Dual-wavelength Spectrophotometry Research Articles

Simultaneous Determination of Mixed Heavy Metal Ions Cr (III) and Co (II) in Wastewater by Cloud Point Extraction Dual Wavelength Spectrophotometry

Using cloud point extraction technology and the principle of absorbance addition in multi-component system, the mixed metal ions Cr (III) and Co (II) in industrial wastewater were enriched and determined at pH 5.0 and 50℃, using ammonium pyrrolidine dithiocarbamate (APDC) as complexing agent and Triton X-114 as extractant. The results indicate that the contents of Cr (III) and Co (II) can be calculated using a simultaneous equation system. The detection limits for Cr (III) and Co (II) are 0.74 ng/ml and 2.12 ng/ml, respectively. The recovery rates are 95.3% -104.0% and 96.9% -103.5%, respectively. This method has the characteristics of high accuracy, good repeatability, and fast detection speed, and has good practical value.

Two methods for determination of a binary mixture of Amlodipine besylate and Atorvastatin calcium using dual-wavelength spectrophotometry

Two simple, clear, and accurate spectrophotometric methods based on two-wavelength selections, were developed for the simultaneous determination of Amlodipine besylate (AML) and Atorvastatin calcium (ATO) in tablet dosage forms. The ratio difference method uses amplitudes between 238 and 288 nm. The measured amplitudes for the parameters: linear range 4-40 μg/ml; precision for AML is 100.22±0.7856, repeatability is 0.9122, precision for ATO is 100.12±0.6439, repeatability is 0.8968. The absorption ratio method using two wavelengths is 221 and 238 nm. The absorption rate method for parameters: linear range 4-40 μg/ml; precision for AML is 100.6±0.9562, repeatability is 1.0124, precision for ATO is 100.86±0.8596, repeatability is 1.1045. Both quantitative methods showed that AML and ATO could be quantified in their mixtures without any extraction at all. The absorption ratio method exhibited quick, simple applicability to both laboratory and commercial drug mixtures.

Green Simultaneous Determination of Amlodipine Besylate and Celecoxib by Dual wavelength and Simultaneous Equation Spectrophotometric Methods

Two facile, accurate, green and sensitive spectrophotometric methods; using dual wavelength spectrophotometry (method I) and simultaneous equation method (method II), were developed for the simultaneous determination of amlodipine besylate (AMO) and celecoxib (CEX). Method I was based on measuring the absorbance difference between 252 nm and 357 nm for determination of CEX, where AMO can be determined directly by measuring the absorbance at wavelength 357 nm as CEX has no absorbance at 357 nm. Method II was based on solving two simultaneous equations for both drugs at 252 nm and 357nm. Linearity range for AMO was found to be 5-65 µg/mL while for CEX was found to be 1-25 µg/mL for both methods. The developed methods were successfully applied for the determination of AMO and CEX in laboratory prepared mixture containing all possible excipients present in tablet dosage form. The mean percentage recovery values were found to be 101.157 ± 0.750, and 101.765 ± 0.140 for method I, but 101.603 ± 0.750, and 100.549 ± 1.262 for method II for AMO and CEX, respectively. The methods were found to be eco-friendly as they were evaluated according to the Green Analytical Procedure Index (GAPI) and Analytical Eco-Scale.

Simultaneous Determination of Diclofenac and Esomeprazole by Reversed phase Liquid Chromatography, Dual Wavelength and Derivative Spectrophotometry

Three methods were developed for simultaneous determination of diclofenac and esomeprazole in their binary mixtures. Method I is dual wavelength spectrophotometry which is based on measurement of absorbance difference ΔA (281.7–315 nm) for determination of diclofenac and ∆A (262.6–301.6 nm) for determination of esomeprazole. Method II is derivative spectrophotometry which is based on measuring 1D at 301.6 nm for determination of diclofenac and 2D at 299.5 nm for determination of esomeprazole. Linearity ranges were found to be 5–25 and 2‒10 μg/mL for diclofenac and esomeprazole, respectively, using methods I and II. Method III is reversed phase HPLC method which involves separation of diclofenac and esomeprazole on XBridgeTMC18 column using a mobile phase consisting of ethanol-phosphate buffer solution (pH 4, 60 : 40, v/v). The flow rate was 1.5 mL/min with ultraviolet detection at 290 nm. The calibration graphs are linear from 2 to 120 μg/mL for diclofenac and from 5 to 60 μg/mL for esomeprazole.

