Nature Of Organic Solvent Research Articles

Extraction of trace amounts of pioglitazone as an anti-diabetic drug with hollow fiber liquid phase microextraction and determination by high-performance liquid chromatography-ultraviolet detection in biological fluids

The applicability of hollow fiber liquid phase microextraction (HF-LPME) for extraction and preconcentration of trace amounts of pioglitazone (PGL) as an anti-diabetic drug in biological fluids, prior to determination by high-performance liquid chromatography (HPLC), was evaluated. In this technique, the target drug was extracted into di- n-hexyl ether immobilized in the wall pores of a porous hollow fiber from 10 mL of the aqueous sample (source phase, SP) with pH 8.0, and then back extracted into the receiving phase (RP) with pH 2.2 located in the lumen of the hollow fiber. The extraction occurred due to a pH gradient between the two sides of the hollow fiber. After extracting for a prescribed time, 24 μL of the RP solution was taken back into the syringe and injected directly into a HPLC instrument for quantification. The Taguchi orthogonal array (OAD) experimental design with an OA 16 (4 5) matrix was employed to optimize the HF-LPME conditions. Different factors affecting the HF-LPME efficiency such as the nature of organic solvent used to impregnate the membrane, pH of the SP and RP, stirring speed, extraction time and ionic strength were studied and optimized. Under the optimum conditions (di- n-hexyl ether as membrane impregnation solvent, pHs of the SP and RP equal to 8.0 and 2.2, respectively, extraction time of 30 min, stirring speed of 500 rpm and 10% (w/v) NaCl for adjusting the ionic strength), preconcentration factor of 180, linear dynamic range (LDR) of 2.5–250 μg L −1 with good correlation of determination ( r 2 > 0.998) and limit of detection (LOD) of 1.0 μg L −1 were obtained for the target drug. The percent relative intra-day and inter-day standard deviations (RSDs%) based on five replicate determinations were 4.7 and 15%, respectively. Once LPME was optimized, the performance of the proposed technique was evaluated for the determination of PGL in different types of biological fluids such as plasma and urine samples. The results showed that the proposed HF-LPME method could be successfully applied to determine trace amounts of PGL in biological samples.

The solvation of L-serine in mixtures of water with some aprotic solvents at 298.15 K

The integral enthalpies of solution ΔsolHm of L-serine in mixtures of water with acetonitrile, 1,4-dioxane, dimethylsulfoxide (DMSO), and acetone were measured by solution calorimetry at organic component concentrations up to 0.31 mole fractions. The standard enthalpies of solution (ΔsolH°), transfer (ΔtrH°), and solvation (ΔsolvH°) of L-serine from water into mixed solvents were calculated. The dependences of ΔsolH°, ΔsolvH°, and ΔtrH° on the composition of aqueous-organic solvents contained extrema. The calculated enthalpy coefficients of pair interactions of the amino acid with cosolvent molecules were positive and increased in the series acetonitrile, 1,4-dioxane, DMSO, acetone. The results obtained were interpreted from the point of view of various types of interactions in solutions and the influence of the nature of organic solvents on the thermochemical characteristics of solutions.

Organometallic catalysis in aqueous–organic two-phase systems: Rhodium-catalyzed coupling reaction of but-3-enoic acid with allyl derivatives; influence of the reaction media

A simple and efficient procedure is described for the synthesis of 2,6- and 3,6-heptadienoic acids and allyl esters consisting of Rh-catalyzed coupling of but-3-enoic acid and allyl derivatives such as allyl bromide, allyl acetate, and allyl methyl carbonate in alkaline water or in alkaline water/organic two-phase systems. 2,6-Heptadienoate derivatives are the main products in water as acids and in biphasic systems as acids and allyl esters. The latter can be selectively obtained via one-pot cascade esterification reaction using allyl bromide in biphasic systems. The nature of organic solvent, the base concentration and the addition of triphenylphosphine (TPP) in biphasic media allow to tune the regioselectivity of the reaction towards 3,6- or 2,6-derivatives. Substituted but-3-enoic acids and allyl bromides, and pent-4-enoic acid led to moderate or poor results.

