Hydrophilic-lypophilic Balance Research Articles

Simultaneous determination of eight neonicotinoid insecticides, fipronil and its three transformation products in sediments by continuous solvent extraction coupled with liquid chromatography-tandem mass spectrometry.

Neonicotinoids (NEOs) and fipronil (FIP) are insecticides that are widely used in modern agriculture and have received considerable attention in recent years due to their adverse effects on non-target organisms in the environment. In the present study, a new method to simultaneously detect eight common NEO insecticides and FIP and its three transformation products (FIPs) in sediments was developed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) based on a combined pretreatment of continuous solvent extraction (CSE) and solid phase extraction (SPE). Under optimized conditions, 5.0g of freeze-dried sediment samples were initially extracted with methanol (20mL)-methanol (15mL)-water (20mL) in sequence, and then the extract was cleaned with hydrophilic-lypophilic balance SPE cartridges, and HPLC-MS/MS analysis was conducted. The established method was validated to be sensitive, linear, accurate, and precise. The limits of detection (LOD) and limits of quantification (LOQ) of target compounds were 0.012-0.055μg/kg d.w and 0.031-0.091μg/kg d.w, respectively. Good linearity (R2>0.990) was observed between 4.0×10-2 and 20.0μg/kg d.w. The recovery rates of all target insecticides were between 75.5% and 98.5%, and the relative standard deviations (RSD) were all less than 15.0% at the low, medium, and high spiked levels. Finally, the optimized method was applied to analyze 12 target insecticides in the sediments obtained from Jiaozhou Bay of China and its main inflow rivers. Acetamiprid, thiamethoxam, fipronil sulfide, and fipronil sulfone were detected in the river sediment samples at the concentration from <LOQ to 0.197μg/kg d.w. Thus, the two types of studied insecticides can enter the sedimentary environment. Overall, the proposed method can be used to investigate the contamination status of typical NEOs and FIP insecticides in sediments and provide base data to comprehensively understand their environmental behavior, safety, and fate.

Formulation of plant based insecticides, their bio-efficacy evaluation and chemical characterization

The aim of this study was to develop Emulsifiable Concentrate (EC) formulations from seed oils of Pongamia pinnata L., Pachyrhizus erosus L. and Annona squamosa L. Insecticidal efficacy of developed formulations was tested in-vitro against cabbage aphid (Brevicoryne brassicae L.) and in-vivo against aubergine aphid (Aphis gossypii G.) and whitefly (Bemisia tabaci G.). EC formulations comprising of seeds extract (40%) were prepared using bio-degradable solvents (50%) and emulsifier blends (10%) with hydrophilic-lypophilic balance (HLB) value (12.54) suitable for the seed oils formulation. Among nine EC formulations prepared from seed oils of each plant, EC-1 type performed well in terms of emulsion stability, cold test, accelerated storage and flash point test indicating feasibility for their commercial production. In-vitro study of A. squamosa 40 EC at 1% dose caused the maximum mortality of 80.7% (LC50 = 0.08%) against B. brassicae at 72 h after the treatment. The bio-efficacy was comparable with the synthetic insecticide dimethoate 30 EC at 0.1% dose. Besides A. squamosa, the 40 EC formulation of P. pinnata at 1% dose having 70.6% mortality at 72 h after treatment (LC50 = 0.19%) was also found promising. In-vivo studies in brinjal also indicated the maximum reduction of aphids (67.3–72.3%) and whiteflies (67.5–75.6%) within 5–14 days after application of A. squamosa 40 EC formulation at 1.0% dose followed by P. pinnata 40 EC. The total flavonoids and phenolic content in all the crude seed extracts varied from 20.9 to 53.9 mg QE/g and 5.8–9.5 mg GAE/g, respectively. Further analysis of the extracts by GC-MS revealed some bioactive constituents belonging to fatty acids, esters, aldehyde, phenols, etc. The study unveiled its significance in developing herbal insecticidal formulations as an alternative to harmful synthetic chemical insecticides and a step forward towards development of a promising eco-friendly technology in crop protection.