Spectrophotometric simultaneous determination of Empagliflozin and Metformin in combined tablet dosage form by absorbance corrected method, area under curve method, and dual wavelength spectrophotometry.

A new, simple, accurate and sensitive UV spectrophotometric three method as been developed for estimation of empagliflozin and metformin in combined tablet dosage form. The first method is absorbance corrected method (method A) the second method is area under curve (method B) the third method is dual wavelength (method C). the first method A the Empagliflozin determined at λmax224nm and Metformin determined at λmax232nm and intercept at λmax 203nm. The second method B wavelength length range 219-229nm and 227-238nm were selected to determined EMPA and MET In the third method C, EMPA was determined by plotting the difference in absorbance at 224-238nm against the conc. of MET. Similarly for the determination of MET, the difference in absorbance at 232-244nm against conc. of EMPA in combined formulation. The methods were validated by following the analytical performance parameters suggested by the International Conference on Harmonization (ICH). Beer's law is obeyed in the concentration range of 2–10μg/ml for EMPA and 4–20μg/mL for MET by the following methods.

Low Plasma Hydrogen Sulfide Is Associated with Impaired Renal Function and Cardiac Dysfunction

Background: Chronic kidney disease (CKD) has been proposed to associate with decreased hydrogen sulfide (H₂S) level. Nevertheless, the role of H₂S in the pathogenesis of CKD has not been fully investigated. Our study aimed to investigate the plasma level of endogenous H₂S in patients with different stages of CKD, and to identify the role of H₂S in the progression of CKD and its relationship with cardiovascular diseases. Methods: A total of 157 non-dialysis CKD patients were recruited in our study, with 37 age- and sex-matched healthy individuals as control. Plasma concentration of H₂S was measured with spectrophotometry. Sulfhemoglobin, the integration of H₂S and hemoglobin, was characterized and measured by dual wavelength spectrophotometry. Serum levels of homocysteine (Hcy), cardiac troponin T (cTnT), and N-terminal pro B type natriuretic peptide were measured using automated analyzers. Conventional transthoracic echocardiography was performed and left ventricular ejection fraction (LVEF) was analyzed as a sensitive parameter of cardiac dysfunction. Results: The plasma H₂S level (μmol/L) in CKD patients was significantly lower than those in healthy controls (7.32 ± 4.02 vs. 14.11 ± 5.24 μmol/L, p < 0.01). Plasma H₂S level was positively associated with estimated glomerular filtration rate (eGFR; ρ = 0.577, p < 0.01) and negatively associated with plasma indoxyl sulfate concentration (ρ = –0.554, p < 0.01). The mRNA levels of cystathionine β-synthase and cystathionine γ-lyase, 2 catalytic enzymes of H₂S formation, were significantly lower in blood mononuclear cells of CKD patients with respect to controls; however, the mRNA level of 3-mercaptopyruvate sulfurtransferase, as another H₂S-producing enzyme, was significantly higher in CKD patients. The serum concentration of Hcy, acting as the substrate of H₂S synthetase, was higher in the CKD group (p < 0.01). Specifically, the content of serum Hcy in CKD stages 3–5 patients was significantly higher than that in CKD stages 1–2, indicating an increasing trend of serum Hcy with the decline of renal function. Examination of ultrasonic cardiogram revealed a negative ­correlation between plasma H₂S level and LVEF (ρ = –0.204, p < 0.05) in CKD patients. The H₂S level also correlated negatively with cTnT concentration (ρ = –0.249, p < 0.01). Conclusions: Plasma H₂S level decreased with the decline of eGFR, which may contribute to the cardiac dysfunction in CKD ­patients.

Chronic ethanol exposure induces SK-N-SH cell apoptosis by increasing N-methyl-D-aspartic acid receptor expression and intracellular calcium.

