keyword
MENU ▼
Read by QxMD icon Read
search

Spectrophotometric estimation

keyword
https://www.readbyqxmd.com/read/29115039/spectroscopic-determination-of-succinylcholine-in-dosage-forms-using-eosin-y
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/28855820/in-vitro-alpha-amylase-inhibition-and-in-vivo-antioxidant-potential-of-momordica-dioica-seeds-in-streptozotocin-induced-oxidative-stress-in-diabetic-rats
#15
P Sailaja Rao, G Krishna Mohan
Momordica dioica Roxb. Commonly known as "Kakora" in Telugu, is used in the Indian traditional system of medicine for the treatment of diabetes. The aim of this study was to investigate the antidiabetic activity of methanolic extract of M. dioica seeds (MEMD) in streptozotocin (STZ) induced diabetic rats. The in vitro α-amylase inhibitory activity of the MEMD was done by spectrophotometric method. Diabetes was induced by STZ (45 mg/kg; i.p), MEMD (100 & 200 mg/kg; b.wt) and standard drug metformin (50 mg/kg; b...
September 2017: Saudi Journal of Biological Sciences
https://www.readbyqxmd.com/read/28830039/spectrophotometric-determination-of-fenoprofen-calcium-drug-in-pure-and-pharmaceutical-preparations-spectroscopic-characterization-of-the-charge-transfer-solid-complexes
#16
Marwa E Mohamed, Eman Y Z Frag, Abla A Hathoot, Essam A Shalaby
Simple, accurate and robust spectrophotometric method was developed for determination of fenoprofen calcium drug (FPC). The proposed method was based on the charge transfer (CT) reaction of FPC drug (as n-electron donor) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4,6-trinitrophenol (picric acid, PA) or 1,2,5,8-tetrahydroxyanthraquinone (Quinalizarin, QZ) (as π-acceptors) to give highly colored charge transfer complexes. Different variables affecting the reaction such as reagent concentration, temperature and time have been carefully optimized to achieve the highest sensitivity...
August 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28826748/effects-of-exposure-to-multiple-heavy-metals-on-biochemical-and-histopathological-alterations-in-common-carp-cyprinus-carpio-l
#17
Sivakumar Rajeshkumar, Yang Liu, Junguo Ma, Hong Ying Duan, Xiaoyu Li
Heavy metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of exposure to mixtures of essential and toxic metals (Cr, Cd and Pb) on biochemical, immunotoxicity level and morphological characteristics of the various tissues of a biomarker freshwater fish common carp using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days, under controlled laboratory conditions...
August 18, 2017: Fish & Shellfish Immunology
https://www.readbyqxmd.com/read/28825535/simultaneous-estimation-of-ofloxacin-clotrimazole-and-lignocaine-hydrochloride-in-their-combined-ear-drop-formulation-by-two-spectrophotometric-methods
#18
Kunjan Bodiwala, Shailesh Shah, Yogini Patel, Pintu Prajapati, Bhavin Marolia, Gajanan Kalyankar
Two sensitive, accurate, and precise spectrophotometric methods have been developed and validated for the simultaneous estimation of ofloxacin (OFX), clotrimazole (CLZ), and lignocaine hydrochloride (LGN) in their combined dosage form (ear drops) without prior separation. The derivative ratio spectra method (method 1) includes the measurement of OFX and CLZ at zero-crossing points (ZCPs) of each other obtained from the ratio derivative spectra using standard LGN as a divisor, whereas the measurement of LGN at the ZCP of CLZ is obtained from the ratio derivative spectra using standard OFX as a divisor...
January 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28825533/analysis-of-closely-related-antioxidant-nutraceuticals-using-the-green-analytical-methodology-of-ann-and-smart-spectrophotometric-methods
#19
Mohamed A Korany, Azza A Gazy, Essam F Khamis, Marwa A A Ragab, Miranda F Kamal
Two new, simple, and specific green analytical methods are proposed: zero-crossing first-derivative and chemometric-based spectrophotometric artificial neural network (ANN). The proposed methods were used for the simultaneous estimation of two closely related antioxidant nutraceuticals, coenzyme Q10 (Q10) and vitamin E, in their mixtures and pharmaceutical preparations. The first method is based on the handling of spectrophotometric data with the first-derivative technique, in which both nutraceuticals were determined in ethanol, each at the zero crossing of the other...
January 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28780456/synthesis-single-crystal-dna-interaction-spectrophotometric-and-spectroscopic-characterization-of-the-hydrogen-bonded-charge-transfer-complex-of-2-aminopyrimidine-with-%C3%AF-acceptor-chloranilic-acid-at-different-temperature-in-acetonitrile
#20
Zulkarnain, Lal Miyan, Afaq Ahmad, Md Fazle Alam, Hina Younus
The charge transfer (CT) interaction of 2-aminopyrimidine (AP) with chloranilic acid (CLA) as π-acceptor was investigated spectrophotometrically in acetonitrile at different temperatures in the range of 25-50°C. The 1:1 stoichiometry of the synthesized CT complex was detected using straight line method. Benesi-Hildebrand equation was used to determine the association constant (KCT), molar extinction coefficient (ε) and other physical parameters. Various thermodynamics parameters such as enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) were determined using UV-Visible spectrophotometry in acetonitrile at different temperatures...
September 2017: Journal of Photochemistry and Photobiology. B, Biology
keyword
keyword
73551
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"