Determination Of Dissolution Rate Research Articles

Immersion Behavior Study of Hydroxyapatite Scaffolds Derived from Bovine Sources In Acidic, Basic, and Neutral Solutions

This research investigates the effects of particle size and compaction pressure on the dissolution behavior of hydroxyapatite scaffolds synthesized from bovine bone in acidic neutral and basic solutions. Hydroxyapatite was extracted through a process involving cutting, cleaning, boiling, soaking in NaOH, sun drying, grinding into powder and calcination at 800°C. The powder was then sieved into two size fractions (75 and 150 microns) and compacted at pressures of 200, 250, and 300 MPa. The mass and dimensions of the scaffolds were measured to calculate porosity, followed by immersion in the respective solutions for 24 hours to determine dissolution rates. Results indicated that smaller particle sizes and higher compaction pressures resulted in reduced porosity and enhanced structural integrity. The dissolution rates varied significantly with pH levels, exhibiting the highest rates in acidic conditions up to 215.83 mg/cm2 and the lowest in basic solutions up to 11.32 mg/cm2. Additionally, scaffolds with smaller particles and higher compaction pressures demonstrated lower dissolution rates across all pH levels due to lower porosity. In conclusion, both particle size and compaction pressure are critical factors influencing the dissolution behavior of hydroxyapatite scaffolds. These findings have significant implications for the design and optimization of hydroxyapatite-based materials for biomedical applications, where controlled dissolution rates are crucial for performance and longevity.

Validation and comparison of UV spectrophotometry and HPLC methods for the determination of dissolution rate of Venlafaxine in Zanfexa 37.5mg tablets

Validation and comparison of UV spectrophotometry and HPLC methods for the determination of dissolution rate of Venlafaxine in Zanfexa 37.5mg tablets

Determination of dissolution rate of prolonged-release tablets in bio-relevant media using USP apparatus III

Determination of dissolution rate of prolonged-release tablets in bio-relevant media using USP apparatus III

Experimental-numerical simulation of soluble formations in reservoirs

Saline inflows and soluble geological formations outcropped in reservoirs contribute to reservoir water salinization (RWS). We set up 32 laboratory tests to better understand rock-water interaction and determination of dissolution rate of Gachsaran geological formation (GGF) in the Parsian dam that is currently under the study phase on the Fahlian river, Iran. Then, we used CE-QUAL-W2 (W2) to simulate GGF dissolution outcropped in some parts of the reservoir. Finally, possible solutions for mitigating the RWS were investigated using W2 driven under different scenarios: (1) having Hamze-beigi saline inflow (a main tributary of the Fahlian river) and GGF dissolution, (2) removing the saline inflow, (3) confining the GGF dissolution, and (4) driving W2 in severe floods. Although the dissolution rates (0.023–0.056 gr/cm2-day) salinize deep water, saline inflow degrades surface waters. Density gradient in the water depth formed the monimolimnion and mixolimnion separated by a distinct pycnocline in the reservoir. The pycnocline established in the early impoundment stage and lasted throughout the study period (2002–2012), leading to a crenogenic meromixis state in the reservoir. W2 driven under the 100–year and 1000–year inflows shows salinity up to 2700 mg/L in top layers from partial chemical mixing in the reservoir in cold months, although no conversion of the lake from the meromixis to holomictic state was observed in warm months. The findings suggest that, although diversion of the saline inflow satisfies the salinity requirement for hydropower generation, peak saline inflow can salinize the reservoir water and downstream river.

Impact of nuclear environment on hydrothermal corrosion and silica transport for CVD SiC in light water reactors

• Corrosion rate of CVD SiC as a function of flow rate and roughness was measured. • Impact of ion irradiation on corrosion was shown to be substantial. • CRUD deposition significantly reduces the SiC dissolution for BWR water chemistry. • Gamma radiation accelerates CRUD deposition for CVD SiC and Zircaloy. • Silica deposition and cladding thickness loss is likely only of concern for BWRs. The development of comprehensive corrosion and silica transport models is essential to estimate the cladding thickness loss of SiC/SiC composites and the free silica content in the coolant under the hydrothermal radiation environment of light water reactors. In the present work, the hydrothermal corrosion behavior of high purity unirradiated and 5.1 MeV Si ion irradiated CVD SiC with different surface finish are examined in a high and a low flow high-pressure flow loops (15 MPa, 300 °C). Experiments carried on CVD surfaces with different surface finish indicated accelerated dissolution of cladding material with an increase in surface roughness and irradiation damage. Further, a first-of-its-kind analysis to understand the impact of CRUD deposition on the CVD SiC corrosion suggests that the SiC dissolution would reduce significantly as a stable CRUD layer grows on the SiC surface. The experimentally determined dissolution rates and the mass transfer mechanisms are implemented in Radiation Chemistry Analysis Loop (RADICAL) code. The spatial inventory of silica deposition is estimated at different components in a typical BWR and PWR primary loops using the updated RADICAL code. Lastly, an enhancement of CRUD growth under gamma radiation on SiC and Zircaloy surfaces was observed.

