Micro-determination of warfarin sodium, nicoumalone and acebutolol hydrochloride in pharmaceutical preparations

A simple, selective and sensitive spectrophotometric method has been developed for the determination of microgram quantities of warfarin sodium (WS), nicoumalone (NIC) and acebutolol hydrochloride (ACBH), either in pure form or in pharmaceutical preparations. This method is based on the haloform reaction with a known and excess of standard iodine solution under alkaline conditions. The excess of iodine is determined at pH 3.0 with metol-INH. The absorbance of the resulting p-N-methyl-benzoquinonemonoimine-INH charge-transfer complex is measured at 620 nm.     

Self-assembly of poly(allylamine hydrochloride) through electrostatic interaction with sodium dodecyl sulfate

The self-assembly of poly(allylamine hydrochloride) (PAH) through an electrostatic interaction with sodium dodecyl sulfate (SDS) was explored. PAH itself showed no self-assembly in water. A light scattering study demonstrated that PAH formed monodispersed spherical aggregates in water in the presence of SDS. The hydrodynamic diameter of the aggregates was estimated to be ca. 170 nm based on the cumulant analysis. The scattering intensity and UV absorbance at 258 nm based on the aggregation increased with an increase in the molar ratio of SDS to the allylamine hydrochloride unit (SDS/AH), indicating an increase in the number of aggregates. On the other hand, the hydrodynamic diameter of aggregates was constant, i.e., independent of the SDS/AH ratio. The constant size of the aggregates in spite of the increase in the number of aggregates suggests the formation of the micellar aggregates by the intramolecular association through an electrostatic interaction.     

Quantitative determination of amorphous nicardipine hydrochloride in long acting formula (NIC-LA) using light anhydrous silicic acid

We investigated a method to quantitatively determine amorphous nicardipine hydrochloride (NIC) in the NIC-long acting formula (LA) model formulas prepared using NIC, light anhydrous silicic acid (LASA) and carboxymethylethylcellulose (CMEC). Consequently, since the quantity of total NIC in the formula can be determined by means of HPLC and crystal NIC can be determined by the differential scanning calorimetry (DSC) method because the heat of fusion (85.08 J/g) of NIC is constant and unaffected by excipients, we developed the HPLC-DSC method by which the quantity of amorphous NIC is calculated as the difference between the quantity of total NIC determined by HPLC and the quantity of crystal NIC determined by DSC. This practical HPLC-DSC method was confirmed to have good accuracy and reproducibility.     

Cell adhesion properties of patterned poly(acrylic acid)/poly(allylamine hydrochloride) multilayer films created by room-temperature imprinting technique

Patterned poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) multilayer films with line structures of different lateral size and vertical height were fabricated by a room-temperature imprinting technique, and their cell adhesion properties were investigated. The nonimprinted PAA/PAH multilayer films are cytophilic toward NIH/3T3 fibroblasts and HeLa cells whether PAA or PAH is the outer most layer. In contrast, the PAA/PAH multilayer films with a 6.5-microm-line/3.5-microm-space pattern structure are cytophobic toward NIH/3T3 fibroblasts and HeLa cells when the height of the lines is 1.29 microm. By either increasing the lateral size of the patters to 69-microm-line/43-mum-space or decreasing the height of the imprinted lines to approximately 107 nm, imprinted PAA/PAH multilayer films become cytophilic. This kind of transition of cell adhesion behavior derives from the change of the physical pattern size of the PAA/PAH multilayer films and is independent of the chemical composition of the films. The easy patterning of layer-by-layer assembled polymeric multilayer films with the room-temperature imprinting technique provides a facile way to tailor the cellular behavior of the layered polymeric films by simply changing the pattern dimensions.     

Determination of doxorubicin hydrochloride by visible spectrophotometry

Four simple and sensitive visible spectrophotometric methods (A-D) have been described for the assay of doxorubicin hydrochloride either in pure form or in pharmaceutical formulations. Method A was developed based on oxidation of the drug with Fe(III) to produce Fe(II), which subsequently reacts with 1.10-ortho-phenanthroline to form a red colored complex (lambda(max): 510 nm) at pH 4.6. Method B involves the reduction of Folin-Ciocalteu (F-C) reagent by the drug and the reduced species formed possesses a characteristic intense blue color (lambda(max): 770 nm). In methods C and D. oxidation of the drug with periodate at specified experimental conditions yields formaldehyde and dialdehyde, which in turn react either with 3-methyl-2-benzothiazolinone hydrazone hydrochloride to form an intensely brilliant blue cationic dye (lambda(max): 620-670 nm. method C) or by condensation with phenylhydrazine hydrochloride (PHH) to form orange-red colored product (lambda(max): 510 nm, method D) in the presence of potassium ferricyanide. All of the variables have been optimized and the reaction mechanisms presented. The concentration measurements are reproducible within a relative standard deviation of 1.0%.     

