Spectrometric, thermal and electron microscope studies of iron complexes of adrenaline hydrogen tartrate and catecholamine

Iron was found to form coloured stable complexes with both adrenaline hydrogen tartrate and catechol as inhibitors for iron corrosion in aqueous solutions of different pH values [2.0-11.5]. The electrochemically formed complexes on the surface of the iron electrode in different media were separated and studied in comparison with the same complexes prepared by chemical method in the same media. The prepared complexes were studied using micro-, electro-and thermal analyses together with electron ionization mass [EI-MS] and IR spectral methods. Both chemically and electrochemically prepared complexes were found to be of the same structures. The electrochemically formed complex in different media was found to be as a chemisorbed layer on the surface of iron electrode. The aim of the present work is to compare the results of chemical and electrochemical techniques in preparation of stable iron chelates of both adrenaline hydrogen tatrate [AHT] and Catechol [Cat.] as inhibitors for iron corrosion. The morphology of the chemisorbed complex layers on the electrode surface was also tested by electron microscope [EMS] and characterized as an amorphous or crystalline adsorbents

Effect of chemical composition of zinc phosphating solution on phosphate coating properties

Phosphate coatings have a wide field of applications in industry. The applications of coatings are classified according to the film thickness and the type of solution employed. In this study the phosphating process in the zinc-phosphating-nitrate accelerator on steel gave a phosphating layer of suitable morphology which was investigated by different instruments like SEM/EDS and XRD. The crystal size and the thickness of phosphating layer were found to be iron content dependent. Therefore, adjusting of phosphate, zinc and iron concentrations is very important to get a suitable phosphating effective process. The aim of the present work is to control the iron concentration in the phosphating bath in order to improve the quality and adhesive properties of zinc phosphating coating on steel sheets that always used for military purposes in Helwan Engineering Company in Egypt

Investigation of molecula structure - chirality relationship of ephedrine and pseudoephedrine drug using thermal analyses and mass spectrometry techniques combined with MO-calculations

Two diastercoisomers ephedra drugs namely; ephedrine [eph.] and pseudoephedrine [psi-eph.] hydrochloride, have been investigated for their chirality using thermal analysis [TA] measurement [TG/DTA] and electron ionization mass spectrometry [EI-MS] at 70 eV. Monte Carlo conformational search technique was used for exploration of conformational space of ephedrine and psi-eph., using Amber force field molecular mechanics method. MO-calculations were performed using semi-empirical PM3 procedure on the obtained conformational sample for investigation of the different molecular properties. The calculations include bond length, bond order, charge distribution, ionization energy and heat of formation, in neutral and positively charged forms for the two drugs. The effect of diastereoisomerism on thermal analysis decomposition behavior of these drugs was studied. The obtained data confirmed the chirality and declared the structure reactivity relationship of these drugs

Electrochemical behavior of copper electrode in different solutions of adrenalin chydrogentatrate and catechol

Galvanic anodic polarization of copper electrode at different current densities in electrolytes of different pH values containing adrenaline hydrogen tartarte [AHT] and catechol [Cat.] have been studied. The effect of complex formation on the underlying anodic reactions and inhibition effect of these complexes on copper electrode is also studied. The cathodic deposition of copper in the prepared complexes on the surface of the cathode is involved to check their stability at different pH values and the effect of this stability on cathodic behavior of copper electrode

Kinetic spectrophotometric methods for the quantitation of sertraline drug in bulk and in formulations

Kinetic methods [fixed concentration, rate constant and fixed time] for the sensitive and accurate spectrophotometric microdetermination of sertraline basic drug have been described. The methods are based on the reaction between sertraline and iodine in 1,2-dichloroethane as a suitable medium. At a fixed time of 10 min, the spectrum of the formed inner and / or outer-sphere complexes [Drug. I+] I- / and or [Drug I2] is measured at a suitable selected lambdamax = 396 nm. The concentration of sertraline drug, in its pure form is calculated using the calibration equation for the fixed time method. Beer's law was obeyed in the concentration range of 1.6-48 microg ml[-1] and the recovery in average was 99.85%. The relative standard deviation RSD [n = 7] at 8 micro g ml[-1] is 0.65% and at 24 micro g ml[-1] is 0.88% within-day, and at 10 micro g ml[-1] is 0.67% and at 20 micro g ml[-1] is 0.84% for between-day, respectively. Therefore, the intera- and inter-day RSD values indicated the ruggedness of the fixed time kinetic method. The method is suitable for quantitative determination of sertraline in the concentration range of 6-20 microg ml[-1] in pharmaceutical formulation [Lustiral] after its separation as a basic form out of drug formulation additives like starch, glucose, ... etc without interference. The results obtained agreed well with the data obtained by an official method. The determination of sertraline by fixed concentration and rate constant methods is feasible with the calibration equations obtained but the fixed time method is more accurate

