Synergistic optical sensing: Selective colorimetric analysis of copper in environmental and biological samples.

A groundbreaking optical sensing membrane has been engineered for the accurate assessment of copper ions. The pliable poly(vinyl chloride) membrane is formulated through the integration of sodium tetraphenylborate (Na-TPB), 4-(2-hydroxy-4-nitro azobenzene)-2-methyl-quinoline (HNAMQ), and tri-n-octyl phosphine oxide (TOPO), in conjunction with o-nitrophenyl octyl ether (o-NPOE). The sensor membrane undergoes a thorough investigation of its composition to optimize performance, revealing that HNAMQ serves a dual role as both an ionophore and a chromoionophore. Simultaneously, TOPO contributes to enhancing the complexation of HNAMQ with copper ions. Demonstrating a linear range for Cu2+ ions spanning from 5.0 × 10-9 to 7.5 × 10-6 M, the proposed sensor membrane showcases detection and quantification limits of 1.5 × 10-9 and 5.0 × 10-9 M, respectively. Rigorous assessments of potential interferences from other cations and anions revealed no observable disruptions in the detection of Cu2+. With no discernible HNAMQ leaching, the membrane demonstrates rapid response times and excellent durability. The sensor exhibits remarkable selectivity for Cu2+ ions and can be regenerated through exposure to 0.05 M EDTA. Successful application of the sensor in determining the presence of Cu2+ in biological (blood, liver and meat), soil, food (coffee, black tea, sour cherry juice, black currant, and milk powder) and environmental water samples underscores its efficacy.

An innovative approach in titanium determination based on incorporating 2-amino-4-((4-nitrophenyl)diazenyl)pyridine-3-ol in a PVC membrane.

A pioneering optical sensor has been effectively developed to achieve precise and reliable detection of titanium ions. The sensor employs an optode membrane composed of 2-amino-4-((4-nitrophenyl)diazenyl)pyridine-3-ol (ANPDP) and sodium tetraphenylborate (NaTPB) incorporated into a plasticized PVC matrix, with dioctyl sebacate (DOS) acting as the plasticizer. When exposed to Ti4+ ions at pH 8.25, the color of the sensing membrane undergoes a distinctive transformation from yellow-orange to violet. Extensive investigations were carried out to assess and optimize various factors influencing the efficiency of ion uptake. Through careful experimentation, the optimum conditions were determined to be 60.0% DOS, 6.0% ANPDP, 30% PVC, and 4.0% NaTPB, with a rapid response time of 5.0 min. Within these conditions, the developed optode demonstrates an impressive linear range of 3.0-225 ng mL-1, boasting detection (LOD) and quantification (LOQ) limits of 0.91 and 2.95 ng mL-1, respectively. Moreover, the precision of the sensor, as indicated by the relative standard deviation (RSD%), remained consistently below 1.55% in six replicate determinations of 100 ng mL-1 Ti4+ across diverse membranes. The selectivity of the sensor was rigorously examined for a range of cations and anions, successfully establishing the tolerance limits for interfering species. Notably, the presence of EDTA as a masking agent did not compromise the high selectivity of the sensor. Consequently, the innovative probe holds significant potential as a reliable analytical tool for quantifying titanium content in various samples, including water, geological materials, soil, plants, paints, cosmetics, and plastics.

The Netherlands Heart Tissue Bank : Strengthening the cardiovascular research infrastructure with an open access Cardiac Tissue Repository.

AIM: Cardiac diseases remain a leading cause of cardiovascular disease (CVD) related hospitalisation and mortality. That is why research to improve our understanding of pathophysiological processes underlying cardiac diseases is of great importance. There is a strong need for healthy and diseased human cardiac tissue and related clinical data to accomplish this, since currently used animal and in vitro disease models do not fully grasp the pathophysiological processes observed in humans. This design paper describes the initiative of the Netherlands Heart Tissue Bank (NHTB) that aims to boost CVD-related research by providing an open-access biobank. METHODS: The NHTB, founded in June 2020, is a non-profit biobank that collects and stores biomaterial (including but not limited to myocardial tissue and blood samples) and clinical data of individuals with and without previously known cardiac diseases. All individuals aged ≥ 18 years living in the Netherlands are eligible for inclusion as a potential future donor. The stored samples and clinical data will be available upon request for cardiovascular researchers. CONCLUSION: To improve the availability of cardiac tissue for cardiovascular research, the NHTB will include extensive (cardiac) biosamples, medical images, and clinical data of donors with and without a previously known cardiac disease. As such, the NHTB will function as a translational bridge to boost a wide range of cardiac disease-related fundamental and translational studies.

