Pure Powder Research Articles

Effect of Cobalt Substitution on the Structural and Magnetic Properties of Bismuth Ferrite Powders

BiFeO3 (BFO) is a multiferroic material with excellent ferroelectric properties but with poor magnetic behavior. Therefore, we focused principally on the enhancement of the magnetic order of BFO. These multiferroic properties make BFO an excellent candidate for magnetoelectric devices at room temperature. Pure and Co-BiFeO3 powders were successfully synthesized via the sol–gel method at 700 °C. The effect of Co substitution on the corresponding structural and magnetic properties of BFO was studied. X-ray diffraction and Fourier Transform Infrared Spectroscopy measurements confirmed the rhombohedral perovskite structure in all samples. A secondary phase of CoFe2O4 (CFO) was detected for 9, 10, and 15% of Co doping. The scanning electron microscopy images of the Co-BFO particles showed a reduction in the particle size compared to the pure BFO powders. Vibrating sample magnetometry measurements evidenced the ferromagnetic hysteresis loop for the Co-BFO powders with values of saturation magnetization of 4.1 emu/g and a coercivity of 1083 Oe for 15% of Co doping. In this work, we report impurity free samples with notable magnetic properties at the same time, which is a difficult challenge in bismuth ferrite synthesis. This is the first step for later applications in future technology.

Microstructure and Wear Characterization of the Fe-Mo-B-C-Based Hardfacing Alloys Deposited by Flux-Cored Arc Welding.

An analysis of common reinforcement methods of machine parts and theoretical bases for the selection of their chemical composition were carried out. Prospects for using flux-cored arc welding (FCAW) to restore and increase the wear resistance of machine parts in industries such as metallurgy, agricultural, wood processing, and oil industry were presented. It is noted that conventional series electrodes made of tungsten carbide are expensive, which limits their widespread use in some industries. The scope of this work includes the development of the chemical composition of tungsten-free hardfacing alloys based on the Fe-Mo-B-C system and hardfacing technology and the investigation of the microstructure and the mechanical properties of the developed hardfacing alloys. The composition of the hardfacing alloys was developed by extending the Fe-Mo-B-C system with Ti and Mn. The determination of wear resistance under abrasion and impact-abrasion wear test conditions and the hardness measurement by means of indentation and SEM analysis of the microstructures was completed. The results obtained show that the use of pure metal powders as starting components for electrodes based on the Fe-Mo-B-C system leads to the formation of a wear-resistant phase Fe(Mo,B)2 during FCAW. The addition of Ti and Mn results in a significant increase in abrasion and impact-abrasion wear resistance by 1.2 and 1.3 times, respectively.

Production, physicochemical investigations, antioxidant effect, and cellular uptake in Caco-2 cells of the supersaturable astaxanthin self-microemulsifying tablets

The purpose of this study was to develop astaxanthin (AST)-loaded self-microemulsifying drug delivery system (SMEDDS) tablets and evaluate their physicochemical and biological properties. The optimized liquid (L)-AST SMEDDS formulation was composed of rice bran oil (33.67%), Kolliphor® RH 40 (34.70%), and Span® 20 (31.63%). Two types of hydrophilic polymers (hydroxypropyl methylcellulose, HPMC, and polyvinyl alcohol, PVA) solutions were selected as a precipitation inhibitor for AST and incorporated into L-AST SMEDDS to obtain supersaturation and enhance dissolution of AST. The formulation was then mixed with microcrystalline cellulose and subsequently transformed to solid S-AST SMEDDS particles using a spray dryer prior to direct compression into tablets. The HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet were characterized for their physicochemical properties, dissolution, AST release, and stabilities. Moreover, the cellular uptake and antioxidant effect of AST SMEDDS tablets were evaluated in Caco-2 cells. With good tablet characters, both HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet dissolution profiles were improved compared to that of raw AST. While initially less than 50% of AST released from HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet in pH 1.2 medium, after 6 h more than 98% of AST releases in pH 6.8 were achieved which was similar to L-AST SMEDDS profile. Cellular antioxidant activities of L-AST SMEDDS and HPMC AST SMEDDS tablet & PVA AST SMEDDS tablet were significantly greater than pure AST powder. HPMC AST SMEDDS tablet showed better uptake and deeper penetration through Caco-2 cells than that in PVA AST SMEDDS tablet and pure powder. Our successfully developed AST SMEDDS tablets were demonstrated to be a potential platform to deliver highly lipophilic AST and improve permeation and bioavailability.

