A Fast,Simple Method for Analysis of Phenoxy Acid Salt and Ester Formulations by High Performance Liquid Chromatography

Abstract

Salt formulations of 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) and dichlorprop [2-(2,4-dichlorophenoxy)propanoic acid] have been analysed by reversed-phase HPLC using a C18-column with 50:50 (v/v) acetonitrile/2% acetic acid as eluant. Internal and external standard HPLC methods are compared.

Ester formulations of 2,4-D and 2,4,5–T are analysed, without hydrolysis, on the same column using 60:40 (v/v) acetonitrile/2% acetic acid as eluant. The method has been used in this laboratory to determine free phenoxy acid in ester formulations, and for the identification of esters in mixed ester formulations.

The methods are fast and accurate, and offer some advantages over previously-described methods.     

Enantiomeric separation of chiral phenoxy acid herbicides by electrokinetic chromatography. Application to the determination of analyte-selector apparent binding constants for enantiomers

The enantiomeric resolution of chiral phenoxy acid herbicides was performed by electrokinetic chromatography using a cyclodextrin as chiral pseudophase (CD-EKC). A systematic evaluation of several neutral and charged cyclodextrins was made. Among the cyclodextrins tested, (2-hydroxy)propyl beta-cyclodextrin (HP-beta-CD) was found to be the most appropriate for the enantioseparation of phenoxy acids. The influence of some experimental conditions, such as nature and pH of the background electrolyte, chiral selector concentration, and temperature, on the enantiomeric separation of phenoxy acids was also studied. The use of a 50 mM electrolyte solution in ammonium formate at pH 5 and a temperature of 40 degrees C enabled the enantiomeric resolution of four of the six phenoxy acids investigated (2-phenoxypropionic acid, 2(3-chlorophenoxy)propionic acid, 2-(4-chlorophenoxy)propionic acid, and 2-(2,4-dichlorophenoxy)propionic acid) obtaining migration times ranging from 9 to 15 min. Mixtures of the two phenoxy acids not enantiomerically resolved (2-(4-chlorophenoxy)-2-methylpropionic acid and 2-(2,4,5-trichlorophenoxy)propionic acid) and up to three of the phenoxy acids enantiomerically resolved were separated in about 15 min. Finally, the apparent binding constants for each enantiomer-HP-beta-CD pair were calculated at two temperature values (20 and 40 degrees C).     

Capillary liquid chromatography of chlorophenoxy acid herbicides and their esters in apple juice samples after preconcentration on a cation exchanger based on polydivinylbenzene-N-vinylpyrrolidone

A capillary liquid chromatography (cLC) method with gradient elution has been used to determine chlorophenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid, 2-(2,4-dichlorophenoxy)propanoic acid, 2-(4-chloro-2-methylphenoxy)propanoic acid, 4-(2,4-dichlorophenoxy)butanoic acid, 4-(4-chloro-2-methylphenoxy)butanoic acid, 2-(2,4,5-trichlorophenoxy)propanoic acid, 2,4-dichlorophenoxyacetic-1-methyl ester and 2,4-dichlorophenoxyacetic-1-butyl ester in spiked apple juice samples with amounts between 0.025 and 0.150 mg kg(-1) of each herbicide. Clean-up and preconcentration of acid and esters were carried out in an Oasis MCX polymer. Detection limits obtained by cLC, between 0.005 and 0.018 mg kg(-1), allowed the determination of chlorophenoxy acids and their esters in apple juice samples around the levels permitted by the European Regulations, with recoveries in the range 84-99% and RSDs between 1 and 4%.     

Solid-phase extraction of acidic herbicides

A discussion of solid-phase extraction method development for acidic herbicides is presented that reviews sample matrix modification, extraction sorbent selection, derivatization procedures for gas chromatographic analysis, and clean-up procedures for high-performance liquid chromatographic analysis. Acidic herbicides are families of compounds that include derivatives of phenol (dinoseb, dinoterb and pentachlorophenol), benzoic acid (acifluorfen, chloramben, dicamba, 3,5-dichlorobenzoic acid and dacthal--a dibenzoic acid derivative), acetic acid [2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)], propanoic acid [dichlorprop, fluazifop, haloxyfop, 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and silvex], butanoic acid [4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB)], and other miscellaneous acids such as pyridinecarboxylic acid (picloram) and thiadiazine dioxide (bentazon).     