Spectrophotometric and spectrofluorimetric methods for analysis of acyclovir and acebutolol hydrochloride

Simple and sensitive spectrophotometric and spectrofluorimetric methods are described for analysis of acyclovir and acebutolol hydrochloride. The proposed methods are based on oxidation of the selected drugs with cerium(IV) ion in acidic medium with subsequent measurement of either the decrease in absorbance at 320nm or the fluorescence intensity of the produced cerous(III) ion at 361-363nm (excitation at 250nm). Beer's law obeyed from 2 to 8, 0.25 to 2.5microgcm-1 acyclovir, 1 to 7 and 0.25 to 2.5microgml-1 acebutolol hydrochloride, using the spectrophotometric and spectrofluorimetric method, respectively. The proposed method were successfully applied for determination of the selected drugs in their pharmaceutical preparations with good recoveries.     

Spectrophotometric and spectrofluorimetric methods for analysis of acyclovir and acebutolol hydrochloride

Simple and sensitive spectrophotometric and spectrofluorimetric methods are described for analysis of acebutolol hydrochloride. The proposed methods are based on oxidation of the selected drug with cerium(IV) ion in acidic medium with subsequent measurement of either the decrease in absorbance at 320 nm or the fluorescence intensity of the produced cerous(III) ion at 363 nm (excitation at 250 nm). Beer's law obeyed from 1.0-7.0 microg ml(-1) and 0.25-2.5 microg ml(-1) acebutolol hydrochloride, using the spectrophotometric and spectrofluorimetric method, respectively. The proposed methods were successfully applied for determination of the selected drug in its pharmaceutical preparation with good recoveries.     

Spectrophotometric methods for the determination of prazosin hydrochloride in tablets

Four simple and sensitive methods for the assay of prazosin hydrochloride (PRH) are developed. These methods are based on the formation of coloured species by treating it either with excess N-bromosuccinimide (NBS) and determining the unconsumed NBS with p-N-methyl aminophenol sulphate (metol)-sulphanilamide (SA) reagent (method A, lambda(max) 520 nm): with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of eerie ammonium sulphate (CAS) (method B, lambda(max) 620 nm) or with acidic dyes such as orange-II (O-II) (method C, lambda(max) 490 nm) and alizarin violet 3B (AV-3B) (method D, lambda(max) 570 nm) under the specified experimental conditions. Regression analysis of Beer's law plot showed good correlation in the concentration range of 1.0-10.0, 2.5-25.0, 1.0-17.5 and 2.5-30.0 mug ml for methods A, B, C and D respectively.     

Layer-by-layer Multilayer Films Self-assembled from a Rare-earth-containing Poly-oxometalate Na_9[Eu(W_5O_(18))_2] and Poly(allylamine hydrochloride) and Their Photoluminescent Properties

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Layer-by-layer self-assembled ultrathin multilayer films of lanthanide polyoxometalates and poly(allylamine hydrochloride) and their photoluminescent properties

Ultrathin multilayer films of two lanthanide polyoxometalates (LPOMs), K(17)[Eu(P(2)W(17)O(61))(2)] (EPW) and K(13)[Eu(SiW(11)O(39))(2)] (ESW), and poly(allylamine hydrochloride) (PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solutions. UV-vis spectroscopy and ellipsometry respectively show that the absorbance values at characteristic wavelengths and the thicknesses of the multilayer films increase linearly with the number of LPOM/PAH bilayers, suggesting that the deposition process is linear and highly reproducible from layer to layer. Average thicknesses of ca. 3.4 and 2.4 nm were determined for the EPW/PAH and ESW/PAH bilayers by ellipsometry, respectively. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) images provide the surface morphology of the LPOM/PAH films, indicating that the film surface is relatively uniform and smooth. The photoluminescent properties of these films have also been investigated by fluorescence spectroscopy. The LPOM/PAH multilayer film has a good thermal stability as shown by UV-vis, X-ray photoelectron, and fluorescence spectra.     

