Determination of organophosphorus pesticides using membrane-assisted solvent extraction combined with large volume injection-gas chromatography-mass spectrometric detection

Eight organophosphorus pesticides (parathion-methyl, fenitrothion, malathion, fenthion, bromophos, bromophos-ethyl, fenamiphos and ethion) in aqueous samples were analysed by means of membrane-assisted solvent extraction. First a 20 ml extraction vial was filled with 15 ml of aqueous sample. Then the membrane bag consisting of nonporous polypropylene was put into the vial and filled with 800 microl of organic solvent. The analytes were separated from the aqueous layer by transporting them through the membrane material into the small amount of solvent. The technique was fully automated and successfully combinable with large volume extraction and GC-MS. To achieve an optimum performance several extraction conditions were investigated. Cyclohexane was chosen as acceptor phase. Then the impact of salt, methanol, pH value, as well as working parameters like stirring rate of the agitator and extraction time, were studied. Moreover, the influence of matrix effects was examined by adding different concentrations of humic acid sodium salt. Detection limits in the ng/l level were achieved using large volume injection with the injecting volume of 100 microl. The recovery values ranged from 47 to 100% and the relative standard deviation for three standard measurements was between 4 and 12% (except for bromophos-ethyl: 22%). The linear dynamic range was between 0.001 and 70 microg/l. The applicability of the method to real samples was tested by spiking the eight organophosphorus pesticides to red wine, white wine and apple juice samples.     

Miniaturized membrane-assisted solvent extraction combined with gas chromatography/electron-capture detection applied to the analysis of volatile organic compounds

A new module of membrane-assisted solvent extraction (MASE) with miniaturized membrane bags was applied to the determination of seven volatile organic compounds (VOCs): chloroform, 1,1,1-trichloroethane, trichloroethylene, 1,1,2-trichloroethane, tetrachloroethene, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane with boiling points between 61 and 147 degrees C in aqueous samples. Different from the known procedure the new, shortened membrane bags were filled with 100 microl of an organic solvent. The membrane bags were placed in a 20 ml headspace vial and filled with 15 ml of the aqueous sample. The vial was transferred into an autosampler where it was stirred for a definite time at elevated temperature. After the extraction, 1 microl of the organic extract was transferred into the spilt/splitless injector of a GC system equipped with an electron-capture detector. This work included optimization of the membrane device, the determination of the optimized extraction conditions such as stirring rate, extraction time and the impact of salt addition. The validation of the method involved repeatability, recovery and detection limit studies, followed of its application towards real water samples. The repeatability, expressed as the relative standard deviation of the peak areas of six extractions was below 10%. The detection limits (LODs) were between 5 ng/l (tetrachloroethene) and 50 ng/l (chloroform). Calibration was performed in a range from 5 ng/l to 150 microg/l, since the concentration in the aqueous samples was expected quite various in this concentration range. Five river water samples of Bitterfeld, Saxony-Anhalt, Germany were analyzed with miniaturized-MASE and the results were compared with those obtained with Headspace-Analysis. The method can be fully automated and moreover, it allows the simultaneous determination of volatile and semi volatile compounds.     

Headspace solvent microextraction and gas chromatographic determination of some polycyclic aromatic hydrocarbons in water samples

Headspace solvent microextraction (HSME) was shown to be an efficient preconcentration method for extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions. A microdrop of 1-butanol (as extracting solvent) containing biphenyl (as internal standard) was used in this investigation. Extraction occurred by suspending a 3 μl drop of 1-butanol from the tip of a microsyringe fixed above the surface of solution in a sealed vial. After extraction for a preset time, the microdrop was retracted back into the syringe and injected directly into a GC injection port. The effects of nature of extracting solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, ionic strength and extraction time on HSME efficiency were investigated and optimized. Finally, the enrichment factor, dynamic linear range (DLR), limit of detection (LOD) and precision of the method were evaluated by water samples spiked with PAHs. The optimized procedure was successfully applied to the extraction and determination of PAHs in different water samples.     