Effect of stress state on graphitization behavior of diamond under high pressure and high temperature

Pure diamond powder and mixed powder of diamond and sodium chloride were treated at high pressures (5 GPa and 10 GPa) and high temperatures (1000–2700 °C), and then the graphitization behavior of diamond powder under non-hydrostatic (pure diamond powder) and quasi-hydrostatic (mixed powder of diamond and sodium chloride) compression was quantitatively studied by analyzing the X-ray diffraction peaks' area of treated samples. It is found that the graphitization under non-hydrostatic compression is much more easily triggered by heating due to the heterogeneous stress distribution within the diamond grains. Under the quasi-hydrostatic compression of 5 GPa, the starting graphitization temperature is about 1600 °C, which is 300 °C higher than that under non-hydrostatic compression. Under a pressure of 10 GPa, graphitization could be observed after pure diamond powder was treated at 1400 °C, but no graphitization occurred in the mixed powder even after a high temperature treatment at 2300 °C. Optimizing the stress distribution among diamond grains by the mixing of grain-size can significantly reduce the graphitization at high temperature even under non-hydrostatic compression.

HPTLC determination of ergosterol in wheat and structure elucidation by NMR: Toward confirming method selectivity

Ergosterol (ERG) is considered as an excellent fungal biomarker, therefore it was utilized for the determination of the degree of fungi infection in wheat grains. A novel, fast, cost-effective and selective high performance thin layer chromatography (HPTLC) with reflectance/absorbance densitometry method was developed and validated for ERG determination. Separation was attained on pre-coated silica gel HPTLC plate with ethyl acetate: petroleum ether (6: 4 v/v) as a mobile phase. This system gave compact bands at retardation factor (Rf) of 0.45 ± 0.002 and quantification was performed at 282 nm over concentration range of 40–600 ng/band. The lower detectable limit was 10.79 ng per band which is three times more sensitive than the previously reported TLC method. The developed method could be utilized efficiently for the detection of ERG in pure powders and in fungi infected wheat samples. Resolution of ERG from other compounds in wheat grain extract allowed utilizing preparative TLC for separating and purifying ERG in a sufficient quantity for structure elucidation by nuclear magnetic resonance spectroscopy (NMR) for the first time. H1 and C13 NMR spectra indicated the purity of ERG extracted from the scrapped silica of preparative TLC plate at the Rf of the standard ERG verifying the method selectivity.

Fabrication of Ta-Ag composite deposits via cold spray: Investigation of bonding mechanism and deposition behavior

Cold spray is a solid-state deposition technology that can achieve deposition of pure metal, alloys, and composites with high efficiency. By taking the advantage of cold spray method, in this work, Ta and Ag were successfully used to fabricate Ta-Ag composite deposits for the first time, despite their significantly different properties. It was found that mechanical bonding was the major deposition mechanism between Ta and Ag. The Ag volume in the mechanically mixed powder influence the deposition between Ag and Ta particles. Deposition of Ta-Ag powder was same as pure Ta powder when Ag volume was low, and the small volume of deposited Ag inhibit the deposition of Ta particles. Higher Ag volume in powder promoted the deposition of Ta particles via mechanical interlocking due to the formation of large Ag agglomerates.

Statistical analysis and ANN modelling of tribological performance of aluminium hybrid composites fabricated by PM method

This study represents the wear behaviour of the aluminium hybrid composites developed through powder metallurgy. The pure Al-matrix powder was blended with Si3N4/ZrO2 ceramic powders in a high-centrifugal ball mill and then compacted at three different compaction pressure. The sintering of the composites was done in an environment-controlled tube furnace at 500 °C for 1 h. The effect of wt% of the reinforcement, compaction pressure and applied load was investigated on the wear results performed on the pin-on-disc setup. The Analysis of variance (ANOVA) and artificial neural network (ANN) was used for the wear loss results prediction. The ANOVA results revealed that load is a highly influential parameter for wear loss followed by reinforcement and compaction pressure. Furthermore, an ANN model using feed-forward backpropagation analysis was built which found that the predicted and experimental results are close.

