scholarly journals Determination of flavonoids and total polyphenol contents in commercial apple juices

2018 ◽  
Vol 36 (No. 3) ◽  
pp. 233-238 ◽  
Author(s):  
Leposava Pavun ◽  
Predrag Đurđević ◽  
Milena Jelikić-Stankov ◽  
Daniela Đikanović ◽  
Snežana Uskoković-Marković
Keyword(s):  
Fruit Juice ◽  
Accurate Determination ◽  
Flavonoid Content ◽  
Dpph Assay ◽  
Total Polyphenol ◽  
Strong Emission ◽  
Spectrofluorimetric Method ◽  
Good Agreement ◽  
Antioxidative Ability

We propose a sensitive and selective spectrofluorimetric method for the determination of flavonoids as expressed in ‘quercetin equivalent’ in apple juices. The method is based on the strong emission of the aluminium(III)-quercetin complex at 480 nm with excitation at 420 nm, and it is successfully applied for the determination of flavonoids in commercial apple juices and compared with results obtained in reference spectrophotometric determination. The flavonoid content in commercial apple juices was found to range from 5.53 to 15.55 mg/l quercetin equivalent. The very good agreement between the two methods indicates the suitability of the proposed spectrofluorimetric method for the precise and accurate determination of flavonoids. In addition, the total polyphenol content was determined spectrophotometrically using the Folin-Ciocalteu (FC) method and the antioxidative activity of the tested juices was tested in a DPPH assay and these values were correlated with each other. The obtained profiles of compounds with antioxidative ability lead us to conclude that fruit juice labels based only on fruit % might sometimes misinform consumers.

scholarly journals Development and validation of spectrofluorimetric and LC–MS/MS methods for the determination of hesperidin in human plasma and pharmaceutical forms

2012 ◽  
Vol 77 (11) ◽  
pp. 1625-1640 ◽  
Author(s):  
Leposava Pavun ◽  
Jasmina Dimitric-Markovic ◽  
Predrag Djurdjevic ◽  
Milena Jelikic-Stankov ◽  
Daniela Djikanovic ◽  
...  
Keyword(s):  
Human Plasma ◽  
Good Accuracy ◽  
Accurate Determination ◽  
Direct Determination ◽  
Strong Emission ◽  
Linearity Range ◽  
Spectrofluorometric Method ◽  
Development And Validation ◽  
Good Agreement

The spectrofluorometric method, based on fluorescence properties of aluminium (III)?hesperidin complex, for the determination of hesperidin in human plasma and pharmaceutical forms has been developed and validated. The complex shows strong emission in the presence of surfactant betain sulfonate SB 12 at 476 nm with excitation at 390 nm. Linearity range in pharmaceutical forms of hesperidin was 0.06 ? 24.4 ?g mL-1 with LOD 0.016 ?g mL-1 and LOQ 0.049 ?g mL-1. Recovery values in the range 99.3 ? 99.7% indicate good accuracy of the method. A linear dependence of the intensity of fluorescence of the complex on the concentration of hesperidin in plasma was obtained in concentration range from 0.1 ? 12.2 ?g mL-1. The LOD was 0.032 ?g mL-1 while LOQ was 0.096 ?g mL-1. Recovery values were in the range 98.4 ? 99.8%. The reliability of the method was checked by LC-MS/MS method for plasma samples and HPLC/UV method for tablets with direct determination of hesperidin after separation. Linearity range in determination of hesperidin in pharmaceutical forms was obtained in the range from 0.05 to 10.00 ?g mL-1. The LOD was 0.01 ?g mL-1 and LOQ was 0.03 ?g mL-1. Linearity range in plasma determination of hesperidin was 0.02 ? 10.00 ?g mL-1 with LOD 0.005 ?g mL-1 and LOQ 0.015 ?g mL-1. Good agreement between two methods indicate the usability of the proposed spectroflurometric method for the simple, precise and accurate determination of hesperidin in clinical and quality control laboratories.

scholarly journals Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms

2014 ◽  
Vol 33 (2) ◽  
pp. 209 ◽  
Author(s):  
Leposava Pavun ◽  
Predrag Đurđević ◽  
Milena Jelikić-Stankov ◽  
Daniela Đikanović ◽  
Andrija Ćirić ◽  
...  
Keyword(s):  
Direct Determination ◽  
Dosage Forms ◽  
Font Size ◽  
Pharmaceutical Dosage Forms ◽  
Strong Emission ◽  
Rp Hplc ◽  
Spectrofluorimetric Method ◽  
Spectrofluorimetric Determination ◽  
Good Agreement