It has been identified that chronic ethanol exposure damages the nervous system, particularly neurons. There is scientific evidence suggesting that neuronal loss caused by chronic ethanol exposure has an association with neuron apoptosis and intracellular calcium oscillation is one of the primary inducers of apoptosis. Therefore, the present study aimed to investigate the inductive effects of intracellular calcium oscillation on apoptosis in SK-N-SH human neuroblastoma cells and the protective effects of the N-methyl-D-aspartic acid receptor (NMDAR) antagonist, memantine, on SK-N-SH cell apoptosis caused by chronic ethanol exposure. SK-N-SH cells were treated with 100 mM ethanol and memantine (4 µM) for 2 days. Protein expression of NR1 was downregulated by RNA interference (RNAi). Apoptosis was detected by Annexin V/propidium iodide (PI) double-staining and flow cytometry and cell viability was detected using an MTS kit. Fluorescence dual wavelength spectrophotometry was used to determine the intracellular calcium concentration and the levels of NR1 and caspase-3 were detected using western blotting. NR1 mRNA levels were also detected using qPCR. It was found that chronic ethanol exposure reduced neuronal cell viability and caused apoptosis of SK-N-SH cells, and the extent of damage in SK-N-SH cells was associated with ethanol exposure concentration and time. In addition, chronic ethanol exposure increased the concentration of intracellular calcium in SK-N-SH cells by inducing the expression of NMDAR, resulting in apoptosis, and memantine treatment reduced ethanol-induced cell apoptosis. The results of the present study indicate that the application of memantine may provide a novel strategy for the treatment of alcoholic dementia.

Development and validation of different spectrophotometric and chromatographic methods for determination of clotrimazole and hydrocortisone in a topical cream

In this study, we developed and validated different spectrophotometric and chromatographic methods for determination of clotrimazole (CLO) and hydrocortisone (HDC) in their combined dosage form. The developed spectrophotometric methods were first derivative spectrophotometry ( 1 D) by measuring the peak amplitude at 247.4 and 236.2 nm for CLO and HDC, respectively, second derivative of ratio spectra ( 2 DD) at 225.4 nm for CLO and 269 nm for HDC, dual wavelength spectrophotometry (DW) by measuring absorbance difference between 225.4 and 264 nm for CLO and between 228 and 247 nm for HDC determination, advanced absorbance subtraction method (AAS) between 225.4 and 264 nm and mean centering of ratio spectra (MCR) spectrophotometric method in the range of 232-265 nm. On the other hand, the proposed chromatographic method was Ultra Performance Liquid Chromatography method (UPLC) using acetonitrile:water (50:50, v : v ) as a mobile phase and the peaks were detected at 228 nm. All these methods were successfully applied to determine the two studied drugs in pure forms; laboratory prepared mixtures and combined dosage form. Methods validations were carried out regarding linearity, accuracy, precision and selectivity. The spectrophotometric methods exhibited a linear dynamic range over 5-40 and 5-45 µg/mL for CLO and HDC, respectively, and over 3-35 and 5-50 µg/mL for UPLC method. Sensitive and selective spectrophotometric and UPLC methods for the determination of clotrimazole and hydrocortisone in their topical formulation were successfully developed and validated. The developed methods were statistically confirmed to be accurate, precise and reproducible.

Memantine Can Reduce Ethanol-Induced Caspase-3 Activity and Apoptosis in H4 Cells by Decreasing Intracellular Calcium.

Caspase-3 activation and apoptosis are associated with various neurodegenerative disorders. Calcium activation is an important factor in promoting apoptosis. We, therefore, assessed the role of intracellular calcium in ethanol-induced activation of caspase-3 in H4 human neuroglioma cells and the protective effect of the NMDA receptor antagonist, memantine, on ethanol-induced apoptosis in H4 cells. H4 cells were treated with 100mM EtOH (in culture medium) for 2days. For interaction studies, cells were treated with memantine (4μM), EDTA (1mM), or BAPTA-AM (10μM) before treatment with EtOH. Knockdown of the gene encoding the NR1 subunit of the NMDA receptor was performed using RNAi. Apoptosis was detected by Annexin V-FITC/PI staining and flow cytometry. Cell viability was detected using an MTS cell proliferation kit. Fluorescence dual wavelength spectrophotometry was used to determine the intracellular calcium concentration. The levels of NR1, caspase-3, IP3R1, and SERCA1 proteins were detected by western blotting. NR1, IP3R1, and SERCA1 mRNA levels were detected by qPCR. We observed increased expression of NR1, IP3R1, SERCA1, and increased intracellular levels of calcium ions in H4 cells exposed to ethanol. In addition, the calcium chelators, EDTA and BAPTA, and RNAi disruption of the NMDA receptor reduced ethanol-induced caspase-3 activation in H4 cells. Memantine treatment reduced the ethanol-induced increase of intracellular calcium, caspase-3 activation, apoptosis, and the ethanol-induced decrease in cell viability. Our results indicate that ethanol-induced caspase-3 activation and apoptosis are likely to be dependent on cytosolic calcium levels and that they can be reduced by memantine treatment.