Pembuatan dan Karakterisasi Self Emulsifying Drug Delivery Systems(SEDDS) Ibuprofen Secara Oral

Self emulsifying drug delivery systems (SEDDS) dikembangkan sebagai metode untuk meningkatkan kelarutan obat lipofilik seperti ibuprofen, serta untuk meningkatkan absorpsi dan laju disolusi obat. Oleh karena itu penelitian ini bertujuan untuk mengembangkan formulasi SEDDS ibuprofen yang memenuhi syarat secara farmasetik dan meningkatkan bioavailabilitas ibuprofen. Formula SEDDS diperoleh dari uji kelarutan ibuprofen dan optimasi formula pada berbagai konsentrasi minyak, surfaktan dan kosurfaktan. Asam oleat, cremophor RH 40 dan propilenglikol masing-masing terpilih sebagai minyak, surfaktan dan kosurfaktan dengan perbandingan fase minyak : (surfaktan + kosurfaktan) 1:9 dan pebandingan surfaktan : kosurfaktan (3:2). Formula SEDDS optimum dievaluasi meliputi pengukuran persen transmitan, pengujian dispersibilitas, pengujian robustness, pengujian stabilitas (sentrifugasi, heating cooling cycle, freeze thaw cycle), penentuan ukuran partikel dan uji laju disolusi. Formula SEDDS ibuprofen terbaik memenuhi persyaratan persen transmitan (99,7% ± 0,872), waktu dispersibilitas (41,48 detik ± 1,3), stabil pada pengujian robustness, tidak terjadi pemisahan fasa pada pengujian stabilitas, serta memiliki ukuran globul dalam kisaran mikrometer yaitu 114,7 ± 0,692 nm. Hasil uji laju disolusi in vitro pada menit ke-10 menunjukkan bahwa sediaan SEDDS ibuprofen lebih tinggi dibandingkan dengan serbuk ibuprofen murni, yaitu masing-masing sebesar 90,04 ± 1,764% dan 59,30 ± 1,638%.

Synthesis and characterization of TiO2/ZnO heterostructural composite for ultraviolet photocatalytic degrading DOM in landfill leachate.

In order to investigate the photocatalytic degradation of dissolved organic matter (DOM) in landfill leachate, TiO2/ZnO heterostructural composite powders were fabricated combining with hydrothermal synthesis and solid-state reaction method. The prepared TiO2/ZnO composite powders consist of anatase TiO2 nanoparticles distributing on the surface of wurtzite ZnO particles. The optical band gap of TiO2/ZnO powder is less than that of pure ZnO or TiO2 powder. TiO2/ZnO catalyzers show high ultraviolet-degradation efficiency for methylene blue and dissolved organic matter. The degradation rate of TiO2/ZnO powder for fulvic acid-like substances in landfill leachate is 2.99 times that of pure ZnO powder, and is 1.30 times that of pure TiO2 powder. The degradation of fulvic acid-like substances by TiO2/ZnO photocatalyst reduced some molecular weight of benzene ring structure substances in leachate. The effective separation of electron and hole in heterostructural TiO2/ZnO photocatalyst is the main reason for its high photocatalytic degradation efficiency of DOM in landfill leachate.

Panelist Acceptance, Proximate Characteristics of Amino Acids and Volatile Compounds, and Color Profile of Fermented Cempedak (Artocarpus champeden) and Oyster Mushroom (Pleurotus ostreatus) Seasoning

The potential of mandai cempedak (Artocarpus champeden) powder to be mixed with other abundant raw materials such as oyster mushroom (Pleurotus ostreatus) as a flavoring ingredient is an exciting thing to study as a unique flavor source for the archipelago. This study aims to observe panelist acceptance, proximate characteristics of amino acid, volatile compounds, and color profiles on five mixed formulas of fermented cempedak (Artocarpus champeden) and oyster mushroom (Pleurotus ostreatus) seasoning. The five seasoning formulas combine 30–70% flavored mushroom powder and 30–70% mandai cempedak powder with control of commercial mushroom powder and pure mandai powder. Hedonic quality assessment on seasoning samples of flavored mushroom powder and mandai cempedak powder played a more critical role in the acceptance of the final product, with a slightly reddish yellow color tendency with a paleness level of around 66–67%. Seasoning samples had a savory taste with dominant amino acid profiles of ileusine (1.46%, w/w), glutamate (1.37%), methionine (0.82%), and aspartic acid (0.72%). All seasoning formulations of flavored mushroom and mandai cempedak powder have a moisture content of 8.4–10.9%, total protein 7.0–9.0%, soluble protein 2.4–3.5%, ash content 4.5–19.2%, fat content 2.3–4.5%, carbohydrates 62.7–79.4%, and the solubility is 31.0–89.4%. The dominant volatile compounds in seasoning are heptanone, dodecoxyethanol, and etradecyloxyethanol with pleasant aroma profiles, pungent fruity, green, citrus, and herbal. In conclusion, mandai cempedak powder to be mixed with other abundant raw materials such as oyster mushroom (Pleurotus ostreatus) can be used as a typical Indonesian flavor ingredient with unique characteristics in terms of its amino acid content, volatile compounds, and essential oils.