<p><span style="font-size: medium;"><span style="font-family: Times New Roman;">The simple, accurate and precise method based on fluorescence properties of aluminium (III)–quercetin complex, for the determination of quercetin has been developed and validated. The complex has strong emission at pH 3.30, </span><em>l</em></span><span style="font-family: Times New Roman;"><span style="font-size: small;"><em><sub>em</sub></em></span><span style="font-size: medium;"> = 480 nm, with </span></span><span style="font-size: medium;"><em>l</em></span><span style="font-family: Times New Roman;"><span style="font-size: small;"><em><sub>ex</sub></em></span><span style="font-size: medium;"> = 420 nm</span><span style="font-size: medium;">. Linearity range of quercetin determination was 1.5 - 60.5 ng mL</span><sup><span style="font-size: small;">-1</span></sup><span style="font-size: medium;"> with LOD 0.09 ng mL</span><sup><span style="font-size: small;">-1</span></sup><span style="font-size: medium;"> and LOQ 0.27 ng mL</span><sup><span style="font-size: small;">-1</span></sup><span style="font-size: medium;">. Recovery values in the range of 99.9 – 100.2 % indicate a good accuracy of the method. The established method was applied for the determination of quercetin in capsules, with </span><span style="font-size: medium;">Recovery value<strong> </strong>98.3 %, standard deviation 0.22 <strong>% </strong>and<strong> </strong>coefficient of variation<strong> </strong>0.09<strong> %</strong>.<strong> </strong></span></span></p><p>  The reliability of the method was checked by RP-HPLC/UV method for capsules with direct determination of quercetin after separation. The good agreement between two methods indicates the applicability usability of the proposed spectroflurometric method for quercetin determination in pharmaceutical dosage forms, with high reproducibility, and enables direct and simple determination without its prior extraction from samples.</p><p>The proposed spectrofluorimetric method has much better sensitivity and about 1000 times lower <em>LOD</em> and <em>LOQ</em> values compared to data reported in literature.</p>

The Proton Magnetic Resonance Spectra of some Chlorinated Polycyclodiene Pesticide Metabolites. Rapid Assessment of Stereochemistry

1971 ◽  
Vol 49 (12) ◽  
pp. 1993-2003 ◽  
Author(s):  
J. D. McKinney ◽  
L. H. Keith ◽  
A. Alford ◽  
C. E. Fletcher
Keyword(s):  
Magnetic Resonance ◽  
Accurate Determination ◽  
Rapid Assessment ◽  
Shift Reagent ◽  
Coupling Constant ◽  
Pesticide Metabolites ◽  
Relative Stereochemistry ◽  
Superimposed Signals ◽  
Good Agreement

The rapid and accurate determination of the relative stereochemistry of some postulated chlorinated polycyclodiene pesticide metabolites without excessive dependence on chemical methods is described. Proton assignments were made employing the new nuclear magnetic resonance (n.m.r.) shift reagent, Eu(DPM)3, which effected the separation of superimposed signals in these systems. The assignments based on coupling constant information and requiring spin decoupling equipment are in good agreement with those obtained from the Eu(DPM)3 studies. The data presented establishes the relative stereochemistry of these biologically important compounds and demonstrates the utility of one or both approaches in elucidating their overall structures.

Validation of Spectrophotometric Methods for the Determination of Total Polyphenol and Total Flavonoid Content

2017 ◽  
Vol 100 (6) ◽  
pp. 1795-1803 ◽  
Author(s):  
Petra Matić ◽  
Marija Sabljić ◽  
Lidija Jakobek
Keyword(s):  
Total Flavonoid ◽  
Chlorogenic Acids ◽  
Flavonoid Content ◽  
Polyphenol Content ◽  
Validation Process ◽  
Total Polyphenol ◽  
Spectrophotometric Methods ◽  
Calibration Curves ◽  
Validation Parameters