Application of UV dissolution imaging to pharmaceutical systems.

UV-vis spectrometry is widely used in the pharmaceutical sciences for compound quantification, alone or in conjunction with separation techniques, due to most drug entities possessing a chromophore absorbing light in the range 190-800nm. UV dissolution imaging, the scope of this review, generates spatially and temporally resolved absorbance maps by exploiting the UV absorbance of the analyte. This review aims to give an introduction to UV dissolution imaging and its use in the determination of intrinsic dissolution rates and drug release from whole dosage forms. Applications of UV imaging to non-oral formulations have started to emerge and are reviewed together with the possibility of utilizing UV imaging for physical chemical characterisation of drug substances. The benefits of imaging drug diffusion and transport processes are also discussed.

Siderite Dissolution in Mars-analog Brines: Kinetics and Reaction Products

Abstract This study examines siderite (FeCO3) reactivity in MgCl2 and MgSO4 brines with varying salt concentrations (0.01M, 1M, and 3M) at both acidic (pH ∼ 2 and pH ≤ 2) and near-neutral (pH ∼ 7) conditions. We measured aqueous Fe concentrations through time to determine dissolution rates and characterized the solid reaction products with scanning electron microscopy, electron dispersive X-ray spectroscopy, and Raman spectroscopy. Iron-based siderite dissolution rates at pH 2 were equivalent in the 0.01M and 1M MgSO4 brines and slower in 3M MgSO4; rates in the MgCl2 brines slow systematically with increasing brine concentration for equivalent initial pH values. Fe-based dissolution rates could not be determined in the neutral pH experiments due to precipitation of iron (hydr)oxide phases. After 1 day in acidic brines, abundant etch pits were observed; however, in the neutral experiments, siderite was identified with Raman spectroscopy even after 1 yr of dissolution along with a range of iron (hydr)oxide phases. Scanning electron microscopy imaging of the neutral experiment products found Mg-sulfate brines produced a chaotic surface texture. Therefore, micron-scale textural observations could be used to discriminate between alteration in chloride and sulfate brines. Initial iron release rates were similar in dilute brines, but decreased by less than an order of magnitude in the two highest-concentration pH 2 brine experiments; therefore, siderite-bearing assemblages exposed to acidic fluids, regardless of salinity, would likely dissolve completely over geologically short periods of time, thus erasing siderite and likely other carbonate minerals from the geologic record.

Determination of Intrinsic Drug Dissolution and Solute Effective Transport Rate during Laminar Fluid Flow at Different Velocities.

The objective of this study was to determine the intrinsic drug dissolution rate (IDR) and the solute effective transport rate of some drugs, using a single particle dissolution technique, satisfying qualified dissolution conditions. The IDR of three poorly water-soluble compounds was measured in milli-Q water using four different fluid velocities. The enveloped surface area of the particles was calculated from the projected area and the perimeter of the particle observed in the microscope. Furthermore, computational fluid dynamics (CFD) simulations were used to theoretically investigate the flow conditions and dissolution rate, comparing box shaped particles and spherical particles with similar dimensions and surface area as the particles used the experiments. In this study, the IDR measurement of the single particles was determined within 5–60 min using particles with an initial projected area diameter () between 37.5–104.6 µm. The micropipette-assisted microscopy technique showed a good reproducibility between individual measurements, and the CFD simulations indicated a laminar flow around the particles at all flow velocities, even though there were evident differences in local particle dissolution rates. In conclusion, the IDR and solute effective transport rate were determined under well-defined fluid flow conditions. This type of approach can be used as a complementary approach to traditional dissolution studies to gain in-depth insights into the dissolution process of drug particles.

Periodicity in the Electrochemical Dissolution of Transition Metals.

