The present study describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of extremely low concentrations of lead. It is based on flotation of a complex of Pb2+ ions and Alizarin yellow between aqueous and n-hexane interface at pH = 6. The proposed procedure is also applied for determination of lead in both tap water and prepared sea water samples. Beer’s Law was obeyed over the concentration range of 3.86 × 10−8 To 8.20 × 10−7 molL−1 (8–170 ngmL−1) with an apparent molar absorptivity of 1.33 × 106 molL−1 cm−1 for a 100 mL aliquot of the water sample. The detection limit (n = 10) was 8.7 × 10−9 molL−1 (1.0 ngmL−1) and the Relative standard deviation (R.S.D), (n = 10) for 7.2 × 10−7 molL−1 (150 ngmL−1) of Pb (II) was 4.36%. A notable advantage of the method is that the determination of Pb (II) is free from the interference of almost all cations and ions found in the environment and waste water samples. The determination of Pb (II) in tap and synthetic seawater samples was also carried out by the present method. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.
flotation-extraction; lead; alizarin yellow; spectrophotometry
Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individually and simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II) to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximum absorbance of these complexes was found at 405 nm and 425 nm, respectively. For [Fe(II)-HNAHBH], Beer's law is obeyed over the concentration range of 0.055–1.373 μg mL−1 with a detection limit of 0.095 μg mL−1 and molar absorptivity ɛ, 5.6 × 104 L mol−1 cm−1. [Co(II)-HNAHBH] complex obeys Beer's law in 0.118–3.534 μg mL−1 range with a detection limit of 0.04 μg mL−1 and molar absorptivity, ɛ of 2.3 × 104 L mol−1 cm−1. Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content.
Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO3) and iodide (KI) to form yellow colored product in aqueous medium at 25 ± 1°C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer’s law is obeyed in the concentration ranges of 2.5–50, 20–560, 5–75 and 10–200 μg mL−1, respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically.
enalapril maleate; spectrophotometry; validation; commercial dosage forms
Simple and rapid spectrophotometric method has been developed and validated for the determination of paroxetine (PRX) in tablets. The proposed method was based on nucleophilic substitution reaction of PRX with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product of maximum absorption peak (λmax) at 488 nm. The stoichiometry and kinetics of the reaction were studied, and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance (A) with PRX concentration (C) was obeyed in the
range of 1–8 μg mL−1. The regression equation for the calibration data was: A = 0.0031 + 0.1609 C, with good correlation coefficients (0.9992).
The molar absorptivity (ε) was 5.9 × 105 L mol−1 1 cm−1. The limits of detection and quantitation were 0.3 and 0.8 μg mL−1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the determination of PRX in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 97.17 ± 1.06
%. The results obtained by the proposed method were comparable with those obtained by the official method.
Two simple, selective, and rapid spectrophotometric methods are described for the determination of mycophenolate mofetil (MPM) in pure form and in tablets. Both methods are based on charge-transfer complexation reaction of MPM with p-chloranilic acid (p-CA) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in dioxane-acetonitrile medium resulting in coloured product measurable at 520 nm (p-CA) or 580 nm (DDQ). Beer's law is obeyed over the concentration ranges of 40–400 and 12–120 μg mL−1 MPM for p-CA and DDQ, respectively, with correlation coefficients (r) of 0.9995 and 0.9947. The apparent molar absorptivity values are calculated to be 1.06 × 103 and 3.87 × 103 L mol−1 cm−1, respectively, and the corresponding Sandell's sensitivities are 0.4106 and 0.1119 μg cm−1. The limits of detection (LOD) and quantification (LOQ) are also reported for both methods. The described methods were successfully applied to the determination of MPM in tablets. Statistical comparison of the results with those of the reference method showed excellent agreement. No interference was observed from the common excipients present in tablets. Both methods were validated statistically for accuracy and precision. The accuracy and reliability of the methods were further ascertained by recovery studies via standard addition procedure.
In this study, a method for the determination of low concentrations of lead in beer samples using solid-phase extraction with a flow injection analysis system and detection by flame atomic absorption spectrometry (FAAS) was developed. Moringa oleifera seeds were used as a biosorbent material. Chemical and flow variables of the online preconcentration system, such as sample pH, preconcentration flow rate, eluent flow rate, eluent concentration, particle size, and sorbent mass, were studied. The optimum extraction conditions were obtained using a sample pH of 6.0, sample flow rate of 6.0 mL min−1, 63.0 mg of sorbent mass, and 2.0 mol L−1 HNO3 at a flow rate of 2.0 mL min−1 as the eluent. With the optimized conditions, the preconcentration factor, precision, detection limit, consumption index, and sample throughput were estimated as 93, 0.3% (10.0 μg L−1, n = 7), 7.5 μg L−1, 0.11 mL, and 23 samples per hour, respectively. The method developed was successfully applied to beer samples and recovery tests, with recovery ranging from 80% to 100%.
