Heterogenic catalytic hydrolysis and analysis of natural pyrethrins in subcritical water coupled with solid phase microextraction (SPME) and GC-MS

The methodology for the detection of picogram quantities of nucleotides directly from TLC plates without the use of radioactive labeling has been developed. The method couples thin-layer chromatography (TLC) separation with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) detection. The TLC/MALDI coupling protocol was studied and optimized for the separation and detection of deoxyribonucleotides. Several ammonia based solvents were examined as potential extraction solvents for the TLC/MALDI coupling protocol. It was found that in order to obtain maximum MALDI signal intensity and minimal analyte spreading, the extraction solvent should produce R_f-values for the analytes in the range of 0.3–0.4. R_f-values above this range led to extensive analyte spreading and those below this range resulted in poor extraction. Various MALDI matrices and co-matrices were investigated, the best results were obtained using 2′,4′,6′-trihydroxyacetophenone (THA) as a matrix. The extraction solvent chosen was an ammonium hydroxide/methanol (100 mM/30%, R_f = 0.28–0.38) solvent system which was found to provide the best sensitivity, minimal lateral spreading and excellent matrix transfer. Using the optimized coupling protocol, the detection limits for the deoxyribonucleotide monophosphates were established at or better than 10 picograms. Received: 27 May 1998 / Revised: 18 June 1999 / Accepted: 22 June 1999     

Study of enrichment factors for six β‐blockers in aliphatic alcohols by hollow‐fiber liquid‐phase microextraction

The selectivity of a suitable organic solvent is key for extraction in liquid‐phase microextraction experiments. Nevertheless, the screening process remains a daunting task. Our research aimed to study the relationship between extraction efficiency and extraction solvents, analytes, and finally select the appropriate extraction solvent. In the present article, β‐blockers and six extraction solvents were chosen as the models and hollow‐fiber liquid‐phase microextraction was conducted. The relationship was built by statistical analysis on the data. Factors affecting extraction efficiency including the logarithms of the octanol/water partition coefficient (logP_o/w) of analytes, acid dissociation constants, the logarithms of the octanol/water partition coefficient of solvents and pH of the sample solution were investigated. The results showed that a low water solubility of extraction solvent is the foundation to ensure higher extraction efficiency. Moreover, when ΔlogP_o/w > 0, a higher extraction efficiency is observed at lower ΔlogP_o/w, on the contrary, when ΔlogP_o/w < 0, extraction efficiency is higher as the absolute value of ΔlogP_o/w becomes greater. Finally, the relationship between enrichment factor and extraction solvents, analytes was established and a helpful guidance was provided for the selection of an optimal solvent to obtain the best extraction efficiency by liquid‐phase microextraction.     

A simple and efficient sample preparation for taxanes in Taxus chinensis needles with natural menthol‐based aqueous deep eutectic solvent

Taxanes are natural anticancer constituents, and the sample preparation from matrix normally depends on organochlorine solvents. In this study, green and natural menthol‐based aqueous deep eutectic solvent was synthesized and used for sample preparation for taxanes. Five key parameters were optimized and the optimal preparation conditions were as follows: menthol/1‐propanol ratio 1:1 (mol/mol), solid–liquid ratio 1:30 g/mL, extraction time 30 min, ultrasonic power 250 W, and water content 80%. Under the above conditions, the total extraction efficiency of seven main taxanes was 1.25‐ to 1.44‐fold to the conventional methods. In addition, a high‐performance liquid chromatography method with C₁₈ column was established for quantitation of seven main taxanes in <25 min, which had excellent linearity (R² > 0.9986), precision (relative standard deviation < 3.00%), repeatability (relative standard deviation < 3.69%), and recovery (90.26–109.00%). This method performed the extraction, and enrichment processes simultaneously, and it had advantages such as high extraction efficiency, simple operation, low cost, and eco‐friendliness. This work indicated that the natural menthol‐based deep eutectic solvent aqueous could be an excellent alternative to the sample preparation from Taxus or other plants.     