Extraction and determination of trace amounts of chlorpromazine in biological fluids using hollow fiber liquid phase microextraction followed by high-performance liquid chromatography

In the present work, hollow fiber liquid phase microextraction (HF-LPME) in conjunction with reversed-phase HPLC/UV was developed for extraction and determination of trace amounts of chlorpromazine in biological fluids. The drug was extracted from an 11 ml aqueous sample (source phase; SP) into an organic phase impregnated in the pores of the hollow fiber (membrane phase; MP) followed by the back-extraction into a second aqueous solution (receiving phase; RP) located in the lumen of the hollow fiber. The effects of several factors such as the nature of organic solvent, compositions of SP and RP solutions, extraction time, ionic strength and stirring rate on the extraction efficiency of the drug were examined and optimized. Under the optimal conditions, enrichment factor of 250, dynamic linear range of 1–500 μg l −1, and limit of detection of 0.5 μg l −1 were obtained for the drug. The percent relative intra-day and inter-day standard deviation (R.S.D.%) based on three replicate determinations were 6.7 and 10.3%, respectively. The method was applied to drug level monitoring in the biological fluids and satisfactory results were obtained.

Separation of Phosphodiester Oligodeoxynucleotides and Phosphorothioate Antisense Oligodeoxynucleotides by Capillary Zone Electrophoresis at a Low pH

Oligodeoxynucleotides (ODNs) may possess biological activity in vivo, and are used for the cancer therapeusis. Synthesized ODNs contains many by-products, and so their purity check and resolution of single-base, i. e., the separation of ODNs differing by one nucleotide in length, become necessary. In this study, capillary zone electrophoresis (CZE) method was developed for the separation of two sets of model compounds of single-stranded oligodeoxynucleotide mixtures (18 - 20 mers), phosphodiester oligodeoxynucleotides (PO-ODNs) and their phosphorothioate modifications (PS-ODNs), with equal sequences differing in a single base. The effects of the CZE operating parameters on the separation were investigated and optimized to further improve the resolution, such as the pH values and the concentrations of running buffer, the varieties and concentrations of additives, the separation voltage as well as the temperature. It was confirmed that the pH value of the buffer played the most important role in the separation, and the urea used as the additive in the system improved significantly the resolution of PS-ODNs. Consequently, the PO-ODNs and PS-ODNs mixtures could be single-based separated on a fused-silica capillary of 50 microm x 49.0 cm (40.7 cm of effective length) under the optimum conditions: the running buffer system of 50 mmol/L NaH2PO4-H3PO4 (pH 2.24)-7 mol/L urea, the pressure injection of 2 kPa x 10 s, the separation voltage of -20 kV, the column temperature of 25 degrees C, and the ultraviolet (UV) detection at 260 nm. The average resolutions for the separation of 18 - 19 mers and 19 - 20 mers of PO-ODNs were 4.68 and 3.20, respectively; and the average resolutions for the separation of 18 - 19 mers and 19 - 20 mers of PS-ODNs were 1.23 and 0.81, respectively. The relative standard deviations of the migration time and the resolution were all less than 5%. This method will be useful for the qualification of PO-ODNs and PS-ODNs samples as they are used in antisense drug development due to the relatively easy operation and good reproducibility of the method in comparing with the capillary gel electrophoresis.

Effect of nature of organic solvent on the absorption spectrum of C60 fullerene

Absorption spectrums of C60 fullerene in 10 various organic solvents in the range of 300–620 nm was studied. In all the solvents the C60 fullerene has four absorption maxima in the range under study. When an aromatic solvent has an ionization potential of 8.1 eV or lower a new additional absorption band appears in the absorption spectrum of C60 fullerene, caused by the formation of a charge-transfer complex (CTC) of the solvent and C60 fullerene.