Physical Vapor Transport Process for Highly Purified Hg2Br2 Crystal: from Powder Purification to Crystal Growth

High quality Hg2Br2 crystal grown <i>via</i> the physical vapor transport (PVT) process is essential for the fabrication of the acousto-optic tunable filters (AOTFs) module. The full process flow, including powder purification and crystal growth, should be systematically established, but there have been few reports about the fully established process flow of single Hg2Br2 crystal. In this study, we report on the entire process, from purification of the Hg2Br2 powder to crystal growth based on the PVT process. We compared the raw powder and purified powder using X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP). Although there was no considerable difference in the XRD and XPS results of the powders before/after purification, the ICP impurity analysis indicated that the purity of Hg2Br2 powder increased from 4N (99.99%) to 5N (99.999%). The Hg2Br2 single crystal grown by the PVT process was then fully characterized by XRD, XPS, and Raman spectroscopy. The vibration bonds constituting the Hg2Br2 lattice were clearly identified from the Raman spectra of the final Hg2Br2 crystal. High quality Hg2Br2 single crystal PVT-grown from the purified powder will lead to the development of a high-performance acousto-optic module. Establishing the systematic growth sequence of the Hg2Br2 based on PVT paves the way to promising AOTF modules.

A two-step heating strategy for low-temperature fabrication of high sinterability and fine MgAlON powder with MgAl2O4 as Mg source

Based on the reaction sequence during synthesis of MgAlON powder by solid-state reaction, a two-step heating strategy is proposed to low-temperature fabricate fine MgAlON powder of high sinterability by using MgAl2O4 as Mg source, respectively together with AlON and Al2O3+AlN. By introduction of an additional dwelling at 1550 °C to the first heating step, more α-Al2O3 dissolve into the solid solution at this temperature. By this way, overlarge particles of Al2O3 by agglomeration could be avoided in the next heating step to enable fast full reaction at a lower temperature. By dwelling 30 min at 1550 °C followed by 60 min at 1700 °C, single phase MgAlON powders were successfully prepared by solid-state reaction of all the two batches. The fine MgAlON powder synthesized by MAS+Al2O3+AlN batch exhibited high sinterability as the MgAlON ceramics pressureless sintered by this powder at 1880 °C without dwelling showed a transmittance up to 68.3%. The phase assemblage and morphology evolution of the mixture during solid-state reaction were monitored, which verified the effectiveness of the proposed two-step heating strategy. The low synthesis temperature of the two-step heating scheme benefits to prepare pure MgAlON powder with small particle size.

Critical assessment of smart calculation-based spectroscopy versus chemometric-assisted methods: Application to combined antibiotic formulations

This work describes a comparative study of two multivariate chemometric and univariate spectrophotometric methods for the determination of a ternary drug mixture containing oxytetracycline HCl, bromhexine HCl, and lidocaine HCl. All methods show high sensitivity and similar linearity range. Meanwhile, the chemometric method has the advantage of higher accuracy, higher specificity and better regression parameters. The two spectrophotometric methods are constant multiplication coupled with spectrum subtraction and successive ratio subtraction coupled with spectrum subtraction while the chemometric method used partial least square and principal component regression models. In addition, a spiking technique was used to increase the concentration of bromhexine HCl in the dosage form, allowing its determination despite its low contribution. Methods were successfully applied in the dosage form Oxyclear® veterinary injection in pure powder as well as in its pharmaceutical formulation. Statistical comparison showed no significant difference between the developed methods and the reference method.

Effect of Dispersions of Al2O3 on the Physical and Mechanical Properties of Pur ties of Pure Copper and Copper-Nick e Copper and Copper-Nickel Allo el Alloy

This paper illustrates the mechanical and physical properties of pure Cu and Cu-Ni (50-50 wt. %) alloy mixed with Al2O3 (1-4 wt. %) as micro-particles reinforcement materials. The attained composite alloy specimens' characteristics were estimated such as microstructure, relative density, electrical and thermal conductivity, hardness, and compression yield stress properties to adjust the suitable optimum percentage of reinforcing material which has the best physical and mechanical properties with different main matrix materials whether pure Cu powder or Cu-Ni mechanical alloy. The micron-sized Al2O3 was added to enhance the mechanical and physical properties of the pure Cu and Cu-Ni alloy composites. The electrical and thermal conductivity for pure Cu alloy composites were improved compared to the copper-nickel alloy matrix composites material. The hardness and compression yield stress of pure copper has enhancement values and for Cu-Ni alloy composites have enhancement values and for Cu-Ni base composites, hardness and compression yield stress have improved with the most positive enhancement values.

