Isopropanol Concentration Research Articles

Evaluation of In-Use Stability of Anticoagulant Drug Products: Warfarin Sodium

The objective of the study was to evaluate the stability of warfarin products during use by patients or caregivers. For evaluation, three commercial products manufactured by different processes were selected and placed at 30°C/75%RH to simulate in use condition. Samples were withdrawn up to 12 weeks and analyzed for the physicochemical changes. Scanning electron microscopy demonstrated increasing holes and craters in the tablets over the timeframe. Near-infrared chemical imaging and powder X-ray powder diffraction corroborated the change arising from conversion of crystalline to amorphous forms of the drug. Hardness and disintegration time of the tablets were found to increase progressively. With increasing time, moisture contents of the products were found to increase and consequent decrease in isopropyl alcohol content of the product. Dissolution of the tablets in media at pH 4.5 demonstrated discrimination between crystalline and amorphous drug products. Overall, percent drug dissolved in each product at 30 min was found to decrease with increasing exposure time. Dissolution of drug decreased from 54% to 38% and 82% to 54% for the two products while the third product maintained consistently high level of dissolution. These results suggest that the drug product quality attributes can change during use.

Occurrence of acetone concentrations>0.10g/L in post-mortem femoral blood and association with ethanol and isopropanol concentrations

Summary The analysis of volatiles in post-mortem blood by gas chromatography sometimes shows the presence of acetone at concentrations exceeding 0.10 g/L, which is the analytical cut-off used in many laboratories. Whether these results reflect ante-mortem ingestion of isopropanol and subsequent oxidation to acetone or if the deceased suffered from a metabolic disorder (diabetes and/or ketoacidosis) is not always obvious. To throw more light on this question, we made a retrospective survey of ∼45,000 post-mortem blood samples and found that in 1366 cases (3%) acetone concentrations were > 0.10 g/L; mean (median) and highest 0.26 g/L (0.19 g/L) and 2.4 g/L, respectively. Of these 1366 blood samples, there were 256 (19%) that contained isopropanol at mean (median) and highest concentrations of 0.30 g/L (0.15 g/L) and 3.1 g/L. Blood-ethanol was positive (> 0.10 g/L) in 500 cases (37%) and the mean (median) and highest concentrations were 1.1 g/L (0.68 g/L) and 6.2 g/L. The concentrations of acetone and isopropanol in blood were highly correlated, r = 0.52 ( P r = −0.16) and ethanol vs isopropanol ( r = −0.04). Relatively low concentrations of acetone in blood (> 0.10 g/L but + biochemical reaction. Analytical results showing higher concentrations of acetone in blood (> 0.30 g/L), with or without isopropanol present, are more likely caused by ante-mortem ingestion of isopropanol and/or acetone for intoxication purposes.

Surface texture and optical properties of crystalline silicon substrates

This paper presents the results of an experimental study of the effects of surface texture on the optical and light trapping properties of silicon wafers. Surface texture is controlled by anisotropic etching with potassium hydroxide (KOH) and isopropyl alcohol (IPA) solutions. The anisotropic etching of (001) crystalline silicon wafers is shown to result in the formation of {111} pyramidal facets on the surfaces of the wafers. A combination of profilometry, optical microscopy, scanning electron microscopy, and atomic force microscopy is used to study the effects of KOH/IPA etching on the morphology and roughness of the textured surfaces. The results show that IPA concentration has the strongest effect on the surface roughness of (001)-single crystal crystals at temperatures up to 80 °C. Above this value, evidence of temperature-induced cracking was revealed on the silicon substrate. The best volume concentration ratio of KOH:IPA is also found to be 2:4. The implications of the study are discussed for the design of light trapping in silicon solar cells.

Pervaporation and vapor permeation characteristics of BTESE-derived organosilica membranes and their long-term stability in a high-water-content IPA/water mixture

Bis(triethocysilyl)ethane (BTESE)-derived organosilica membranes were applied for the dehydration of aqueous isopropanol (IPA) solutions in pervaporation and vapor permeation. The stability of the membranes under high-water-content systems was demonstrated in pervaporation and vapor permeation. The membranes showed excellent stability in the long-term pervaporation of a 50wt% IPA aqueous solution at 75°C. The membranes were also stable in vapor permeation with a high-water-content stream (IPA concentration of 50wt%) at 100°C. These results clearly demonstrated that BTESE-derived organosilica membranes are applicable for the dehydration of high-water-content mixtures. The effect of the feed component and operating temperature on dehydration performance was also investigated. An analysis of the permeation resistance through the membranes was conducted based on a simple series-resistance modeling approach and revealed that the permeation resistance of the support layer strongly inhibited the water permeability, particularly when the water content in the feed was high.