Nanoparticles formation for metallocene catalyzed cyclic olefin copolymer via a continuous supercritical anti-solvent process

Nanoparticles of the metallocene catalyzed cyclic olefin copolymer (mCOC) were prepared with a lab scale continuous supercritical anti-solvent (SAS) apparatus. Several experimental parameters were investigated to explore their influences on the morphology and the mean size of the products. These parameters included the character of carbon dioxide injector, precipitation pressure and temperature, anti-solvent density, the polymer concentration, the flow rate of feed, and the nature of organic solvents. The phase states of the mixtures of solvent + anti-solvent in precipitation stage may govern the mean size of the resulting particles. Nanoparticles of mCOC were obtained in the homogeneous compressed liquid or supercritical region, while sub-micrometric particles were formed in the vapor–liquid coexistence region. The morphology of precipitates was also significantly changed, turning from spherical nanoparticles to microfibrils, as the polymer concentration of feed was increased from 2 to 4 wt.%. Under 15 MPa and 306.2 K, the mean size of the resultant primary mCOC particles as small as 39 nm with a standard deviation of about 6 nm could be produced. The residual solvent was about 1.6 wt.% in the sample after SAS processing by analyzing with a thermogravimetric analyzer (TGA), and the particle samples exhibited sub-glass transition behavior according to the thermal histograms of differential scanning calorimeter (DSC).

Extraction and preconcentration of salbutamol and terbutaline from aqueous samples using hollow fiber supported liquid membrane containing anionic carrier

This paper presents a new three-phase liquid-phase microextraction (LPME) strategy for extraction and preconcentration of salbutamol (SB) and terbutaline (TB) from aqueous samples, including urine. The drugs were extracted from 11 ml of aqueous sample (source phase; SP) into an organic phase with microliter volume located inside the pores of a polypropylene hollow fiber, and then back-extracted into 24 μl of a second aqueous solution as the receiving phase (RP), located in the lumen of the hollow fiber. In preliminary experiments, we tried to transport the drugs using a pH gradient between the two sides of the hollow fiber. Due to the existence of both amine and phenolic groups on the drugs, very little transport occurred and enrichment factors (EF) less than one were obtained. Further experiments were done in the presence of bis(2-ethylhexyl) monohydrogenphosphoric acid (D2EHPA) or methyltrioctylammonium chloride (Aliquat 336) in the organic phase, to extract drugs from acidic and basic matrices, respectively. Results showed that transport of drugs from alkaline solution into 1 M of sodium bromide occurred when the membrane was impregnated with dihexyl ether containing 20% Aliquat 336. To optimize the EF, the effects of different parameters such as the nature of organic solvent used to impregnate the membrane, compositions and volumes of SP and RP, type and concentration of carrier, extraction time and stirring rate were investigated. Optimal results were obtained in the presence of 0.005 M of NaOH (pH 11.70) in the SP, 1 M of NaBr in the RP, 20% of Aliquat 336 in dihexyl ether as membrane impregnation solvent, stirring rate of 500 rpm and extraction time of 60 min. Under these conditions, enrichment factors of 52.9 and 213.1, dynamic linear ranges of 20–5000 and 10–5000, and limits of detection of 2.5 and 0.5 ng/ml were obtained for salbutamol and terbutaline, respectively. Also determination of drugs in environmental water and urine samples in the range of nanograms per millilitre with RSDs < 10% was possible using HPLC–photodiode array detection or HPLC–MS.

Liquid-phase microextraction for sample preparation in analysis of unconjugated anabolic steroids in urine

The applicability of in-vial two-phase liquid-phase microextraction (LPME) in porous hollow polypropylene fiber was studied for the sample preparation of unconjugated anabolic steroids in urine. Four different anabolic steroids – metabolites of fluoxymesterone, 4-chlorodehydromethyltestosterone, stanozolol and danazol – were used as test compounds and methyltestosterone as an internal standard. A standard two-phase LPME method for use with liquid chromatography/mass spectrometry (LC/MS) was set up and the influence of different parameters, including the nature of organic solvent, extraction time, salting-out and temperature, on the LPME process was investigated. Taking advantage of the preliminary studies, a novel two-phase LPME method utilizing simultaneous in-fiber silylation was developed and validated for gas chromatographic/mass spectrometric (GC/MS) analysis of a danazol metabolite in urine. In all, LPME allowed a very straightforward, simple and selective way to prepare urine samples for steroid analysis, being most suitable for hydrophobic steroids. The LPME method with in-fiber derivatization for GC/MS analysis exhibited high sensitivity, repeatability and linearity and enabled simultaneous filtration, extraction, enrichment and derivatization of the analyte from urine matrix without any other steps in sample pretreatment.