Abstract The aim of this study was to validate spectrophotometric methods for the measurement of total polyphenol (TP; via the Folin–Ciocalteu method) and total flavonoid (TF) content [via the aluminum chloride (AlCl3) method]. Validation parameters of these methods were determined, including linearity, sensitivity, precision (intra-assay and intermediate), accuracy, LOD, and LOQ. For the validation process, groups of polyphenol standards were used, including phenolic acids (gallic, p-coumaric, caffeic, and chlorogenic acids), flavan-3-ols [(+)-catechin and procyanidins B1 and B2], flavonols (quercetin and quercetin-3-rutinoside), and dihydrochalcones (phloretin and phloretin-2-glucoside). Obtained validation parameters were within acceptable ranges with high determination coefficients, reasonably low LODs and LOQs, and high slopes in the calibration curves for both methods, except for phloretin and phloretin-2-glucoside, for which there were low slopes in the calibration curves for the AlCl3 method. To evaluate differences in polyphenol content, the validated spectrophotometric methods were used to determine TP and TF content in wines (Plavac, Graševina, and Vranac) and juices (blueberry, strawberry, and blackcurrant juice) according to the polyphenol calibration curves. Polyphenol contents were different for both methods in all wines and juices.

Determination of the flexural stiffness of thin plates from small deflection measurements using optical holography

1982 ◽  
Vol 17 (1) ◽  
pp. 53-61 ◽  
Author(s):  
M J Marchant ◽  
M B Snell
Keyword(s):  
Numerical Method ◽  
Accurate Determination ◽  
Metal Plate ◽  
Thin Plates ◽  
Flexural Stiffness ◽  
Interference Fringes ◽  
Small Deflection ◽  
Stiffness Properties ◽  
Good Agreement

A technique is presented for accurate determination of the flexural stiffness of thin plates using optical holography. Measurements of the interference fringes on thin rhombic plates in anticlastic bending are used to calculate the components of curvature by a simple numerical method Control experiments on a metal plate give good agreement with the results of small deflection bending theory. The method appears ideally suited to the measurement of anisotropic flexural stiffness properties.

Determination of Antioxidant Components and Activity of Tamarix ramosissima Comparative with Vaccinium myrtillus on Streptozotocin-diabetic Mice

2018 ◽  
Vol 69 (7) ◽  
pp. 1860-1865
Author(s):  
Luciana Teodora Rotaru ◽  
Renata Maria Varut ◽  
Mihai Banicioiu Covei ◽  
Irina Iuliana Costache ◽  
Marius Novac ◽  
...  
Keyword(s):  
Lipid Peroxides ◽  
Thiobarbituric Acid ◽  
Vaccinium Myrtillus ◽  
Tamarix Ramosissima ◽  
Diabetic Mice ◽  
Flavonoid Content ◽  
Thiobarbituric Acid Reactive Substances ◽  
Total Polyphenol

Tamarix ramosissima (Tamaricaceae) is a small tree that grows spontaneously in Europe and Asia, being considered an invasive species in geographical areas with warm climates. The chemical composition is partially elucidated, being empirically used for antiinflammatory, analgesic, antibacterial and antioxidant effect. Our study aimed to evaluate the total polyphenol and flavonoid content of vegetal extracts and to test in vivo antioxidant therapeutic effect of it, comparative with Vaccinium myrtillus, using streptozotocin-induced diabetic mice. After five weeks the animals were sacrificed and we determined erythrocyte activities of superoxide dismutase, glutathione peroxidase, glutathione reductase and level of lipid peroxides as thiobarbituric acid reactive substances. Antioxidant enzymes had highest activities in mice treated with T. ramosissima extract and the level of lipid peroxides was the lowest. The tested extract had higher content of polyphenols comparative with V. myrtillus. Our results sustain the efficiency of T. ramosissima extracts on normalizing the effects of oxidative stress in diabetes.

scholarly journals Corrections to the Hipparcos proper motions in declination for 807 stars

2008 ◽  
pp. 109-113 ◽  
Author(s):  
G. Damljanovic ◽  
N. Pejovic
Keyword(s):  
Accurate Determination ◽  
Annual Number ◽  
Time Interval ◽  
Proper Motions ◽  
Hipparcos Catalogue ◽  
Time Variations ◽  
Better Than ◽  
Good Agreement

We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations ?? for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years) much longer than that of the Hipparcos mission (less than 4 years). In addition, the annual number of observations for every PZT programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2), aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our ?? and the EOC-2 ones for the star sample used in the present paper.

scholarly journals Development of spectrofluorimetric stability indicating method for determination of naratriptan hydrochloride in pharmaceutical dosage form

