Dissolution Procedure Research Articles

Development and Validation of Dissolution Procedures for Ciprofloxacin.

Development and Validation of Dissolution Procedures for Ciprofloxacin.

A new approach for determination of crustal and trace elements in airborne particulate matter

An ICP-OES procedure was developed for fast and accurate determination of various crustal (Al, Ca, Fe, Mg, Si) and trace elements (Ba, Cu, Mn, Na, K, Sr, Ti, Zn) in airborne particulate matter. The method is based on a preliminary treatment of the aerosol samples with a mixture of nitric acid and hydrogen peroxide at elevated temperature leading to a mineralization of the organic sampling substrate, dissolution of soluble material and homogeneous suspension of the remaining non-soluble fraction. After dilution the derived slurry solutions were measured using ICP-OES. The reproducibility of analysis given as the relative standard deviation (% RSD) varied between 3.2 and 6.8% for bulk constituents such as Al, Ca, Fe, Mg and Si whereas values ranging from 3.5 to 9.1% were obtained for trace metals present with distinctly lower abundance in PM10 (e.g. Ba, Cu, Mn, Sr, Zn). The limits of detection (LOD) calculated as three times the standard deviation (3σ) of the signal derived from filter blank samples ranged from approximately 1 ng m−3 (Sr) to 71 ng m−3(Ca). The developed procedure was evaluated by comparing the obtained results with the findings derived for the same set of aerosol samples analyzed using a microwave procedure for sample dissolution with subsequent ICP-OES analysis. Finally the developed procedure was applied for the analysis of crustal and trace elements in PM10 samples collected at an urban site (Getreidemarkt, Vienna) and a rural site (Hartberg, Styria), in Austria. The concentrations of the investigated crustal elements varied between some hundred ng m−3 and few µg m−3 with highest concentrations for Fe and Si, distinctly reduced concentrations ranging from some ng m−3 (Sr) to more than hundred ng m−3 (K) were found for trace elements. Observed PM10 concentrations were found to be in accordance to literature findings from urban sites in central Europe.

Development and validation of a stability-indicating HPLC method for the determination of buclizine hydrochloride in tablets and oral suspension and its application to dissolution studies

A method using liquid chromatography has been developed and validated for determination of buclizine in pharmaceutical formulations and in release studies. Isocratic chromatography was performed on a C18 column with methanol:water (80:20 v/v, pH 2.6) as mobile phase, at a flow rate of 1.0 mL/min, and UV detection at 230 nm. The method was linear, accurate, precise, sensible and robust. The dissolution test was optimized and validated in terms of dissolution medium, apparatus agitation and rotation speed. The presented analytical and dissolution procedures can be conveniently adopted in the quality and stability control of buclizine in tablets and oral suspension.

습식분해 및 직접용해법에 따른 천일염 중 무기성분 함량 비교

The aims of this research were to determine the proximate composition of various salts and to compare two digestion methods (direct digestion without heating, and microwave digestion) for the determination of the main mineral contents of various salts. Twelve salt samples were divided into three groups of four samples each (imported, Korean gray, and Korean white salts). As a result, the NaCl contents of the Korean white, Korean gray, and imported salts were 85.1, 89.3, and 91.3%, respectively. The salts in the three groups were analyzed for their main mineral contents via AAS. The sodium (Na) content of the Korean white salt was found to be slightly lower than that of the imported salt while the magnesium (Mg) and potassium (K) contents of the Korean white salt were found to be higher than those of the imported salt. The mineral composition (% Na:Mg) obtained using microwave-assisted digestion procedures, and the other dissolutions for the subsequent sample analysis, were 89:1 (for both the imported and Korean gray salts) and 82:3 vs. 81:3 (Korean white salt), respectively. The data regarding the mineral contents and composition of the sun-dried salts obtained through the analysis method of wet digestion and the dissolution procedure were compared, and no significant difference was found between the two datasets. Consequently, in this paper, a direct dissolution procedure is suggested for the analysis of the mineral composition of salt.