Electrostatic cross-linking-induced self-assembly of poly(allylamine hydrochloride) using Allura Red AC

The self-assembly of poly(allylamine hydrochloride) (PAH) through electrostatic cross-linking using Allura Red AC (AR) was explored in an aqueous solution. PAH showed no self-assembly in the absence of AR. A light-scattering study demonstrated that PAH formed aggregates of ca. 300-nm diameter by the addition of AR at 0.1 of the molar ratio of the SO₃Na unit of AR to NH₃Cl of PAH (SO₃Na/NH₃Cl). The PAH diameter decreased as the SO₃Na/NH₃Cl ratio increased up to 0.5 and thereafter rapidly increased due to sedimentation of the aggregates. The analysis of the normalized time correlation function of the scattered field confirmed that the electrostatic cross-linking by AR provided polydispersed aggregates of PAH. The UV analysis revealed that the PAH self-assembly caused a blue shift of AR. The size of the aggregates was independent of the PAH concentration. On the other hand, the aggregate size was strongly dependent on the temperature.     

The sensitive, anion-selective detection of arsenate with poly(allylamine hydrochloride) by single particle plasmon-based spectroscopy

The use of single gold nanoparticle plasmon-based spectroscopy for the sensitive, anion-selective detection of arsenate is described. The method is based on the selective formation of electrostatic complexes between arsenate and poly(allylamine hydrochloride) (PAH) and changes in the single particle plasmon in Rayleigh scattering profiles. PAH, when modified with gold nanoparticles, binds arsenate via its amine-functionalities. The scattering properties of the resulting selectively formed complexes are altered, leading to significant changes in the surface plasmon resonance wavelength. The limit of detection of the method was determined to be 10 nM, which is ca. 13 times more sensitive than U.S. EPA regulation levels. The response is essentially linear in the concentration range of 50-300 nM. The method also shows good selectivity for arsenate in the presence of other environmentally relevant anions, including H(2)PO(4)(-), SO(4)(2-), NO(3)(-), and Cl(-).     

Spectrophotometric simultaneous determination of rabeprazole sodium and itopride hydrochloride in capsule dosage form

A new simple, economical, rapid, precise and accurate method for simultaneous determination of rabeprazole sodium and itopride hydrochloride in capsule dosage form has been developed. The method is based on ratio spectra derivative spectrophotometry. The amplitudes in the first derivative of the corresponding ratio spectra at 231nm (minima) and 260nm were selected to determine rabeprazole sodium and itopride hydrochloride, respectively. The method was validated with respect to linearity, precision and accuracy.     

Simultaneous spray coating of interacting species: general rules governing the poly(styrene sulfonate)/poly(allylamine) system

Simultaneous spraying of two solutions of interacting species onto a substrate held vertically leads to the formation of nanometer-sized coatings. Here we investigate the simultaneous spraying of poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) solutions leading to the formation of a film composed of PSS/PAH complexes. The thickness of this film increases linearly with the cumulative spraying time. For a given spraying rate of PAH (respectively PSS), the growth rate of the film depends strongly upon the PSS/PAH ratio and passes through a maximum for a PSS/PAH ratio lying between 0.55 and 0.8. For a PSS/PAH ratio that is maintained constant, the growth speed of the film increases linearly with the spraying rate of polyelectrolyte of both solutions. Using X-ray photoelectron spectroscopy, we find that the film composition is almost independent of the PSS/PAH (spayed) ratio, with composition very close to 1:1 in PSS:PAH film. The 1:1 PSS:PAH composition is explained by the fact that the simultaneous spraying experiments are carried out with salt-free solutions; thus, electroneutrality in the film requires exact matching of the charges carried by the polyanions and the polycations. Zeta potential measurements reveal that, depending on whether the PSS/PAH spraying rate ratio lies below or above the optimal spraying rate ratio, the film acquires a positive or a negative excess charge. We also find that the overall film morphology, investigated by AFM, is independent of the spraying rate ratio and appears to be composed of nanometer-sized grains which are typically in the 100 nm range.     

A validated HPLC method for assay of morphine hydrochloride and hydromorphone hydrochloride in pharmaceutical injections

Summary A sensitive and rapid routine HPLC method is proposed for quantitative estimation of morphine hydrochloride and hydromorphone hydrochloride in pharmaceutical dosage forms. The drugs were chromatographed on a C₁₈ reversed-phase column; the mobile phase was acetonitrile-water, 35:65 (v/v), containing sodium dodecyl sulphate (0.5%, w/v), as ion pairing reagent, and acetic acid (0.4% v/v). Detection was at 230 nm. The optimized method was validated and linearity (r>0.999), precision, and accuracy were found to be acceptable within the concentration ranges 86–124 μg mL⁻¹ for morphine hydroloride and 60–180 μg mL⁻¹ for hydromorphone hydrochloride. The method is being used to investigate the stability of morphine hydrochloride and hydromorphone hydrochloride in solution used for intramuscular injection.     