Asthma in COVID-19: Mitigating or exacerbating? An interesting case report.

Introduction: Bronchial asthma is an age-old disease whereas COVID-19 is an officially declared pandemic on March 11, 2020 by WHO. Since both are primarily a disease of the respiratory system, researchers across the globe tried to explore the potential relationship between them; to date, there is no convincing data. Here, we tried to present a case to explore potential relationships between these two, if present. Case presentation: A 30-year-old male patient with well-controlled cough variant asthma was diagnosed with a case of covid-19 infection 12 months back. All other sign symptoms subsided except dry cough. The patient is treated with an inhaled bronchodilator, oral and inhaled steroid, Tab montelukast as well as other conservative management like hot water vapor, lozenge, honey, etc but symptoms were not controlled for the last 12 months. The patient could not do his job because of this problem. All examination and investigation findings were normal. After long-term use of inhaled steroids, he is now 50-60% improved and gradually improving. Discussion: Covid can exacerbate cough in an asthmatic patient. Neuronal activation and neuroinflammatory mechanisms may aggravate this cough after covid. Diagnosis confirmed clinically with the relevant improvement of symptoms. Other important differentials were excluded by appropriate history, examinations, and investigation. Cough is improved by steroids in this case. Conclusion: Summary of conclusion: Cough variant asthma may be aggravated with covid 19 infection and meticulous history, treatment, and follow up needed for an asthmatic patient who is infected with covid 19.

Data on self-awareness, self-determination, and self-efficacy of opioid-dependent patients receiving methadone treatment before and after getting individual psycho-educational (i-SEAZ) intervention.

The readiness to change among drug addicts is a key strength for successful treatment. Self-awareness, self-determination, and self-efficacy have been identified as the fundamentals of readiness that should be embraced by drug addicts while in treatment. In this article, the shared data were applied to assess the effect of individual psycho-educational intervention based on integrated self-awareness and self-determination theories (i-SEAZ) on self-efficacy amongst opioid-dependent patients undergoing methadone treatment (MT). The effectiveness of the i-SEAZ module was evaluated in a total of 75 opioid-dependent MT participants from five Methadone Clinics under the Ministry of Health, Malaysia located across Klang Valley. The experimental group consisted of 38 participants who received 10 sessions of individual i-SEAZ alongside MT, whereas 37 participants of the control group only received MT. The shared data were collected through three questionnaires, namely Scale for Self-Consciousness Assessment (SSCA), Treatment Motivation Questionnaire (TMQ), and General Self Efficacy (GSE). Data collection was performed twice; the first instance was two weeks prior to initiation of i-SEAZ (pretest), and the second was two weeks post completion of i-SEAZ (posttest). The extracted data were precisely represented in terms of means and standard deviations (SDs).

Extractive Spectrophotometric Determination of Nortriptyline Hydrochloride Using Sudan II, IV and Black B.

A simple spectrophotometric methods has been developed for the determination of nortriptyline hydrochloride in pure and in pharmaceuticalformulations based on the formation of ion-pair complexes with sudun II (SII), sudan (IV) (SIV) and sudan black B (SBB). The selectivity of the method was improved through extraction with chloroform. The optimum conditions for complete extracted colour development were assessed. The absorbance measurements were made at 534, 596 and 649 nm for SII, SIV and SBB complexes, respectively. The calibration graph was linear in the ranges 0.5- 280. 0.5- 37.5 and 0.5 - 31.0 µg ml-1 of the drug usiny the same reagents, respectively. The precision of the procedure was checked by calculating the relative standard deviation of ten replicate determinations on 15 µg ml-1 of nortriptyline HCI and was found to be 1.7, 1.3 and 1.55% using SII, SIV, and SBB complexes, respectively. The molar absorptivity and Sandell sensitivity for each ion-pair were calculated. The proposed methods were successfully applied to the deterniination of pure nortriptyline HCI and in pharmaceutical formulations, and the results demonstrated that the method is equally accurate, precise and reproducible as the official method.

Association between telomere length and chromosome 21 nondisjunction in the oocyte.