Paper Chromatographic Separations of Metal Ions on Collidinium Tungstoarsenate Papers

Abstract

A systematic study of the chromatography of metal ions on collidinium tungstoarsenate papers has been performed using seven different mixed solvent systems. R_f values of 30 metal ions have been determined by ascending technique and are discussed. The study demonstrates that specific extraction of both Sn(ii) and Sn(iv) is possible in 0.1 mol dm^?3 HNO₃ in 80% (v/v) 1-propanol and their mutual separation can be carried out in solvent system 1 mol dm^?3 HCl in 33% (v/v) 1-propanol. In addition some binary and ternary separation of metal ions have also been achieved on these papers. For a comparison R_f values on plain papers have also been determined in all the solvent systems.     

Photophysical Properties of Coumarin‐30 Dye in Aprotic and Protic Solvents of Varying Polarities¶

Experimental results on various photophysical properties of coumarin‐30 (C30) dye, namely, Stokes' shift (Δv), fluorescence quantum yield (τ_f), fluorescence lifetime (τ_f), radiative rate constant (k_f) and nonradiative rate constant (k_nr), as obtained using absorption and fluorescence measurements have been reported. Though in most of the solvents the properties of C30 show more or less linear correlation with the solvent polarity function, Δf= [(ε ‐ 1)/(2ε+ 1) ‐ (n² ‐ 1)/ (2n²+ l)], they show unusual deviations in nonpolar solvents at one end and in high‐polarity protic solvents at the other end. From the solvent polarity and temperature effect on the photophysical properties of the dye, following inferences have been drawn: ( 1 ) in nonpolar solvents, the dye exists in a nonpolar structure, where its 7‐NEt₂ substituent adopts a pyramidal configuration and the amino lone pair is out of resonance with the benzopyrone π cloud; ( 2 ) in medium to higher polarity solvents, the dye exists in a polar intra‐molecular charge transfer structure, where the 7‐NEt₂ group and the 1,2‐benzopyrone moiety are in the same plane and the amino lone pair is in resonance with the benzopyrone π cloud; ( 3 ) in protic solvents, the dye‐solvent intermolecular hydrogen bonding influences the photophysical properties of the dye; and ( 4 ) in high‐polarity protic solvents, the excited C30 undergoes a new activation‐controlled nonradiative deexcitation process because of the involvement of a twisted intra‐molecular charge transfer (TICT) state. Contrary to most other TICT molecules, the activation barrier for this deexcitation process in C30 is observed to increase with solvent polarity. A rational for this unusual behavior has been given on the basis of the solvent polarity‐dependent stabilization and crossing of relevant electronic states and the relative propensity of interconversion among these states.     

Influence of the solvent on the extraction of copper(II) from nitrate medium using salicylideneaniline

Different solvents including cyclohexane, dichloromethane, chloroform, toluene, 1-octanol, and methyl isobutyl ketone (MIBK) have been evaluated in extracting copper(II) from nitrate medium by salicylideneaniline. Extracted species differs from solvent to solvent: CuL₂ in cyclohexane, toluene, 1-octanol, and methyl isobutyl ketone. However, in dichloromethane or chloroform, there are two complexes of the type CuL₂ and CuL₂(HL). The extraction constants and percentage of extraction (%E) are calculated for different solvents. Solvent played an important role in recovering copper(II) from the aqueous solution, thus affecting the extraction equilibrium and extraction efficiency. The nonpolar solvent showed better performance than the polar solvent. The maximum extraction efficiency was 85.75% at pH?=?4.5, which was from cyclohexane.     

LC Determination of Chloramphenicol in Honey Using Dispersive Liquid–Liquid Microextraction

A novel method, dispersive liquid–liquid microextraction coupled with liquid chromatography-variable wavelength detector (LC-VWD), has been developed for the determination of chloramphenicol (CAP) in honey. A mixture of extraction solvent (30 μL 1,1,2,2-tetrachloroethane) and dispersive solvent (1.00 mL acetonitrile) were rapidly injected by syringe into a 5.0 mL real sample for the formation of cloudy solution, the analyte in the sample was extracted into the fine droplets of C₂H₂Cl₄. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was determined by LC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time, sample solution pH, sample volume and salt effect were investigated and optimized. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 3 to 2,000 μg kg^?1 for target analyte. The enrichment factor for CAP was 68.2, and the limit of detection (S/N = 3) were 0.6 μg kg^?1. The relative standard deviation (RSD) for the extraction of 10 μg kg^?1 of CAP was 4.3% (n = 6). The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at μL level. Honey samples were successfully analyzed using the proposed method.     