Fully automated analytical system using liquid-solid extraction and liquid chromatography for the determination of CGP 6140 in plasma

Liquid-solid extraction on disposable extraction columns (DECs) and liquid chromatography can be combined in a completely automated analyser. The Gilson ASPEC system was used to develop a procedure for the determination of CGP 6140 in plasma. Both sample preparation via C8 Bond-Elut DECs and injection were fully automatic. The fully automated system prepared the samples by performing the same operations as for a manual procedure. The DEC was first wetted with methanol, then with water. A 400-microliters volume of plasma and 40 microliters of the internal standard solution, diluted with 1 ml of water, were applied to the DEC, rinsed with 10(-2) mol/l dipotassium hydrogenphosphate and eluted from the DEC with 300 microliters of acetonitrile-methanol (50:50, v/v). The eluting strength of the eluate was reduced by dispensing 1 ml of water into each vial prior to direct injection into a Spherisorb ODS column via a 1-ml loop. This allowed the reconcentration of the extracted compounds on the top of the column, as they were injected in a large volume of solvent of lower eluting strength than the mobile phase [acetonitrile-methanol-4 x 10(-3) mol/l ammonia solution (54.5:5:40.5, v/v/v)]. Reproducibility results are presented.     

Temperature-controlled headspace liquid-phase microextraction device using volatile solvents

A novel temperature-controlled headspace liquid-phase microextraction (TC-HS-LPME) device was established in which volatile solvents could be used as extractant. In this device, a PTFE vial cap with a cylindrical cavity was used as the holder of the extraction solvent. Up to 40 μl of extraction solvent could be suspended in the cavity over the headspace of aqueous sample in the vial. A cooling system based on thermoelectric cooler (TEC) was used to lower the temperature of extractant in PTFE vial cap to reduce the loss of volatile solvent during extraction process and increase the extraction efficiency. The selection of solvents for HS-LPME was then extended to volatile solvents, such as dichloromethane, ethyl acetate and acetone. The use of volatile extraction solvents instead of semi-volatile solvent reduced the interference of the large solvent peak to the analytes peaks, and enhanced the compatibility of HS-LPME with gas chromatograph (GC). Moreover, the use of larger volume of extractant solvent increases the extraction capacity and the injection volume of GC after extraction, thus improving detection limits. Several critical parameters of this technique were investigated by using chlorobenzenes (CBs) as the model analytes. High enrichment factors (498–915), low limits of detection (0.004–0.008 μg/L) and precision (3.93–5.27%) were obtained by using TC-HS-LPME/GC-FID. Relative recoveries for real samples were more than 83%.     

Trace analysis of chlorobenzenes in water samples using headspace solvent microextraction and gas chromatography/electron capture detection

In the present work, a rapid method for the extraction and determination of chlorobenzenes (CBs) such as monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene in water samples using the headspace solvent microextraction (HSME) and gas chromatography/electron capture detector (ECD) has been described. A microdrop of the dodecane containing monobromobenzene (internal standard) was used as extracting solvent in this investigation. The analytes were extracted by suspending a 2.5 μl extraction drop directly from the tip of a microsyringe fixed above an extraction vial with a septum in a way that the needle passed through the septum and the needle tip appeared above the surface of the solution. After the extraction was finished, the drop was retracted back into the needle and injected directly into a GC column. Optimization of experimental conditions such as nature of the extracting solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, the ionic strength and extraction time were investigated. The optimized conditions were as follows: dodecane as the extracting solvent, the extraction temperature, 45 °C; the sodium chloride concentration, 2 M; the extraction time, 5.0 min; the stirring rate, 500 rpm; the drop volume, 2.5 μl; the sample volume, 7 ml; the microsyringe needle temperature, 0.0 °C. The limit of detection (LOD) ranged from 0.1 μg/l (for 1,3-dichlorobenzene) to 3.0 μg/l (for 1,4-dichlorobenzene) and linear range of 0.5–3.0 μg/l for 1,2-dichlorobenzene, 1,3-dichlorobenzene and from 5.0 to 20.0 μg/l for monochlorobenzene and from 5.0 to 30 μg/l for 1,4-dichlorobenzene. The relative standard deviations (R.S.D.) for most of CBs at the 5 μg/l level were below 10%. The optimized procedure was successfully applied to the extraction and determination of CBs in different water samples.     