Theory of Retention in Reversed Phase Liquid Chromatography with Ternary Mobile Phases

The partition model of retention is developed for reversed phase liquid chromatography with multicomponent mobile phases. Simple equations for the retention and selectivity in ternary mobile phases are derived. For the systems in which the ratio of volume fractions of organic modifiers remains fixed, new linear dependences for retention factor and selectivity are proposed. These equations are successfully used to describe experimental data found in the literature. An influence of the nature of organic solvents and proportion in which they are mixed on retention and selectivity is discussed.

Random Macropore Formation in p-Type Silicon in HF-Containing Organic Solutions: Host Matrix for Metal Deposition

Random macropore formation in variously doped p-type silicon substrates by electrochemical anodization in aqueous HF-containing dimethylsulfoxide, dimethylformamide, or acetonitrile was investigated under different operating conditions. A systematic study of the effect of the main parameters controlling the macropore formation is reported. The results revealed that the nature of organic solvent, the concentration of HF, and the substrate doping level play major roles in determining pore formation and morphology. Also, the behavior of these macropores in contact with an aqueous solution of in the dark and at room temperature is investigated and a possible reaction mechanism for the deposition process is proposed.

Potential application of waste activated bleaching earth on the production of fatty acid alkyl esters using Candida cylindracea lipase in organic solvent system

Production of fatty acid alkyl esters by lipase-catalyzed alcoholysis of waste plant oil from oil processing industry with primary alcohols in an organic solvent system was investigated. The catalytic activity of several commercial lipases on waste vegetable oil absorbed in activated bleaching earth and in organic solvent system was screened. Alcoholysis of palm oil with methanol was chosen for optimization of reaction conditions. Several variables, such as alcohol molar ratio, effect of organic solvent nature, and enzyme concentration were examined. Lipase from Candida cylindracea showed the highest activity in n-hexane only when waste activated bleaching earth was present, and during the first 4 h of reaction more than 78±6% (w/w) fatty acid alkyl ester with short chain length alcohols was attained. When C. cylindracea lipase-catalyzed alcoholysis with 1-butanol, 96% (w/w) of fatty acid alkyl ester was produced in 8 h of reaction, but low activity was displayed in the presence of long chain alcohols. Reverse catalyzed reaction was also observed after reaching maximum conversion, leading to a gradual decrease in alkyl ester concentration. These results show a promising reutilization method of industrial waste resources containing waste vegetable oils for the production of fatty acid alkyl esters targeted for biodiesel application.

Enhanced Enzyme Activity and Enantioselectivity of Lipases in Organic Solvents by Crown Ethers and Cyclodextrins

Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated βCyD (Me1.78βCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30°C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78βCyD-PCL co-lyophilizate, the reaction rate even at 0°C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds.

Enhanced enzyme activity and enantioselectivity of lipases in organic solvents by crown ethers and cyclodextrins

Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated βCyD (Me1.78βCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30°C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78βCyD-PCL co-lyophilizate, the reaction rate even at 0°C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds.

Effect of organic solvents on stability and activity of two related alcohol dehydrogenases: a comparative study

A comparative study was performed regarding the catalytic activity and stability of two related enzymes (thermophilic alcohol dehydrogenase from Thermoanaerobacter brockii and its mesophilic counterpart from yeast) in the presence of a number of miscible and immiscible organic solvents. The study was performed in view of the practical usefulness of organic solvents for alcohol dehydrogenases which have been shown to catalyse a variety of industrially-important dehydrogenation reactions. A number of organic solvents of different physicochemical characteristics were used and substantial stabilization was achieved. The non-polar solvents utilized showed the ability to enhance thermal stability of both proteins. Protection against thermal denaturation was especially pronounced by n-dodecane, the solvent with the highest log P used in the present study. Dimethylformamide and dioxane, employed as two miscible organic solvents, showed the ability to cause substrate inhibition and changes in protein conformation as indicated by kinetic and fluorescence studies. A higher resistance of the thermophilic protein to the deleterious effect of pyridine and thermostabilization of the mesophilic enzyme by non-polar solvents are especially emphasized. Combined differences in protein structure and nature of organic solvents are suggested to explain the differences in stability and catalytic activity observed in the present investigation.