Chromosome 21 nondisjunction in oocytes is the most common cause of trisomy 21, the primary chromosomal abnormality responsible for Down syndrome (DS). This specific type of error is estimated to account for over 90 % of live births with DS, with maternal age being the best known risk factor for chromosome 21 nondisjunction. The loss of telomere length and the concomitant shortening of chromosomes are considered a biological marker for aging. Thus, we tested the hypothesis that mothers who had a maternal nondisjunction error leading to a live birth with DS (n = 404) have shorter telomeres than mothers with live births without DS (n = 42). In effect, our hypothesis suggests that mothers of children with DS will appear "biologically older" as compared to the mothers of euploid children. We applied a quantitative PCR assay to measure the genome-wide relative telomere length to test this hypothesis. The results of our study support the hypothesis that young mothers of DS babies are "biologically older" than mothers of euploid babies in the same age group and supports telomere length as a biomarker of age and hence risk for chromosome nondisjunction.

A comparative study between fine needle aspiration cytology findings and histopathological report of major salivary gland neoplasm in a tertiary hospital of Bangladesh.

Salivary gland tumours are relatively uncommon and most of the tumours arise from parotid gland. Fine needle aspiration cytology (FNAC) is advised preoperatively as diagnostic tool but sometimes found to shown both false positive and false negative results. This study was aimed to find out distribution of neoplasm of major salivary glands and also to explore the sensitivity and specificity of FNAC. The present cross sectional study was done in the Dept. of Otolaryngology Head and Neck Surgery, BSMMU from January 2007 to December 2008. A total number of 60 gender-matched patients with major salivary neoplasm, confirmed by FNAC, were recruited in the study. Operated salivary gland specimens were sent for histopathological examination, histopathological findings were compared. Overall male to female ratio was 1:1. Out of 60 cases, 47 (78.3%) patients had parotid and 13 (21.7%) patients submandibular gland neoplasm. Male to female ratio for parotid tumour was 1:1.1 and for submandibular 1.6:1. Mean age of the patients was 44.5 with range of 14-85 years. Of the total 60 cases 47 (78.3%) were benign and 13 (21.7%) malignant. Out of 47 parotid tumour 85.1% were benign and 14.9% malignant. Among the parotid tumour 97% were superficial lobe and 3.0% deep lobe. In case of submandibular gland 53.84% were benign and 46.15% tumour malignant. According to the sides of involvement, 25 (53.2%) cases of parotid neoplasm tumour were in the left and 22 (46.8%) the right. In submandibular gland the distribution was 7 (53.8%) and 6 (46.16%) respectively. Statistically incidence of parotid tumour was significantly higher than submandibular tumour (p < 0.05). Out of 60 cases in 56 (93.3%) preoperative FNAC and postoperative histopathological findings were same. There was 1.7% false positive and 5% were false negative results. Sensitivity, specificity of FNAC were 80% and 97.8% respectively. Positive predictive value was 92.3% and negative predictive 93.6% for FNAC.FNAC though cheap and safe but its diagnostic accuracy was 93.3%.Histopathologial examination remained to be of value for diagnostic confirmation of major salivary gland neoplasm.

Fever-triggered ventricular arrhythmias in Brugada syndrome and type 2 long-QT syndrome.

The risk for lethal ventricular arrhythmias is increased in individuals who carry mutations in genes that encode cardiac ion channels. Loss-of-function mutations in SCN5A, the gene encoding the cardiac sodium channel, are linked to Brugada syndrome (BrS). Arrhythmias in BrS are often preceded by coved-type ST-segment elevation in the right-precordial leads V1 and V2. Loss-of-function mutations in KCNH2, the gene encoding the cardiac ion channel that is responsible for the rapidly activating delayed rectifying potassium current, are linked to long-QT syndrome type 2 (LQT-2). LQT-2 is characterised by delayed cardiac repolarisation and rate-corrected QT interval (QTc) prolongation. Here, we report that the risk for ventricular arrhythmias in BrS and LQT-2 is further increased during fever. Moreover, we demonstrate that fever may aggravate coved-type ST-segment elevation in BrS, and cause QTc lengthening in LQT-2. Finally, we describe molecular mechanisms that may underlie the proarrhythmic effects of fever in BrS and LQT-2. (Neth Heart J 2010;18:165-9.).

Respiratory infection of camels associated with parainfluenza virus 3 in Sudan.