Analysis of polychlorinated biphenyls in aqueous samples by microwave-assisted headspace solid-phase microextraction

The hyphenated technique namely microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) was developed and studied for the simultaneous extraction/enrichment of polychlorinated biphenyls (PCBs) in aqueous samples prior to the quantification by gas chromatography (GC). The PCBs in aqueous media are extracted onto a solid-phase micro fibre via the headspace with the aid of microwave irradiation. The optimum conditions for obtaining extraction efficiency, such as the extraction time, addition of salts, addition of methanol, ratio of sample to headspace volume, and the desorption parameters were investigated. Experimental results indicated that the proposed MA-HS-SPME method attained the best extraction efficiency under the optimized conditions, i.e., irradiation of extraction solution (20 ml aqueous sample in 40 ml headspace vial with no additions of salt and methanol) under 30 W microwave power for 15 cycles (1 min power on and 3 min power off of each cycle). Desorption at 270 degrees C for 3 min provided the best detection results. The detection limit obtained were between 0.27 and 1.34 ng/l. The correlation coefficient for the linear dynamic range from 1 to 80 ng/l exceeded 0.99 for 18 PCBs.     

Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection

Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.     

Determination of phenols in water using liquid phase microextraction with back extraction combined with high-performance liquid chromatography.

Liquid phase microextraction with back extraction (LPME/BE) combined with high-performance liquid chromatography (HPLC) was studied for the determination of a variety of phenols in water samples. The target compounds were extracted from 2-ml aqueous sample adjusted to pH 1 (donor solution) through a microliter-size organic solvent phase (400-microl n-hexane), confined inside a small PTFE ring, and finally into a 1-microl basic aqueous acceptor microdrop suspended inthe aforementioned solvent phase from the tip of a microsyringe needle. After extracting for a prescribed time, the microdrop was taken back into the syringe and directly injected into an HPLC for detection. Factors relevant to the extraction procedure were studied. At the optimized extraction conditions, a large enrichment factor (more than 100-fold) can be achieved for most of the phenols within 35 min. The detection limit range was 0.5-2.5 microg/l for different analytes in aqueous samples. The results demonstrate the suitability of the LPME/BE approach to the analysis of polar compounds in aqueous samples.     

New approach to characterise physicochemical properties of solid substrates by inverse gas chromatography at infinite dilution. II. Study of the transition temperatures of poly(methyl methacrylate) at various tacticities and of poly(methyl methacrylate) adsorbed on alumina and silica

A simple device was developed for in-vial liquid-liquid extraction using a polymer membrane (nonporous polypropylene) to separate an aqueous sample from an organic extractant. The membrane consisted of tubing with an internal diameter of 6 mm and a wall thickness of 0.05 mm, which was heat-sealed at the lower end and filled with 500 microl hexane. This membrane bag was incorporated into a conventional 20 ml headspace vial suitable for a multi-purpose sampler (MPS 2, Gerstel, Mülheim, Germany) directly interfaced to a gas chromatograph with a mass-selective detector. The sampler enabled the extraction vial to be mixed at a defined temperature with subsequent large-volume injection of the organic extract taken from the membrane bag. The method was evaluated using several triazines, 2,4-dichloroaniline, alpha-hexachlorocyclohexane and phenanthrene as model compounds. Extraction parameters such as temperature, agitation speed, and extraction time were optimised. Recoveries of 60-90% were achieved after 30 min extraction. By increasing the injection volume to 100 microl, detection limits of 1-10 ng/l were determined.     