Top 80 over 80: incidence and characteristics of the 80 highest blood alcohol concentrations obtained in suspected impaired drivers in Ontario

This retrospective study characterizes the findings from the 80 highest blood alcohol concentrations (BACs) determined at the Centre of Forensic Sciences (Toronto, ON) in suspected impaired drivers between 1988 and 2007. Blood and serum samples were analyzed for ethanol and other volatiles by headspace gas chromatography with flame ionization detection. The mean BAC for drivers (n = 70) was 428 ± 44 mg of alcohol in 100 mL of blood (mg/100 mL) (range: 382–570 mg/100 mL). The mean serum alcohol concentrations (SAC) for drivers (n = 10) was 532 ± 103 mg/10 mL (range: 445–764 mg/100 mL). Incidental concentrations of acetone (n = 22), isopropanol (n = 3), and methanol (n = 2) were detected in some cases. The occurrences were examined for the time of day, day of week, reason for police involvement, as well as characteristics and observations of the individual either operating or in care or control of the motor vehicle. When available, hospital analyses (n = 10) and breath tests (n = 2) were also examined in comparison to the laboratory blood or serum analysis. The SACs and BACs reported in this study are sufficient to cause death in non-tolerant individuals and indicate that these drivers possessed significant tolerance to the central nervous system depressant effects produced by alcohol.

Surfactant-coated graphitized multiwalled carbon nanotubes as the pseudostationary phase in electrokinetic chromatography for the analysis of phytochemical compounds in biological fluids.

This report describes the use of surfactant-coated graphitized multiwalled carbon nanotubes (SC-GMWNTs) as a novel pseudostationary phase in CE with diode array detection for the determination of phenolic acids and tanshinones in herbal and urine samples. Several parameters influencing the separation were studied, such as the concentrations of SDS, GMWNTs, and isopropanol; choice of carbon nanotubes; sodium borate content; and buffer pH. The results revealed that the presence of SC-GMWNTs in buffer enhanced the separation efficiency for the target analytes relative to conventional micelles due to the strong interaction between the surface of the GMWNTs and the target compounds. Under the optimum conditions, the method showed good linearity, with correlation coefficients higher than 0.9950. LODs were in the range of 0.71-3.10 μg/mL. Furthermore, satisfactory separations were achieved with good recovery values in the range of 89.97 and 103.30% when 10 mM borate, 30 mM SDS, 10% isopropanol, and 6 μg/mL SC-GMWNTs were introduced into the buffer solution.

Equivalent Isopropanol Concentrations of Aromatic Amino Acids Interactions with Lipid Vesicles.

We show that the interaction of aromatic amino acids with lipid bilayers can be characterized by conventional 1D [Formula: see text]H NMR spectroscopy using reference spectra obtained in isopropanol-d8/D[Formula: see text]O solutions. We demonstrate the utility of this method with three different peptides containing tyrosine, tryptophan, or phenylalanine amino acids in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-sn-glycero-3-phosphoserine lipid membranes. In each case, we determine an equivalent isopropanol concentration (EIC) for each hydrogen site of aromatic groups, in essence constructing a map of the chemical environment. These EIC maps provide information on relative affinities of aromatic side chains for either PC or PS bilayers and also inform on amino acid orientation preference when bound to membranes.

Isopropanol dehydration via extractive distillation using low transition temperature mixtures as entrainers

Low transition temperature mixtures (LTTMs), also known as deep eutectic solvents, show properties that make them suitable as entrainers for extractive distillation. Two different low transition temperature mixtures were considered as potential entrainers for the extractive distillation of the azeotropic mixture (isopropanol+water). (Lactic acid+choline chloride) (2:1) and (glycolic acid+choline chloride) (3:1) were selected for this work. (Vapor+liquid) equilibrium measurements of the pseudo-binary systems (isopropanol+LTTM) and (water+LTTM) were measured at different concentrations of LTTM in a pressure range of 10 to 100kPa. (Vapor+liquid) equilibrium data of the pseudo-ternary system (isopropanol+water+LTTM) were also measured at constant pressure (100kPa) and constant LTTM molar fraction of 0.05 and 0.1. It was found that these LTTMs cannot break the azeotrope at those concentrations. However, the azeotrope was displaced to a much higher isopropanol concentration. The NRTL model was successfully applied to fit the experimental data.