The formation of grignard compounds—III : The influence of the solvent

The reaction of 6-bromo-1-hexene with Mg was studied in order to obtain information on the role of the solvent during the formation of Grignard reagents. The 5-hexenyl radical (R_nc^.) is known to cyclize rapidly and irreversibly to the cyclopentylmethyl radical (R_c^.). Changes in yields of the cyclized and non-cyclized Grignard compounds have been found on varying the solvent. Information on the radical pairs involved is obtained from the yields of the three possible coupling products (R_ncR_nc, R_ncR_c and R_cR_c). Results are correlated to the intensity of the CIDNP spectra of the Grignard compounds. It is found that basicity and viscosity of the solvents influence the reactions at the site of single electron transfer. Formation of Grignard compounds via radical pairs increases: (a) with decreasing basicity of the solvent, (b) with decreasing viscosity of the solvent, and (c) on dilution of THF with benzene. It is proposed that interaction between the radical and the π-electron rich solvent benzene plays a role in reactions run in Bz/THF mixtures.     

Biodegradable shape‐memory polymer—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock copolymer

In this study, biodegradable shape‐memory polymers—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock (PLAGC) copolymers—were synthesized by the coupling reaction of both macrodiols of polylactide (PLLA‐diol) and poly(glycolide‐co‐caprolactone) (PGC‐diol) in the presence of 1,6‐hexanediisocyanate as coupling agent. The copolymers formed were found to be thermoplastic and easily soluble in common solvents. The compositions of the copolymers were determined by ¹H‐NMR and the influences of segment lengths and contents of both macrodiols on the properties of the PLAGC copolymers were investigated. It was found that the copolymers had adjustable mechanical properties which depended on contents and segment lengths of both macrodiols. The copolymers showed such good shape‐memory properties that the strain fixity rate (R_f) and the strain recovery rate (R_r) exceed 90%. By means of adjusting the compositions of the copolymers, PLAGC copolymers with transition temperatures around 45°C could be obtained. The degradation rate determination showed that the PLAGC copolymers have fast degradation rates, the mechanical strengths of the PLAGC copolymers would be completely lost within 1–2 months depending on molecular weights and contents of the both segments of PLLA and PGC. Copyright © 2005 John Wiley & Sons, Ltd.     

Microwave‐assisted preparation of poly(ionic liquids)‐modified magnetic nanoparticles for pesticide extraction

Novel poly(ionic liquids) were synthesized and immobilized on prepared magnetic nanoparticles, which were used to extract pesticides from fruit and vegetable samples by dispersive solid‐phase extraction prior to high‐performance liquid chromatography analysis. Compared with monomeric ionic liquids, poly(ionic liquids) have a larger effective contact area and higher viscosity, so they can achieve higher extraction efficiency and be used repeatedly without a decrease in analyte recovery. The immobilized poly(ionic liquids) were rapidly separated from the sample matrix, providing a simple approach for sample pretreatment. The nature and volume of the desorption solvent and amount of poly(ionic liquid)‐modified magnetic material were optimized for the extraction process. Under optimum conditions, calibration curves were linear (R² > 0.9988) for pesticide concentrations in the range of 0.100–10.000 μg/L. The relative standard deviations for repeated determinations of the four analytes were 2.29–3.31%. The limits of detection and quantification were 0.29–0.88 and 0.97–2.93 μg/L, respectively. Our results demonstrate that the developed poly(ionic liquid)‐modified material is an effective absorbent to extract pesticides from fruit and vegetable samples.     