A new, simple and low cost spectrophotometric method for the determination of methyldopa in pharmaceutical preparations was developed. The method was based on the coupling of methyldopa with 2,6-dichloroquinone-4-chlorimide (DCQ). The absorbance maximum (λmax) of the resulted colored product was at 400 nm. Different buffers were used to determine the optimal pH for the reaction. About 1% w/v acetate buffer with pH 8.0 gave the optimal pH required for the reaction. Of the different solvents tried, water and ethanol were found to be the most suitable solvents. Beer’s law was obeyed in concentration range of 4–20 μg/ml methyldopa. The correlation coefficient was found to be (r = 0.9975). The limit of detection and limit of quantification were 1.1 μg/ml and 3.21 μg/ml, respectively. The reaction ratio between methyldopa and DCQ was studied and found to be 1:3. The work included the study of the possible interference of hydrochlorothiazide found in combination with methyldopa tablets. The method was validated and results obtained for the assay of two different brands of methyldopa tablets were compared with the BP method (colorimetric). The repeatability and reproducibility of the developed method were evaluated and the obtained results quoted. The derivative formed as a result of the reaction of methyldopa with DCQ was isolated and its possible mechanistic pathway was suggested.
Methyldopa; Pharmaceutical preparations; Spectrophotometric analysis; 2,6-Dichloroquinone-4-chlorimide (Gibbs reagent)
Simple, accurate and precise spectrophotometric methods have been developed for the determination of sitagliptin and vildagliptin in bulk and dosage forms. The proposed methods are based on the charge transfer complexes of sitagliptin phosphate and vildagliptin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetrachloro-1,4-benzoquinone (p-chloranil). All the variables were studied to optimize the reactions conditions. For sitagliptin, Beer’s law was obeyed in the concentration ranges of 50-300 μg/ml, 20-120 μg/ml and 100-900 μg/ml with DDQ, TCNQ and p-chloranil, respectively. For vildagliptin, Beer’s law was obeyed in the concentration ranges of 50-300 μg/ml, 10-85 μg/ml and 50-350 μg/ml with DDQ, TCNQ and p-chloranil, respectively. The developed methods were validated and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms.
vildagliptin; sitagliptin phosphate; spectrophotometry; charge transfer reaction; pharmaceutical preparation
This study represents the first report on the development of a novel spectrophotometric method for determination of cinacalcet hydrochloride (CIN) in its tablet dosage forms. Studies were carried out to investigate the reaction between CIN and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 8.5), an orange red-colored product exhibiting maximum absorption peak (λmax) at 490 nm was produced. The stoichiometry and kinetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed in the development of a simple and rapid visible-spectrophotometric method for determination of CIN in its tablets. Under the optimized reaction conditions, Beer's law correlating the absorbance with CIN concentration was obeyed in the range of 3 - 100 μg/ml with good correlation coefficient (0.9993). The molar absorptivity (ε) was 4.2 × 105 l/mol/cm. The limits of detection and quantification were 1.9 and 5.7 μg/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations (RSD) did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of CIN in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.80 - 102.23 ± 1.27 - 1.62%. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories.
Cinacalcet HCl; 1,2-Naphthoquinone-4-sulphonate; Kinetic; Spectrophotometry; Pharmaceutical analysis
A simple and sensitive spectrophotometric method was developed for the determination of Oxacillin sodium. The method was based on charge transfer complexation reaction of the drug with iodine in methanol – dichloromethane medium. The absorbance was measured at 365 nm against the reagent blank. Under optimized experimental conditions, Beer’s law is obeyed in the concentration ranges 2–8 μg/ml for Oxacillin Sodium. The method was validated for specificity, linearity, precision, accuracy, limit of quantitation, robustness and ruggedness. The LOD and LOQ value were 0.39 and 1.18 μg/ml respectively. The method was successfully applied to the analysis of Oxacillin sodium in Human Urine samples with good accuracy and precision.
Oxacillin sodium; iodine; spectrophotometer; validation; human urine
The main objective was to develop and validate a simple, accurate, precise, and sensitive ion-pair spectrophotometric extraction method for the assay of gemifloxacin mesylate (GFX) in pure, tablets and spiked human urine.
Materials and Methods:
The method is based upon the reaction of gemifloxacin with methyl orange, forming a yellow-colored complex in acidic medium, which is extracted in chloroform and analyzed. The extracted complexes showed absorbance maxima (λmax) found to be at 427 nm.