Extensive research efforts are currently dedicated to the search for new electrocatalyst materials in which expensive and rare noble metals are replaced with cheaper and more abundant transition metals. Recently, numerous alloys, oxides, and composites with such metals have been identified as highly active electrocatalysts through the use of high‐throughput screening methods with the help of activity descriptors. Up to this point, stability has lacked such descriptors. Hence, we elucidate the role of intrinsic metal/oxide properties on the corrosion behavior of representative 3d, 4d, and 5d transition metals. Electrochemical dissolution of nine transition metals is quantified using online inductively coupled plasma mass spectrometry (ICP‐MS). Based on the obtained dissolution data in alkaline and acidic media, we establish clear periodic correlations between the amount of dissolved metal, the cohesive energy of the metal atoms (E coh), and the energy of oxygen adsorption on the metal (ΔH O,ads). Such correlations can support the knowledge‐driven search for more stable electrocatalysts.

Development and Validation of a Novel Analytical Method for the Determination of Dissolution Rate of Acetylsalicylic Acid in Enteric-Coated Tablet Dosage Form by Liquid Chromatography

Objective: The aim of this study is to determine the applicability of UV detection method by the sensitive, simply, precise, specific, and low-cost High-Performance Liquid Chromatography (UHPLC) for acetylsalicylic acid in presence of its degradation product. Methods: Method development and determination of dissolution rate for acetylsalicylic acid, were achieved by using reversed-phase liquid chromatography with PDA (Photodiode Array Detector) and TUV (Tunable UV Detector) detection by HCLASS-UHPLC. The new proposed method utilized by the Waters Acquity UHPLC® TUV and PDA systems using a UHPLC column Waters Acquity, BEH, C18, 2.1mm x 50mm, 1.7μm particle size with a mixture of heptane-1-sulphonic acid sodium salt solution which was prepared in acetonitrile: deionized water (15%: 85% v/v) in isocritic mode at a flow rate of 0.5ml/ min, at 25°C with a load of 5μL. The detection for all eluted compounds was carried out at 280nm.

Accelerated electrochemical methods of testing austenitic corrosion resistant steels for resistance to intercrystallite corrosion

The purpose of research is to study and clarify accelerated electrochemical methods of testing austenitic corrosion-resistant steels for resistance to intergranular corrosion (IGC) and provide recommendations for their wide use. Methods. Comparative tests for resistance to IGC by long-time and accelerated methods were performed on samples of 03Cr18Ni11, 08Cr18Ni10Ti, 03Cr17Ni14Mo3 and 02Cr25Ni22Mo3 steels not susceptible to IGC and specimens with varying degrees of susceptibility to IGC. AMU and DU methods according to GOST 6032 were used as long-term methods and electrochemical methods according to GOST 9.914 and methods of electrolytic etching metallographic sections in a 10 % solution of oxalic acid (EOA) at anode current density of 1 A/cm2 for 1,5 minutes were used as accelerated methods. Additionally, electrochemical studies of steels were performed by constructing anode potentiodynamic curves (APC) and potentiostatic etching (PE) samples in a solution of perchloric acid and sodium chloride. The mechanism of corrosion at grain boundaries was studied by chemical analysis of test solutions for the content of ions of main alloying elements of steels and determination of dissolution rates of steels and artificial carbides in transient and transpassive regions of potentials. Microstructure of steels was studied by light microscopy after testing. Results. Results of comprehensive comparative tests of austenitic corrosion-resistant steels for resistance to IGC by long-term and accelerated electrochemical methods were obtained. Mechanisms of corrosion occurring at the boundaries of steel grains have been determined during testing by accelerated electrochemical methods and corresponding long-term methods according to GOST 6032. Scientific novelty. New quantitative criteria of satisfactory resistance of steels to ICC in testing by PE method were proposed. Practical relevance. It was recommended to use accelerated electrochemical PE and EOA methods in acceptance tests of steels for resistance to IGC in order to shorten the technological cycle and improve production efficiency.