Papierchromatographische Strukturanalyse

Zusammenfassung Der AusdruckR _M = logR _f/1–R _f, berechnet aus dem papierchromatographischenR _f-Wert einer organischen Verbindung, läßt sich additiv aus Konstanten für die einzelnen strukturellen Einheiten des betrachteten Moleküls zusammensetzen. Die Zahlenwerte dieser Konstanten sind von der Zusammensetzung des zur Papierchromatographie verwendeten Lösungsmittels abhängig. Wählt man zwei Lösungsmittelgemische, die in allen ihren Gruppenkonstanten mit Ausnahme einer einzigen übereinstimmen, so ist es möglich, durch einfachen Vergleich derR _M Werte in den beiden Gemischen eine papierchromatographische Strukturanalyse durchzuführen. Nach diesem Prinzip wird in der vorliegenden Arbeit die Bestimmung der Anzahl von Carboxylgruppen in organischen Verbindungen beschrieben. Als erstes Lösungsmittel wird Aceton/Essigsäure oder Essigester/Eisessig/Wasser, als zweites Lösungsmittel Aceton/Ammoniumacetatlösung verwendet. Eine verläßliche Carboxylgruppenbestimmung war bei allen bisher geprüften Verbindungen möglich, derenR _f-Werte in den genannten Lösungsmitteln 0,90 nicht überstiegen und deren Molekül keine sterisch unmittelbar benachbarten Carboxylgruppen enthielt.

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Summary The expressionR _M = logR _f/1–R _f, calculated from the paper chromatographicR _f-value of an organic compound, can be constructed additively from the constants of the individual structural units of the molecule under consideration. The numerical values of these constants are dependent on the composition of the solvents used in the paper chromatography. By choosing two solvent mixtures, which agree with respect to all of their group constants with the exception of one, it is possible, by simple comparison of theR _M values in the two mixtures, to carry out a paper chromatographic structural analysis. In the present paper, this principle is used to determine the number of carboxyl groups in organic compounds. The first solvent consisted of acetone/acetic acid or acetic ester/glacial acetic acid/water, the second of acetone/ammonium acetate solution. A reliable carboxyl group determination was possible in all the compounds tried thus far, provided theR _f-values in these solvents did not exceed 0.90 and also provided that the molecule contained no sterically directly adjacent carboxyl groups.

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Résumé L'expressionR _M = logR _f/1–R _f, calculée à partir de la valeur deR _f obtenue par chromatographie sur papier, peut s'établir à partir de constantes additives relatives aux unités structurelles individuelles de la molécule organique considérée. Les valeurs de ces constantes dépendent de la composition du solvant employé pour la chromatographie sur papier. En choisissant deux mélanges de solvants qui donnent des résultats concordants pour toutes leurs constantes de groupements à l'exception d'une seule d'entre elles, il est possible d'effectuer une analyse de structure par simple comparaison des valeurs deR _M qu'ils permettent respectivement d'obtenir. L'application de ce principe a permis la détermination du nombre de groupements carboxyles contenus dans des combinaisons organiques; elle est décrite dans le présent travail. Le premier mélange solvant est constitué par de l'acétone et de l'acide acétique ou de l'ester acétique, de l'acide acétique et de l'eau et le second par de l'acétone et une solution d'acétate d'ammonium. Jusqu'à présent il a été possible d'effectuer une détermination sûre des groupements carboxyles dans toutes les combinaisons éprouvées dont la valeur deR _f ne dépasse pas 0,90 dans les solvants énumérés et dont la molécule ne contient aucun groupement carboxyle en voisinage stérique immédiat.

     

Quick and selective extraction of Z‐ligustilide from Angelica sinensis using magnetic multiwalled carbon nanotubes

A facile and highly efficient magnetic solid‐phase extraction method has been developed for Z‐ligustilide, the major therapeutic agent in Angelica sinensis. The solid‐phase adsorbent material used was prepared by conjugating carbon nanotubes with magnetic Fe₃O₄ nanoparticles via a hydrothermal reaction. The magnetic material showed a high affinity toward Z‐ligustilide due to the π–π stacking interaction between the carbon nanotubes and Z‐ligustilide, allowing a quick and selective exaction of Z‐ligustilide from complex sample matrices. Factors influencing the magnetic solid‐phase extraction such as the amount of the added adsorbent, adsorption and desorption time, and desorption solvent, were investigated. Due to its high extraction efficiency, this method was proved highly useful for sample cleanup/enrichment in quantitative high‐performance liquid chromatography analysis. The proposed method had a linear calibration curve (R² = 0.9983) over the concentration between 4 ng/mL and 200 μg/mL Z‐ligustilide. The accuracy of the method was determined by the recovery, which was from 92.07 to 104.02%, with the relative standard deviations >4.51%.     