Development and Validation of Spectrophotometric and Spectrofluorimetric Methods for the Determination of Cyclobenzaprine HCl

Five simple and sensitive methods were developed for the determination of cyclobenzapirine hcl (CB) in presence of its degradation product anthraquinone (AQ). Method A dual wavelength spectrophotometry (DW); where two wavelengths were selected for the drug 283 and 306 nm in such a way that the difference in absorbance was zero for its degradation. Method B ratio difference spectrophotometry (RD) was depended on measuring the ratio difference between 290 and 305 nm. Method C was depended on measuring the peak amplitude of the first derivative of the ratio spectra (1DD) at 282 and 306 nm. Method D Isoabsorptive Point (ISO) at 280 nm Coupled with Second Derivative (2D). Method E depending on spectrofluorimetric determination of cyclobenzapirine HCl through quenching of uranyl acetate with ʎexi 228 nm and ʎem at 458 nm. Linearties were obtained in concentration range 5 μg/ml – 30 μg/ml in case of methods A, B, C and D, while in case of methods E linearity was obtained in concentration range of 1 μg/ml –10 μg/ml. The five methods were found to be specific for CB in presence of different concentration % of its degradation product. The five proposed methods were successfully applied for the determination of CB in Multirelax tablets. Statistical comparison between the results obtained by the proposed methods and that obtained by the official one for the determination of the drug was done, founding that there were no significant differences between them.

Spectrophotometric Methods for Quantitative Determination of Chlorhexidine Gluconate and its Major Impurity, Metabolite and Degradation Product: Para-chloro-aniline

Four simple, specific, accurate and precise spectrophotometric methods are developed for determination of chlorhexidine gluconate (CG) in presence of its impurity and/or degradation product namely; para-chloro-aniline (PCA). Method A is derivative spectrophotometry, where CG is determined by first derivative D1 spectrophotometric method in presence of its degradation product PCA at 272 nm, while PCA is determined in presence of CG by second derivative D2 spectrophotometric method at 248.6 nm. Method B is first derivative of ratio spectra spectrophotometry which allows determination of both CG at 266.8 nm and PCA at 328 nm without interference of each other. Method C is dual wavelength spectrophotometry (DWS), where two wavelengths; 233 and 253 nm for CG and 253.8 and 262 nm for PCA are selected for each component in such a way that the difference in absorbance is zero for the second one. Method D is ratio subtraction and extended ratio subtraction spectrophotometry (EXRS), where CG can be determined by dividing the spectrum of the mixture by divisor concentration of 5 μg mL-1 of PCA, while PCA can be determined by dividing the spectrum of the mixture by divisor concentration of 50 μg mL-1 of CG. The specificity of the developed methods is investigated by analyzing different laboratory prepared mixtures of the CG and PCA. Standard deviation values are less than 1.5 in the assay of raw material and tablets. The four methods were statistically compared to the reported method with no significant difference regarding accuracy and precision; assuring their applicability in quality control analysis of drug product.