Structure investigation of piroxicam and tenoxicam using thermal analyses, mass spectrometry and semi-empirical MO calculations

Steroidal and non-steroidal anti-inflammatory agents such as oxicam group [e.g. piroxicam [Pir] and tenoxicam [Ten] were investigated using thermal analyses [TA] measurements [TGA, DTGA, DTA and DDTA] in comparison with El mass spectral [MS] fragmentation at 70 eV. Semi-emperical molecular orbital [MO] calculations have been carried out using PM3 described by Stewart on Pir and Ten both as neutral molecules and the corresponding positively charged molecular ions. These calculations included molecular geometries such as bond length, bond order, bond strain, atomic charge distribution and hybridization, and heat of formation of these drugs. Thermal analyses reveal a high response of Pir and Ten to temperature variation with a cleavage of six bonds in aliphatic side chains around O, S, and N heteroatom, leaving aromatic radicals as final products, which become volatile at high temperature. TA mostly involved fragmentation of SO2 gas molecule at first followed by C, N, and O containing fragments as CH3CN, CHO, NHCONHCO, and NHCO. The MS fragmentations indicate the presence of the same final products as given by TA technique. Mass fragmentation pathways refer to the loss of more or less the same fragments via cleavage of seven bonds of Pir and nine bonds of Ten molecular ions, in parallel and many consecutive steps as explained by geometries values calculated by MOC. These may refer to the instability of Pir and Ten molecular ions in comparison with their neutral forms. This instability is explained by comparison of the calculated partial charges on their atoms and/or their heat of formation values. The best pathway in both TA and MS techniques is that starts with the loss of SO2 gas molecule and followed by the loss of HCO and CH3CN molecules. The partial charge values and the stereo structures of ionic and neutral form refer to a distinct phenomenon of collection of voluminous charge density on SO2 group covering in space most atoms behind. It is explained by the highest electron withdrawing abilities of the heteroatom, two O and S in this group as a result of their high electro negativities. This rationalized the starting of fragmentation process in TA and MS with the loss of SO2 gas molecules. Therefore, a MOC was applied to declare both TA and MS observations

Study of reaction mechanism between piroxicam and tenoxicam drugs with iodate and N-bromosuccinamide oxidants and their microdetermination by spectrophotometric and potentiometric measurements

Piroxicam [Pir] and tenoxicam [Ten] are specified as nonsteriodal anti-inflammatory drugs. They are used in the symptomatic management of osteoarthritis, rheumatoid arthritis and in short term management of soft-tissue injury. Therefore, their reactions with oxidants, Iodate and N-bromosuccinamide [NBS] are suggested, discussed and used for microdeterminations of these essential biomedical drugs. A sensitive Spectrophotometric method has been suggested and used in comparison with a potentiometric one to follow these reactions mechanisms aiming to apply them in microdetermination of piroxicam [Pir] and tenoxicam [Ten]. No interference from excipients was observed in both techniques. The Spectrophotometric procedure was better than the potentiometric one, because of the sensitivity of the former to detect lower concentration ranges [50 to 1100 micro g ml[-1]] of the pure standard drugs and the detection of high concentration range [300 to 3980 micro g ml[-1]] by the latter. The high molar absorptivity [e = 0.25-0.29 x 10[3] L.mol[-1] cm[-1]] and Sandell sensitivity [1.2 - 13 micro g cm[-2]] refer to the high selectivity of the Spectrophotometric method. The between -day precision of the potentiometric procedure refers to the greater stability and good reliability of this procedure in high concentration [% recovery = 99 to 102%]. These procedures were applied for successful microdetermination of Pir and Ten in many pharmaceutical preparations, such as tablets and capsules. The values of SD [0.03 to 0.6 for five replicates] and RSD [0.6 to 1.2%] refer to reproducibility and precision of the applied procedures. The results of analyses of these drugs were compared with those obtained by the application of the official method using Ringbom, t-test and f-test. These results gave t- value of 2.776 and f-value of 6.31 at 95% confidence level. The obtained results also refer to the robustness of the proposed procedures

Investigation of malonanilide and its dinitro-isomers using thermal analyses, mass spectrometry and semi-empirical MO calculation