Assessing subsidence rates and paleo water-depths for Tahiti reefs using U–Th chronology of altered corals

We present uranium–thorium chronology for a 102m core through a Pleistocene reef at Tahiti (French Polynesia) sampled during IODP Expedition 310 “Tahiti Sea Level”. We employ total and partial dissolution procedures on the older coral samples to investigate the diagenetic overprint of the uranium–thorium system. Although alteration of the U–Th system cannot be robustly corrected, diagenetic trends in the U–Th data, combined with sea level and subsidence constraints for the growth of the corals enables the age of critical samples to be constrained to marine isotope stage 9. We use the ages of the corals, together with δ18O based sea-level histories, to provide maximum constraints on possible paleo water-depths. These depth constraints are then compared to independent depth estimates based on algal and foraminiferal assemblages, microbioerosion patterns, and sedimentary facies, confirming the accuracy of these paleo water-depth estimates. We also use the fact that corals could not have grown above sea level to place a maximum constraint on the subsidence rate of Tahiti to be 0.39mka−1, with the most likely rate being close to the existing minimum estimate of 0.25mka−1.

Preparation of true solutions of monomeric amyloidogenic protein/peptide: A critical prerequisite for aggregation kinetic study

Our dynamic laser light scattering (LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution; namely, there always exist a trace amount of interchain aggregates, which greatly affect the association kinetics, partially explaining why different kinetics were reported even for a solution with identical protein and solvent. Recently, using a combination of the conventional dissolution procedure and our newly developed ultra-filtration method, we have developed a novel protocol to prepare a true solution of amyloidogenic protein/peptide without any interchain aggregates. The resultant solutions remain in their monomeric state for at least one week, which is vitally important for further study of the very initial stage of the interchain association under the physiological conditions because more and more evidence suggests that it is those small oligomers rather than large fabric aggregates that are cytotoxic. In addition, this study shows that combining static and dynamic LLS can lead to more physical and microscopic information about the protein association instead of only the size distribution.

Shape Selectivity in the Conversion of Methanol to Hydrocarbons: The Catalytic Performance of One-Dimensional 10-Ring Zeolites: ZSM-22, ZSM-23, ZSM-48, and EU-1

The methanol-to-hydrocarbon (MTH) reaction, a process in which low-value carbon-rich feedstocks are converted to value-added petrochemical products, is studied over one-dimensional 10-ring zeolites: ZSM-22 (TON), ZSM-23 (MTT), ZSM-48 (*MRE), and EU-1 (EUO). The latter three are little studied as MTH catalysts and were expected to display interesting product-shape-selective properties. The influence of slight differences in channel systems of the materials (size and shape) on product distribution and stability is investigated under various reaction conditions. In addition, the influence of coke deposition on product selectivity is investigated. Temperatures between 350 and 500 °C and WHSV between 2 and 6 g g–1 h–1 are investigated using a fixed bed reactor. The products are analyzed using online GC, and hydrocarbons trapped in the channels of the material during the reaction were liberated using the standard HF dissolution procedure and analyzed using GC/MS. Despite the small differences in the channel sha...

Determination of uranium, thorium and rare-earth elements in zircon samples using ICP-MS

Zircon is an accessory mineral, which occurs at low concentrations in a wide variety of rocks and is a host for hafnium, rare-earth elements (REE) and radio active elements like uranium and thorium. The presence of uranium in zircon has led to its increased use in the age determination of rocks. Zirconium is also considered as a strategic, hi-tech element because of its various applications, especially in the manufacturing, nuclear and aerospace industries. Analysis of zircon constitutes one of the tough tasks in analytical chemistry as it is a highly resistant mineral and it is extremely difficult to achieve its complete decomposition. In the present work, inductively coupled plasma mass spectrometry has been applied to the determination of hafnium, REE, uranium and thorium in zircon samples using two different sample dissolution procedures, one employing sodium peroxide fusion and another using a fusion mixture of KHF2 and NaF in 3:1 ratio. Some selected zircon samples originating from different places on the eastern coast of India have been analysed by both the methods and values obtained by both methods were found to be in good agreement with each other. Though a number of international zircon reference materials are available, certified or even proposed values are available only for a very few elements in them. Two zircon reference materials have also been analysed by both methods and usable values have been proposed in this paper. The values obtained by both methods were found to compare well with each other and as well with those reported in literature. The % RSD for all the estimated elements varied from 1.0 to 12.0% at different concentration levels.