This study was undertaken to investigate the role of parainfluenza virus 3 (PIV3) in respiratory infection of camels. A total of 273 lung specimens from camels with pneumonia lesions were collected from slaughterhouses in four different areas of Sudan. In addition, eight specimens were collected from outbreaks of respiratory infection in camels. Using antigen detection sandwich ELISA kits, six out of the 281 specimens tested were positive for the PIV3 antigen (2.1%); the highest prevalence was noted in Eastern Sudan (4.2%), then in Central and Northern Sudan (1.4%). The direct immunofluorescent test (FAT) was used to confirm the positive reactions for PIV3 by ELISA. The polymerase chain reaction (RT-PCR) was applied for the detection of the PIV3 genome in lungs of camels; two out of four samples which were positive by the PIV3 ELISA were also positive by RT-PCR. Virus isolation was attempted for PIV3 in MDBK cells; four specimens yielded cytopathic virus when inoculated onto the cell culture. The cytopathic effect (CPE) consisted of cell rounding, multinucleated cells, sloughing and elongation of cells, and some syncytia were observed on the 3rd to 7th day post-inoculation. Using commercially available indirect ELISA kits for antibodies to PIV3, 495 camel sera were tested, and the seroprevalence detected was 82.2%. The highest seroprevalence was observed in Central (92.6%), then in Eastern (92.2%) and Central to South Sudan (82.5%); the lowest prevalence was found in Northern Sudan (64.8%).

Respiratory syncytial virus infection of camels (Camelus dromedaries).

This study aimed to investigate the occurrence of respiratory syncytial virus (RSV) infections in camels in Sudan. A total of 272 camel lung specimens showing pneumonia were collected from slaughter houses at four different areas in Sudan, additionally 8 specimens were collected from outbreaks of respiratory infection in camels. Using sandwich ELISA kits for RSV antigen detection 4 out of 280 tested lungs (1.4%) were positive, all were from Central Sudan (Tambool slaughter house). FAT was used to confirm the ELISA positives. Polymerase chain reaction RT/PCR was applied for the detection of RSV genome in camel lungs; 1 out of 4 ELISA positives was positive by RT/PCR. Using indirect ELISA kits 135 out of 495 (27.3%) camel sera showed antibodies to RSV, highest prevalence was observed in Western (33.5%) then Central (31.6%) and Eastern Sudan (23.5%). Based on the manufacturer specified calculations for OD readings, most of positive sera (90/135) were low reactive (1+). This is the first report for the detection of RSV antigen, genome and antibody in camels in Sudan.

Natural exposure of Dromedary camels in Sudan to infectious bovine rhinotracheitis virus (bovine herpes virus-1).

The occurrence of bovine herpes virus-1 (BHV-1) in camels was studied. A total of 186 pneumonic camel lungs were collected from slaughter houses at four different areas in Sudan during 2000-2006. Using sandwich ELISA 1.6% of 186 tested lungs were found positive for BHV-1 antigen, all were from Tambool at Central Sudan. Direct fluorescent antibody test (FAT) was used to confirm the BHV-1 ELISA positives, all ELISA positives were also positive. PCR was used to detect BHV-1 genome with three positive results. BHV-1 was isolated from two camel lungs in MDBK cells. Isolates were identified using ELISA and FAT. Indirect ELISA was used to detect antibodies to BHV-1 in 260 camel sera; 76.9% were found positive. Highest prevalence was observed in sera from Kordofan (84%) then Blue Nile (80%) and Tambool (76.3%). This is the first report for the detection of BHV-1 antigen, genome using PCR, isolation in cell culture and antibodies in camels in Sudan.

Kikuchi-Fujimoto Disease presenting with fever, lymphadenopathy and dysphagia.

Kikuchi Fujimoto Disease (KFD) can present with dysphasia, fever and lymphadenopathy. A young Bangladeshi girl presented with fever, cervical lymphadenopathy, dysphasia, weight loss and skin rash. Antitubercular drugs were given on clinical judgement, with no improvement after one month. Later, fine needle aspiration and histopathology of Lymph Node suggested KFD. Computerized Tomography (CT) scan of neck revealed enlarged retropharyngeal lymphnode (LN) causing pharyngeal narrowing. Oral Prednisolone was given showing improvement and no relapse was encountered. KFD may present with dysphasia uncommonly along with fever and lymphadenopathy. Awareness of this disorder by clinicians and pathologists will help prevent misdiagnosis and inappropriate treatment.