This paper illustrates the mechanical and physical properties of pure Cu and Cu-Ni (50-50 wt. %) alloy mixed with Al2O3 (1-4 wt. %) as micro-particles reinforcement materials. The attained composite alloy specimens' characteristics were estimated such as microstructure, relative density, electrical and thermal conductivity, hardness, and compression yield stress properties to adjust the suitable optimum percentage of reinforcing material which

The recent booming in the power network industry inspired a lot of researchers to develop models to estimate the optimum cost of transmission towers. Unlike previous researches which depended on design the tower from scratch, this research depends on collecting actual database from several projects around the globe and applying the well-known (GP) technique to develop a model to predict the tower weight. The accuracy of the developed formula was about 84%. The developed model could be used in early tender stage or to check design economy.

Separation of silicon carbide and silicon powders in kerf loss slurry of loose abrasive sawing by means of phase transfer separation method with mixed cationic-anionic surfactant collectors addition

Kerf loss slurry generated from the slicing process of silicon wafer by using loose abrasive sawing method contains silicon carbide (SiC) and silicon (Si) powders. This study attempted to separate SiC and Si powders in kerf loss slurry through phase transfer separation method with mixed cationic-anionic surfactant collectors addition. Isooctane and water were employed as the two phases. Dodecylamine acetate (DAA) and sodium oleate (NaOL) was used as the cationic and anionic surfactant collector, respectively. The effects of single surfactant collector addition (DAA/NaOL) and mixed cationic-anionic surfactant collectors addition (DAA + NaOL) on the transfer of individual SiC and Si powders from the water phase to the isooctane phase, as well as on the separation of SiC and Si powders in kerf loss slurry, were investigated and compared.The results indicated that DAA could improve the transfer of both SiC and Si powders to the isooctane phase, and the improvement for SiC powder was higher than for Si powder. In contrast, NaOL could only improve the transfer of SiC powder to the isooctane phase, and the improvement for SiC powder was less than DAA did. Compared to single DAA/NaOL addition, mixed DAA + NaOL addition could improve the separation of SiC and Si powders in kerf loss slurry at lower surfactant collector dosages. In addition, the dosage of NaOL in mixed DAA + NaOL addition had more significant effect on improving their mutual separation than that of DAA did. The optimal separation results were obtained with mixed surfactant collectors addition of 0.01 kg/ton DAA and 0.05 kg/ton NaOL at pH 5. The purity and recovery of SiC powder recovered from the isooctane phase was 90.0% and 92.0%, respectively, and those of Si powder recovered from the water phase was 89.5% and 87.0%, respectively. The total dosage of surfactant collectors was 40% reduced.

Preparation of Posaconazole Nanosponges for Improved Topical Delivery System

The objective of the current research was to develop the posaconazole (PCZ) loaded NS into the carbopol 934 polymeric gel for prolonged drug release and improved topical delivery; seven different nanosponge formulations of PCZ were formulated using the emulsion solvent diffusion method using various amounts of polymer (ethylcellulose, EC). The aqueous and dispersed phases were prepared using polyvinyl alcohol (PVA) and dichloromethane. The prepared nanosponges (NS) were studied for particle size, structural appearance, and in vitro drug release. Furthermore, the selected formula was formulated as hydrogel and was evaluated for physical characteristics, drug content, and in-vitro drug release. Morphological studies revealed irregular shapes, rough and porous surfaces of nanosponges. The particle sizes were in the range of 201.6 ± 29.9 to 4904.7 ± 540.4 nm. In-vitro release studies revealed the sustained release pattern of the drug-loaded nanosponges. The lyophilized PCZ-NS formula had a 12-fold increase in saturation solubility over PCZ pure powder. Fourier transform infrared spectroscopy (FTIR) of the selected formula showed no significant shifts in the positions of wavenumbers compared to that of pure drug. This indicates there is no interaction between drug and excipients used. PCZ NS loaded hydrogel significantly improved the dissolution rate, which was significantly higher (p is less than 0.05) than that of pure PCZ hydrogel.