Formulation and evaluation of bi-layer floating tablets of ziprasidone HCl and trihexyphenidyl HCl

The purpose of this research study was to establish ziprasidone HCl NR 40 mg and trihexyphenidyl HCl SR 4mg in the form of bi-layer sustained release floating tablets. The tablets were prepared using sodium HPMC K4M / HPMC K15M as bio-adhesive polymers and sodium bicarbonate acting as a floating layer. Tablets were evaluated based on different parameters such as thickness, hardness, friability, weight variation, in vitro dissolution studies, content of active ingredient and IR studies. The physico-chemical properties of the finished product complied with the specifications. In vitro release from the formulation was studied as per the USP XXIII dissolution procedure. The formulations gave a normal release effect followed by sustained release for 12 h which indicates bimodal release of ziprasidone HCl from the matrix tablets. The data obtained was fitted to Peppas models. Analysis of n values of the Korsmeyer equation indicated that the drug release involved non-diffusional mechanisms. By the present study, it can be concluded that bi-layer tablets of ziprasidone HCl and trihexyphenidyl HCl will be a useful strategy for extending the metabolism and improving the bioavailability of Ziprasidone HCl and Trihexyphenidyl HCl.

Development of a Performance Verification Test for USP Apparatus 4

To evaluate salicylic acid tablets as a candidate reference material in a Performance Verification Test (PVT) when a USP performance test for dissolution (General Chapter <711>) relies on USP Apparatus 4 (flow-through cell). We developed a dissolution procedure relying on Apparatus 4 and salicylic acid tablets. Thereafter, a designed experiment was conducted to identify operational variables that significantly affect salicylic acid dissolution in this apparatus. Four variables (size of glass beads, cell temperature, flow rate, level of deaeration) and one combination effect (deaeration/bead size) were significant for mean percent dissolved. Two variables (tablet orientation, level of deaeration) were significant for standard deviation results, but these effects were less pronounced than those for mean percent dissolved results. Three variables (analyst, tester manufacturer, amount of glass beads) had no statistically significant effects on either the mean or standard deviation of the responses. The proposed PVT is capable of probing effects of changes in several critical operational parameters of Apparatus 4. Salicylic acid tablets were shown to be a suitable reference material for the PVT. The PVT using salicylic acid tablets satisfies important aspects of a PVT.

국내 건축자재에 함유된 석면의 함량에 대한 X-선회절분석 연구

대표적인 일부 건축자재의 석면 함량을 일본공업표준법 (JIS)에 따른 X-선회절분석으로 측정하였고, 분석과정에서의 광물학적 성분변화와 문제점을 검토하였다. 국내의 슬레이트, 벽재, 천장재의 대표적인 건축자재에 대해 석면 함량을 정량한 결과, 슬레이트 시료가 6.87~6.93%의 온석면을 함유하여 가장 많은 석면을 함유하고 있는 것으로 분석되었다. 분석된 다른 건축자재들에서도 1.35~3.98%의 범위로 다양한 양의 온석면이 포함되어 있는 것으로 분석되었다. 이번 연구에서 국내에서 처음으로 일부 건축자재의 석면 함량에 대한 X-선회절방법에 의한 분석결과를 제시하였으며, 이런 방법을 통하여 국내에서 최근에 개정된 규정(노동부 산업안전보건법 제2007-26호)에서 규정한 석면의 허용기준량 0.1% 함량을 평가하는데 효과적인 것으로 나타났다. 일부 시료에서 온석면과 함께 투각섬석이 소량 수반되고 있음이 나타났으나, 이들의 결정형태와 그 함량과 지질학적 산출상태 등으로 보아, 석면 활용의 목적으로 첨가한 것이 아니고 온석면에 본래 수반되었던 볼순광물로 나타난 것으로 생각된다. X-선회절분석으로 석면상과 비석면상의 구분이 어렵기 때문에 형태를 관찰할 수 있는 광학현미경과 전자현미경의 보조적인 관찰도 필요한 것으로 나타났다. 이번에 사용한 X-선회절분석 방법에서는 가열처리와 산처리에 의한 소실율이 많아 석면의 농집도가 높은 건축자재 시료에 가장 효과적인 것으로 나타났다. The asbestos contents in some representative building materials were analyzed using JIS (Japanese Industrial Standard) X-ray diffraction (XRD) method. The changes in mineral composition during analysis process and problems in JIS method were also examined. XRD analysis of some representative domestic building materials used for roof, wall, ceiling, and floor indicates that slate have the highest asbestos content having 6.87~6.93% of chrysotile. Other building materials analyzed in this study also have 1.35~3.98% of chrysotile contents. The XRD analysis results of asbestos contents in some domestic building materials are presented in this study. This method is very effective for the asbestos content evaluation of building materials according to newly modified asbestos content regulation (Law of Industrial Safety and Health, 2007-26) that limits asbestos content less than 0.1% by Ministry of Employment and Labor. Small amount of tremolite as well as chrysotile were also observed in some samples. With consideration of crystal shape, contents and geological occurrence, it is considered that tremolite is an associated mineral of chrysotile and is not intentionally added. Complemental analyses with optical microscope and SEM/EDS are also necessary because XRD method cannot distinguish asbestiform from non-asbestiform. The XRD method applied in this study is very effective in the asbestos content analysis of building materials, specially building materials showing high asbestos concentration in residues due to the high loss rate with ashing and acid dissolution procedure.

