Reduction In Extraction Efficiency Research Articles

Box-Behnken Design-Based Optimization of Phytochemical Extraction from Diplazium esculentum (Retz.) Sw. Associated with Its Antioxidant and Anti-Alzheimer's Properties.

A previous study reported that the ethanolic extract of the edible fern, Diplazium esculentum (Retz.) Sw. (DE), obtained from a non-optimized extraction condition exhibited anti-Alzheimer's disease (AD) properties through the inhibition of a rate-limiting enzyme in amyloid peptide formation, β-secretase-1 (BACE-1). Nevertheless, a non-optimized or suboptimal extraction may lead to several issues, such as a reduction in extraction efficiency and increased time and plant materials. In this study, extraction of the DE was optimized to obtain appropriate BACE-1 inhibition using a Box-Behnken design (BBD) and response surface methodology (RSM). Data revealed that the optimal extraction condition was 70% (v/v) aqueous ethanol, 50 min extraction time, 30 °C extraction temperature, and 1:30 g/mL solid/liquid ratio, giving BACE-1 inhibition at 56.33%. In addition, the extract also exhibited significant antioxidant activities compared to the non-optimized extraction. Metabolomic phytochemical profiles and targeted phytochemical analyses showed that kaempferol, quercetin, and their derivatives as well as rosmarinic acid were abundant in the extract. The optimized DE extract also acted synergistically with donepezil, an AD drug suppressing BACE-1 activities. Data received from Drosophila-expressing human amyloid precursor proteins (APPs) and BACE-1, representing the amyloid hypothesis, showed that the optimized DE extract penetrated the fly brains, suppressed BACE-1 activities, and improved locomotor functions. The extract quenched the expression of glutathione S transferase D1 (GSTD1), inositol-requiring enzyme (IRE-1), and molecular chaperone-binding immunoglobulin (Bip), while donepezil suppressed these genes and other genes involved in antioxidant and endoplasmic reticulum (ER) stress response, including superoxide dismutase type 1 (SOD1), activating transcription factor 6 (ATF-6), and protein kinase R-like endoplasmic reticulum kinase (PERK). To sum up, the optimized extraction condition reduced extraction time while resulting in higher phytochemicals, antioxidants, and BACE-1 inhibitors.

Extraction of Citrus deliciosa Tenore petitgrain (leaf) essential oil by steam distillation under different operating pressures

ABSTRACT This work aimed to evaluate the effect of system absolute pressure on the yield and composition of petitgrain essential oil of Citrus deliciosa Tenore, extracted by steam distillation. The extractions were carried out at the absolute pressures of 760, 610, 460, and 310 Torr, for 1 h. The chemical composition of the essential oil was determined by GC/MS and GC-FID. According to the results, the reduction of pressure reduced essential oil yield, from 0.6% v/w at 760 Torr to 0.3% v/w at 310 Torr. Regarding the chemical composition, there was an increase in methyl N-methylanthranilate content with the reduction of system pressure, from 88.3 wt.% at 760 Torr to 97.6 wt.% at 310 Torr. However, it was observed a reduction in extraction efficiency due to the lower steam temperature. On the other hand, lower temperatures may imply a smaller degradation of thermolabile compounds. This process may be an alternative to other deterpenation techniques because it couples in a sole stage the extraction and purification/separation of essential oil components.

Hybrid ZIF-8-90 for Selective Solid-Phase Microextraction of Exhaled Breath from Gastric Cancer Patients.