Determination of 7-aminoflunitrazepam in urine by dispersive liquid-liquid microextraction with liquid chromatography-electrospray-tandem mass spectrometry

Dispersive liquid-liquid microextraction (DLLME) and liquid chromatography-electrospray-tandem mass spectrometry (LC-ES-MS/MS) procedure was presented for the extraction and determination of 7-aminoflunitrazepam (7-aminoFM2), a biomarker of the hypnotic flunitrazepam (FM2) in urine sample. The method was based on the formation of tiny droplets of an organic extractant in the sample solution using water-immiscible organic solvent [dichloromethane (DCM), an extractant] dissolved in water-miscible organic dispersive solvent [isopropyl alcohol (IPA)]. First, 7-aminoFM2 from basified urine sample was extracted into the dispersed DCM droplets. The extracting organic phase was separated by centrifuging and the sedimented phase was transferred into a 300 μl vial insert and evaporated to dryness. The residue was reconstituted in 30 μl mobile phase (20:80, acetonitrile:water). An aliquot of 20 μl as injected into LC-ES-MS/MS. Various parameters affecting the extraction efficiency (type and volume of extraction and dispersive solvent, effect of alkali and salt) were evaluated. Under optimum conditions, precision, linearity (correlation coefficient, r² = 0.988 over the concentration range of 0.05-2.5 ng/ml), detection limit (0.025 ng/ml) and enrichment factor (20) had been obtained. To our knowledge, DLLME was applied to urine sample for the first time.     

Headspace single-drop microextraction for the analysis of chlorobenzenes in water samples

Exposing a microlitre organic solvent drop to the headspace of an aqueous sample contaminated with ten chlorobenzene compounds proved to be an excellent preconcentration method for headspace analysis by gas chromatography-mass spectrometry (GC-MS). The proposed headspace single-drop microextraction (SDME) method was initially optimised and the optimum experimental conditions found were: 2.5 microl toluene microdrop exposed for 5 min to the headspace of a 10 ml aqueous sample containing 30% (w/v) NaCl placed in 15 ml vial and stirred at 1000 rpm. The calculated calibration curves gave a high level of linearity for all target analytes with correlation coefficients ranging between 0.9901 and 0.9971, except for hexachlorobenzene where the correlation coefficient was found to be 0.9886. The repeatability of the proposed method, expressed as relative standard deviation varied between 2.1 and 13.2% (n = 5). The limits of detection ranged between 0.003 and 0.031 microg/l using GC-MS with selective ion monitoring. Analysis of spiked tap and well water samples revealed that matrix had little effect on extraction. A comparative study was performed between the proposed method, headspace solid-phase microextraction (SPME), solid-phase extraction (SPE) and EPA method 8121. Overall, headspace SDME proved to be a rapid, simple and sensitive technique for the analysis of chlorobenzenes in water samples, representing an excellent alternative to traditional and other, recently introduced, methods.     

Ultrasound‐assisted emulsification microextraction combined with injection‐port derivatization for the determination of some chlorophenoxyacetic acids in water samples

An efficient method based on ultrasound‐assisted emulsification microextraction followed by injection‐port derivatization GC analysis was developed to determine 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 4‐chloro‐2‐methylphenoxyacetic acid (MCPA) in natural water samples. In this procedure, 12.5 μL of 1‐undecanol was injected slowly into a 12 mL home‐designed centrifuge glass vial containing an aqueous sample of the analytes located inside an ultrasonic water bath. The resulting emulsion was centrifuged, and 1 μL of the separated organic solvent together with 1 μL of the derivatization reagent were injected into a GC equipped with a flame ionization detector. Several factors that influence the derivatization and extraction were optimized. Under the optimal conditions, the LODs were 0.33 and 1.7 μg/L for MCPA and 2,4‐D, respectively. Preconcentration factors of 670 and 836 were obtained for MCPA and 2,4‐D, respectively. The precision of the proposed method was evaluated in terms of repeatability, which was <5.7% (n = 5). The applicability of the proposed method was evaluated by extraction and determination of chlorophenoxyacetic acids from some natural waters, which indicated that the matrices of natural waters have no significant effect on the extraction and derivatization efficiency of this method.     