Comparative study of spectrophotometric methods manipulating ratio spectra: An application on pharmaceutical binary mixture of cinnarizine and dimenhydrinate

Four simple, specific, accurate and precise spectrophotometric methods are developed and validated for simultaneous determination of cinnarizine (CIN) and dimenhydrinate (DIM) in a binary mixture with overlapping spectra, without preliminary separation. The first method is dual wavelength spectrophotometry (DW), the second is a ratio difference spectrophotometric one (RD) which measures the difference in amplitudes between 250 and 270nm of ratio spectrum, the third one is novel constant center spectrophotometric method (CC) and the fourth method is mean centering of ratio spectra (MCR). The calibration curve is linear over the concentration range of 4–20 and 10–45μg/ml for CIN and DIM, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. The validity of results was assessed by applying standard addition technique. The results obtained were found to agree statistically with those obtained by a reported method, showing no significant difference with respect to accuracy and precision.

Desaturation Is Related to the Presence of Dense Red Blood Cells in Sickle Cell Patients and Is Reversed By Hydroxyurea

Production of abnormal hemoglobin (HbS) in sickle-cell disease (SCD) results in its polymerization in deoxygenated conditions and in sickled-RBC formation. Dense RBCs (DRBCs), defined as density >1.11 and characterized by increased rigidity, viscosity and HbS concentration (main polymerization factor), are absent in normal AA subjects, but present at percentages that vary from 1 SCD patient to another but remain stable throughout adulthood for each patient. Polymerized, but not nonpolymerized, HbS has reduced affinity for oxygen, demonstrated by the rightward shift of the oxygen-dissociation curve, leading to disturbances in oxygen transport. We recently described a correlation between %DRBCs and some clinical SCD manifestations. Notably, some SCD patients have unexplained, very low oxygen saturation (SpO2), without heart or lung dysfunctions. %DRBC variability within SCD patients could be the main pathophysiological explanation of those manifestations. This study was undertaken to determine whether a link exists between the %DRBCs and Hb affinity for oxygen, and to look for a potential clinical implication for SCD patients.92 patients (44.6 ± 7.7 years; 51 women and 41 men) were included in the study. Blood samples were obtained at steady state to measure hemorheological and hematological parameters. Using a Percoll-gradient fractionation method, total RBCs were separated into non-DRBCs (NDRBC) (d<1.11) and DRBCs (d>1.11) fractions. The %DRBCs was determined using the phthalate-gradient method. P50 in venous blood gases was measured with a radiometry analyzer. Oxygen-affinity curves of Hb dissociation and association in RBC fractions were obtained with dual wavelength spectrophotometry. All patients had a 6-minute walking test (6MWT) and 10 of them (38.1 ± 6.1 years; 6 men and 4 women) had done so before and after >6 months (>6M) on hydroxyurea (HU). Times <90% and <88% transcutaneous SpO2 of Hb and a SpO2 decrease ≥4% during the test (delta SpO2 >4%) were evaluated to investigate the physiological impact on patients during exertion. Patients, divided into quartiles according to their values (Q1: 0–25th centile, Q2–Q3: 25th–75th centiles, and Q4: >75th centile), were analyzed for the times <88% SpO2, <90% SpO2 and with delta SpO2 >4%, for the distance walked.DRBCs had increased MCHC and decreased %HbF and 2,3 DPG, leading to more polymerization and modulation of Hb affinity for oxygen, compared to NDRBCs. Moreover, dissociation and association curves of SS RBC fractions differed (compared to AA RBCs), with rightward shifts of NDRBCs and, more importantly, DRBC-association curves, thereby confirming the role of HbS polymerization in the loss of affinity (Fig 1). Bivariate analysis showed that the P50 was positively correlated with the %DRBCs (P<0.0001, r²=0.34), reflecting a link between the total Hb–oxygen affinity and %DRBCs in SCD patients. Conversely, P50 and %HbF were negatively correlated (P<0.0001, r²=0.25). The clinical impact of %DRBCs was studied with the 6MWT. Q4 patients for the times <90% SpO2 and <88% SpO2 had higher %DRBCs than Q1 patients (P=0.03 and P=0.04, respectively). No between-group differences were observed for the times <90% SpO2 and <88% SpO2 for Hb or %HbF. Finally, in agreement with our previous demonstration that HU strongly decreased the %DRBCs >M6 of therapy and that the %DRBCs impacted the time at low SpO2, the 10 SCD patients’ 6MWT results before and >M6 of HU therapy showed significantly decreased times <90% SpO2 (P=0.002) and <88% SpO2 (P=0.01) (Fig 2), and with delta SPO2 <4% (P=0.02). In conclusion, according to our results, the %DRBCs directly affects SCD patients’ SpO2 during exercise; HU improves oxygen affinity in correlation with the %DRBC decline. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Quantitative determination of zopiclone and its impurity by four different spectrophotometric methods