The surfactant sensitized analytical reaction of cerium(IV) with some triphenylformazan derivatives.

Cationic surfactant, cetylpyridinium bromide (CPB), sensitizes the colour reaction of cerium(IV) with 1,3-o-hydroxyphenyl-5-phenylformazan(I), 1-m-hydroxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(II) and 1-m-carboxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(III). The formation of a soluble ternary complex of stoichiometric ratio 1:1:1 (Ce(IV)-R-CPB) is responsible for the observed enhancement in the molar absorptivity and Sandell sensitivity of the formed complex, when a surfactant is present. The ternary complex exhibits absorption maxima at 596, 571 and 607 nm (epsilon=6.05 x 10(4), 6.28 x 10(4) and 8.06 x 10(4)L mol(-1)cm(-1)) using triphenylformazan derivatives I, II and III, respectively. Beer's law is obeyed between 0.15 and 2.5 microg ml(-1), whereas, optimum concentration range applying Ringbom method is in the range 0.30-2.25 microg ml(-1). Conditional formation constants in the presence and absence of CPB for Ce(IV) complexes have been calculated. The proposed method has been successfully applied to the analysis of magnesium-base cerium alloys and synthetic mixtures corresponding to various cerium alloys.

Novel Brugada syndrome-causing mutation in ion-conducting pore of cardiac Na+ channel does not affect ion selectivity properties.

AIM: Brugada syndrome is an inherited cardiac disease with an increased risk of sudden cardiac death. Thus far Brugada syndrome has been linked only to mutations in SCN5A, the gene encoding the alpha-subunit of cardiac Na+ channel. In this study, a novel SCN5A gene mutation (D1714G) is reported, which has been found in a 57-year-old male patient. Since the mutation is located in a segment of the ion-conducting pore of the cardiac Na+ channel, which putatively determines ion selectivity, it may affect ion selectivity properties. METHODS: HEK-293 cells were transfected with wild-type (WT) or D1714G alpha-subunit and beta-subunit cDNA. Whole-cell configuration of the patch-clamp technique was used to study biophysical properties at room temperature (21 degrees C) and physiological temperature (36 degrees C). This study represents the first measurements of human Na+ channel kinetics at 36 degrees C. Ion selectivity, current density, and gating properties of WT and D1714G channel were studied. RESULTS: D1714G channel yielded nearly 80% reduction of Na+ current density at 21 and 36 degrees C. At both temperatures, no significant changes were observed in V(1/2) values and slope factors for voltage-dependent activation and inactivation. At 36 degrees C, but not at 21 degrees C, D1714G channel exhibited more slow inactivation compared with WT channel. Ion selectivity properties were not affected by the mutation at both temperatures, as assessed by either current or permeability ratio. CONCLUSION: This study shows no changes in ion selectivity properties of D1714G channel. However, the profoundly decreased current density associated with the D1714G mutation may explain the Brugada syndrome phenotype in our patient.

Spectrophotometric microdetermination of nefopam, mebevrine and phenylpropanolamine hydrochloride in pharmaceutical formulations using alizarins.

Simple and rapid spectrophotometric procedures have been established for quantitation of nefopam hydrochloride (NF) mebevrine hydrochloride (MB) and phenylpropanolamine hydrochloride (PP). The procedures are based on the reaction between the examined drugs (NF, MB and PP) and alizarin (I), alizarin red S (II), alizarin yellow G (III) and quinalizarin (IV) producing ion-pair complexes which can be measured at the optimum wavelength. The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 0.5-30.0 microg ml(-1). The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficient was > or =0.9988 (n=6) with a relative standard deviation (R.S.D.) of < or =1.3, for six determinations of 20 microg ml(-1). The methods are successfully applied to the determination of NF, MB and PP in their pharmaceutical formulations.

Spectrophotometric studies and applications for the determination of yttrium in pure and in nickel base alloys.