Determination of Active Pharmaceutical Substances Dissolution Rate by Laser Light Diffraction Method

Introduction . The strategy of quality control of drugs provides for compliance with the requirements of regulatory documentation methods and critical quality indicators that determine its effectiveness. Special attention should be paid to the properties of the initial pharmaceutical substance (lipophilicity logP, area of the topological polar surface of TPSA, particle size, polymorphism), which determine the solubility and dissolution rate of the active pharmaceutical substance (APS) in terms of their impact on the bioavailability of the finished drug in vivo [1–3]. Since the assessment of pharmacopoeia solubility of APS is reduced to a visual procedure and the use of approximate terms, we have developed an original method for determining the dissolution rate of substances using the laws of chemical kinetics. Validation of the analytical method is carried out at introduction of the new method, and also at change of conditions of analysis of medicines carried out during the life cycle (product lifecycle) of a pharmaceutical product and its manufacturing process [4]. The proposed technique for laser determination of the dissolution rate in water of a medicinal substance of fluoroquinolone group has been tested; elements have been included in validation studies: repeatability, precision, linearity and range. Aim . Development of the method for determining the dissolution rate of active pharmaceutical substances by laser light diffraction with validation elements. Materials and methods . Determination of the dissolution rate of moxifloxacin hydrochloride was carried out in water for laboratory analysis of purity level 1 (ultra-pure water) obtained on the Milli-Q ® Integral, the quality of which corresponds to ISO 3696:1987. To achieve this goal, a pharmacopoeia method of research was used – low-angle scattering of laser light (laser diffraction method); instrument equipment – laser dispersion meter Malvern 3600 EC. Results and discussion . An additional analytical method for determination of API dissolution rate by laser light diffraction method was developed. Validation studies on parameters: precision (repeatability, intra-laboratory/intermediate), linearity, analytical region. Precision was estimated based on the results of 18 measurements, the coefficient of variation was 8 %, the relative error of average 4 %. Linearity was determined (correlation coefficient R = 0.992). The range of application of the analytical technique depends on its purpose, is determined in the linearity analysis and ranges from 5 · 10 -3 g/ml to 5 · 10 -2 g/ml. Conclusion . The proposed methodology can be used as an independent test of the properties of pharmaceutical substances both at the stage of their development and preclinical studies, and in the process of quality control in addition to the existing pharmacopoeia test to assess the solubility of pharmaceutical substances, expressed in terms of conditional.

First determination of dissolution rates of oriented UO2 single crystals

Abstract:Millimetre UO2 single crystals were cut and oriented at JRC Karlsruhe. The orientation of each face of the parallelepiped single crystals was determined with Laue diffraction and the corresponding surface area by geometric measurements. Then, the (111), (100), (110) faces of each single crystal were polished to optical grade and characterized by XRD in order to confirm the surface orientation. The dissolution of the three single crystals was achieved in nitric acid media under dynamic conditions, at room temperature. Two dissolution regimes were observed for all samples. The normalized dissolution rate measured in the first step was not influenced by the crystallographic orientation of the faces. However, during the second step, (110) oriented faces were found to dissolve 4 times faster than the (100) faces. One explanation could involve the atomic composition of each oriented surface in the fluorite-type structure

Determination of actual dissolution rates from some rock properties in construction of deep salt cavern for natural gas storage

Available energy resources should be efficiently used to meet the global energy demand. The storage of energy resources, especially as natural gas, is important to balance extreme fluctuations in demand and supply of energy. Underground caverns in deep salt domes are used as storage for natural gas due to the low permeability and appropriate creep conditions of salt. Several projects are being carried out in Turkey to store imported natural gas. The design and construction parameters of these deep salt caverns should be determined to provide reliable and durable storage. Dissolution rate, which is an important parameter affecting the design and construction of underground salt caverns, is generally measured from core samples in laboratory settings. However, results do not match actual underground dissolution rates. The aim of this study was to predict actual dissolution rates from some rock properties. The physical and mechanical salt properties were determined from core samples obtained from different depths of drilled wells opened for salt caverns. The relationships between salt properties and actual dissolution rates were statistically analyzed. A statistical model was developed to predict actual dissolution rates using uniaxial compressive and tensile strengths, Poisson's ratio, and cohesion and experimental vertical dissolution rates. The model is reliable for predicting actual dissolution rates in construction of underground gas storage caverns in salt domes. Predicted dissolution rates can be used in the design of underground gas storage caverns in salt domes.

Linking Isotope Exchange with Fe(II)-Catalyzed Dissolution of Iron(hydr)oxides in the Presence of the Bacterial Siderophore Desferrioxamine-B.