Identification, quantification and localization of secondary minerals in mixed Fe0 fixed bed reactors

Passivating secondary minerals in mixed Fe0 reactive fixed bed filters for the reductive dechlorination of chlorinated hydrocarbons were investigated with different techniques. Uncemented cast iron grains were obtained from long term corrosion experiments. Magnetite and chukanovite were identified as major corrosion products. Gravimetric and sieve analyses revealed a strong influence of inorganic carbon on corrosion product buildup. Surface area analyses indicated that magnetite, together with cryptocrystalline corrosion products, increase the surface area more than chukanovite. A heterogeneous morphology was found in corrosion products formed in deionized water by scanning electron microscopy. Corrosion products formed in the presence of inorganic carbon revealed a homogeneous and almost completely covering layer. Transects were analyzed with backscatter electron detection. Electron microscopic investigations on the cross sections of gravel and cast iron granules indicated that corrosion products only occur on reactive surfaces. Additional dissolution and washing procedures confirmed that corrosion products do not grow or precipitate on non-reactive interfaces. The results indicate that precipitation out of the solution plays a minor role compared with the growth of corrosion products on the iron surface.

Classical and New Procedures of Whole Rock Dissolution for Trace Element Determination by ICP‐MS

Sample digestion is a critical stage in the process of chemical analysis of geological materials by ICP‐MS. We present a new HF/HNO3 procedure to dissolve silicate rock samples using a high pressure asher system. The formation of insoluble AlF3 was the major obstacle in achieving full recoveries. This was overcome by setting an appropriate digestion temperature and adding Mg to the samples before digestion. Sodium peroxide sintering was also investigated and the inclusion of a heating step to the alkaline sinter solution improved the recoveries of thirteen elements other than the lanthanides. The results of these procedures were compared with data sets generated by common acid decomposition techniques. Forty‐one trace elements were determined using an ICP‐QMS equipped with a collision cell. Under optimum conditions of gas flow and kinetic energy discrimination, polyatomic interferences were eliminated or attenuated. The measurement bias obtained for eight reference materials (BCR‐2, BHVO‐2, BIR‐1, BRP‐1, OU‐6, GSP‐2, GSR‐1 and RGM‐1) and intermediate precision (RSD) were generally better than ± 5%. The expanded measurement uncertainties estimated for two certified reference materials were mostly between 7 and 15%. New data sets for the reference materials are provided, including constituents with previously unavailable values and also for the USGS candidate reference material G‐3.