Beer's law was obeyed for a wide concentration range, i.e., 10–80 μg/ mL as the extracted species seemed well defined and stable. The surface or an interphase adsorption phenomenon was not a problem. Optimization of the reaction was carried out with factors such as buffer strength, stability of complex, and molar ratio of drug: Dye and extraction time. The proposed method was validated as per the ICH guidelines. The recovery studies confirmed the accuracy and precision of the method.
The above-mentioned method was a rapid tool for routine analysis of GFX in the bulk and pharmaceutical dosage forms.
Gemifloxacin mesylate; ion-pair; spectrophotometry; methyl orange; validation
A simple, sensitive, rapid, accurate and precise spectrophotometric method has been developed for estimation of ropinirole hydrochloride in bulk and tablet dosage forms. Ropinirole hydrochloride shows maximum absorbance at 250 nm with molar absorptivity of 8.703×103 l/mol.cm. Beer's law was obeyed in the concentration range of 5-35 μg/ml. Results of analysis were validated statistically and by recovery studies.
Ropinirole hydrochloride; spectrophotometric estimation; tablets
A simple, sensitive, rapid, accurate and precise spectrophotometric method has been developed for the estimation of bicalutamide in bulk and pharmaceutical dosage forms. Bicalutamide shows maximum absorbance at 272 nm with molar absorptivity of 2.3399×104 l/mol/cm. Beer's law was obeyed in the concentration range of 1.5-18 μg/ml. The limit of detection and limit of quantification were found to be 0.1 and 0.4 μg/ml, respectively. Results of analysis were validated statistically and by recovery studies.
Bicalutamide; UV spectroscopy; tablet dosage forms
The presence of matrix metalloproteinase-2 (MMP-2) in dentin has been reported, but its distribution and activity level in mature human coronal dentin are not well understood. The purpose of this study was to determine the MMP-2 distribution and relative activity in demineralized dentin. Crowns of twenty eight human molars were sectioned into inner (ID), middle (MD), and outer dentin (OD) regions and demineralized. MMP-2 was extracted with 0.33 mol·L−1 EDTA/2 mol·L−1 guanidine-HCl, pH 7.4, and MMP-2 concentration was estimated with enzyme-linked immunoabsorbant assay (ELISA). Further characterization was accomplished by Western blotting analysis and gelatin zymography. The mean concentrations of MMP-2 per mg dentin protein in the dentin regions were significantly different (P=0.043): 0.9 ng (ID), 0.4 ng (MD), and 2.2 ng (OD), respectively. The pattern of MMP-2 concentration was OD>ID>MD. Western blotting analysis detected ∼66 and ∼72 kDa immunopositive proteins corresponding to pro- and mature MMP-2, respectively, in the ID and MD, and a ∼66 kDa protein in the OD. Gelatinolytic activity consistent with MMP-2 was detected in all regions. Interestingly, the pattern of levels of Western blot immunodetection and gelatinolytic activity was MD>ID>OD. The concentration of MMP-2 in human coronal dentin was highest in the region of dentin that contains the dentinoenamel junction and least in the middle region of dentin. However, levels of Western blot immunodetection and gelatinolytic activity did not correlate with the estimated regional concentrations of MMP-2, potentially indicating region specific protein interactions.
matrix metalloproteinase-2; human coronal dentin; distribution; gelatinolytic activity
The present research work discusses the development of a UV estimation method for lafutidine. Simple, accurate, cost efficient, and reproducible spectrophotometric method has been developed for the estimation of Lafutidine in bulk and pharmaceutical dosage form.
Materials and Methods:
The Stock solution was prepared in a mixture of water and methanol (1:1). Further dilutions were made in water.
The drug was determined at maximum wavelength (λmax) 279 nm. Beers law was obeyed in the concentration range of 10–50 μg/ml having line equation y = 0.0100x + 0.035 with correlation coefficient of 0.999. Results of the analysis were validated statistically and by recovery study.
The result of analysis was validated as per ICH guidelines and this method can be used for the routine analysis of lafutidine formulation.
