveira, Camelia Henriquez, Lidiane C Nunes, Elias A G Zagatto
Multivariate calibration involving partial least squares was exploited in the flow-based spectrophotometric determination of molybdenum in river waters relying on the Mo(VI)-catalyzed iodide oxidation by H2O2 under acidic conditions. Two sample aliquots were simultaneously inserted into the carrier stream, and differential pumping was accountable for in-line addition of sulfuric acid to one of them. Pronounced gradients (acidity and reagent concentrations) were established along the complex sample zone formed, and the absorbance-time function was characterized by local maximum and minimum values...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29304150/non-invasive-assessment-of-cerebral-oxygenation-a-comparison-of-retinal-and-transcranial-oximetry
#2
Karel Van Keer, Jan Van Keer, João Barbosa Breda, Vahid Nassiri, Cathy De Deyne, Cornelia Genbrugge, Luís Abegão Pinto, Ingeborg Stalmans, Evelien Vandewalle
BACKGROUND: To investigate the correlation between cerebral (SO2-transcranial), retinal arterial (SaO2-retinal) and venous (SvO2-retinal) oxygen saturation as measured by near-infrared spectroscopy (NIRS) and retinal oximetry respectively. METHODS: Paired retinal and cerebral oxygen saturation measurements were performed in healthy volunteers. Arterial and venous retinal oxygen saturation and diameter were measured using a non-invasive spectrophotometric retinal oximeter...
2018: PloS One
https://www.readbyqxmd.com/read/29247820/a-study-of-salivary-opiorphin-levels-using-different-anesthetic-drugs-and-techniques-a-randomized-controlled-clinical-study
#3
Kumar Parida Soumendra, T Guruprasad, V B Krishnakumar Raja, Poornima Ravi
PURPOSE: This study aimed at assessing the change in salivary opiorphin levels before and after administration of local anesthesia, with the use of three different local anesthetic agents, and different anaesthetic techniques. METHODS: The investigators implemented a randomized controlled clinical study in 144 patients who required tooth extraction after administration of local anaesthesia. A total of 288 samples were collected in sterile containers before and after administration of local anesthetics...
December 13, 2017: Journal of Stomatology, Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/29188769/chromatographic-method-development-and-validation-for-the-determination-of-valsartan-in-biological-fluid
#4
Sana Ghayas, Muhammad Harris Shoaib, Fahad Siddiqui, Rabia Ismail Yousuf, M Ali Masood, Fakhsheena Anjum, Rabia Bushra, Lubna Bashir, Shazia Naz, Iyad Naeem Muhammad
A swift, precise and simple HPLC bioanalytical technique with UV detection was established and validated for quantitative estimation of valsartan in human plasma. The analyte was separated from plasma by protein precipitation with acetonitrile and chromatographically separated on Zorbax SB-C18 (5μm, 4.6mm × 15cm) column. The solvent mixture system consisting of acetonitrile, water and glacial acetic acid (40:59:1 v/v), was pumped using isocratic mode at 1mL/min flow rate. Samples' detection of drug was made spectrophotometrically at a wavelength of 264nm...
November 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29188767/development-and-validation-of-stability-indicating-assay-method-for-cinitapride-in-bulk-tablets
#5
Attaur Rehman, Anwar Ejaz Beg, Rabia Bushra, Maria Ashfaq, Farya Zafar, Huma Ali, Mehwish Rizvi
A simple stability indicating UV-spectrophotometric method has been developed and validated for the determination of cinitapride hydrogen tartrate (CHT) in bulk and solid pharmaceutical dosage form. Drug absorption was measured in different analytical mediums however; maximum absorption was seen in 0.1 N HCl at wavelength (λmax) of 266 nm. The calibration curve was found to be linear over the concentration range from 6 to14μg/mL with the correlation coefficient value (r) of 0.999. The LOD and LOQ were estimated to be 0...