Dissolution of Fe(III) phases is a key process in making iron available to biota and in the mobilization of associated trace elements. Recently, we have demonstrated that submicromolar concentrations of Fe(II) significantly accelerate rates of ligand-controlled dissolution of Fe(III) (hydr)oxides at circumneutral pH. Here, we extend this work by studying isotope exchange and dissolution with lepidocrocite (Lp) and goethite (Gt) in the presence of 20 or 50 μM desferrioxamine-B (DFOB). Experiments with Lp at pH 7.0 were conducted in carbonate-buffered suspensions to mimic environmental conditions. We applied a simple empirical model to determine dissolution rates and a more complex kinetic model that accounts for the observed isotope exchange and catalytic effect of Fe(II). The fate of added tracer 57Fe(II) was strongly dependent on the order of addition of 57Fe(II) and ligand. When DFOB was added first, tracer 57Fe remained in solution. When 57Fe(II) was added first, isotope exchange between surface and solution could be observed at pH 6.0 but not at pH 7.0 and 8.5 where 57Fe(II) was almost completely adsorbed. During dissolution of Lp with DFOB, ratios of released 56Fe and 57Fe were largely independent of DFOB concentrations. In the absence of DFOB, addition of phenanthroline 30 min after tracer 57Fe desorbed predominantly 56Fe(II), indicating that electron transfer from adsorbed 57Fe to 56Fe of the Lp surface occurs on a time scale of minutes to hours. In contrast, comparable experiments with Gt desorbed predominantly 57Fe(II), suggesting a longer time scale for electron transfer on the Gt surface. Our results show that addition of 1–5 μM Fe(II) leads to dynamic charge transfer between dissolved and adsorbed species and to isotope exchange at the surface, with the dissolution of Lp by ligands accelerated by up to 60-fold.

Incipient chemical weathering at bedrock fracture interfaces in a tropical critical zone system, Puerto Rico

Abstract The processes that control chemical weathering of bedrock in the deep critical zone at a mm-scale are still poorly understood, but may produce 100 s of meters of regolith and substantial fluxes of silicate weathering products and thus may be important for modeling long-term, global CO2. Weathering controls are also difficult to ascertain, as laboratory determined dissolution rates tend to be 2–5 orders of magnitude faster than field determined dissolution rates. This study aims to establish (i) the incipient processes that control the chemical weathering of the Bisley bedrock and (ii) why weathering rates calculated for the watershed may differ from laboratory rates (iii) why rates may differ across different scales of measurement. We analyzed mineralogy, elemental chemistry, and porosity in thin sections of rock obtained from drilled boreholes using Scanning Electron Microscopy (SEM) with energy dispersive spectrometry, electron probe microanalysis, and synchrotron-based Micro X-ray Fluorescence (µXRF) and X-ray Absorption Near Edge Structure (XANES). Weathering ages were determined from U-series isotope analysis. Mineral specific dissolution rates were calculated from solid-state mineralogical gradients and weathering ages. Mineralogical and elemental transects across thin sections and SEM images indicate that trace pyrite is the first mineral to dissolve. Micro-XRF mapping at 2 µm resolution revealed sulfate in pore space adjacent to dissolving pyrite, indicating that the incipient reaction is oxidative. The oxidative dissolution of pyrite produces a low pH microenvironment that aids the dissolution of pyroxene and chlorite. The rate-limiting step of weathering advance, and therefore the creation of the critical zone in the Bisley watershed, is pyrite oxidation, despite the low abundance (∼0.5 vol%) of pyrite in the parent rock. The naturally determined dissolution rates presented here either approach, converge with, or in some cases exceed, rates from the literature that have been experimentally determined. The U-series weathering age data on the mm-scale integrates the weathering advance rate over the ∼4.2 ± 0.3 kyrs that the weathering rind took to form. The weathering advance rate calculated at a watershed scale (from stream chemistry data) represents a contemporary weathering advance rate, which compares well with that calculated for the weathering rind, suggesting that the Bisley watershed has been weathering at steady-state for the last ∼4 kyrs.

Discriminatory Dissolution Testing for Liquisolid Compacts Containing a Poorly Water-Soluble Drug (Hydrochlorothiazide)