Mixed surfactant (altering chain length and head group) aggregates as an effective carrier for tuberculosis drug

Surface properties and aggregation behavior of cationic-cationic and cationic-non-ionic mixed surfactant systems viz. Dodecylethyldimethylammonium bromide (DDAB) with a series of double chain cationic surfactants (DiDDAB, DMDTAB, and DODAB) and non-ionic surfactants (Brij 96, Tyloxapol and Tween 80) were analysed using surface tension and transmission electron microscopy (TEM). The effect of chain length of cationic surfactant and hydrophilic-lypophilic balance (HLB) prominently observed in critical aggregation (cac) value. The aqueous solubility of anti-tuberculosis drug: rifampicin (RIF) was comparatively studied by UV–vis spectroscopy in presence of formulated micelles and vesicles. RIF was significantly solubilised in aqueous medium using all the formulated aggregates. RIF is very unstable in basic medium (above pH-7) and in oxidizing media. Therefore, stability at pH-13 as well as in strong oxidising environment was monitored using UV–vis spectroscopy. To trace the locus of the drug encapsulation in the micelles/vesicles, fluorescence spectroscopy and TEM studies were carried out. Both the techniques stemmed in complimentary results and confirmed that, RIF is majorly populated at polar medium in cationic-cationic vesicles and favour to reside at hydrophobic medium of the nonionic-cationic micelles.

The structure and activity of fungal lipases in bile-salt solutions

The changes in structure and catalytic properties of fungal lipases (Candida rugosa, Rhizomucor miehei, Mucor javanicus) were investigated in micellar solutions of bile salts that differ in hydrophilic-lypophilic balance and reaction medium properties. The methods of circular dichroism and tryptophan fluorescence were applied to estimate the changes in peptide structure within complexes with bile salt micelles. Bile salts do not exert a significant influence on the structure of the enzymes under study: in Rh. miehei and M. javanicus lipases the alpha helix content slightly decreased, the influence of bile salts on the C. rugosa structure was not revealed. Despite negligible structural modifications in the enzymes, in bile salt solutions a considerable change in their catalytic properties was observed: an abrupt decrease in catalytic effectiveness. Substrate-bile salts micelles complex formation was demonstrated by the NMR self-diffusion method. The model of a regulation of fungal lipase activity was proposed.

Synthesis and Heteroannulation of Pyridine and Related Heterocyclic Systems Having Surface and Biological Activities.

Possible approaches to the synthesis of functionalized, pyrazole, isoxazole, pyrimidine, pyridine and fused pyridine derivatives The sequence involves the heterocyclization of ethyl 3-oxo-2-(4-stearamidobenzoyl)butanoate (3) with appropriate reagents. Propoxylated of these heterocycles using propylene oxide to produce nonionic surface active agents having a long alkyl chain with molecular weight suitable for becoming an amphiphilic molecule with correct hydrophilic-lypophilic balance which enhances solubility, biodegradability and hence lowers the toxicity to human beings and becomes environmentally friendly. The antimicrobial activity of the newly synthesized was examined and it was found that some of these compounds have similar or higher activity compared with commercial antibiotic drugs (sulphadiazine), which make them suitable for diverse applications like the manufacturing of drugs, pesticides, emulsifiers, cosmetics, etc.

Sustainable Building Blocks for Today's Chemistry: Hydrophilic/lipophilic Balance of Cellulosic Nanobiomaterials

In an effort to obtain systems with ability to act as a surfactant, new types of amphiphilic graft and block copolymers were synthesized based on hydrophobic cellulose triacetate (CTA) and hydroxyl terminated oligomeric species of CTA (HCTA) by using hydrophilic polyethylene oxide (PEO) with Mn 600 and 2000 as [CTA-g-PEO, 600]; [CTA-g-PEO, 2000]; [HCTA-co-PEO, 600] and [HCTA-g-PEO, 2000], respectively. The structural, physicochemical and morphological properties of the copolymers were determined by using FTIR, 1H NMR, GPC, differential scanning calorimetry (DSC), intrinsic viscosity measurements, dynamic light scattering (DLS) and transmission electron microscopy (TEM). X-ray diffraction patterns as well as DSC thermograms indicate that the HCTA is indeed in the CTA II state. The obtained results indicated that the hydrophobic blocks make a significant influence on the physicochemical characteristics of the synthesized surfactants. Moreover, a comparison of the crystalinity of the synthesized surfactants indicated that their structures are influenced by hydrophilic/lypophilic balance (HLB). Consequently, to regulate a suitable formulation of amphiphilic copolymer in water, a highly hydrophobic surfactant is necessary. Our experiments to tune up cellulosic surfactants with the best optimized HLB are ongoing.