An effective route for size- and morphology-controlled synthesis of Pt nanomaterials in aqueous solutions via proton beam irradiation

We present a facile one-pot synthetic route for the production of Pt nanomaterials via a simple proton beam irradiation process at room temperature. Size- and shape-controlled Pt nanostructures were prepared in an aqueous phase-based solution without the addition of any harsh reductants. We observed that the sizes and the morphologies of the resulting Pt nanoparticles were easily varied by changing the proton beam current and duration time. We also observed that the addition of isopropyl alcohol to the reaction mixture played a vital role in the morphology-controlled synthesis of Pt nanomaterials. We found that the size of the prepared Pt nanoparticles increased as the beam irradiation time was increased under the same beam current. When the beam irradiation time was set the same, the average particle size decreased as the beam current was increased. We also observed that the average size of the Pt nanocrystals generally increased as the concentration of isopropyl alcohol was increased, and more importantly, a gradual morphology change of the Pt nanocrystals was observed.

Extraction of rebaudioside-A by sonication from Stevia rebaudiana Bertoni leaf and decolorization of the extract by polymers.

Optimization of steviol glycosides extraction from Stevia rebaudiana Bertoni leaf was carried out by investigating the effects of isopropyl alcohol concentration (60%, v/v), time (6-24min), temperature (30°C) and sonic power (300-480W) on extraction of rebaudioside A from Stevia rebaudiana leaves and decolorization of the extract by polymer (Separan AP30 and Resin ADS-7). The results showed that isopropyl alcohol was suitable for the extraction of rebaudioside A from Stevia rebaudiana leaves and the yield of rebaudioside A achieved 35.61g/100g when the output power was 360W and treatment time was 18min. The sonication had influence on the particle size of stevia leaf and the color of the extracted solution. As the sonication intensity increased, the particle size decreased. The colour of differently treated stevia solutions were significantly different (P < 0.05). Separan AP30 and adsorption resin ADS-7 were performed to remove the colour impurity. The results showed that more than 65% of the coloured impurity was removed by Separan AP30 combined with Calcium oxide (CaO).

금속산화물 촉매상에서 플라즈마를 이용한 IPA 저감

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide (Fe2O3) or copper oxide (CuO) was loaded on a monolithic porous α-Al2O3 support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of Fe2O3/α-Al2O3 < CuO/α-Al2O3 < α-Al2O3 from low to high. Under the condition (flow rate: 1 L min -1 ; IPA concentration: 5,000 ppm; O2 content: 10%; discharge power: 47 W), the selectivity towards CO2 was about 40, 80 and 95% for α-Al2O3, CuO/α-Al2O3 and Fe2O3/α-Al2O3, respectively, indicating that Fe2O3/α-Al2O3 is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.

Chemical stability of heparin, isopropanol, and ethanol line lock solutions

BackgroundEthanol line locks are used in the US to prevent catheter associated bloodstream infections. Heparin precipitates in solution with ethanol. However, isopropanol may reduce precipitate formation. We aimed to determine the chemical stability of heparin, isopropanol, and ethanol line lock for a 10day period at 2–8°C and 25°C. MethodsForty samples were prepared for analysis. Each sample was prepared identically using a 5ml syringe capped with a Combi-stopper: 1ml 70% isopropanol, 1ml 70% ethanol, and 1ml heparin sodium 10 IU/ml. Twenty syringes were stored at 2–8°C and 20 at 25°C. Analysis was carried out on days 1, 3, 6, 8, and 10 with a single syringe from each condition being tested in duplicate. Samples were assessed visually. Sub-visible particle count analysis was carried out using a CLIMET particle counting system. Heparin concentration was analysed using an anti-Xa assay. Ethanol and isopropanol concentrations were analysed by gas chromatography. ResultsSamples remained clear and colourless throughout the study. Sub-visible particle counts remained within limits specified in British Pharmacopoeia 2013 when stored at 2–8°C and 25°C, 60% humidity for up to 10days. There was no significant change in ethanol or isopropanol concentration during the study. However, heparin activity fell by >10% after 1day storage and to 65% of original activity after 10days. ConclusionsThis study shows that addition of isopropanol to heparin and ethanol prevents precipitation. However, this solution shows a progressive decline in heparin activity over time making it unsuitable for extended shelf life.