A Novel Strategy for Synthesis of Optically Active Polyanilines in Organic System

Abstract Optically active polyanilines that were readily soluble in various organic solvents were prepared by oxidation of aniline with an electron acceptor, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in the presence of (+)- or (−)-camphorsulfonic acid (CSA). Their chiroptical properties in solutions are strongly dependent on the nature of organic solvents and structure of monomers.

Surfactant–lactoperoxidase complex catalytically active in organic media

A surfactant–lactoperoxidase (LPO) complex catalytically active in organic solvents was developed by the emulsion coating method. The oxidation of 2,6-dimethoxyphenol (2,6-DMP) was conducted by the surfactant–LPO complex in organic media. The LPO complex efficiently catalyzed the oxidation of 2,6-DMP in various organic solvents, although lyophilized LPO did not display the catalytic activity at all. To optimize the preparation and reaction conditions for the surfactant–LPO complex, we examined the effects of pH value in the water pools of W/O emulsions, kinds of oxidants, and the nature of organic solvents on the oxidation reaction. Its optimum activity was obtained when the pH value of the aqueous enzyme solution was adjusted to ca. 8 at the preparation stage. The LPO complex exhibited the highest catalytic activity in chloroform when H 2O 2 was employed as the oxidant. Furthermore, the storage stability of the surfactant–LPO complex was far better than that of the surfactant–horseradish peroxidase complex. This high storage stability of the LPO complex will be a benefit for industrial usage of peroxidases.

Parameters influencing the antigen release from spray-dried poly( dl-lactide) microparticles

Microparticles were produced by spray-drying from a high molecular weight polylactide (PLA R207) for the development of long-lasting controlled release systems of vaccines, which may be designed to obviate the need for booster doses. The current investigation considered the effect of both technological parameters (inlet air temperature and spray rate of feed) and polymeric solutions (polymer concentration and nature of organic solvents) on characteristics of microparticles (morphology, size and antigen loading) containing a water-soluble model antigen (bovine serum albumin, BSA). Following parameters chosen, microparticles were characterized by a mean size from 3.08±0.06 to 9.43±0.26 μm and a BSA loading from 2.45±0.13 to 18.20±2.25% (w/w). The BSA release rate from microparticles varied from 11.17±2.20 to 92.60±3.46% in 24 h. The modification of the inlet temperature, the spray-rate of feed or the use of a mixture of dichloromethane/chloroform (DCM/CFM) instead of DCM alone resulted in the modification of the BSA burst release. This burst release was followed by a BSA release rate slower for microparticles with a low BSA loading. Moreover, the increase of the R207 concentration resulted in a decrease of the BSA release rate while the burst release was not modified. SDS-PAGE electrophoresis and isoelectric focusing analyses of the BSA released from microparticles confirmed the preservation of its physicochemical characteristics. Together, results showed that the spray-dried microparticles loaded with hydrophilic antigen could be used as a potential delivery system for the long-lasting controlled release of vaccines.

Preparation of detergent-lipase complexes utilizing water-soluble amphiphiles in single aqueous phase and catalysis of transesterifications in homogeneous organic solvents