November 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29180286/the-estimation-of-oxime-efficiency-is-affected-by-the-experimental-design-of-phosphylated-acetylcholinesterase-reactivation
#6
Nikolina Maček Hrvat, Tamara Zorbaz, Goran Šinko, Zrinka Kovarik
Reactivation of acetylcholinesterase (AChE), an essential enzyme in neurotransmission, is a key point in the treatment of acute poisoning by nerve agents and pesticides, which structurally belong to organophosphorus compounds (OP). Due to the high diversity of substituents on the phosphorous atom, there is a variety of OP-AChE conjugates deriving from AChE inhibition, and therefore not only is there no universal reactivator efficient enough for the most toxic OPs, but for some nerve agents there is still a lack of any reactivator at all...
November 24, 2017: Toxicology Letters
https://www.readbyqxmd.com/read/29115039/spectroscopic-determination-of-succinylcholine-in-dosage-forms-using-eosin-y
#7
Magda M Ayad, Fathalla Belal, Mervet M Hosney, Samah Abo El Abass, Nora Elsayed
Two simple and sensitive analytical assay methods using spectrophotometry and spectrofluorimetry techniques were developed for the estimation of succinylcholine chloride (SUC) in pharmaceutical preparations. The suggested methods are based on the formation of an ion pair complex formed between the drug and eosin Y spectrophotometrically (Method I), or the suppressive effect of succinylcholine on the native fluorescence property of eosin Y (Method II). The spectrophotometric method (Method I) involves measuring the absorbance of the complex between succinylcholine and eosin Y at 550 nm in Britton Robinson buffer of pH 3...
November 8, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/29101230/glutathione-limits-aquacopper-i-to-sub-femtomolar-concentrations-through-cooperative-assembly-of-a-tetranuclear-cluster
#8
M Thomas Morgan, Lily Anh H Nguyen, Haylie L Hancock, Christoph J Fahrni
The tripeptide glutathione (GSH) is a crucial intracellular reductant and radical scavenger, but may also coordinate the soft Cu(I) cation and thereby yield pro-oxidant species. The GSH-Cu(I) interaction is thus a key consideration for both redox and copper homeostasis in cells. However, even after nearly four decades of investigation, the nature and stability of the GSH-Cu complexes formed under biologically relevant conditions remain controversial. Here, we revealed the unexpected predominance of a tetranuclear [Cu4(GS)6] cluster that is sufficiently stable to limit the effective free aquocopper(I) concentration to the subfemtomolar regime...
November 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29084161/molecular-analysis-of-the-srd5a1-and-srd5a2-genes-in-patients-with-benign-prostatic-hyperplasia-with-regard-to-metabolic-parameters-and-selected-hormone-levels
#9
Aleksandra Rył, Iwona Rotter, Anna Grzywacz, Iwona Małecka, Karolina Skonieczna-Żydecka, Katarzyna Grzesiak, Marcin Słojewski, Aleksandra Szylińska, Olimpia Sipak-Szmigiel, Małgorzata Piasecka, Kinga Walczakiewicz, Maria Laszczyńska
Introduction: The etiology of benign prostatic hyperplasia (BPH) has not so far been fully explicated. However, it is assumed that changes in the levels of hormones associated with aging can contribute to the development of prostatic hyperplasia. Dihydrotestosterone combines with the androgen receptor (AR) proteins of the prostate gland. Enzyme activity is based on two isoenzymes: type 1 and type 2. 5α-reductase type 1 is encoded by the SRD5A1 gene, and type 2 is encoded by the SRD5A2 gene. The aim of our study was to determine the frequency of the SRD5A1 (rs6884552, rs3797177) and SRD5A2 (rs523349, rs12470143) genes' polymorphisms, and to assess the relationships between the genotypes of the tested mutations, and the levels of biochemical and hormonal parameters in patients with BPH...
October 30, 2017: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/29079840/selective-colorimetric-detection-of-nitrite-in-water-using-chitosan-stabilized-gold-nanoparticles-decorated-reduced-graphene-oxide
#10
Baishnisha Amanulla, Selvakumar Palanisamy, Shen-Ming Chen, Te-Wei Chiu, Vijayalakshmi Velusamy, James M Hall, Tse-Wei Chen, Sayee Kannan Ramaraj
Excess nitrite (NO2(-)) concentrations in water supplies is considered detrimental to the environment and human health, and is associated with incidence of stomach cancer. In this work, the authors describe a nitrite detection system based on the synthesis of gold nanoparticles (AuNPs) on reduced graphene oxide (rGO) using an aqueous solution of chitosan and succinic acid. The AuNPs-rGO nanocomposite was confirmed by different physicochemical characterization methods including transmission electron microscopy, elemental analysis, X-ray diffraction, UV-visible (UV-vis) and Fourier transform infrared spectroscopy...