Physicochemical behaviors of cationic gemini surfactant (14-4-14) based microheterogeneous assemblies.

A comprehensive study of micellization and microemulsion formation of a cationic gemini surfactant (tetramethylene-1,4-bis(dimethyltetradecylammonium bromide; 14-4-14) in the absence or presence of hydrophobically modified polyelectrolyte, sodium carboxymethylcellulose (NaCMC), has been conducted by conductometry, tensiometry, microcalorimetry, and fluorimetry methods at different temperatures. Both critical micelle concentration and degree of ionization of the surfactant have been observed to increase with increasing temperature. The interfacial and thermodynamic parameters were evaluated. The standard Gibbs free energy of micellization (ΔGm°) is negative, which decreases with increase in temperature. Larger entropic contribution is observed compared to the enthalpy. The interaction of 14-4-14 with NaCMC produces coacervates which was determined from turbidimetry method. The pseudoternary phase behavior of the microemulsion systems comprising water (or NaCMC as additive), 14-4-14, isopropanol (IP) or n-butanol (Bu) as cosurfactant, and isopropyl myristate (IPM) were studied at 298 K. Phase diagrams reveal that IP derived microemulsions (in the absence of NaCMC) offer a large isotropic region compared to Bu-derived systems at comparable physicochemical conditions. Increasing the concentration of IP or Bu decreases the isotropic region in the phase diagram. NaCMC influences the microemulsion zone, depending upon its concentration, and type of cosurfactant and surfantant/cosurfactant ratio. Dynamic light scattering and conductometric measurements show the size of the droplet, threshold temperature of percolation, scaling parameters, and activation energy of the percolation process of 14-4-14/IP or Bu derived microemulsion systems without/with NaCMC at various physicochemical conditions. Bu exerts a greater effect to reduce θt than IP as a cosurfactant (in the absence of NaCMC) at comparable ω. On the other hand, IP showed better percolating effect than Bu in the presence of NaCMC. Bu and IP (as cosurfactant) and NaCMC (as additive) influenced the microemulsion droplet size (Dh) to different extents under comparable conditions. Temperature insensitive microemulsions have been reported at the studied temperature range (298–353 K). 14-4-14/IP (1:2)-derived microemulsion showed a fractured surface at fixed ω = 15, where ω is the water and surfactant molar ratio, and temperature (298 K); whereas, large scale mesospheres comprising multiple closely winded nanoslices and spheroid morphology were formed in 14-4-14/IP and 14-4-14/Bu microemulsions, respectively, in the presence of 0.01 g % NaCMC, at comparable conditions. These systems revealed good antimicrobial activity toward the strains of Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria at 298 K, and inhibitory effect was governed by ω, type of cosurfactant, and bacterial strains.