A novel method of preparing detergent-enzyme complexes that can be employed in organic media was developed utilizing newly synthesized water-soluble nonionic gemini-type detergents, N,N-bis(3- d-gluconamidopropyl)-3-(dialkyl- l-glutamatecarbonyl)propanamides (BIG2CnCA: n = 10,12,14,16,18) and N,N-bis(3- d-lactonamidopropyl)-3-(dialkyl- l-glutamatecarbonyl)propanamides (BIL2CnCA: n = 16,18), and nonionic twin-headed detergents, N,N-bis(3- d-gluconamidopropyl)alkanamides (BIG1Cn: n = 12,14,16,18,Δ 9). This method simply entails mixing a selected enzyme with an appropriate detergent in an aqueous solution followed by lyophilization, and it offers the advantages of enhanced enzymatic activity in organic solvents and eliminates both enzyme loss and the necessity for an organic solvent in the preparation stage. Using various modified lipases originating from Aspergillus niger (Lipase A), Candida rugosa (Lipase C), Pseudomonas cepacia (Lipase P), and porcine pancreas (PPL), prepared using the novel method and detergents, including conventional synthesized nonionic detergents such as dialkyl N- d-glucona- l-glutamates (2CnGE: n = 12,18Δ 9) and octanoyl- N-methylglucamide (MEGA-8), enantioselective transesterifications of 6-methyl-5-hepten-2-ol (sulcatol) and 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) with a vinyl or isopropenyl carboxylate were carried out in an organic solvent. The modified lipase activity was influenced by both the lipases and the structure of the detergents. The value for the hydrophile-lipophile balance (HLB) of the detergent provided a means of correlating the structure and the obtained modified lipase activity. For detergents of the same class with a HLB value of approximately 9 and 12, the highest activity was obtained for Lipase A and Lipase P, and Lipase C and PPL, respectively. Among detergents of the same HLB value tested, the gemini-type detergents possessing the most bulky head and tail were most effective as a modifier for lipases of all types. The preparation and reaction conditions for these novel gemini-type detergent-modified lipases were optimized using BIG2C 12CA (HLB = 9.4) by studying the effect of the detergent/lipase ratio and the nature of organic solvents on the complex formation. The high enzymatic activities of the BIG2C 12CA-modified lipases were independent of the solubility of the lipases in organic solvents, unlike in the case of 2CnGE-modified lipases prepared using the conventional suspension system.

Preparation of Detergent-Lipase Complexes Utilizing Water-Soluble Amphiphiles in Single Aqueous Phase and Catalysis of Transesterifications in Homogeneous Organic Solvents.

A novel method of preparing detergent-enzyme complexes that can be employed in organic media was developed utilizing newly synthesized water-soluble nonionic gemini-type detergents, N,N-bis(3-D-gluconamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIG2CnCA: n = 10,12,14,16,18) and N,N-bis(3-D-lactonamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIL2CnCA: n = 16,18), and nonionic twin-headed detergents, N,N-bis(3-D-gluconamidopropyl)alkanamides (BIG1Cn: n = 12,14,16,18,delta9). This method simply entails mixing a selected enzyme with an appropriate detergent in an aqueous solution followed by lyophilization, and it offers the advantages of enhanced enzymatic activity in organic solvents and eliminates both enzyme loss and the necessity for an organic solvent in the preparation stage. Using various modified lipases originating from Aspergillus niger (Lipase A), Candida rugosa (Lipase C), Pseudomonas cepacia (Lipase P), and porcine pancreas (PPL), prepared using the novel method and detergents, including conventional synthesized nonionic detergents such as dialkyl N-D-glucona-L-glutamates (2CnGE: n = 12,18delta9) and octanoyl-N-methylglucamide (MEGA-8), enantioselective transesterifications of 6-methyl-5-hepten-2-ol (sulcatol) and 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) with a vinyl or isopropenyl carboxylate were carried out in an organic solvent. The modified lipase activity was influenced by both the lipases and the structure of the detergents. The value for the hydrophile-lipophile balance (HLB) of the detergent provided a means of correlating the structure and the obtained modified lipase activity. For detergents of the same class with a HLB value of approximately 9 and 12, the highest activity was obtained for Lipase A and Lipase P, and Lipase C and PPL, respectively. Among detergents of the same HLB value tested, the gemini-type detergents possessing the most bulky head and tail were most effective as a modifier for lipases of all types. The preparation and reaction conditions for these novel gemini-type detergent-modified lipases were optimized using BIG2C12CA (HLB = 9.4) by studying the effect of the detergent/lipase ratio and the nature of organic solvents on the complex formation. The high enzymatic activities of the BIG2C12CA-modified lipases were independent of the solubility of the lipases in organic solvents, unlike in the case of 2CnGE-modified lipases prepared using the conventional suspension system.