Four simple, sensitive and selective spectrophotometric methods are presented for determination of Zopiclone (ZPC) and its impurity, one of its degradation products, namely; 2-amino-5-chloropyridine (ACP). Method A is a dual wavelength spectrophotometry; where two wavelengths (252 and 301nm for ZPC, and 238 and 261nm for ACP) were selected for each component in such a way that difference in absorbance is zero for the second one. Method B is isoabsorptive ratio method by combining the isoabsorptive point (259.8nm) in the ratio spectrum using ACP as a divisor and the ratio difference for a single step determination of both components. Method C is third derivative (D3) spectrophotometric method which allows determination of both ZPC at 283.6nm and ACP at 251.6nm without interference of each other. Method D is based on measuring the peak amplitude of the first derivative of the ratio spectra (DD1) at 263.2nm for ZPC and 252nm for ACP. The suggested methods were validated according to ICH guidelines and can be applied for routine analysis in quality control laboratories. Statistical analysis of the results obtained from the proposed methods and those obtained from the reported method has been carried out revealing high accuracy and good precision.

SIMULTANEOUS ESTIMATION OF AMLODIPINE BESYLATE AND INDAPAMIDE BY DUAL WAVELENGTH SPECTROPHOTOMETRIC METHOD FOR COMBINED PHARMACEUTICAL DOSAGE FORM

A simple, accurate, precise, rapid, economical UV spectrophotometry method, dual wavelength spectrophotometry, has been developed and validated for estimation of Indapamide (IND) and Amlodipine besylate (AML) in combined tablet dosage form and can be used in routine analysis. In this method, the absorbance at 360 nm and 256 nm of AML were same and no interference of IND at 360 nm. was observed. So, absorbance difference at 256-360 is used for estimation of IND and absorbance at 360 nm used for AML. The method was found to be linear in the concentration range of 3-18 μg/mL for IND (r2&gt;0.99962) and 10-60 μg/mL for AML (r2&gt;0.99969). Mean assay was found to be 99.32% and 101.34% for IND and AML respectively. In first order derivative spectrophotometry, the absorbance at 237.4 nm (ZCP of AML) and 241 nm (ZCP of IND) were used for estimation of IND and AML respectively. The method was found to be linear in the concentration range of 1.5-9 μg/mL for IND(r2=0.99983) and 5-30 μg/mL for AML(r2=0.99966). Mean assay was found to be 99.72% and 100.28% for IND and AML respectively.

First order derivative and dual wavelength spectrophotometry methods development and validation for simultaneous estimation of alogliptin and pioglitazone in bulk and dosage form

Simple, sensitive, rapid and accurate UV spectroscopic methods have been developed for the Simultaneous estimation of Alogliptin and Pioglitazone bulk and pharmaceutical dosage forms. First order derivative and Dual wavelength methods were developed and validated using solvent methanol. Both methods show linearity at 5-30 g/ml. The first order derivative spectra of each solution were obtained. ZCP of Alogliptin was found 275.60 nm and ZCP of Pioglitazone was found 268.20 nm. The zero crossing point (ZCP) of Alogliptin at which Pioglitazone is measured and ZCP of Pioglitazone at which Alogliptin is measured. In Dual wavelength method, spectra two wavelengths 270.20 nm and 265 were selected as ? 1 and ? 2 for the estimation of Alogliptin. Pioglitazone shows the same absorbance at these wavelengths. Similarly, wavelengths 280 nm and 271 nm were selected as ? 3 and ? 4 for estimation of Pioglitazone. Alogliptin shows the same absorbance at these wavelengths. The methods were validated based on ICH guidelines. There are simple, sensitive, and reliable and results are reproducible for the routine analysis of Alogliptin and Pioglitazone.