촉매-플라즈마 반응 시스템을 이용한 아이소프로필 알코올 산화

본 연구에서는 휘발성유기화합물의 일종인 아이소프로필 알코올(IPA) 산화에 촉매-플라즈마 반응 시스템을 이용하였다. <TEX>${\alpha}-Al_2O_3$</TEX>로 이루어진 다공성 세라믹에 산화구리를 0.5% (w/w) 담지하여 촉매로 사용하였으며, 촉매상에 직접 플라즈마를 생성시켜 표면이 바로 플라즈마에 노출되도록 하였다. 촉매-플라즈마 공정의 특성을 파악하기 위하여 방전전압 및 온도 변화에 따른 IPA 및 분해부산물의 농도를 측정하였다. 촉매-플라즈마 반응기를 단열시키지 않았을 경우, 전압 17 kV (방전전력 : 28 W)에서 반응기 온도가 <TEX>$120^{\circ}C$</TEX>까지 증가하였으며, 유량 <TEX>$1L\;min^{-1}$</TEX> (산소 : 10% (v/v); IPA : 1000 ppm) 조건에서 IPA가 모두 제거되었다. 그러나 <TEX>$120^{\circ}C$</TEX> 이하의 온도에서는 바람직한 생성물인 이산화탄소 이외에도 아세톤, 포름알데하이드, 일산화탄소와 같은 유해 분해 부산물이 생성되었다. 반면 촉매-플라즈마 반응기 외부를 단열했을 때는 같은 조건에서 반응기 내부 온도가 <TEX>$265^{\circ}C$</TEX>까지 증가하였으며, IPA가 대부분 이산화탄소로 산화되었다. 다공성 세라믹에 산화구리를 담지하지 않았을 때는 촉매-플라즈마 반응기를 단열해도 이산화탄소와 일산화탄소가 유사한 비율로 생성되었다. 한편, 플라즈마를 생성시키지 않고 촉매만 단독으로 사용했을 때는(반응온도 : <TEX>$265^{\circ}C$</TEX>), 분해된 IPA의 70% 이상이 또 다른 휘발성유기화합물인 아세톤으로 전환되었으며, 이를 통해 촉매 단독공정보다 촉매-플라즈마 복합 공정이 IPA 산화에 더 효과적임을 알 수 있었다. A catalytic plasma reactor was employed for the oxidation of isopropyl alcohol (IPA) classified as a volatile organic compound (VOC). Copper oxide (Cu : 0.5% (w/w)) supported on a multichannel porous ceramic consisting of <TEX>${\alpha}-Al_2O_3$</TEX> was used as a catalyst, which was directly exposed to the plasma created in it. The effects of discharge voltage and reaction temperature on the concentrations of IPA and its byproducts were examined to understand the behavior of the catalytic plasma reactor. Without thermal insulation, the reactor temperature increased up to <TEX>$120^{\circ}C$</TEX> at an applied voltage of 17 kV (discharge power : 28 W), and the IPA at a flow rate of <TEX>$1L\;min^{-1}$</TEX> (<TEX>$O_2$</TEX> : 10% (v/v); IPA : 1000 ppm) was completely removed. At temperatures below <TEX>$120^{\circ}C$</TEX>, however, besides the desirable product <TEX>$CO_2$</TEX>, several unwanted byproducts such as acetone, formaldehyde and CO were also formed from IPA. On the other hand, when the reactor was thermally insulated, the plasma discharge increased the temperature up to <TEX>$265^{\circ}C$</TEX> under the same condition and most of IPA was oxidized to <TEX>$CO_2$</TEX>. Without loading CuO on the ceramic support, the plasma discharge in the thermally insulated reactor produced nearly equal amounts of <TEX>$CO_2$</TEX> and CO. On comparison, with the catalyst alone (temperature : <TEX>$265^{\circ}C$</TEX>), more than 70% of the removed IPA was simply converted into another type of VOC (acetone), indicating that the catalyst assisted by the plasma is more effective in the oxidation of IPA than that of the catalyst-alone process.

Effect of peroxide and softness modification on properties of ramie fiber

Ramie fiber is one of the natural cellulose fibers that have undergone rapid development due to its good performance. This study confirmed that hydrogen peroxide and isopropyl alcohol can be used as very efficient agents for simultaneous removal of non-cellulosic substances and improvement of ramie fiber properties. The factors influencing the properties of modified fiber with combined chemicals were investigated. Optimum treatment conditions were achieved at 85 °C, 60 min, pH 11.0, hydrogen peroxide concentration 7 %, and isopropyl alcohol concentration 4 %. SEM, XRD, and FT-IR were used to elucidate the effects of preparation and modification. Results showed that fiber preparation and chemical modification process in the same bath solution could successfully remove most of the gummy materials. The treated fibers demonstrated improved softness, elongation, and fineness properties as compared to the alkali or peroxide method.

Fabrication of SiO2–ZrO2 (50/50) membranes on the porous stainless steel-tube support for pervaporation

The SiO2–ZrO2 membranes were fabricated with silica–zirconia sols on a porous stainless steel-tube support (O.D. = 10 mm, length = 20 mm, 316L SUS, Mott Corp. USA) by a dipping–rolling–freezing–fast drying (DRFF) and/or soaking–rolling–freezing–fast drying (SRFF) method. After coating of SiO2–ZrO2 sol, single gas permeation characteristics (He, H2, and N2) for SiO2–ZrO2 membranes were evaluated at room temperature, and the pervaporation experiments were performed at a specified feed isopropyl alcohol concentration of 90 wt% at 50°C with silica–zirconia membranes. The morphology of surface and the cross sections of the membrane were investigated with FE-SEM analysis. Judging from FE-SEM analysis, the surface of silica–zirconia membrane on the PSS tube support was denser, and the number of surface defects considerably reduced than DRFF method, and the additional modification via the SRFF significantly diminished surface defects, which could not be avoided during the DRFF step. The membrane the silica–zirconia membrane showed hydrogen permeability under 10−7 mol m−2 s−1 Pa−1 and low water selectivity in the range of 10–23. The silica–zirconia membranes with a smooth surface on the stainless steel tube supports, was quite well prepared by the DRFF and SRFF method in this study.