Effects of medium and pore‐fluid compressibility on chemical‐dissolution front instability in fluid‐saturated porous media

SUMMARYTheoretical analysis and computational simulations have been carried out to investigate how medium and pore‐fluid compressibility affects the chemical‐dissolution front propagation, which is associated with a fully‐coupled nonlinear problem between porosity, pore‐fluid pressure, pore‐fluid density and reactive chemical‐species transport within a deformable and fluid‐saturated porous medium. When the fully‐coupled nonlinear system is in a subcritical state, some analytical solutions have been derived for a special case, in which the ratio of the equilibrium concentration to the solid molar density of the chemical species is approaching zero. To investigate the effect of either medium compressibility or pore‐fluid compressibility on the evolutions of chemical dissolution fronts in supercritical chemical dissolution systems, numerical algorithms and procedures have been also proposed. The related theoretical and numerical results have demonstrated that: (i) not only can pore‐fluid compressibility affect the propagating speeds of chemical dissolution fronts in both subcritical and supercritical systems, but also it can affect the growth and amplitudes of irregular chemical dissolution fronts in supercritical systems; (ii) medium compressibility may have a little influence on the propagating speeds of chemical dissolution fronts, but it can have significant effects on the growth and amplitudes of irregular chemical dissolution fronts in supercritical systems; and (iii) both medium and pore‐fluid compressibility may stabilize irregular chemical‐dissolution‐fronts in supercritical chemical dissolution systems. Copyright © 2011 John Wiley &amp; Sons, Ltd.

The permeability of enteric coatings and the dissolution rates of coated tablets.

The effect of an increasing concentration of plasticizer and pigment on the permeability to both water vapour and simulated gastric juice of cellulose acetate phthalate and polyvinyl acetate phthalate has been evaluated. There were significant differences between the permeability coefficients of each polymer, particularly with regard to water vapour. The presence of additives within the film coatings had a greater effect on the properties of cellulose acetate phthalate than those of polyvinyl acetate phthalate. Suitable formulations of each polymer were used to enteric coat 325 mg aspirin tablets, which were subsequently subjected to both the Disintegration Test for Enteric Coated Tablets B.P. and a dissolution procedure to monitor the release of drug in simulated gastric juice and simulated intestinal fluid. Both polymers demonstrated their suitability for producing enteric coatings. However, polyvinyl acetate phthalate yielded a faster release of aspirin in simulated intestinal fluid than did cellulose acetate phthalate.

Letter to the Editor on Fougerite

AbstractFougerite (IMA 2003-057) was accepted by the Commission on New Minerals and Mineral Names of the International Mineralogical Association (IMA) in 2004 as a new mineral to represent the green rust (GR) family. The data on which it was approved, however, are inconsistent. X-ray diffraction patterns from the Fougères soils contain no peaks that could meaningfully be attributed to a GR phase. The sequential dissolution procedure used to identify GR in the soils was not rigorously tested for selectivity. If indeed it is selective, the results indicate the presence of 40–78% Fe in minerals other than GR. Other Fe-bearing phases were not included in the interpretation of the spectroscopy data that were presented. The data are consistent with the presence of Fe-bearing clays and other silicate minerals. In light of the ambiguous and conflicting data, we recommend that the case for fougerite as a mineral be re-evaluated by the IMA.

Assessment of heavy metal contamination and mineral magnetic characterization of the Asopos River sediments (Central Greece)

The content and distribution of heavy metals in sediments of the intermittent and contaminated Asopos River, located in Central Greece, was assessed by means of total dissolution, dilute acid and sequential extraction procedures. Mineral magnetic properties were used as proxy parameters of transport mechanisms of land-derived material to the sea. The combination of enrichment factors estimated against local background levels and the levels of labile metals revealed that surface sediments are enriched in Cu, Cd, Ni and Cr. The low flow of the system allows particles and organic matter to accumulate in the estuarine shallow “pools” where they undertake a series of redox reactions, authigenic formation, etc. The most fine of these particles, which are metal rich, are transported to relatively long distances off the Asopos River mouth, even under low energy conditions, converting the system to a secondary source of pollution for the adjacent marine environment.

Direct synthesis of hexagonal Mg(OH)2 nanoplates from natural brucite without dissolution procedure

A facile, dissolution-free route to direct synthesis of hexagonal magnesium hydroxide nanoplates from natural brucite is reported. Stable brucite undergoes disaggregation into thin nanosheets and subsequent solid-solid transformation in the presence of p-toluene sulfonate, circumventing the threshold of size effect from bulk brucite to Mg(OH)(2) nanoplates.