Mo-Si-B Alloy Formed by Optional Laser Melting Process.

In this research article, the molybdenum alloy was prepared by solid-solid doping, selecting pure Mo powder, amorphous Si powder, and B powder as the experimental raw materials for SLM molding. The density and mechanical properties of Mo-Si-B alloys prepared by SLM technology under different processes and compositions were explored, and at the same time, the microstructure of the obtained alloy was observed. The result shows that, with a laser power of 250 W, a scanning speed of 500 mm/s, and a scanning distance of 60 μm, the Mo4.5-Si2-B (at.%) alloy has the highest forming rate under the 120°parameters of the rotating scanning strategy, and the highest density is 94.22%.

Synthesis of graphene oxide coated metal powders with improved flowability and reduced reflectance

In this study, a method has been developed to coat metal powder particles (Fe, 316L stainless steel and Cu) with graphene oxide (GO). The method is based on using a pH window where opposite zeta potentials cause the GO sheets to be attracted to the passive oxide layer of the metal powder surface and a rotary evaporator mixing to achieve good dispersion and control the concentration of GO. The pH-dependent interactions of GO and Cu and Fe metal powders in solution have been investigated by mixing the metal powder with GO dispersions between pH 4.2 and 11.3, and it could be observed that GO attached to the metal powder surfaces up to pH ~8 for both Cu and Fe. At lower pH the zeta potential of GO becomes less negative and oxidation of the metal becomes more prominent. Based on these observations, a pH window just below the IEP of the surface metal oxides was used to adhere GO on metal powders in a rotary evaporator with controlled GO concentrations and good distribution of the GO sheets which was verified with SEM and Raman spectroscopy mapping. X-ray diffraction and Raman spectroscopy has been used to evaluate the GO and the metal oxides. Some relevant powder properties were investigated before and after coating of GO. The reflectance of Cu powders in the near-infrared 1070 nm wavelength range was reduced by up to 66 %, depending on the amount of GO coating. Flowability measurements showed that the flowability of the coated 316L powder could be improved significantly while the flowability of pure Fe powder was relatively unaffected by the coating. The results show that GO coated metal powder can be useful in additive manufacturing processes using a laser powder fusion technique where low reflectance and high flowability are important.

Use of Alternative Indicator Organisms for The Microbiological Assay of Four Antibiotics Commonly Sold in Uyo, Nigeria

Background: The accurate measurement of antibiotics potency is essential for quality checks, and microbiological assays have been used extensively for this purpose. Unfortunately, in most places especially in the developing countries, the indicator organisms recommended for these assays are difficult to obtain as there are no culture collection centers that keep them. Alternative indicator organisms which will meet the specifications of the reference books were therefore sought for and used in the microbiological assay of some commonly used antibiotics. Pure powders of four commonly used antibiotics to be assayed were obtained and confirmed using the Fourier infrared spectroscopy. Nine strains of organisms which are Escherichia coli WG5, Enterococcus duranss ATCC 11576 and Staphylococcus aureus NCTC6571, Pseudomonas aersuginosa ATCC 27853, Enterococcus gallinarium ATCC 49573, Enterococcus faecium ATCC 49185, Stenotrophomonas maltophilia ATCC 13637, Aeromonas hydrophilia ATCC 7966 and Listeria monocytogenes were randomly selected and screened for their suitability to be used based on their susceptibility to the antibiotics to be assayed, growth characteristics, linearity on a dose response curve and pathogenicity. Selected organisms were eventually used as indicator organisms in the microbiological assay of different brands of Ampicillin, Amoxicillin, Tetracycline and Erythromycin obtained in Uyo, Nigeria using the 6x6(3+3) Latin square design on assay plates. Results: Results obtained confirmed the standard antibiotic powders and showed that Staphylococcus aureus NCTC6571 could be used to assay Amoxicillin while Enterococcus durans ATCC 11576 and Escherichia coli WG5 could be used to assay Erythromycin, Ampicillin. and Tetracycline Results further showed that the antibiotics assayed had percentage potency of between 104 and168%. All assayed products were within acceptable limits confirming all the antibiotics assayed to be of good quality, except the amoxicillin capsule which exceeded the percentage potency limit allowed. Conclusion: It is concluded that alternative indicator organisms that meet the specifications of reference books can be used for the microbiological assay of antibiotics in the absence of those recommended.