Extraction of fullerenes from environmental matrices as affected by solvent characteristics and analyte concentration

Fullerenes possess unique chemical properties that make the isolation of these compounds from heterogeneous environmental matrices difficult. For example, previous reports indicate that toluene‐based extraction techniques vary in their ability to extract C₆₀, especially from highly carbonaceous solid matrices. Here, we examined the effects of (i) solvent type (toluene alone versus an 80:20 v/v mixture of toluene and 1‐methylnaphthalene) and (ii) analyte concentration on the extraction efficiency of an isotopically labeled surrogate compound, ¹³C₆₀. The toluene/1‐methylnaphthalene mixture increased fullerene extraction efficiency from carbon lampblack by a factor of five, but was not significantly different from 100% toluene when applied to wood stove soot or montmorillonite. Recovery of the ¹³C₆₀ surrogate declined with decreasing analyte concentration. The usefulness of isotopically labeled surrogate is demonstrated and the study provides a quantitative assessment regarding the dependence of fullerene extraction efficiencies on the geochemical characteristics of solid matrices.     

Precise Manipulation of Temperature-Driven Chirality Switching of Molecular Universal Joints through Solvent Mixing

Three chiral bicyclic pillar[5]arene derivatives termed as molecular universal joints (MUJs), were synthesized and separated enantiomerically. These MUJs showed temperature-driven chirality switching in certain solvents. Herein, it is demonstrated that temperature-driven chirality switching could also be realized by mixing two miscible organic solvents, in each of which chirality inversion is not accomplishable. Additionally, solvent mixing drastically varied the inversion temperature of the MUJs, for example, from far below zero to room temperature. Moreover, the temperature-driven S_p/R_p to R_p/S_p chirality switching direction could be reversed by the solvent mixing and it was critically controlled by the mixing ratios of the two solvents. These observations allowed precise manipulation of the chirality switching behavior of the MUJs. Such a chirality switching was ascribed to the influences of solvent and temperature on the in–out equilibrium of the side rings, which is delicately controlled by several processes, including the solvation/desolvation and the inclusion/exclusion of the side rings and solvent molecules. Crucially, the solvent mixing introduced new supramolecular processes, in particular the desolvation of solvent molecules from the mixed solvent system and the solvation of the side ring by the mixed solvent, which significantly disturbed the original in–out equilibrium of MUJs and drastically switched the entropy and enthalpy changes of conformational interconversion.     

An efficient biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles for quantification of bisphenol A in water samples by gas chromatography‐mass spectrometry detection

In this work, a simple, fast, sensitive, and environmentally friendly method was developed for preconcentration and quantitative measurement of bisphenol A in water samples using gas chromatography with mass spectrometry. The preconcentration approach, namely biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles was performed based on the formation of microdroplet of rhamnolipid biosurfactant throughout the aqueous samples, which accelerates the mass transfer process between the extraction solvent and sample solution. The process is then followed by the application of magnetic nanoparticles for easy retrieval of the analyte‐containing extraction solvent. Several important variables were optimized comprehensively including type of disperser solvent and desorption solvent, rhamnolipid concentration, volume of disperser solvent, amount of magnetic nanoparticles, extraction time, desorption time, ionic strength, and sample pH. Under the optimized microextraction and gas chromatography with mass spectrometry conditions, the method demonstrated good linearity over the range of 0.5–500 µg/L with a coefficient of determination of R² = 0.9904, low limit of detection (0.15 µg/L) and limit of quantification (0.50 µg/L) of bisphenol A, good analyte recoveries (84–120%) and acceptable relative standard deviation (1.8–14.9%, n = 6). The proposed method was successfully applied to three environmental water samples, and bisphenol A was detected in all samples.     