Dissolution Method for Milnacipran Hydrochloride Capsules: Development, Validation, and Study of Changes in Dissolution Rate after Storage

A dissolution test for milnacipran hydrochloride capsules was developed and validated according to international guidelines. After selection of the best conditions, the method was validated using USP Apparatus 1 (baskets), 50-rpm rotation speed, 900 mL of 0.01 N HCl, and test time of 60 min. The drug released was determined by both LC–UV (PDA) and UV–D methods. The kinetic parameters of drug release (mathematical models, t80%, and dissolution efficiency) were investigated, and the stability of the dosage form was evaluated by analyzing changes in the dissolution rate of milnacipran hydrochloride capsules during storage at 40 °C and 75% RH for different periods. INTRODUCTION Dissolution testing can provide information not only on the rate and extent of drug absorption in the body but also on the effects of drug biopharmaceutical properties and formulation principles on the release properties of a pharmaceutical product (1). Therefore, in vitro dissolution tests are usually used to assess the lot-to-lot quality of a drug product, guide development of new formulations, an d ensure continued product quality and performance after certain changes such as formulation, manufacturing process, site of manufacture, and the scale-up of the manufacturing process (2). The dissolution procedure requires an apparatus, a dissolution medium, and test conditions that provide a method that is discriminating yet sufficiently rugged and reproducible for day-to-day operation and capable of being transferred between laboratories. With regard to stability, the dissolution test should appropriately reflect relevant changes in the drug product caused by temperature, humidity, photosensitivity, and other stresses over time (3). Milnacipran hydrochloride (MNC), [101152-94-7], C15H22N2O⋅HCl, molecular weight 282.81 g/mol (Figure 1), is a racemic mixture with the chemical name (±)-[1R(S),2S(R)]-2-(aminomethyl)-N,N-diethyl-1-phenylcyclopropanecarboxamide hydrochloride, and its solubility in water is 19 mg/mL (4–6). MNC is a selective serotonin and norepinephrine reuptake inhibitor (SNRI) indicated as an antidepressant and for the management of fibromyalgia. It shows preferential blockade of norepinephrine reuptake over serotonin and minimal activity at other receptors or transporters (6–8). MNC is well absorbed after oral administration with maximum concentrations reached within 2–4 h, and its absorption is not affected by food. It presents an absolute bioavailability of approximately 85–90% (9). The solubility and absolute bioavailability data for this drug classify it as Class I (high solubility and high permeability) based on the Biopharmaceutical Classification System. This is the case where the drug is well absorbed, and for immediate-release dosage forms that dissolve very rapidly, the absorption rate is controlled by the gastric emptying rate, and some correlation with dissolution rate is expected only if the dissolution is slower than gastric emptying (10). Methods for quantitation of milnacipran in combination with other antidepressants and their metabolites in biological fluids have been proposed (11–17). However, there is no compendial method to assay milnacipran hydrochloride in pharmaceutical dosage forms. A stability-indicating liquid chromatographic method with UV detection (LC–UV) and a second-order derivative UV spectroscopic method (UV–D) for quality control of milnacipran in capsules were developed and validated by the authors (18) according to guidelines (19–21). Therefore, the purpose of this work was to develop and validate a dissolution test for MNC in capsules (50 mg) based on its physicochemical characteristics and apply the LC–UV and UV–D methods to quantify the drug released from the capsules during the dissolution procedure. The kinetic parameters of drug release were investigated, and the stability of the dosage form was evaluated by analyzing changes in the dissolution rate of MNC capsules over time and in various storage conditions. EXPERIMENTAL Chemicals Milnacipran hydrochloride was purchased from Synfine Research (Canada). The pharmaceutical dosage form *Corresponding author. diss-18-03-06.indd 47 8/31/2011 1:38:15 PM dx.doi.org/10.14227/DT180311P47

Estabelecimento de condições para ensaio de dissolução de cápsulas de cinarizina empregando planejamento fatorial

This work describes the establishment of dissolution test conditions for 75 mg cinnarizine capsules using a multivariate approach. A 23 full factorial design was carried out to achieve the best conditions and HCl 0.1 mol L-1 as dissolution medium, basket as apparatus at 100 rpm and collect time at 30 min were considered adequate. The quantification was carried out by spectrophotometry at 251 nm. Both dissolution procedure and analytical method were validated and all parameters were within the acceptable limits. Since there is no official monograph for this pharmaceutical product, this dissolution test could be applied for quality control routine.