Metal-organic frameworks (MOFs) are a new kind of microporous materials whose unique properties make them promising as coatings for solid phase microextraction (SPME). However, previous MOF coatings for SPME exclusively focus on single-linker MOFs, and the selective enrichment of polar or nonpolar targets depends on the polarity of linker on the surface of MOFs, which greatly limits the application of MOF coating for SPME in real samples. Here, we report a hybrid MOF-coated stainless steel fiber for SPME of biomarkers in exhaled breath from gastric cancer patients. Zeolitic imidazolate framework-8-90 (ZIF-8-90) possesses the aldehyde groups and methyl groups in the framework as a model MOF, and eight biomarkers (ethanol, acetone, hexanal, hexanol, nonane, isoprene, heptane, and decane) were used as the target analytes. The ZIF-8-90-coated fiber shows high enrichment efficiency for hydrophilic targets and hydrophobic targets, wide linearity (three orders of magnitude), and low detection limits (0.82-2.64 μg L-1). The ZIF-8-90-coated fiber exhibited higher enrichment performance for all the investigated analytes as a result of the synergy of methyl and aldehyde groups, the porous structure, and the suitable pore size of ZIF-8-90 (4-5 Å). The relative standard deviation (RSD) of six repetitions for extractions using the same ZIF-8-90-coated fiber ranged from 2.5 to 7.3%. The reproducibility between the three fibers prepared in parallel varied in the range of 4.8-12% (RSD). The fabricated ZIF-8-90-coated fiber lasted for at least 120 cycles of extraction/desorption/conditioning without an obvious reduction in extraction efficiency and precision. Finally, the developed ZIF-8-90-coated SPME fiber has been successfully used for the analysis of exhaled breath samples from gastric patients with satisfied recoveries (88-106%).

Investigation of Phenolic Content in Five Different Pine Barks Species Grown in Turkey by HPLC-UV and LC-MS.

Investigation of phenolic content from different pine bark species grown in Turkey was performed using a reversed-phase high pressure liquid chromatography with ultraviolet (RP-HPLC-UV) method. All phenolic constituents were separated in <26min on reversed-phase C18 column with gradient mobile phase that consists of orthophosphoric acid, methanol and acetonitrile. Detections were made on an UV detector at 280nm and at a flow rate of 1mL/min. Samples were prepared according to Masqueller's conventional sample preparation method with slight modifications. To avoid the reduction in extraction efficiency the sample preparation step was carried out under argon atmosphere. The linearity of the method was between 0.9994 and 0.9999. The detection limits for the five phenolic constituents ranged from 0122 to 0.324mg/L. Catechin and taxifolin were found in all pine barks at a concentration of 0.065±0.002-1.454±0.004 and 0.015±0.001-23.164±0.322mg/g, respectively. Epicatechin was determined in four pine barks between 0.027±0.001 and 0.076±0.002mg/g, ferulic acid in two pine barks between 0.010±0.001 and 0.022±0.001mg/g and epicatechin gallate in only one of the pine barks at 0.025±0.001mg/g. Finally, the total amount of phenolic compounds and antioxidant capacities of the pine barks were found to be very high.

Oil acidity reduction by extraction with imidazolium ionic liquids: Experimental, COSMO description and reutilization study

Crude oil acidity, usually quantified through total acid number (TAN) and mainly due to carboxylic compounds, is a main problem because causes high corrosion rates and fouling during refining process. Reduction of crude oil TAN by means of ionic liquids (ILs) can be due to neutralization (basic ILs) or to extraction (ILs acting as solvent).In this work, a synthetic crude oil (SC, 150 g/mol, TAN equal to 3.8) was treated with [EMIm][EtSO4], [EMIm][SCN], and [EMIm][Cl] in the temperature range 30–120 °C and IL/crude ratio in the range 0.03–1 g/g. TAN reductions were up to 50% at high temperature and IL/SC ratio.Water washing and reuse of [EMIm][SCN] were studied. No structural changes were detected but IL TAN increased and reduced the extraction efficiency, probably due to the strong interaction between IL and acid that makes washing with water not completely efficient. However, the reduction in extraction efficiency was much faster for IL without any treatment and such reuse is not possible.The COSMO-RS model was used for the ILs characterization through the σ-profile and was successfully included in the simultaneous correlation of all the experimental data. COSMO-Therm was used to study the liquid-liquid equilibria and the predictions of the TAN of the organic phase were in fair agreement with the experimental results. However, COSMO-RS was unable to predict the effect of temperature and described a decrease in TAN reduction as temperature increases.Reuse of IL was also modelled with COSMO-RS and the decrease in extraction efficiency was correctly described related to the IL acid content.