A case of complete hydatidiform mole with coexistent fetus leading to peripartum cardiomyopathy

The cell-associated glucansucrase from Leuconostoc citreum SK24.002 was isolated, purified, characterized and used for de novo synthesis of α-glucan and acceptor-products. The final specific glucansucrase activity was 1.4 U/mg protein with 13.2-fold purification. The obtained glucansucrase had a molecular weight of 186 kDa, Tm of 61.7 °C and ⿳H of 176.7 kJ/mol. The enzyme showed maximum activity at pH 5.0-6.0 and 45 °C. The enzyme activity was enhanced by Ca2+, Mn2+ or Co2+ ions, whereas the activity decreased as the methanol, ethanol, n-butanol, DMSO or isopropanol concentration increased. The chemical inhibitors including BD, DTNB, EDC or NBS also significantly inhibited enzyme activity. Km, Vmax and kcat of glucansucrase were 10.9 mM, 3.6 U/mg and 306.6 1/s, respectively. For de novo synthesis from sucrose, α-glucan polymer with molecular weight of 1.5 ÿ 107 g/mol and maltose acceptor products (trisaccharide, tetrasaccharide and pentasaccharide) were obtained by glucansucrase via glucosyltransfer reactions, respectively.

Graphene-coated quartz crystal microbalance for detection of volatile organic compounds at room temperature

The detection of volatile organic compounds (VOCs) at room temperature with rapid response and recovery is important for early explosive alarm. Herein, we demonstrate significantly enhanced VOC-sensing properties of quartz crystal microbalance (QCM) coated with monolayer graphene film. The monolayer graphene was firstly synthesized by the chemical vapour deposition (CVD) method on Cu foil and then transferred to the gold electrode of the QCM for VOC-sensing application. The gas-sensing properties of the graphene-coated QCM sensor were examined at room temperature for various concentrations of numerous VOCs, including butanol, isopropanol, acetone, and ethanol. The results revealed that the graphene-coated QCM sensor exhibits the best performance with ethanol gas. The gas-sensing mechanism of the graphene-coated QCM sensor was attributed to the adsorption and desorption of VOC molecules on the defect sites of graphene sheet.

Application of Response Surface Methodology for Optimization of Permeabilization Process of Baker’s Yeast

Abstract Permeabilization was used for the purpose of transforming the cells of microorganisms into biocatalysts with an enhanced enzyme activity. Baker’s yeast cells were permeabilized with various organic solvents. A high degree of catalase activity was observed upon permeabilization with acetone, chloroform, isopropyl alcohol and ethyl acetate. Response surface methodology was used to model the effect of concentration of isopropyl alcohol, temperature and treatment time on the permeabilization of baker’s yeast cells to maximize the decomposition of H2O2. The optimum operating conditions for permeabilization were observed at 53.7% concentration of isopropyl alcohol, treatment time of 40 min and temperature of 15.6oC. A maximum value of catalase activity was found to be 6.188 U/g wet wt. and was ca. 60 times higher than the catalytic activity of yeast not treated by the permeabilization process.

Process optimization for reverse micellar extraction of stem bromelain with a focus on back extraction

In the current study, reverse micellar extraction (RME) for the purification of stem bromelain was successfully achieved using the sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane system. A maximum forward extraction efficiency of 58.0% was obtained at 100 mM AOT concentration, aqueous phase pH of 8.0 and 0.2 M NaCl. Back extraction studies on altering stripping phase pH and KCl concentration, addition of counter-ion and iso-propyl alcohol (IPA) and mechanical agitation with glass beads indicated that IPA addition and agitation with glass beads have significant effects on extraction efficiency. The protein extraction was higher (51.9%) in case of the IPA (10% v/v) added system during back extraction as compared to a cetyltrimethylammonium bromide (100 mM) added system (9.42%). The central composite design technique was used to optimize the back extraction conditions further. Concentration of IPA, amount of glass beads, mixing time, and agitation speed (in rpm) were the variables selected. IPA concentration of 8.5% (v/v), glass bead concentration of 0.6 (w/v), and mixing time of 45 min at 400 rpm resulted in higher back extraction efficiency of 45.6% and activity recovery of 88.8% with purification of 3.04-fold. The study indicated that mechanical agitation using glass beads could be used for destabilizing the reverse micelles and release of bromelain back into the fresh aqueous phase.