Drug release from liquisolid compacts is dependent on several variables and changes in experimental parameters, like drug loading and the type and quantity of the carrier material, which affect the dissolution rate, significantly. Therefore, a dissolution method is needed that can discriminate among in vitro release profiles of liquisolid compacts of varying nature. The objective of this study was to develop and validate a discriminatory dissolution testing method for liquisolid compacts of hydrochlorothiazide (HCTZ) to evaluate the effect of formulation and process variables on dissolution rate. Various experimental conditions were optimized, and the method was validated according to USP and ICH guidelines for different parameters like linearity, specificity, accuracy, precision, and stability of solution. Analysis of dissolution samples was carried out by high-performance liquid chromatography (HPLC). The discriminatory nature of the method was confirmed by determining dissolution rates of liquisolid compacts of HCTZ prepared with different load factors. A model-independent approach was applied for comparison of different dissolution profiles. Based on a screening study, USP apparatus I (basket method) was selected. The best in vitro dissolution profile was obtained using purified water containing Tween-80 (0.5% v/v) as the dissolution medium (900 mL), stirred at 75 rpm. Complete dissolution (99.83 ± 1.03%) was achieved within 60 min and dissolution media had no interference with sample analysis. HCTZ exhibited a linear response (r2 = 0.9974) in the selected dissolution medium and showed accurate results (98%–100%) in the concentration rage of 80%–120% of the dose. All validation parameters were found in acceptable range (%RSD > 2), and drug samples prepared in dissolution medium were stable for the specified period. Comparison of dissolution profiles in the official and developed media showed significant differences in f1 and f2 values. The developed dissolution test exhibited higher discriminative capacity in differentiating release profiles of HCTZ and can be applied during formulation development and quality control analysis of liquisolid compacts.

Direct Determination of Dissolution Rates at Crystal Surfaces Using 3D X-ray Microtomography

Investigations of mineral surface reactivity have recently challenged the classical approach of determining dissolution rates from mineral powders as crystals often exhibit heterogeneous and/or anisotropic reactivity. However, face-specific measurements are restricted to small areas at the surface and limited depth and ignore the contribution of the crystal edges to the whole process. Here, we provide a detailed characterization of the dissolution kinetics at pH 4.0 of a single calcite crystal in 3D using X-ray microtomography with a resolution less than 1 μm. The imaging method allows 3D mapping of the crystal surface topography, providing a description of the time-dependent local dissolution fluxes all over the crystal surface, and the calculation of the crystal dissolution rates. The global rate determined at the crystal scale integrates the contribution of all the crystal features, including the faces, edges, and corners, which can be detailed in the local rate distributions. Under acidic conditions, ...

Determination of Dissolution Rates of Ag Contained in Metallurgical and Mining Residues in the S2O32−-O2-Cu2+ System: Kinetic Analysis

The materials used to conduct kinetic study on the leaching of silver in the S2O32−-O2-Cu2+ system were mining residues (tailings) from the Dos Carlos site in the State of Hidalgo, Mexico, which have an estimated concentration of Ag = 71 g∙ton−1. The kinetic study presented in this paper assessed the effects of the following variables on Ag dissolution rate: particle diameter (d0), temperature (T), copper concentration [Cu2+], thiosulfate concentration [S2O32−], pH, [OH−], stirring rate (RPM), and partial pressure of oxygen (PO2). Temperature has a favorable effect on the leaching rate of Ag, obtaining an activation energy (Ea) = 43.5 kJ∙mol−1 in a range between 288 K (15 °C) and 328 K (55 °C), which indicates that the dissolution reaction is controlled by the chemical reaction. With a reaction order of n = 0.4, the addition of [Cu2+] had a catalytic effect on the leaching rate of silver, as opposed to not adding it. The dissolution rate is dependent on [S2O32−] in a range between 0.02 mol·L−1 and 0.06 mol·L−1. Under the studied conditions, variables d0, [OH−] and RPM did not have an effect on the overall rate of silver leaching.

Iron(III) and aluminium(III) based mixed nanostructured hydroxyphosphates as potential vaccine adjuvants: Preparation and physicochemical characterization

Adjuvants are substances that, when combined with an antigen in a vaccine formulation, potentiate the immune response against that antigen. Aluminium hydroxyphosphate is among the currently used adjuvants in vaccines, while studies on its iron analogue, ferric hydroxyphosphate, are quite limited. In this article we report on the preparation and physicochemical characterization of novel nanostructured iron and aluminium based mixed hydroxyphosphates as potential vaccine adjuvants, prepared by controlled co-precipitation from mixed solutions of Fe(III) and Al(III) chlorides with sodium phosphate and sterilized by autoclaving. The obtained hydroxyphosphates consisted of a network of platy nanoparticles (20–40nm in size), which aggregated in aqueous medium to form secondary micron-sized particles. The obtained nanostructured hydroxyphosphates were characterized by energy dispersive X-ray spectroscopy for elemental composition, X-ray powder diffraction, infrared spectroscopy, zeta-potential measurements for determination of isoelectric point, protein adsorption, and dissolution rate in sodium citrate solution.