Highly efficient extraction of phenolic compounds from oil mixtures by trimethylamine-based dicationic ionic liquids via forming deep eutectic solvents

In this article, dicationic ionic liquids (DILs), including N,N,N,N′,N′,N′-hexaethyl-ethane-1,2-diammonium dibromide (HEDBr), N,N,N,N′,N′,N′-hexaethyl-propane-1,3-diammonium dibromide (HPDBr) and N,N,N,N′,N′,N′-hexaethyl-butane-1,4-diammonium dibromide (HBDBr), were designed and used to extract phenolic compounds from model oil and coal tar oil. The effects of stirring time, temperature, DIL:phenol mole ratio, and initial phenol concentration on the extraction of phenol were studied. It is found that the DIL:phenol mole ratio is only around 0.3 when the highest extraction efficiency of phenol is obtained. The extraction process completes within 5min at room temperature, and the extraction efficiency is not dependent on temperature. Also, the ultimate phenol concentration remains constant despite the difference in initial phenol concentrations. Of these DILs, HPDBr shows the lowest ultimate phenol concentration of 3.9g/dm3, and the extraction efficiency of phenol can reach as high as 97.0%. These DILs can be regenerated by anti-solvent method and reused several times without significant reduction in extraction efficiency. In addition, HPDBr was demonstrated to extract phenolic compounds from real coal tar oil, and its extraction efficiency of phenolic compounds is 92.7%. The mechanism, analyzed by FT-IR, shows that there is a hydrogen bond between phenol and DIL.

Efficient extraction of indole from wash oil by quaternary ammonium salts via forming deep eutectic solvents

Indole plays a significant role in the production of products such as spices, medicines, and exogenous auxins. Deep eutectic solvents (DESs) formed by indole and quaternary ammonium salts (QASs, including tetraethylammonium chloride-TEAC, tetrapropylammonium chloride-TPAC, triethylmethyl-ammonium chloride-TEMAC) were found and proposed to efficiently extract indole from model wash oil. The effects of time, temperature, mole ratio of QAS to indole and initial indole concentration on the extraction of indole were studied. The results indicate that these QASs can extract indole from wash oil with efficiencies up to 96.7% (TPAC). The extraction process can be finished within 5 min. It is also found that the ultimate concentrations are almost identical for one kind of QAS although their initial concentrations are different, and the indole concentration in model wash oil can be reduced to a very low level of 1.3 g/dm3 (TPAC). The maximum distribution coefficients of indole are 40.8 for TEAC, 91.9 for TPAC, and 29.5 for TEMAC at the studied conditions, and the extraction ability follows the order of TPAC > TEAC > TEMAC. Moreover, QASs in DESs can be reused without obvious reduction in extraction efficiency. The extraction mechanism was studied by FT-IR, and the results indicate that there is a hydrogen bond between QAS and indole. Finally, a comparison was made between this method and other methods to verify and demonstrate its desirable properties of efficiency and environmentally friendliness.

Enhancing Electron Beam Radiative Energy Extraction Efficiency in Free-Electron Laser Oscillators Through Beam Energy Ramping

Free-electron lasers are used to generate laser radiation using an accelerated electron beam. In this paper, an electrostatic accelerator was used with a thermionic cathode. Lasing pulses of the order of tens of microseconds were generated by passing the current pulses through a wiggler and resonator combination. The change in lasing power as a result of postsaturation variation of the energy of the electron beam during the lasing period is presented in this paper in the form of experimental measurements and simulations. In the experiments, the initial electron beam energy was ~1.4 MeV and the current was 1.13 A, whilst the lasing frequency was always close to 102 GHz. It is shown that postsaturation, positively ramping the beam energy increases the radiation extraction efficiency by around 50%. Whilst a falling beam energy results in a reduction in extraction efficiency.