Spectrophotometric methods for the determination of labetalol hydrochloride in pure and dosage forms

Simple and sensitive Spectrophotometric methods for the determination of labetalol hydrochloride are described. The first two are based on the oxidative coupling reaction of labetalol hydrochloride withp-N,N-dimethyl-phenylenediamine dihydrochloride (method A, _max 685 nm) and 3-methyl-2-benzothiazolinone hydrazone hydrochloride (method B, _max 545 nm) in the presence of sodium hypochlorite and eerie ammonium sulphate as oxidants, respectively. The third depends on the formation of an ion-association complex of labetalol hydrochloride with suprachen violet 3B at pH 1.3, which is extracted into chloroform (method C, _max 565 nm). The methods obey Beer's law and the precision and accuracy of the methods were checked against the B.P. reference method and the relative standard deviations were in the range 0.35–0.52%. These methods are applied to the determination of labetalol in dosage forms.     

Layer—by—layer Multilaryer Films Self—assembled from a Rare—earth—containing Poly—oxometalate,Na9[Eu（W5O18）2] and Poly （allylamine hydrochloride） and Their Photoluminescent Properties

Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na9[Eu(W5O18)2](EW) and poly (allymamine hydrochloride)(PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solution.The fabrication process of the EW/PAH multilaryer films was followed by UV-vis spectroscopy and ellipsometry,which show that the deposition process is linear and highly reproducible from layer to layer.An average EW/PAH bilayer thickness of ca.2.1nm was determined by ellipsometry.In addition,the scanning electron microscopy(SEM) image of the EW/PAH film indicates that the film surface is relatively uniform and smooth.The photoluminescent properties of these films were also investigated by fluorescence spectroscopy.     

Tuning the architecture of cellulose nanocrystal-poly(allylamine hydrochloride) multilayered thin films: influence of dipping parameters

Multilayered thin films consisting of alternating cationic polyelectrolyte, poly(allylamine hydrochloride) (PAH), and anionic cellulose nanocrystals (CNs) were constructed using the dipping procedure by screening different experimental parameters: the drying step between each layer adsorption, the dipping time, the ionic strength of the PAH solution, and the concentration of CNs dispersion. We showed that the drying process and the ionic strength of PAH solution were crucial parameters for the successful construction of 8-bilayer films. Film thickness is mainly influenced by dipping time and CN concentration when using the dipping procedure without drying. Two architectures of adsorbed CN layers-a single or a double layer of CNs-were revealed on the basis of the thickness increment per bilayer, depending on experimental conditions. The layer adsorption process was investigated in real-time using quartz crystal microbalance with dissipation (QCM-D) experiments in an aqueous environment or by incorporating a drying step. On the basis of in situ construction of PAH-CN films in wet media, QCM-D data were indicative of highly hydrated films for which the progressive layer stacking is disturbed or prevented. QCM-D monitoring of CNs and PAH layer adsorption was monitored by incorporating a drying process. The impact of experimental parameters on PAH-CN multilayered construction and on CN layer configuration is discussed. This study offers new opportunities for tailoring the architecture of CN-based multilayer films.     

Estimation of propranolol hydrochloride

A simple calorimetric method for the determination of propranolol hydrochloride has been worked out. The method involves nitration of the drug with a mixture of potassium nitrate and sulphuric acid. The coloured nitro-derivative has an absorption maxima at 360 nm. The working concentration range is 10-50 mug/ml. The method is applicable to analysis of pharmaceutical preparations.     

Conductive Polypyrrole and Poly(allylamine hydrochloride) Nanotubes Fabricated with Layer‐by‐Layer Assembly

Summary: Conductive nanotubes were fabricated by the alternate adsorption of negatively charged polypyrrole (PPy) and positively charged poly(allylamine hydrochloride) (PAH) onto the inner pores of polycarbonate templates. Nanotubes are obtained by the subsequently removal of the template. Using several microscopic and spectroscopic techniques, we demonstrate that the yielded materials possess a tubular structure and conductive properties. The conductivity of PPy/PAH nanotubes is measured as 0.008 S · cm⁻¹.

SEM image of eight bilayer PPy/PAH nanotubes after the removal of the template.