Generalized correlations for molecular weight and concentration dependence of zero-shear viscosity of high polymer solutions

Data are presented to show that two correlations of viscosity–concentration data are useful representations for data over wide ranges of molecular weight and up to at least moderately high concentrations for both good and fair solvents. Low molecular weight polymer solutions (below the critical entanglement molecular weight M_c) generally have higher viscosities than predicted by the correlations. One correlation is η_sp/c[η] versus k′[η], where η_sp is specific viscosity, c is polymer concentration, [η] is intrinsic viscosity, and k′ is the Huggins constant. A standard curve for good solvent systems has been defined up to k′[η]c ≈? 3. It can also be used for fair solvents up to k′[η]c ≈? 1.25· low estimates are obtained at higher values. A simpler and more useful correlation is η_R versus c[η], where η_R is relative viscosity. Fair solvent viscosities can be predicted from the good solvent curve up to c[η] ≈? 3, above which estimates are low. Poor solvent data can also be correlated as η_R versus c[η] for molecular weights below 1 to 2 × 10⁵.     

Polymerization of diallyl phthalate in solution by γ-radiation

The polymerization of diallyl phthalate has been studied in two solvents, benzene (G_Radical = 0.7) and chloroform (G_R = 11.2), γ-radiation being used to investigate the effect of the solvent on the rates of polymerization and also chain transfer to the solvent. Kinetic analysis shows that in benzene solution the initiating species come almost exclusively from the monomer, but in chloroform they arise only from the solvent. The latter was further confirmed from the chlorine analysis of the polymer wherein chloroform appears to have telomerized with diallyl phthalate. In neither of the solvents was high molecular weight polymer obtained. The k_p/k_t^1/2 for the polymerization of DAP was found to be 3.3 × 10^?4 and 1.17 × 10^?3 in benzene and chloroform solutions, respectively. The chain-transfer constant C_S was 11.25 × 10^?3 and 9.75 × 10^?3 for benzene and chloroform, respectively.     

SFE of PAHs from soils with a high carbon content and analyte collection via combined liquid/solid trapping

Polynuclear aromatic hydrocarbons (PAHs) are recovered from a soil with a high carbon content (ca. 50%) with supercritical fluid extraction (SFE) as well as with conventional Soxhlet extraction. The influence of temperature and modifier volume on SFE efficiency and the effect of a combined liquid/solid trap for analyte collection are investigated in this study. Such traps, which make analyte collection and clean-up possible in one step, are compared with conventional analyte collection in pure organic solvents. A comparison between reproducibility and efficiency of SFE and Soxhlet extraction is presented.     

Physicochemical and macromolecular properties of sodium amylose xanthate in dilute solution

Sodium amylose xanthate has been studied in dilute solution. Potato starch was fractionated for this purpose into amylose and amylopectin fractions. Amylose was xanthated in solution under alkaline conditions and the Na amylose xanthate was then characterized by reaction with I₂ solution and ultraviolet spectra of the xanthate groups determined. Stability of the xanthate in alkaline condition under both oxygen and nitrogen atmospheres was also investigated. From light scattering measurements of dilute salt solutions of Na amylose xanthate, the weight-average molecular weight M _w as well as the molecular dimensions were determined. In 0.11M NaCl, which conforms to the θ solvent, Na amylose xanthate molecules appear to have a random-coil configuration. Two other configurational parameters, such as the effective bond length b, and the steric factor σ, i.e., (R₀²)^1/2/(R_f² )^1/2, where (R₀²)^1/2 is the Root-mean-square end-to-end distance in the unperturbed state and (R_f² )^1/2 is the unperturbed value calculated on the assumption of free rotation about each intermonomer C? O bond of the amylose chain were also calculated and found to be 6.24 and 1.020, respectively. It is thus concluded that the amylose chain in Na amylose xanthate behaves as a typical flexible coil in dilute salt solution.     

Ultrasonic studies of polysaccharide (pectin) in aqueous media at 298.15 K

The ultrasonic velocity, density and viscosity of pectin in aqueous medium were measured at 298.15 K. The acoustical parameters such as adiabatic compressibility (β), free length (L _f), free volume (V _f), internal pressure (π_i), acoustical impedance (Z), and relative association (R _A), Rao’s constant (R) and Wada’s constant (W) are calculated. The results are interpreted in terms of molecular interaction between the components of the mixtures. Further, some more acoustical parameters such as relaxation time (τ), absorption coefficient (α/f ²) and relaxation strength (r) are calculated with various percentage of pectin has been studied which reveals interaction between the solvent and the polymer (pectin) at various concentration of the polymer. The observed values suggested the solute-solvent interaction is favored.