Influence of produced natural gas on CO2-crude oil systems and the cyclic CO2 injection process

In cyclic CO2 injection practice, CO2 has always been recycled to improve CO2 utilization and reduce cost. To study the influence of produced natural gas on CO2-crude oil systems and the cyclic CO2 injection process, the extraction efficiency and solubility of a mixture of CO2 and natural gas were investigated by extraction and solubility experiments. Interfacial tension (IFT) was measured by using the axisymmetric drop shape analysis technique, and cyclic injection experiments were conducted to study the performance of gas injection with various compositions. The results showed that both the CO2 extraction capability and solubility in the crude oil can be reduced when adding the produced natural gas in the CO2 stream. The reduction of extraction efficiency and solubility increases with increasing pressure. The interfacial tension (IFT) between crude oil and CO2 linearly decreases with increasing pressure over two distinct ranges. The IFT generally increases as more natural gas is added to CO2. In the low pressure range, the interfacial tension increase is caused by the reduced solubility of CO2, while in the high pressure range, the weakened extraction efficiency of CO2 is responsible for the increase. Increased interfacial tension results in a rise of 71.1% of the minimum miscibility pressure and an increase of 92.4% of the first contact miscibility pressure. Recovery of the cyclic CO2 injection in the coreflooding is, therefore, lowered by 6.2% in the immiscible case and by 10.7% in the miscible case. The higher the injection pressure is, the more the recovery will be decreased.

Use of Polyacrylic Acid and Polydimethylsiloxane Mixture for In‐Needle Microextraction of Volatile Aroma Compounds in Essential Oils

A prototype stainless steel needle (Hamilton 90022, 22 gauge, 718 µm o.d., 413 µm i.d., 51 mm length, bevel tip) packed with polyacrylic acid (PAA) and polydimethylsiloxane (PDMS) mixture (7:3 ratio) having a micro‐bore tunnel (290 µm i.d., ca. 61.5 µm thickness, 10 mm length) was newly prepared as a device of headspace in‐needle microextraction (HS‐INME). Design of the needle, optimization of adsorption, desorption parameters, and validation of analytical methods were conducted to evaluate the HS‐INME efficiency for volatile organic compounds. The optimized adsorption conditions were 60 °C for 20 min and desorption conditions were 240 °C for 2 min. The calibration curves showed good linearity with the squared correlation coefficient value (r2) over 0.99. The limit of detection for linalool, (+)‐limonene, and eugenol were 13.5, 10.9, and 9.1 ng while limit of quantification were 45.1, 36.4, and 30.5 ng, respectively. The recovery results showed the acceptable range between 95.6 and 115.3%. The relative standard deviations for intra‐ and inter‐assay showed the values less than 10%. It was applied to analyze seven essential oils for polar and nonpolar volatile aroma compounds successfully. From the results obtained in this study, HS‐INME was advantageous to low cost due to ease of fabrication, reuse without loss of absorbent or reduction of extraction efficiency, and no use of solvent. In conclusion, a needle packed with PAA and PDMS mixture having a micro‐bore tunnel is a new development of INME that may complement the shortcomings of the current headspace extraction methods.

Modified Diglycolamides for the An(III) + Ln(III) Co-separation: Evaluation by Solvent Extraction and Time-Resolved Laser Fluorescence Spectroscopy

The use of two recently developed diglycolamide-based extractants for the co-separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) is described and compared to the well-known extractant TODGA (N,N,N’,N’-tetraoctyl diglycolamide). The addition of one or two methyl groups to the central methylene carbon atoms of the TODGA molecule leads to a reduction of the extraction efficiency for An(III) and Ln(III). This is attributed to a lower complex formation constant, which was proven by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS). Conditional stability constants were determined by solvent extraction and TRLFS. The reduction in extraction efficiency leads to overall reduced distribution ratios of all tested metal ions, including Sr(II). The reduced Sr(II) extraction is beneficial as a co-extraction in a solvent extraction process could be avoided, while an efficient extraction of the desired An(III) and Ln(III) is still achieved. Furthermore, this might be a benefit, as the stripping behavior might be improved, even at moderate nitric acid concentrations. The slightly higher affinity of the diglycolamides towards Eu(III) over Am(III) is represented by all ligands, although the selectivity is rather low. This results in promising extraction properties of the modified diglycolamides towards the development of continuous solvent extraction processes.