2018 ◽  
Vol 9 (3) ◽  
pp. 251-257
Author(s):  
Mohamed Rizk ◽  
Maha Sultan ◽  
Mona Elshahed ◽  
Mourad Ali
Keyword(s):  
Reference Method ◽  
Forced Degradation ◽  
Pharmaceutical Dosage Form ◽  
Stability Indicating ◽  
Stability Indicating Method ◽  
Spectrofluorimetric Method ◽  
Lower Detection ◽  
Spectral Behaviour ◽  
Good Agreement

A stability indicating spectrofluorimetric method is developed for the determination of naratriptan hydrochloride in pharmaceutical formulation. The proposed method is based on investigation of the native fluorescence spectral behaviour of the drug in aqueous phosphate buffer (pH = 7.0±0.2).The fluorescence intensity is measured at 355.0 nm after excitation at 230.0 nm. The fluorescence-concentration plot is linear over the concentration range 8.0-80.0 ng/mL, with lower detection limit of 2.6 ng/mL and quantification limit of 7.6 ng/mL. The method is successfully applied to the analysis of the studied drug in its commercial tablet. Furthermore, the proposed method is applied in dissolution study of tablet; the results are in good agreement with those obtained with the reference method. The proposed method is approved to be a stability-indicating assay after exposure of the drug to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to International Conference on Harmonization guidelines.

scholarly journals Stability-Indicating Micelle-Enhanced Spectrofluorimetric Method For Determination of Tamsulosin Hydrochloride In Dosage Forms.

2015 ◽  
Vol 11 (2) ◽  
pp. 3513-3531 ◽  
Author(s):  
Mona Elsayed Elshahed ◽  
Ibrahim Habib
Keyword(s):  
Fluorescence Intensity ◽  
Sodium Dodecyl ◽  
Pharmaceutical Formulations ◽  
Official Method ◽  
Forced Degradation ◽  
Ich Guidelines ◽  
Spectrofluorimetric Method ◽  
Highly Sensitive ◽  
Good Agreement

A rapid, simple and highly sensitive spectrofluorimetric method is developed for the determination of Tamsulosin hydrochloride (Tams.HCl) in pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behavior of Tams.HCl in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution of Tris buffer of pH 7±0.2, SDS causes marked enhancement in the fluorescence intensity of Tams.HCl (about +110%). The fluorescence intensity is measured at 328 nm after excitation at 280 nm and the fluorescence-concentration plots are rectilinear over the range 0.1-1.2 µg ml-1, with lower detection limit of 0.027 µg ml-1 and quantification limit of 0.09 µg ml-1. The method is successfully applied to the analysis of the studied drug in its commercial capsules, and the results are in good agreement with those obtained with the official method. The application of the proposed method is extended to stability studies of Tamsulosin hydrochloride after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines.

scholarly journals Spectrofluorimetric determination of carvedilol in dosage form and spiked human plasma through derivatization with 1-dimethylaminonaphthalene-5-sulphonyl chloride

2010 ◽  
Vol 16 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Fattah El-Sayed ◽  
Taghreed Mohamed ◽  
Anwer Taha
Keyword(s):  
Human Plasma ◽  
Reaction Pathway ◽  
Biological Fluid ◽  
Spiked Human Plasma ◽  
Spectrofluorimetric Method ◽  
Limit Of Quantitation ◽  
Spectrofluorimetric Determination ◽  
Yield Formation ◽  
Good Agreement

A sensitive, simple and selective spectrofluorimetric method was developed for the determination of carvedilol (CA) in pharmaceutical formulation and a biological fluid. The method is based on the reaction between the drug and 1-dimethylaminonaphthalene- 5-sulphonyl chloride (dansyl chloride) in the presence of mixture (acetone:0.5 M sodium carbonate, 3:2) at pH 10 to yield a highly fluorescent derivative that is measured at 445 nm after excitation at 350 nm. Different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence concentration plot was rectilinear over the range of 5.0-80.0 ng ml-1 with a lower detection limit (LOD) of 1.90 ng ml-1 and the limit of quantitation (LOQ) of 5.15 ng ml-1. Quantum yield, formation constant (K) and free energy change (?G) values were calculated. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official titrimetric method [1,2]. Furthermore, the method was applied for the determination of CA in spiked human plasma, the mean % recovery (n = 5) is 97.82?0.373. A proposal of the reaction pathway was presented.

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