In this paper malonanilide compound [M 1], and its dinitro-isomers [M 2 - M 4] compounds were investigated. The evaluation has been performed using thermal analyses [TA] measurements in comparison with electron ionization [EI] mass spectral [MS] fragmentation. Knowledge gained from experimental work was combined with theoretical calculations for neutral molecules, using the Modified Neglect of Diatomic Overlap [MNDO] semi-empirical MO calculations. The theoretical calculations include molecular geometry, bond order, charge distribution and heats of formation. For all the studied compounds, the major fragmentation pathways in TA and MS [including intermediates] is a CO-CH 2 bond rupture, followed by ketene [COCH 2] loss to form the nitroaniline structure. The MNDO procedure provides a basis for fine distinction among sites of initial bond cleavage, which is crucial to the rationalization of subsequent fragmentation of the molecule. Also, the thermal behavior decomposition due to ortho effect for o,o-dinitromalonanilide is discussed in terms of experimental and the MO calculations

Spectrophotometric determination of levodopa, carbidopa and alpha-methyldopa

The dopamine derivatives participate in the regulation of a wide variety of physiological functions in human body and in medication life. A sensitive spectrophotometric method is developed for the determination of levodopa [LD], carbidopa [CD] and alpha methyldopa [MD]. It proposed on the bases of metal complex formation of these compounds with copper tetramine then coupling with 4-aminoantipyrine. The optimum conditions [pH, time, ratio and sequence of addition] are established. The method permits the determination of LD, CD and MD as a rectlinear relation in calibration curve over a concentration range 19.72 to 69.02, 13.79 to 63.34 and 31.24 to 98.94 micro g ml -1, respectively. The obtained data of SD [0.174 to 0.59], CV [0.68 to 1.16%] and correlation coefficient [0.995 to 0.999] reflect the reliability, reproducibility and accuracy of this procedure. The method is applicable to the assay of LD and MD in pharmaceutical drugs [Levocare and Aldomet respectively], and the results are in a good agreement with those obtained by the official method. The method was simple, rapid, reproducible and accurate to follow of medication of schizophrenic patient

Spectrophotometric assay of levodopa and alpha-methyldopa in pharmaceutical products and in biological samples of schizophrenic patients using copper complex and tri-iodide reagent

Two simple, rapid and sensitive spectrophotometric methods are proposed for the determination of levodopa [LD] I, and alpha-methyldopa [alpha -MD] II. The first method is based on coupling of 4-aminoantipyrine [4-AAP] with LD and a alpha -MD to give new ligands that react with copper-tetramine complex to give intense colored chelates of ratios [1:1:1, LD or alpha -MD: 4-AAP: copper tetramine]. The colored products are quantified spectrophotometrically at 520 and 545 nm for LD and a alpha -MD, respectively. The optimization of the experimental conditions is described. The method has been used for the determination of 19.72-69.02 and 31.24-98.94 micro g ml[-1] of drugs I and II, respectively. The accuracy of the method is indicated by the values of recovery [100 +/- 0.2%] and the precision is supported by the low standard deviation [SD 0.17-0.22] and relative standard deviation [RSD=0.59-1.54%]. The second method is based on the formation of ion-pair iodinated inner sphere or outer sphere colored complexes between the drug and iodine or tri-iodide negative ions at pH 5 and room temperature [25 +/- 3°C]. This method has been used for the determination of LD within the concentration range 39.44-78.88 micro g ml[-1] with SD=022-0.24 and recovery percent=100 +/- 0.3%. The sensitivity of the two methods is indicated by Sandell factor of 0.014- 0.016 g cm[2]. The results of the two methods are compared with those of the official method. The interference from common drug additives, degradation products and excepients was also studied. The proposed methods were applied successfully to the determination of LD and alpha-MD in dosage forms. The second method was also successfully applied for the analysis of LD and carbidopa [CD] synthetic mixture of concentration of these drugs similar to that of Aldomost drug form of LD, and also the determination of these drugs in urine of some schizophrenic patients with good precision and accuracy. The reliability of the methods was established by parallel determinations against the official British pharmacopoeia method

Determination of paracetamol bromopotentio-metrically using silver amalgam and bromide ion-selective electrode

A study of the oxidation of paracetamol with bromine in acetate buffer media has been carried out using potentio bromometric techniques. The different variables such as ratio of the reactants, temperature, pH and time affecting the microdetermination of paracetamol were investigated. The optimum conditions obtained at [Br[2]] / [p-AAP] = 3.0, T = 303K, pH = 4.0 and t = 5 - 10 min, permit the quantitative determination of paracetamol in the concentration range of 0.113 to 13.61 mg using silver amalgam electrode or in the concentration range of 143 to 638 micro g ml[-1] using bromide ion-selective electrode. Application of the proposed techniques for rapid, simple and direct determination of paracetamol in ten different pharmaceutical preparations was demonstrated