Effect of aqueous phase pH on liquid–liquid extraction with impinging-jets contacting technique

The influence of aqueous phase pH on the rate of liquid–liquid extraction was investigated using a two impinging-jets contacting device with a high velocity of jet flows. The recommended chemical system of toluene–acetone–water was employed. Applying pH values from its natural value of 5.6–8, a range in which most industrial waters are lain, for the jets colliding force within 70.3–214.6 mN, leads a reduction in extraction efficiency and overall volumetric mass transfer coefficient up to about 18.9% and 35.2% respectively. A significant high variation is observed when the aqueous phase pH exceeds the water neutral value toward alkali conditions. These variations can be attributed to the adsorption of hydroxyl ions and lowering interfacial tension. A comparison between the results in this work and those for drop dispersion extraction indicates a high sensitivity in the impinging technique. As expected, increasing jets force improves the performance of the contacting device; however, simultaneously, the retarding effect of pH would be intensified. The variation of interfacial tension with pH was obtained and with the aid of dimensionless numbers, an empirical correlation was developed for the prediction of overall volumetric mass transfer coefficient.

Hierarchical transport networks optimizing dynamic response of permeable energy-storage materials

Channel widths and spacing in latticelike hierarchical transport networks are optimized to achieve maximum extraction of gas or electrical charge from nanoporous energy-storage materials during charge and discharge cycles of specified duration. To address a range of physics, the effective transport diffusivity is taken to vary as a power, m , of channel width. Optimal channel widths and spacing in all levels of the hierarchy are found to increase in a power-law manner with normalized system size, facilitating the derivation of closed-form approximations for the optimal dimensions. Characteristic response times and ratios of channel width to spacing are both shown to vary by the factor 2/m between successive levels of any optimal hierarchy. This leads to fractal-like self-similar geometry, but only for m=2 . For this case of quadratic dependence of diffusivity on channel width, the introduction of transport channels permits increases in system size on the order of 10;{4} , 10;{8} , and 10;{10} , without any reduction in extraction efficiency, for hierarchies having 1, 2 and, 8 levels, respectively. However, we also find that for a given system size there is an optimum number of hierarchical levels that maximizes extraction efficiency.

CESIUM EXTRACTION FROM A NOVEL CHEMICAL DECONTAMINATION PROCESS SOLVENT USING MAGNETIC MICROPARTICLES1

The chemical, 1-hydroxyethane-1,1-diphosphonic acid (HEDPA), has been the subject of recent publications and patents regarding decontamination and decommissioning applications, and its superiority as a decontamination agent has been highlighted in various field demonstrations. To recycle the aqueous HEDPA solvent and/or facilitate waste formation, it would be advantageous to remove dissolved radionuclides that originated from the contaminated surfaces. Cesium isotopes (137, 135Cs) comprise the vast majority of radioactivity found in potential applications at nuclear power facilities. The present study evaluated magnetic microparticles containing embedded silicotitanate powders for uptake of 137Cs from HEDPA solution. Results indicate that the kinetics are rapid, reaching ∼95% of equilibrium within 10 min. The distribution coefficient (K d) was between 3000 and 10,000 mL/g (90–98% 137Cs removed) depending on particle mass-to-solution volume ratios. The excellent sorption of 137Cs indicates that particle batches may be reused many times without a reduction in extraction efficiency. However, particle degradation and magnetic susceptibility reduction may be a problem due to the dissolution of the magnetite component by the diphosphonic acid. This may be overcome by substituting the magnetite component with other ferromagnetic materials such as Ni or Co alloys. *The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Single-mode, singly resonant, pulsed periodically poled lithium niobate optical parametric oscillator

