scholarly journals Determination of the Dissociation Constants of Metformin from a Second Derivative UV Spectrum

2020 ◽  
Vol 11 (1) ◽  
pp. 790-796 ◽  
Author(s):  
Khalid Waleed S. Al-Janabi ◽  
Ali Khalil Mahmood ◽  
Hasan M. Luaibi
Keyword(s):  
Aqueous Solution ◽  
Dissociation Constants ◽  
Correlation Coefficients ◽  
Pharmaceutical Compounds ◽  
Second Derivative ◽  
Uv Spectrum ◽  
Established Method ◽  
Ultraviolet Spectra ◽  
The Mean

An environmentally begnin second derivative spectrometric approach was developed for the estimation of the dissociation constants pKa(s) of metformin, a common anti-diabetic drug.  The ultraviolet spectra of the aqueous solution of metformin were measured at different acidities, then the second derivative of each spectrum was graphed. The overlaid second derivative graphs exhibited two isobestic points at 225.5 nm and 244 nm pointing out to the presence of two dissociation constants for metformin pKa1 and pKa2, respectively. The method was validated by evaluating the reproducibility of the acquired results by comparing the estimated values of the dissociation constants of two different strategies that show excellent matching. As well as, the whole procedure was repeated with a new set of standard solutions and buffers for further verification. The average calculated values of pKa1 and pKa2 were found to be 2.72±0.01 and 11.61±0.08, with correlation coefficients ( R2) of 0.9916 and 0.9614, respectively. The established method was fast, affordable, reproducible, and the mean pKa values obtained were accurate and can be applied for the estimation of the dissociation constants of other active pharmaceutical compounds

scholarly journals Determination of DiazaCon in Quail Feed and Quail Serum by Ion Pair Reversed-Phase Chromatography

2001 ◽  
Vol 84 (3) ◽  
pp. 634-639 ◽  
Author(s):  
John J Johnston ◽  
Margaret J Goodall ◽  
Jerome C Hurley ◽  
Christi A Yoder ◽  
Lowell A Miller
Keyword(s):  
Aqueous Solution ◽  
Ion Pairing ◽  
Reversed Phase ◽  
Ion Pair ◽  
Butyl Chloride ◽  
Reversed Phase Chromatography ◽  
Limits Of Detection ◽  
The Mean ◽  
Liquid Chromatographic

Abstract Liquid chromatographic (LC) methods were developed for quantitating the potential avian contraceptive DiazaCon in quail feed and serum. DiazaCon was extracted from ground quail feed with basic n-butyl chloride. The n-butyl chloride extract was evaporated to dryness. The DiazaCon residues were dissolved in an aqueous methanolic ion pairing solution and quantitated by LC at 206 nm. Avian sera was combined with an equal volume of a pH 4 aqueous solution of ion pairing reagent and filtered to remove interfering proteins. DiazaCon was quantitated by LC. Mean recoveries for 500 and 2000 ppm fortified feed were 89.1 and 91.0%, respectively. The mean recovery for sera fortified at 5 levels ranging from 35 to 2000 ppm was 84.9%. Method limits of detection were approximately 14 and 13 ppm for feed and sera, respectively.

Determination of total protein in human milk: comparison of methods.

1986 ◽  
Vol 32 (1) ◽  
pp. 120-123 ◽  
Author(s):  
R P Keller ◽  
M C Neville
Keyword(s):  
Human Milk ◽  
Total Protein ◽  
Milk Proteins ◽  
Correlation Coefficients ◽  
Established Method ◽  
Spectrophotometric Methods ◽  
Coomassie Blue ◽  
Different Types ◽  
Bca Assay

Abstract We evaluated four spectrophotometric methods for suitability in determining total protein in human milk samples. Results were compared with those by an established method for the determination of total nitrogen (micro-Kjeldahl). Values for total protein by all four methods significantly correlated with micro-Kjeldahl. For the biuret assay, Lowry-Peterson assay, Bio-Rad Coomassie Blue assay, and Pierce BCA assay, the correlation coefficients were 0.96, 0.97, 0.89, 0.99, respectively. We also assessed the sensitivity of each assay to several purified human milk proteins. The Pierce BCA assay showed the least difference in values among different types of protein. For this reason, and because it showed the greatest precision (with acceptable constant and proportional error), we recommend the BCA method.

scholarly journals Second Derivative Synchronous Fluorescence Spectroscopy for the Simultaneous Determination of Metoclopramide and Pyridoxine in Syrup and Human Plasma

2008 ◽  
Vol 91 (3) ◽  
pp. 542-550 ◽  
Author(s):  
Nahed El-Enany
Keyword(s):  
Simultaneous Determination ◽  
Human Plasma ◽  
High Sensitivity ◽  
Second Derivative ◽  
Native Fluorescence ◽  
Highly Sensitive ◽  
Experimental Parameters ◽  
The Mean ◽  
Good Agreement

Abstract A rapid, simple, and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous determination of metoclopramide (MT) and pyridoxine (PY) in a binary mixture. The method is based on measurement of the native fluorescence of these drugs at = 80 nm in methanol. The different experimental parameters affecting the native fluorescence of the drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges of 0.020.4 and 0.12 g/mL for MT and PY, respectively. The limits of detection were 0.003 and 0.007 g/mL and the limits of quantification were 0.008 and 0.02 g/mL for MT and PY, respectively. The proposed method was successfully applied to the determination of MT and PY in synthetic mixtures and in commercial syrup. The results were in good agreement with those obtained with a reported method. The high sensitivity attained by the proposed method allowed the determination of MT in spiked and real human plasma samples. The mean percent recoveries of MT from spiked and real human plasma (n = 3) were 93.72 3.15 and 89.72 2.19, respectively.

scholarly journals Second-Derivative Spectrometric Determination of Urea in Milk Using the Diacetyl Monoxime Reagent

2010 ◽  
Vol 93 (2) ◽  
pp. 485-491 ◽  
Author(s):  
Steven A Nyanzi ◽  
Maureen Isiko ◽  
Francis Kateregga ◽  
Wolfgang Schwack
Keyword(s):  
Correlation Coefficients ◽  
Colorimetric Determination ◽  
Second Derivative ◽  
Linear Calibration ◽  
Colored Complex ◽  
Spectral Bands ◽  
Sensitivity And Selectivity ◽  
Diacetyl Monoxime ◽  
Second Derivative Method

Abstract The application of derivative spectrometry to resolve overlapping spectra and improve the sensitivity and selectivity of the colorimetric determination of urea in milk using diacetyl monoxime is presented. With first-derivative (1D) spectrometry, the max of the colored complex was established to be 525 nm. The absorption band at max 525 nm in normal absorption (0D) spectrometry was resolved into three clearly distinct spectral bands with minima at 497, 530, and 566 nm with second-derivative (2D) spectrometry. With the second-derivative (2D530) technique, the depth of the trough of the strongest signal at 530 nm was used to determine urea in milk samples. Linear calibration curves for urea were obtained over a concentration range of 0.21.4 mg/L, with correlation coefficients greater than 0.999. The LOD and LOQ of the method were 0.01 and 0.03 mg/L, respectively. Recoveries of 99100 of spiked urea in milk with RSD values below 2.0 were obtained. The second-derivative method is simple, affordable, sensitive, and selective for the determination of urea in milk.

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