Dual-wavelength dual-indicator catalytic kinetic spectrophotometry for determination of trace Ru(III)

A new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace Ru(III) was studied. This method was based on Ru(III)-catalyzing oxidation of Arsenazo I and indigo carmine by potassium bromate in sulfuric acid. The absorbances of the catalytic and noncatalytic systems were measured at 510 and 610 nm, respectively. Under the optimum conditions, the linear range of determination is 0–0.12 μg·ml−1 and the detection limit is 1.21 × 10−4 μg·ml−1. The method was applied for the determination of trace Ru(III) in ore samples with satisfactory results.

Simultaneous determination of Cinnarizine and Domperidone by area under curve and dual wavelength spectrophotometric methods

Accurate, selective and sensitive spectrophotometric methods have been developed and validated for simultaneous determination of Cinnarizine and Domperidone, a binary mixture with overlapping spectra, without preliminary separation. These methods include area under the curve (AUC) and dual wavelength spectrophotometry. For the AUC method, the area under curve of mixture solutions in the wavelength ranges 241–258nm and 280–292nm were selected for determination of Cinnarizine and Domperidone and by applying Cramer’s rule, concentration of each drug was obtained. In dual wavelength method, two wavelengths were selected for each drug in a way so that the difference in absorbance is zero for another drug. Domperidone shows equal absorbance at 240.2nm and 273.2nm, where the differences in absorbance were measured for the determination of Cinnarizine. Similarly, differences in absorbance at 230.8nm and 259.2nm were measured for determination of Domperidone. The proposed methods were applied for determination of Cinnarizine and Domperidone over the concentration ranges of 2–20 and 2–22μgmL−1, respectively. The suggested methods were validated as per USP guidelines and the results revealed that they are reliable, reproducible and precise for routine use with short analysis time. The results obtained by the proposed methods were statistically compared to the reported method, and there was no significant difference between them regarding both accuracy and precision.

Relationship between Polymorphism of &lt;I&gt;Wx&lt;/I&gt; Gene and Amylose Content in Hulless Barley

Hulless barley ( Hordeum vulgare L. var. nudum Hook. f.) is a typical crop in Tibetan Plateau in China. Starch, including amylopectin and amylose, is the main storage component in hulless barley, of which amylose is in low content or even absent in the endosperm of waxy barley. The Waxy gene ( Wx ) located on the short arm of chromosome 7H is a key gene responsible for amylose synthesis, and also acts as a favorable gene in breeding of hulless barley. However, it is difficult to select hulless barley germplasm with Wx due to lack of effective molecular markers. This study aimed to find out molecular markers applicable in the identification of Wx gene. A total of 150 accessions of hulless barley were primarily tested by staining endosperm with I 2 -KI, and four accessions (IG107028, Puebla, Huzhushuangcaoren, and APM-HC1905) were found as waxy genotypes. The amylose contents (AC) of the 150 accessions measured using dual-wave length spectrophotometry method varied from 12.4% to 38.5% with an average of 26.0%. The amylose contents of the four waxy genotypes namely IG107028, Brachvtic, Kunlun 2, and Huzhushuangcaoren，were 12.4–18.6% with an average of 16.7%. No genotype was found without amylose. We selected 51 accessions with obvious difference in AC to validate the polymorphism of four pairs of SSR markers. Primers P1 and P3 showed no polymorphism among the 51 accessions, and primer P4 exhibited four types of amplified product, and the fragment size positively correlated with amylose content. The P4 primer was designed according to the sequence of Wx gene on chromosome 7H of barley. Primer P4 can be used as an effective marker in the selection of waxy hulless barley cultivars.

Three different methods for determination of binary mixture of Amlodipine and Atorvastatin using dual wavelength spectrophotometry

Three simple, specific, accurate and precise spectrophotometric methods depending on the proper selection of two wavelengths are developed for the simultaneous determination of Amlodipine besylate (AML) and Atorvastatin calcium (ATV) in tablet dosage forms. The first method is the new Ratio Difference method, the second method is the Bivariate method and the third one is the Absorbance Ratio method. The calibration curve is linear over the concentration range of 4–40 and 8–32μg/mL for AML and ATV, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Methods are validated according to the ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit. The mathematical explanation of the procedures is illustrated.