We report single longitudinal mode operation of a pulsed Nd:YAG pumped periodically poled lithium niobate optical parametric oscillator (OPO). The combination of a prism and an etalon provides both coarse and fine spectral resolution, thereby eliminating parasitic resonant oscillation of cascaded signal wavelengths, idler wavelengths, and adjacent longitudinal modes of the signal field. Optical bandwidths of less than 300 MHz have been obtained at signal wavelengths between 1.47 and 1.59 mum. In comparison with broadband operation, the single-mode OPO shows only a 9% reduction in pump depletion with a negligible reduction in extraction efficiency.

Efficiency of Hexane Extraction of Napropamide from Aldrich Humic Acid and Soil Solutions

AbstractDissolved organic matter (DOM) has been shown to form a stable complex with Napropamide [2(α‐naphthoxy)‐N,N‐diethyl propionamide] and to facilitate its transport through soil columns. Liquid‐liquid extraction of organics is a common method to transfer napropamide from water into an organic phase for gas chromatography analysis. A study was conducted to determine the effect of Aldrich humic acid, soil‐derived dissolved organic matter, electrical conductivity, and hydrogen ion activity on the ability of hexane to extract napropamide from solutions and from soil extracts. The electrical conductivity of Aldrich humic acid solutions (0.0, 48, and 100 mg C L−1) were adjusted to 0.01, 0.97, and 1.69 dS m−1 by adding NaCl and CaCl2, and pH (8.2, 7.4, and 5.6) was adjusted using HCl and NaOH. Electrical conductivity had no effect on extraction efficiency. In the absence of DOM pH had no effect on extraction efficiency. Extraction efficiency decreased with increasing DOM concentration. Maximum reduction in extraction efficiency occurred in the presence of DOM when solution pH was near neutrality. A maximum extraction efficiency of 100% was observed in the absence of DOM and a minimum of 68% when napropamide was added to DOM solutions at pH 8.2 and then lowered to pH 5.6. Management practices such as liming and allowing napropamide to dry on the soil may increase environmental transport. Also quantification of napropamide in environmental samples can be affected by DOM.

Analysis of antioxidants extracted from polypropylene by supercritical fluid extraction

Maximal potential migration of six antioxidants (AO) from five polypropylene (PP) formulations was determined by two supercritical fluid extraction (SFE) procedures, both of which contained static and dynamic steps. All analytical conditions affecting the extraction were studied and optimized using Irgafos 168 as standard. SFE was more efficient as temperature and fluid density increased. During the static step in which the samples were exposed to the fluid without flux, the introduction of hexane and methanol as fluid modifiers significantly improved the extraction. Hexane appears to facilitate polymer swelling while methanol solvates the antioxidants. In the dynamic step (in which the extraction actually occurs) time is the key parameter. Extraction for 90 min results in an efficiency of around 75%. The introduction of modifiers during this step (by an HPLC‐SFE procedure) did not produce any significant improvement. When SFE was carried out on all samples, extraction efficiency was around 75% except for Irganox 1010 and Hostanox O3. The large molecular volume of these antioxidants may be responsible for the considerable reduction of extraction efficiency. Particle size and shape of polymer sample were also important. The greater the surface to volume ratio the greater the extraction efficiency.

Gas-phase postderivatization following solid-phase microextraction for determining acidic herbicides in water.