Yttrium reacts with 5-(4'-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (I), 5-(2'-bromophenylazo)-6-hydroxypyrimidine-2,4-dione (II), 5-(2',4'-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (III), 5-(4'-nitro-2',6'-dichlorophenylazo)-6-hydroxypyrimidine-2,4-dione (IV), 5-(2'-methyl-4'-hydroxyphenylazo)-6-hydroxypyrimidine-2,4-dione (V) to form a dark pink complexes, having an absorption maximum at 610, 577, 596, 567 and 585 nm, respectively. The complex formation was completed spontaneously in theil buffer solution and the resulting complex was stable for at least 3 h after dilution. Under the optimum conditions employed, the molar absorptivities were found to be 1.60 x 10(4), 1.29 x 10(4), 1.96 x 10(4), 1.45 x 10(4) and 1.21 x 10(4) l mol(-1) cm(-1) and the molar ratios were (1:1) and (1:2) (M:L). The linear ranges were found within 95 microg of yttrium in 25 ml solution. One of the characteristics of the complex was its high tolerance for calcium and hence a method of separation and enrichment of microamounts of yttrium by using calcium oxalate precipitate was developed and applied to measure yttrium in nickel-base alloys. Interfering species and their elimination have been studied. The precision and recovery are both satisfactory.

Utility of formazans and cetylpyridinium chloride in rapid spectrophotometric determination of zinc in biological materials and pharmaceutical formulations.

A facile, rapid and sensitive spectrophotometric method for the determination of zinc is performed, based on complexation reaction between the metal ion and 1,5-diphenyl-3-acetylformazan (I) 1-(o-carboxyphenyl)-3-acetyl-5-acetylformazan (II), 1-(o-carboxyphenyl)-3-acetyl-5-phenylformazan (III), and 1-(o-carboxyphenyl)-3-acetyl-5-m-tolylformazan (IV) in the presence of cationic surfactant cetylpyridinium chloride (CPC). The important analytical parameters and their effects on the reported system are investigated. Zinc reacts with the reagents (I-IV) and CPC in the ratio 1:1:2 (metal:reagent:CPC) in the pH range 8.5, 7.5, 5.5 and 6.5 to form a ternary complex with an absorption maximum 616, 656, 672 and 599 nm, respectively. The reaction was extremely rapid at room temperature, and the absorbance value remains unchanged for at least 1 week. The apparent stability constant of the complex were found to be 13.1 9.2, 11.4 and 12.3, and adheres to Beer's law for 0.05-3.50 microg per 10 ml of zinc. For more accurate analysis, Ringbom optimum concentration range was found from 0.08 to 3.20 microg per 10 ml of zinc. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. Taking a constant concentration of metal ion and determining its concentration in the presence of large number of foreign ions tested the effect of foreign ions. The method was applied for determination of zinc in serum, human hair and pharmaceutical formulations, where excellent agreements between reported and obtained results were achieved. The relative standard deviation was better than 1.67%.

Ion-association method for the colorimetric determination of neomycin sulphate in pure and dosage forms.

A simple, fairly rapid, sensitive and accurate method is described for the colorimetric determination of neomycin sulphate (NMS), based on the measurement of the absorbance of the extracted organic soluble ion-association complex formed between neomycin dictation and a bulky counter anion. Different chromotropic acid azo dyes were examined as counter ions. The effect of pH, the counter ion concentration, sequence of addition and solvents for extraction were also illustrated. The most suitable system is based on reagent VIII (pH 7.5) with chloroform as the extraction solvent. The use of other counter ions, in conjunction with their respective solvents, was found to be less sensitive. The neomycin-reagent VIII system exhibits negligible or no interference when used for the determination of up to 58 microgml(-1) of NMS in the presence of several drug excipiences. The method has been used for the determination of up to 58 microgml(-1) with a good recovery (99.8+/-1.5%), and the precision is supported by the low relative standard deviation

Utility of oxidation-reduction reaction for the determination of ranitidine hydrochloride in pure form, in dosage forms and in the presence of its oxidative degradates.

Three simple, accurate and sensitive colorimetric methods (A, B and C) for the determination of ranitidine HCl (RHCl) in bulk sample, in dosage forms and in the presence of its oxidative degradates are described. The first method A is based on the oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measurement of the decrease in absorbance of amaranth dye (AM) at a suitable lambda(max)=520 nm. The methods B and C involve the addition of excess Ce(4+) and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable lambda(max)=528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max)=526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.2-3.6, 0.1-2.8 and 0.1-2.6 microg ml(-1) for methods A, B and C, respectively. The apparent molar absorptivity. Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.3-3.4, 0.2-2.6 and 0.2-2.4 microg ml(-1) for methods A, B and C, respectively. Analyzing pure and dosage forms containing RHCl tested the validity of the proposed methods. The relative standard deviations were