Lubricity of an oil in water emulsion in metal cutting: The effect of hydrophilic/lypophilic balance of emulsifiers

A steel disc is cut using a single point tool. The coefficient of friction of the nascent cut surface is measured by a spherical steel pin situated in close proximity of the point of cutting. The tool, disc and the friction pin are immersed in an oil in water emulsion bath during the experiment. The purpose of the experiments conducted here is to record the effect of hydrophilic/lypophilic balance (HLB) of the emulsifier on the lubricity experienced in the cutting operation. The more lypophilic emulsifiers were found to give greater lubricity than what is recorded when the emulsifier is more hydrophilic. XPS and FTIR spectroscopy are used to explore the tribofilm generated on the nascent cut surface to indicate a possible rationale for the effect.

Surface active properties and biological activity of novel nonionic surfactants containing pyrimidines and related nitrogen heterocyclic ring systems

A series of annelated pyrimidine derivatives has been synthesized via different heterocyclization reactions of suitably functionalized 6-(4-octadecyloxyphenyl)-4-oxo-2- thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile (4) with different electrophiles and nucleophiles. These heterocycles bear an active hydrogen atom (NH, OH or COOH) which could be propoxylated using propylene oxide with different moles, 5, 10 and 15, to produce nonionic surfactant having a long alkyl chain with molecular weight suitable for becoming an amphiphilic molecule with correct hydrophilic-lypophilic balance which enhances solubility, biodegradability and hence lowers the toxicity to human beings and becomes environmentally friendly. In addition, the antimicrobial activities of these compounds were screened and it was found that some of these compounds have similar or higher activity compared with commercial antibiotic drugs (sulphadiazine), which make them suitable for diverse applications like the manufacturing of drugs, pesticides, emulsifiers, cosmetics, etc.

Study of Winsor I to Winsor II Transitions in a Lattice Model

Experiments show that with increasing temperature, microemulsion systems undergo Winsor transitions. The transitions occur from Winsor I (oil droplets in water media) to Winsor II (water droplets in oil media) via Winsor III (bicontinuous phase) with an increase in the temperature. In this paper, it has been shown, for the first time, how one can study the qualitative effects of temperature, head, tail, and oil chain lengths, on these transitions. Simple cubic lattice with excluded volume and periodic boundary conditions is used to mimic the box of the simulation as a bulk of solution. The simulations have been done using the standard traditional Metropolis algorithm in the canonical ensemble (N, V, T). Configurational bias Monte Carlo and reptation moves are used with an equal probability to relax the systems. A very simple interaction model, i.e., the repulsions of water (or heads of surfactants) with oil (or tails of surfactants), is used due to the main characteristic of oil-water mixtures or amphiphilic molecule that is the hydrophobicity. The interfacial tension between oil and water (gammaow) is related to the averaged total energy of the lattice. The model shows that the Winsor III has a minimum interfacial tension (gammaow) similar to experimental results. Changing the phase structure from Winsor III to Winsor I (or Winsor II), increases the interfacial tension which is in agreement with experiments. To relate interfacial tension with the interaction parameter, the simple theory of Bragg-Williams has been used. All of the results such as the effects of oil chain length, head and tail beads number are all similar to the experimental results. Using the Davies method for calculating hydrophilic-lypophilic Balance (HLB), similar to the experimental results, Winsor III phase is formed at HLB value nearly to 10.

Food-grade microemulsions based on nonionic emulsifiers: media to enhance lycopene solubilization.

Water-dilutable food-grade microemulsions consisting of ethoxylated sorbitan esters, and in some cases blended with other emulsifiers, water, (R)-(+)-limonene, ethanol, and propylene glycol, have been prepared. These microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. Lycopene, an active natural lipophilic antioxidant from tomato, has solubilized in water-in-oil, bicontinuous, and oil-in-water types of microemulsions up to 10 times the oil [(R)-(+)-limonene] dissolution capacity. The effects of aqueous-phase dilution, nature of surfactant (hydrophilic-lypophilic balance), and mixed surfactant on solubilization capacity and solubilization efficiency were studied. Structural aspects studied by self-diffusion NMR were correlated to the solubilization capacity, and transformational structural changes were identified.