October 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29047750/vector-representation-of-spectrophotometric-measurements-of-medium-composition
#11
Alexander M Liudchik, Pavel N Paulenka
A rigorous theoretical description of the standard spectrophotometric method for determining medium composition is given using a vector representation of measured signals. Further modifications, methods of orthogonal optical absorption spectroscopy (OOAS) and differential optical absorption spectroscopy (DOAS), are also substantiated. It is shown that the conventional criterion, the difference between the measured spectrum and the spectrum simulated on the basis of calculations, does not serve as an indicator of quality of the latter...
September 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29039320/pharmacokinetic-and-bioequivalence-studies-of-fast-dispersible-ketoprofen-tablets-in-healthy-volunteers
#12
Farya Zafar, Muhammad Harris Shoaib, Rabia Ismail Yousuf, Huma Ali, Rabia Bushra
In the present study the pharmacokinetic and bioequivalence parameter of Ketoprofen 100 mg fast dispersible tablets (test) were measured with marketed (reference) product. This study was accomplished following FDA guidance. A single dose, open labeled, cross over (two way), randomized study design was used to conduct investigation on 12 Pakistani healthy volunteers. At various time points blood samples (10mL) were drawn i.e. at 0.25, 0.5, 1, 1.5, 2, 3, 4, 8, 12 and 13hr. Plasma was then separated and ketoprofen concentrations were estimated by validated HPLC technique using LC 20A pump (Shimadzu Corp, Japan) and Spectrophotometric SPD-20Adetector (Shimadzu Corp, Japan)...
July 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28979303/artificial-neural-networks-ann-for-the-simultaneous-spectrophotometric-determination-of-fluoxetine-and-sertraline-in-pharmaceutical-formulations-and-biological-fluid
#13
Hamid Reza Akbari Hasanjani, Mahmoud Reza Sohrabi
Simultaneous spectrophotometric estimation of Fluoxetine and Sertraline in tablets were performed using UV-Vis spectroscopic and Artificial Neural Networks (ANN). Absorption spectra of two components were recorded in 200-300 nm wavelengths region with an interval of 1 nm. The calibration models were thoroughly evaluated at several concentration levels using the spectra of synthetic binary mixture (prepared using orthogonal design). Three layers feed-forward neural networks using the back-propagation algorithm (B...
2017: Iranian Journal of Pharmaceutical Research: IJPR
https://www.readbyqxmd.com/read/28965564/concentration-of-selenium-zinc-copper-cu-zn-ratio-total-antioxidant-status-and-c-reactive-protein-in-the-serum-of-patients-with-psoriasis-treated-by-narrow-band-ultraviolet-b-phototherapy-a-case-control-study
#14
Marta Wacewicz, Katarzyna Socha, Jolanta Soroczyńska, Marek Niczyporuk, Piotr Aleksiejczuk, Jolanta Ostrowska, Maria H Borawska
BACKGROUND: Psoriasis is a common, an inflammatory skin disease. Trace elements may play an active role in the pathogenesis of psoriasis. OBJECTIVE: The aim of this study was to estimate the concentration of selenium (Se), zinc (Zn), copper (Cu) and Cu/Zn ratio as well as total antioxidant status (TAS) and c-reactive protein (CRP) in the serum of patients with psoriasis. METHODS: In this case-control study sixty patients with psoriasis and fifty-eight healthy people were examined...
December 2017: Journal of Trace Elements in Medicine and Biology
https://www.readbyqxmd.com/read/28962772/synthesis-of-chitosan-based-magnetic-molecularly-imprinted-polymers-for-selective-separation-and-spectrophotometric-determination-of-histamine-in-tuna-fish
#15
Mahdi Hashemi, Zahra Nazari, Nooshin Noshirvani
A novel chitosan molecularly imprinted polymers (CHI/MIPs) coated on Fe3O4 magnetic nanoparticles (MNPs) for selective solid phase extraction (SPE) of histamine (His) was synthesized by cross-linking of CHI with (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) in the presence of His as the template molecule, and GPTMS/MNPS. Synthesized sorbent was characterized by scanning electron microscopy, X-ray diffraction, FT-IR and via adsorption kinetics and adsorption isotherms. The application of this sorbent was investigated in preconcentration and spectrophotometric determination of His by charge transfer complexation...