Headspace solvent microextraction: a very rapid method for identification of volatile components of Iranian Pimpinella anisum seed

At the present study, a new and rapid headspace solvent microextraction (HSME), for the extraction and pre-concentration of the volatile components of plant sample into a microdrop was applied. The extraction occurred by suspending a microliter drop of the solvent from the tip of a microsyringe to the headspace of a ripen and powdered dry fruit sample (Iranian Pimpinella anisum seed) in a sealed vial for a preset extraction time, then the microdrop was retracted back into the microsyringe and injected directly into a GC injection port. The chemical composition of the HSME extracts were confirmed according to their retention indexes and mass spectra (EI, 70 eV); and quantitative analysis was performed by GC-FID.Parameters such as the nature of the extracting solvent, particle size of the sample, temperatures of the microdrop and sample, volume of sample and the extraction time were studied and optimized, and the method's performance was evaluated. The optimized conditions were: sample particle size, 1 mm; sample volume, 5 ml (in a 15 ml vial); sample temperature, 60 °C; microsyringe needle temperature, 0 °C; and extraction time, 10 min. Finally, accordingly, the percentage of trans-anethole (the major compound of P. anisum) and the relative standard deviation for extraction and determination of trans-anethole (seven-replicated analysis) were determined to be 90% and 3.9%, respectively.     

Determination of residual monomer in polymer latex by full evaporation headspace gas chromatography

This study demonstrated a full evaporation (FE) headspace gas chromatographic technique for the determination of residual monomer in methyl methacrylate (MMA) polymer latex. A very small amount (approximately 10-30 mg) of latex was added to a sealed headspace sample vial (20 ml). A near-complete monomer mass transfer from both liquid (aqueous phase) and solid phase (polymer particles) to the vapor phase (headspace) is achieved within 5 min at a temperature of 110 degrees C. The method eliminates sample pretreatment procedures such as the solvent extraction. Thus, it avoids the risk of polymer deposition on the GC system caused by a directly injection of extraction solvent in the conventional GC monomer analysis. The present method is simple, rapid, and accurate.     

Directly Suspended Droplet Microextraction and Analysis of Amitriptyline and Nortriptyline by GC

Directly Suspended Droplet Microextraction (DSDME) was used for the determination of two tricyclic antidepressant drugs (TCAs), amitriptyline and nortriptyline. In this technique, an aqueous sample is agitated with a stirring bar, creating a mild vortex at the center of the vial. A droplet of an immiscible organic solvent is placed at the bottom of the vortex. After 20 min a portion of the organic droplet is withdrawn with a syringe and injected into the GC. Experimental conditions, such as the extraction solvent, extraction time, solvent volume, stirring rate, pH and salt addition were optimized. In order to evaluate the practical application of the method, relative standard deviations, linearity range and limits of detection were calculated. Typical enrichment factors were 167 and 179 for amitriptyline and nortriptyline, respectively. The method was applied to the determination of these drugs in urine samples.     

Simultaneous derivatization and extraction of anilines in waste water with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometric detection

The one-step derivatization and extraction technique for the determination of anilines in river water by dispersive liquid-liquid microextraction (DLLME) is presented. In this method the anilines are extracted by DLLME and derivatized with pentafluorobenzaldehyde (PFBAY) in aqueous solution simultaneously. In this derivatization/extraction method, 0.5 ml acetone (disperser solvent) containing 10 microl chlorobenzene (extraction solvent) and 30 g/l pentafluorobenzaldehyde (PFBAY) dissolved in methanol was rapidly injected by syringe into 5 ml aqueous sample (pH 4.6). Within 20 min the analytes extracted and derivatized were almost finished. After centrifugation, 2 microl sedimented phase containing enriched analytes was determined by GC-MS. The effects of extraction and disperser solvent type and their volume, pH value of sample solution, derivatization and extraction time, derivatization and extraction temperature were investigated. Linearity in this developed method was ranging from 0.25 to 70 microg/l, and the correlation coefficients (R2) were between 0.9955 and 0.9989, and reasonable reproducibility ranging from 5.8 to 11.8% (n=5). Method detection limits (MDLs) ranged from 0.04 to 0.09 microg/l (n=5).     