Aggregation stability of natural rubber latex with low dry rubber content (DRC) in acidic medium

Natural rubber latex was diluted from its original ca. 61% DRC (Dry Rubber Content) to 10% and the resulting material was studied with respect to its aggregation stability. Two non-ionic surfactants with distinct HLB (hydrophilic–lypophilic balance) and cloud point values were used to stabilize the dilute latex. The stability of the obtained materials was evaluated through the addition of acetic acid solutions of different concentrations, and measurement of the pH and coagulation times of the resulting mixtures. Independently of the nature and concentration of the surfactants, the same behavior was observed for all the systems. All the latex solutions were stable after the addition of the acetic acid solutions for at least thirty days.

Comportamiento reológico no estacionario de emulsiones aceite en agua estabilizadas con un palmitato de sacarosa.

Non-steady flow properties of concentrated oil in water emulsions containing oil (60-80% wt.), water and sucrose palmitate (1-5% wt.) of high hydrophilic-lypophilic balance were investigated. Stress growth, steady flow and linear viscoelastic measurements were carried out for this study. The emulsions studied exhibited a thixotropic behavior showing a very rapid stress overshoot. The stress decay was fitted to a Figoni-Shoemaker model using two exponentials. An stress undershoot was also produced under certain conditions. Shear brought about strong structural changes, such as droplet size redistribution at high oil content and temperature. Thus, the steady state viscosity does not fit an Arrhenius type equation with temperature. A shear thinning behavior was found for the steady state viscosity and the peak viscosity.

Direct determination of the residual acrylamide concentration in inverse (water-in-oil) polyacrylamide emulsions following phase inversion: Size exclusion chromatography using a micellar mobile phase

A rapid and low cost method has been developed for the direct analysis of the residual monomer concentration of acrylamide from inverse-emulsion reactions. Inverse-emulsion polymerizations involve the dispersion of a water soluble monomer in aqueous solution in a continuous organic phase. The addition of a low-medium hydrophilic-lypophilic balance (HLB) steric stabilizer and continuous agitation is required to maintain emulsification. This method consists in inverting the “inverse” (water-in-oil) emulsion by utilizing a high HLB surfactant, large amounts of water and rapid stirring to produce a “direct” (oil-in-water) emulsion. Once the residual acrylamide is in the continuous aqueous phase, aliquots of this inverted mixture are then injected into a liquid chromatograph where the polymer and the residual acrylamide are separated by size exclusion chromatography using an aqueous micellar mobile phase. The micellar mobile phase is used to solubilize the organic phase and emulsifier present in the original inverse-emulsion recipe. The organic phase present in the original water-in-oil emulsion is trapped inside the micelles of the mobile phase and these elute with a retention volume comparable to that of the polymer. The large pore volume of the column separates the polymers from the residual monomer and provides sharp and symmetric acrylamide peaks with a good plate count. This method results in linear calibration curves for the acrylamide monomer up to 100 ppm. Further, the elimination of an organic mobile phase reduces the analysis cost considerably. In addition, the sample preparation time is reduced from between 30 minutes to several days for the traditional methods to 15 minutes for the newly proposed method. Therefore, this inversion procedure is suitable for rapid data analysis from reaction mixtures obtained from inverse-emulsion polymerizations. © 1996 John Wiley & Sons, Inc.

Photosynthetic activity of cyanobacteria in water‐in‐oil microemulsions

The solubilization and the photosynthetic activity of cyanobacteria (Anabaena variabilis) in water-in-oil microemulsions consisting of (Tween85/Span80)/hexadecane/water is investigated. Transparent and stable solutions containing up to 10(8) cells/mL could be obtained. The physical state and stability of the cells in the microemulsion, as evidenced from optical and electron microscopy, is dependent upon the physical parameters of the system, and in particular on the hydrophilic-lypophilic balance (HLB) of the surfactant system. Conditions could be found, under which the cells in the microemulsion system display photosynthetic activity This was judged by measuring polarographically the oxygen evolution and by studying the photosynthetic activity in the presence of specific inhibitors.