Lafutidine; UV spectrophotometry; validation
A simple rapid spectrophotometric method has been developed for estimation of cefuroxime axetil from bulk drug and tablet dosage form by using 1-nitroso-2-napthol and sodium hydroxide. The method is based on the formation of yellow-orange coloured complex of drug with 1-nitroso-2-napthol having absorbance maxima at 424 nm. The Beer’s law is obeyed in the concentration range of 10-50 μg/ml of the drug but more precisely it obeys in the range of 10- 30 μg/ml. The slope and intercept values are 0.0101 and 0.0838, respectively. Results of analysis of this method were validated statistically and by recovery studies. The method is applied to the marketed tablet formulation. Result of analysis of tablet formulation given as percentage of label claim ±standard deviation is 99.17±1.57. The precision and accuracy was examined by performing recovery studies and was found to be 99.50±1.82. Sandell’s correlation coefficient is calculated as 0.4434. The developed method is simple, sensitive and reproducible and can be used for routine analysis of cefuroxime axetil from bulk and tablet dosage form.
Cefuroxime axetil; yellow orange complex; spectrophotometry; 1-nitroso-2-napthol
In the present investigation, hydrotropic solution of urea was employed as a solubilizing agent for spectrophotometric determination of poorly water-soluble drug rosiglitazone maleate. In solubility determination study, it was found that there was more than 14-folds enhancement in solubility of rosiglitazone maleate in a 6M solution of urea. Rosiglitazone maleate obeys Beer's law in concentration range of 5-300 μg/ml. Linearity of rosiglitazone maleate was found in the range of 80-120% of the label claim. The proposed method has been applied successfully to the analysis of the cited drug in pharmaceutical formulations with good accuracy and precision. The method herein described is new, simple, eco-friendly, economic, and accurate and can be utilized in routine analysis of rosiglitazone maleate in bulk drug and tablet dosage form.
Hydrotropic solubilization; rosiglitazone; spectrophotometric determination
Two simple and selective spectrophotometric methods have been proposed for the determination of gabapentin (GBP) in pure form and in capsules. Both methods are based on the proton transfer from the Lewis acid such as 2,4,6-trinitrophenol (picric acid; PA) or 2,4-dinitrophenol (2,4-DNP) to the primary amino group of GBP which works as Lewis base and formation of yellow ion-pair complexes. The ion-pair complexes formed show absorption maximum at 415 and 420 nm for PA and 2,4-DNP, respectively. Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 1.25–15.0 and 2.0–18.0 μg mL−1 GBP for PA and 2,4-DNP methods, respectively. The molar absorptivity, Sandell's sensitivity, detection and, quantification limits for both methods are also reported. The proposed methods were applied successfully to the determination of GBP in pure form and commercial capsules. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level, and there was no significant difference between the reference and proposed methods with regard to accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition technique.
Rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of pipazethate HCl (PiCl) and dextromethorphan HBr (DEX) either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. Beer’s law is obeyed in the concentration range of 2.0-16 and 2.0-15 μg mL-1 for PiCl and DEX, respectively with correlation coefficient (n=6) ≥ 0.9993. The apparent molar absorptivity and sandell sensitivity values are in the range 1.062-1.484 × 104, 3.35-4.51 × 104 L mol-1 cm-1 and 29.36-41.03, 8.21-11.06 ng cm-2 for PiCl and DEX, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods.
spectrophotometry; pipazethate HCl; dextromethorphan HBr; potassium permanganate; oxidation reactions; pharmaceutical formulations
To develop and validate a simple, precise and accurate spectrophotometric method for the simultaneous estimation of nabumetone and paracetamol in their combined tablet dosage form. This method is based on first-order derivative spectroscopy.
Materials and Methods:
For determination of sampling wavelengths, each of nabumetone and paracetamol were scanned in the wavelength range of 200–400 nm in the spectrum mode and sampling wavelengths were selected at 261 nm (zero crossing of nabumetone) where paracetamol showed considerable absorbance and at 248.2 nm (zero crossing of paracetamol) where nabumetone showed considerable absorbance.
Beer's law obeyed in the concentration range of 3-18 μg/ml for both the drugs. The correlation coefficients were found to be 0.9992 and 0.9998 for nabumetone and paracetamol, respectively. Mean recoveries were found satisfactory.
The proposed method can be successfully applied for simultaneous estimation of nabumetone and paracetomol.
First-order derivative spectroscopy; nabumetone; paracetamol; spectrophotometric
Three UV spectrophotometric methods have been developed, simultaneous equation method, multicomponent analysis (II) and derivative spectroscopy method (III). The absorption maxima of the drugs were found to be 247, 259 and 272 nm, respectively for efavirenz, tenofovir disoproxil fumarate and lamivudine in methanol:water (50:50) solvent system. Efavirenz, tenofovir disoproxil fumarate and lamivudine obeyed Beer’s law in the concentration range of 10-60, 5-30 and 5-30 μg/ml, respectively. Results of analysis for all the three methods were analyzed and validated for various parameters according to ICH guidelines.