This study analyzes acidic herbicides from an aqueous sample by developing a methylated postderivatization on the fiber following solid-phase microextration (SPME) with diazomethane gas procedure combined with GC/MS. Analysis results indicate that a silica fiber coated with polyacrylate (PA) yields a higher extraction efficiency than that obtained with poly(dimethylsiloxane) (PDMS) using the SPME technique. Detection limits are achieved at the level of 10-30 ng/L. Linearity is obtained over a wide range, with precision below 12% RSD. In addition, the significant reduction in extraction efficiency is attributed to the concentration of humic acids exceeding 5 mg/L. Various degradation compounds of acidic herbicides in basic solution are also detected, including 2,4-dichlorophenol, 2,4,5-trichlorophenol, 4-chloro-3-methylphenol, pentachlorinated biphenyl, and tetrachlorinated biphenyl. Moreover, the amount of pentachlorinated biphenyl and tetrachlorinated biphenyl increases over time.

Reduction in extraction efficiency of charged particles from the ion source as the cause of matrix effects in the GC-MS analysis of drugs.

Previous studies have shown that the ion response of a compound can be suppressed by the presence of a large amount of a coeluting substance in a gas chromatographic-mass spectrometric (GC-MS) system. In the present study, the change in the ion current of a constant amount of diazepam-d5 in the presence of a 100-fold amount of diazepam was used to monitor this condition in the Hewlett Packard mass selective detector (MSD). It was observed that a reduced recovery of ions occurred when the potentials of the MSD source elements were established by the autotune algorithm. Increasing the ion focus or the entrance lens potentials or both increased the recovery of the ion current of diazepam-d5 in the presence of large amounts of diazepam. The data suggested that the decreased recovery of ion current observed when the autotune source parameters were used was due to insufficient energy on the focusing lenses to extract a constant fraction of the ions from the source when a high concentration of molecules was present.

Combinaison d'une cellule d'extraction liquide-liquide en continu et d'un couplage CG-SM en vue de l'analyse des pesticides dans les eaux

The occurrence of synthetic organic chemicals in drinking water supplies has prompted the European Economic Community to establish standards for pesticides. Currently, the limit on total pesticides is 500 ng l −1 with no individual pesticide to exceed 100 ng l −1. The variability of pesticides, both in concentration and composition, indicates that composite rather than grab samples are desirable for analysis of the water quality. Furthermore, the variability in composition makes a broad spectrum analysis preferable to individual compound analysis so that many compounds can be analysed simultaneously. Although composite broad spectrum samples are desirable from a collection point of view, the occurrence of many pesticides in one sample presents a problem for individual compound quantification and identification. For this reason, gas chromatography (GC) is used to separate the compounds and mass spectrometry (MS) is used to identify and quantify the compounds. Coupled GS-MS avoids interferences which may occur in GC by using a separate method (other than retention time or volume) to identify compounds. This research compared liquid-liquid extraction (LLE) in the batch and continuous mode. The LLE process is accomplished in a continuous mode by mixing the water and solvent in a coil, allowing the water and solvent to separate in a quiescent decantation cell, then recirculating the solvent by a separate distillation cell while the water goes to waste. Tap water was spiked with pesticides at 10, 50 and 100 ng l −1. Extraction efficiency was compared at each of the three spiking concentrations. The extracts were analysed on GC-MS using a moving needle injection technique to enhance sensitivity. The identification and quantification of compounds were accomplished by MS using the fragmentometry technique which enhance sensitivity of the analysis. The results indicate that continuous LLE will recover an average of 75% (± 14%) of the pesticides in the 10–100 ng l −1 range recoverable by batch LLE. There was no significant difference in recovery for structurally different pesticides (chlorinated, nitrogenous or phosphoric) as all fell in the 75 ± 14% range. Eighteen pesticides were identified and quantified by the GC-MS in a 25 min analysis. This demonstrates that the continuous LLE technique can be used to automate collection of composite samples if the reduction in extraction efficiency is taken into account. The continuous LLE can handle much larger volumes of water than the batch LLE. Composite samples can be continuously collected over time, a sampling regime not possible with batch LLE. This technique when coupled with GC-MS can be used to identify and quantify pesticides at the ng l −1 level and can be applied routinely for analysis of pesticides at approximately the same price as individual pesticides analysis.