Low-density solvent-based solvent demulsification dispersive liquid-liquid microextraction for the fast determination of trace levels of sixteen priority polycyclic aromatic hydrocarbons in environmental water samples

For the first time, the low-density solvent-based solvent demulsification dispersive liquid-liquid microextraction was developed for the fast, simple, and efficient determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in environmental samples followed by gas chromatography-mass spectrometric (GC-MS) analysis. In the extraction procedure, a mixture of extraction solvent (n-hexane) and dispersive solvent (acetone) was injected into the aqueous sample solution to form an emulsion. A demulsification solvent was then injected into the aqueous solution to break up the emulsion, which turned clear and was separated into two layers. The upper layer (n-hexane) was collected and analyzed by GC-MS. No centrifugation was required in this procedure. Significantly, the extraction needed only 2-3 min, faster than conventional DLLME or similar techniques. Another feature of the procedure was the use of a flexible and disposable polyethylene pipette as the extraction device, which permitted a solvent with a density lighter than water to be used as extraction solvent. This novel method expands the applicability of DLLME to a wider range of solvents. Furthermore, the method was simple and easy to use, and some additional steps usually required in conventional DLLME or similar techniques, such as the aforementioned centrifugation, ultrasonication or agitation of the sample solution, or refrigeration of the extraction solvent were not necessary. Important parameters affecting the extraction efficiency were investigated in detail. Under the optimized conditions, the proposed method provided a good linearity in the range of 0.05-50 μg/L, low limits of detection (3.7-39.1 ng/L), and good repeatability of the extractions (RSDs below 11%, n=5). The proposed method was successfully applied to the extraction of PAHs in rainwater samples, and was demonstrated to be fast, efficient, and convenient.     

Membrane-assisted solvent extraction of seven phenols combined with large volume injection-gas chromatography-mass spectrometric detection

Membrane-assisted solvent extraction (MASE) was applied for the determination of seven phenols (phenol, 2-chlorophenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol and pentachlorophenol) with log Kow (octanol-water-partition-coefficient) between 1.46 (phenol) and 5.12 (pentachlorophenol) in water. The extraction solvents cyclohexane, ethyl acetate and chloroform were tested and ethyl acetate proved to be the best choice. The optimisation of extraction conditions showed the necessity of adding 5 g of sodium chloride to each aqueous sample to give a saturated solution (333 g/L). The pH-value of the sample was adjusted to 2 in order to convert all compounds into their neutral form. An extraction time of 60 min was found to be optimal. Under these conditions the recovery of phenol, the most polar compound, was 11%. The recoveries of the other analytes ranged between 42% (2-chlorophenol) and 98% (2,4-dichlorophenol). Calibration was performed using large volume injection (100 microL injection volume). At optimised conditions the limits of detection were between 0.01 and 0.6 microg/L and the relative standard deviation (n = 3) was on average about 10%. After the method optimisation with reagent water membrane-assisted solvent extraction was applied to two contaminated ground water samples from the region of Bitterfeld in Saxony-Anhalt, Germany. The results demonstrate the good applicability of membrane-assisted solvent extraction for polar analytes like phenols, without the necessity of derivatisation or a difficult and time-consuming sample preparation.     

Selective dissolution and one step separation of terpene trilactones in ginkgo leaf extracts for GC-FID determination

Under ultrasonication, the ginkgo terpene trilactones, ginkgolides and bilobalide, in ginkgo extracts can be selectively dissolved in 10% aqueous NaH(2)PO(4) solution at a temperature of 50-60 degrees C and separated from the solution by extraction with a mixture of ethyl acetate/tetrahydrofuran in a capped vial. After derivatization, these terpene trilactones can be quantified using GC-FID. This method has a detection limit of 10 ng, and the RSD was 6% (n=5). Twelve commercial GBE products in powder, liquid, tablet and capsule forms were analyzed. The total time required for analyzing these samples from sample preparation to final data processing was less than 6 h, and the total organic solvent consumption was less than 40 ml. This procedure proves to be a simple, fast, safe, and effective method for all types of Ginkgo biloba extracts (GBE) including the "complex" or "advanced" formulas.