Derivative spectroscopy; efavirenz; lamivudine.; multicomponent analysis; simultaneous equation method; tenofovir disoproxil fumarate
Two simple, economical, rapid, precise, and accurate methods for simultaneous determination of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage form have been developed. The first method is based on ratio spectra derivative spectrophotometry, and the second method is zero-crossing difference spectrophotometry. The amplitudes in the first derivative of the corresponding ratio spectra at 231.0 and 271.0 nm were selected to determine olmesartan medoxomil and hydrochlorothiazide, respectively. Measurements of absorbance were carried out at zero-crossing wavelengths 257.8 and 240.2 nm for olmesartan medoxomil and hydrochlorothiazide by zero-crossing difference spectrophotometric method. Beer’s law is obeyed in the concentration range of 08–24 µg/mL for olmesartan medoxomil (OLM) and 05–15 µg/mL for hydrochlorothiazide (HCT) by ratio spectra derivative and 05–30 µg/mL for OLM and HCT by zero-crossing difference spectrophotometric method. The results of the assay were found to be 100.46 ± 0.95 for OLM and 100.4 ± 0.27 for HCT by ratio spectra derivative and 99.06 ± 1.14 for OLM and 100.05 ± 0.90 for HCT by zero-crossing difference spectrophotometric method. These methods passes F test and t test. Both methods were validated statistically and by performing recovery study.
hydrochlorothiazide; olmesartan medoxomil; ratio spectra derivative spectrophotometry; zero-crossing difference spectrophotometry
A simple chemometrics-assisted spectrophotometric method for the simultaneous determination of lamivudine and stavudine in pharmaceutical tablets is described. The UV absorption spectra of the studied drugs, in the range of 200–310 nm, showed a considerable degree of spectral overlapping ([Di]0.5 = 94.9%). Resolution of the mixture has been accomplished by using classical least-squares regression analysis (CLS) and principle components regression analysis methods (PCR). Beer’s law was obeyed for both drugs in the general concentration ranges of 2–12 and 3–15 μg ml−1 for lamivudine and stavudine, respectively. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures. The overall recoveries percent were found 98.58 ± 1.53–101.30 ± 1.35 (CLS) and 98.62 ± 1.65–101.13 ± 1.04 (PCR) for lamivudine and 98.43 ± 1.62–99.42 ± 1.55 (CLS) and 98.23 ± 1.97–101.20 ± 1.79 (PCR) for stavudine, respectively. The commercial tablets percentage content was found 98.10 ± 2.5–102.47 ± 2.94 (CLS) and 99.12 ± 1.71–100.92 ± 1.54 (PCR) for lamivudine and 96.00 ± 2.94–98.17 ± 1.72 (CLS) and 97.40 ± 1.55–97.80 ± 1.92 (PCR) for stavudine, respectively. Good percentage recoveries and proper statistical data obtained with both the laboratory prepared mixtures and the commercial tablets proved the suitability and efficiency of the proposed procedures for routine analysis and quality control purposes with quite satisfactory precision. A comparison of the obtained results from CLS and PCR were also performed with those obtained from reported method. The obtained F- and t-values obtained indicating no significant differences between the results of the proposed and reported methods.
Chemometrics; Pharmaceuticals; Spectrophotometry; HIV-inhibitors
Simple, accurate and precise spectrophotometric methods have been developed for the determination of saxagliptin in bulk and dosage forms. The proposed methods are based on the charge transfer complexes of saxagliptin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). All the variables were studied to optimize the reactions’ conditions. Beer’s law was obeyed in the concentration ranges of 50-300 μg/ml and 10-110 μg/ml with DDQ and TCNQ, respectively. The developed methods were validated and proved to be precise and accurate for the quality control of the saxagliptinin its pharmaceutical dosage form.
saxagliptin; spectrophotometry; charge transfer reactions; pharmaceutical preparation
Bovine fecal samples (1 g) negative for Cryptosporidium sp. oocysts were seeded with 7 x 10(4) Cryptosporidium parvum oocysts and purified by either water-ether concentration, sucrose density flotation, or zinc sulfate flotation to evaluate oocyst recovery. The effect of these purification techniques on the viability of recovered oocysts was also evaluated. Significantly higher numbers of seeded oocysts were recovered by water-ether concentration (recovery rate, 46 to 75%) than by sucrose density (24 to 65%) or zinc sulfate (22 to 41%) flotation methods. In addition, water-ether concentration did not exert a significant effect on the viability of the population of oocysts recovered, whereas sucrose density flotation and zinc sulfate flotation selectively concentrated viable oocysts. The water-ether concentration procedure is recommended for use in epidemiological studies in which both oocyst enumeration and viability assessment are required.