Ammonium adsorption properties on clinoptilolite as soil amendment

The physical, chemical and mineralogical properties of the zeolite were examined by different physicochemical methods of analyses. Chemical analysis of major elements and determination of Si/Al atomic ratio were performed aiming to compare its content with the standard sample. The clinoptilolite samples was subjected to a physico- chemical study for evaluation of its cation exchange capacity [CEC]. The quantitative determination of CEC through molecular sieving properties indicated that it was controlled by particle size, so that the increase in the particle size slightly decreased the CEC values. Two particle sizes [20-50 and 50-75 mum] of K-clinoptilolite were used to study the exchange of K+ by NH4+ on zeolite. It has been shown that the amount of NH4+ uptake on clinoptilolite is higher for the smaller particle size fraction, increasing with increase of NH4+ concentration

Spectrophotometric microdetermination of aluminum in al - hard anodizing baths using aluminum indicator at Helwan engineering industrial company [HEIC]

Due to the importance of using AI as a protective layer on the surface of parts of automobile engine; the aluminon indicator was used as a selective spectrophotometric reagent for microdetermination of AI under optimum conditions in both Al-anodizing and Al-hard coat anodizing baths in HEIC at Helwan, Cairo. The effect of pH on the spectra of the AI- aluminon complex was studied at the acidic pH range similar to that of the anodizing baths and the most suitable pH for its microdetermination was found to be 4.0 at lambda[max] = 520 nm using 0.01 M indicator. Beer's Law was obeyed in the AI concentration range of 1 to 22.5 ppm with a percent recovery of 87 to 100.5 percent. The AI determined by this spectrophotometric method was found to be, in four corners of the first bath, 1.39 to 1.51 ppm 1[-1] and in the second bath 2.57 to 2.7 ppm ml[-1]; and at three depths 1.32 to 1.4 and 2.54 to 2.59 ppm ml"1 in both baths respectively. The f- and t-tests of the spectrophotometric results in comparison with the atomic absorption data gave a confidence level of 99.0 percent. The SD values of the AI results from six replicates in both baths were found to be in the range 0.037 to 0.479. These values show the reliability and reproducibility of these results. This procedure has been applied successfully for monitoring of AI concentration in anodizing baths of automotive engine parts made from Al-alloys at HEIC factory 99 in Egypt

Microdetermination of aminophenols and cresols via their reactions with bromine

The oxidation of aminophenols [APs] and cresols [CRs] with bromine in aqueous solution was investigated and used for microdetermination of these reductants under selected optimum conditions of pH, temperature, catalyst, time of contact of reactants and concentration ratios. The potentiometric-argentimetric titration of the librated bromide using silver amalgam electrode was found to be independent of the bromine concentration. Possible schemes, for the course of these reactions were simply suggested. The reactions were quantitative at concentration ranges of APs, 9.80 to 22.24 mg, percent recovery 98 to 103 percent and SD = 0.11 to 0.023 at [Br[2]]/[APs] ratio 2 to 4 and CRs in the concentration range 3.24 to 25.95 mg, percent recovery = 96.6 to 104.8 percent and SD = 0.19 to 0.03 at Br[2]]/[APs] ratio 2 to 6. The reaction between Br[2] and APs was fast in the order p-AP > o-AP > m-AP and with CRs it was in the order O-CR > m-CR > P-CR under the selected optimum conditions

Spectral and thermal studies of uranyl-pyrocatechol complexes and their application for determination of uranyl ions

The information and stability of uranyl ion complexes with pyrocatechol [P.C.] were studied spectrophotometrically, through the effect of pH and time on the coloured complexes formed, the determination of their stoichiometry and the calculation of their stability constants. Based on these studies, general conclusions on the stability, structure and optical properties of UO[2] -P.C. complexes were derived and their significance and the sensitivity for spectrophotometric determination of UO[2++] in aqueous solution were outlined. The solid UO[2]-P.C. complexes were isolated in two ratios 1:2 and 1:3 and characterized using elemental analysis, IR spectra and thermal analysis [DTA and TG] in order to investigate their structures and thermal stability