December 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28961528/new-insights-on-the-spectrophotometric-determination-of-melatonin-pka-values-and-melatonin-%C3%AE-cd-inclusion-complex-formation-constant
#16
A Zafra-Roldán, S Corona-Avendaño, R Montes-Sánchez, M Palomar-Pardavé, M Romero-Romo, M T Ramírez-Silva
Using UV-Vis spectrophotometry a stability study of melatonin at different pH values was done in aqueous media, finding that at acidic pH melatonin is unstable when interacting with the environment, however it becomes stable protecting it from light and oxygen. From the UV-Vis spectra and SQUAD software, melatonin pKa values, in a completely protected aqueous medium, were estimated as 5.777±0.011 and 10.201±0.024. Using the same techniques, the melatonin and β-cyclodextrin inclusion complex formation constants were assessed at pH3, 7 and 11...
September 19, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28957378/quantifying-pco2-in-biological-ocean-acidification-experiments-a-comparison-of-four-methods
#17
COMPARATIVE STUDY
Sue-Ann Watson, Katharina E Fabricius, Philip L Munday
Quantifying the amount of carbon dioxide (CO2) in seawater is an essential component of ocean acidification research; however, equipment for measuring CO2 directly can be costly and involve complex, bulky apparatus. Consequently, other parameters of the carbonate system, such as pH and total alkalinity (AT), are often measured and used to calculate the partial pressure of CO2 (pCO2) in seawater, especially in biological CO2-manipulation studies, including large ecological experiments and those conducted at field sites...
2017: PloS One
https://www.readbyqxmd.com/read/28874228/multivariate-validated-models-for-simultaneous-determination-of-ibuprofen-and-famotidine-in-the-presence-of-related-substances
#18
Eman S Elzanfaly, Hala E Zaazaa, Aya T Soudi, Maissa Y Salem
Two multivariate validated spectrophotometric methods, namely partial least-squares (PLS) and principal component regression (PCR), were developed and validated for the determination of ibuprofen and famotidine in presence of famotidine degradation products and ibuprofen impurity (4-isobutylacetophenone). A calibration set was prepared in which the two drugs together with the degradation products and impurity were modeled using a multilevel multifactor design. This calibration set was used to build the PLS and PCR models...
September 6, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28867635/effect-of-human-placental-extract-in-the-management-of-biofilm-mediated-drug-resistance-a-focus-on-wound-management
#19
Sutapa Goswami, Ratul Sarkar, Pritam Saha, Amit Maity, Tridib Sarkar, Debmalya Das, Piyali Datta Chakraborty, Subhasri Bandyopadhyay, Chandan Kumar Ghosh, Sanmoy Karmakar, Tuhinadri Sen
Management of infectious wounds, particularly chronic wounds and burn injuries, is a matter of global concern. Worldwide estimates reveal that, billions of dollars are being spent annually for the management of such chronic ailments. Evidently, bacterial biofilms pose a greater problem in the effective management of infection in chronic wounds, since most of the currently available antibiotics are unable to act on the microorganisms residing inside the protected environment of the biofilms. Accordingly, in the present study, we have attempted to evaluate the anti-biofilm properties of human placental extract (PLX) and also other virulence factors that are mediated via the quorum sensing (QS) signalling system...
October 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28855956/kinetic-modelling-an-integrated-approach-to-analyze-enzyme-activity-assays
#20
Jelena Boeckx, Maarten Hertog, Annemie Geeraerd, Bart Nicolai
BACKGROUND: In general, enzyme activity is estimated from spectrophotometric data, by taking the slope of the linear part of the progress curve describing the rate of change in the substrate or product monitored. As long as the substrate concentrations are sufficiently high to saturate the enzyme and, the velocity of the catalyzed reaction is directly proportional to the enzyme concentration. Under these premises, this velocity can be taken as a measure of the amount of active enzyme present...
2017: Plant Methods
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