Studies on the reaction products of iron with catecholamine and noncatecholamine

Catecholamine plays essential roles in the life chemistry, viz., the nature of biosynthesis, secretion and metabolism [1,2] It has direct action on sympathetic effective cells interacting with the receptor sites on the cell membrane, in cases where the sympathetic nerve has been cut or inhibited pharmacologically. On the other hand, noncatecholamines exert at least part of their effect by releasing physiological catecholamine from the postganglionic nerve fibers [3]. The choice of the extraction method and procedure of separation of catechol-and non-catecholamines depend on the nature of biological materials from which they have been separated and is suitable for direct bioassay or their colourimetric determination [4]. A number of extensive reviews have been appeared, covering aspects of environments of catecholamine in biological materials [3-6]. Many very stable complexes and chelates have been formed between mono, di-and polyhydric phenols with transition metals. Visible and ultravilot spectra of several transition metal complexes of pyrocatechol and tiron were studied. [7] Electronic absorption spectra of Co [III] and Cu [II] pyrocatechol complexes in solid state and in aqueous were also studied [8]. Reactions of 1,2 diphenol with iron [III] solutions were reported by Lumir et al[9] The main objective of the present study involves structure elucidation of the chelates formed between complexed iron and catecholamine. The combination between analytical and inorganic studies on the mixed ligand chelates formed enables understanding the nature of chemical reactions occurring

Studies on spectral characteristics of o,p-,m- aminophenols in comparison with catechol and pyrogallol in solutions of sodium hydroxide

The absorption spectra of 5 phenol derivatives indicators in alcohol water mixture disclose absorption peaks whose position is dependent on alkali concentration and alcohol content of the medium. The peaks are slightly shifted towards higher wave lengths with rise in alkali concentrations. Indicators with OH ions are ionized in the solution by proton loss rather than by hydroxide addition. The molar extinction coefficient epsilon, epsilon a and epsilon HA of the partially ionized, completely ionized and non-ionized forms of each indicator are calculated. The values of these coefficients are then used for the computation of the indicator ratios [I] of the different indicators in the various solutions. In addition, the pKa-values of the indicators are obtained by plotting [log I-log COH] against COH and extrapolating to zero concentration. These values of I and pKa are of importance in the evaluation of the acidity function H of the different solutions

Studies on the acidity function H-of solutions of KOH and NaOH in ethanol water-mixtures using m-aminophenol dimer and o-aminophenol polymer as indicators

Attempts are made to calculate the value of H- from the spectrophotometrically determined molar extinction coefficients epsilon, epsilon A- and epsilon HA of m-aminophenol polymer and p- aminophenol dimer in solutions of KOH and NaOH in ethanol-water mixtures. The value of these coefficients are then used for the computation of the indicator ratios I of the different indicators in the various solutions. In addition, the pKa, values of the indicators in questions are obtained from [log I-log CoH] plots. The relating H- with medium composition disclose several maxima and minima, the locations of which depends on alkali concentration and identity. The basic strength in water and pure ethanol increases according to the order KOH > NaOH, whereas in ethanol-water mixtures it is a composite function of alkali concentration and medium composition

Evaluation of o-and p-aminophenol polymers as indicators for acidity function spectrophotomerically

The Ultraviolet absorption spectra of o-aminophenol and p-aminophenol redox product polymers as indicators in different acidic solutions are investigated. They support the idea that the indicator reacts with H+ ions existing in solutions by proton transfer. The values of the indicator ratios I and thermodynamic ionization constant pkBH+ are calculated. Also, the evaluation of the acidity function H degree of the different solutions are given. Values of Hammett's acidity function of different concentrations for acetic acid, hydrochloric, nitric and sulphuric acids in aqueous and ethanolic solutions are computed from the spectrophotometrically measured indicator ratios of o-AP and p-AP polymers. The order of acid strength of the investigated acids in these media is discussed. In case of o-polymer the rate of decrease of log I-log CH with CH is appreciably decreased with the increase of CH in the order of protonation of p-polymer is more pronounced by H2SO4. It was found that, generally, the o-AP polymer indicator is more sensitive than the p-AP polymer in measurements of the acidity function H degree of different solutions

Structure investigation of xylenols and their redox products by thermal and spectral methods of analysis

The structures of 2,6- and 3,4-xylenols together with their iodine redox products 1-3 were studied and critically investigated. Characterization of these materials involved elemental, thermogravimetric, differential thermogravimetric and differential thermal analyses. IR and NMR spectrometry were used for the study of structural formulae of the obtained redox products. The identification and characterization of these materials confirmed the proposed schemes representing redox reactions of xylenols with iodine. It also explained the schemes representing fragmentation of the investigated compounds by thermal analyses. Thin layer chromatography was also used for separation and identification of redox products obtained in the reaction media