Multiresidue determination of chlorophenoxy acid herbicides in human urine samples by use of solid-phase extraction and capillary LC–UV detection

Chlorophenoxy acid herbicides are intensively applied to get rid of unwanted plants because of their low cost and selectivity. Due to their toxicity, which depends on their chemical form, the European Community has established legal directives to restrict their use and to control their maximum residue levels in several matrices. Determination of chlorophenoxy acids—2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP), 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB) and 2-(2,4,5-trichlorophenoxy)propanoic acid (2,4,5-TP) in spiked human urine samples has been carried out by capillary LC, after solid-phase extraction on a column packed with silica C₁₈ restricted-access material. Chromatographic analysis was performed in gradient-elution mode at 25 °C, with injection of 20 μL low-organic-solvent composition herbicide solutions for focusing purposes on the head of the capillary column, and diode array detection at 232 nm. Urine samples collected during 24 h from healthy and unexposed volunteers were spiked in the concentration range 25–150 μg L⁻¹; recoveries obtained were between 66 and 100% (n = 6 for each spiked level) and RSDs (relative standard deviations) were between 1 and 5%. Detection limits in the urine samples from volunteers were between 3.5 and 6.0 μg L⁻¹. The developed methodology has allowed the clean-up and preconcentration of low volumes of untreated human urine without previous treatment, showing the effectiveness of the employed SPE sorbent for extracting the target analytes and ultimately resulting in the reduction of the sample-preparation time.     

Chiral separation of newly synthesized arylpropionic acids by capillary electrophoresis using cyclodextrins or a glycopeptide antibiotic as chiral selectors

Summary The chiral separation of two newly synthesized arylpropionic acids of pharmaceutical interest, namely 2-[(5′-benzoil-2′-hydroxy)phenyl]-propionic acid (DF-1738y) and 2-[(4′-benzoiloxy-2′-hydroxy)phenyl]-propionic acid (DF-1770y), was performed by Capillary Zone Electrophoresis (CZE) using either cyclodextrins or antibiotics as chiral selectors in coated capillary. In order to optimize the separation, the effect on the migration time and resolution of type and concentration of the chiral selector, the buffer pH and the capillary temperature were studied. Several cyclodextrins, namely the charged 6^A-monomethylamino-β-cyclodextrin (MeNH-β-CD) and the neutral methyl-β-cyclodextrins (M-β-CD) and heptakis-2,3,6-tri-O-methyl-β-cyclodextrin (TM-β-CD), were tested for the enantiomeric separation of aryl propionic acids (APAs) compounds. Of these TM-β-CD provided the highest enantiomeric resolution at pH 5, however only DF-1738y optical isomers were baseline resolved. Using background electrolytes (BGEs) at higher pHs (pH=6–7) supported with the above listed CDs, an enantioresolution increase was recognized only for compound DF-1738y. In contrast DF-1770y exhibited the highest resolution at the lowest pH value studied (pH 4). The macrocyclic antibiotic vancomycin was therefore added to the BGE and tested as chiral selector using the partial filling counter current mode in order to obtain a sensitive analysis, high resolution and reduced antibiotic adsorption on the capillary wall. 5 mM vancomycin dissolved in the BGE at pH 5 and 25°C provided relatively high enantiomeric resolution (R _DF-1738y=3.4,R _DF-1770y=2.22) of both compounds.     

Application of solid-phase extraction and micellar electrokinetic capillary chromatography to the study of hydrolytic and photolytic degradation of phenoxy acid and phenylurea herbicides

A degradation study of two phenoxy acid [(2,4-dichlorophenoxy) propanoic acid and (2,4,5-trichlorophenoxy) acetic acid] and two phenylurea (diuron and monolinuron) herbicides, spiked at 50 ppb in water, was performed. Some samples were subjected to neutral and basic hydrolysis; other samples were subjected to photolysis using either sunlight or a xenon arc lamp. After degradation, the water samples were preconcentrated using solid-phase extraction (SPE) with Carbopack B columns and analysed by a micellar electrokinetic capillary chromatography (MECC) system with UV detection at 210 nm. Phenoxyacetic acids were not degraded neither by hydrolysis nor by sunlight photolysis, but they were photodegraded when they were exposed to a xenon arc lamp, with half-lives around 300 min. Phenylurea herbicides were hydrolysed at the two-tested pH, with half-lives varying from 25 to 290 days. The main hydrolysis products were the corresponding chloroanilines. Diuron and monolinuron were also degraded when they were exposed to sunlight and xenon arc lamp. The main photodegradation pathway for diuron corresponded to dehalogenation, while for monolinuron dealkylation and hydroxylation were also postulated. The toxicity of the studied herbicides and their degradation products was evaluated by means of Microtox tests. The obtained results indicated that the toxicity of the degraded samples was higher than the toxicity of the herbicides.     

整体柱在线固相微萃取-高效液相色谱同步富集检测水中的苯氧羧酸类除草剂

采用C18毛细管整体柱作为固相微萃取整体柱,构建在线固相微萃取-高效液相色谱联用系统,同步富集检测环境水样中的5种苯氧羧酸类除草剂。详细考察了联用系统运行条件对富集检测的影响。联用系统运行最佳参数为:固相微萃取整体柱长度20 cm,进样流速0.04 mL/min,进样13 min,洗脱流速0.02 mL/min,洗脱5 min。在最佳条件下,5种苯氧羧酸类除草剂的检出限为:9 μg/L (苯氧丙酸)、4 μg/L (2-(2-氯)-苯氧丙酸)、4 μg/L (2-(3-氯)-苯氧丙酸)、5 μg/L (2,4-二氯苯氧乙酸)、5 μg/L (2-(2,4-二氯苯氧基)丙酸)。与HPLC系统直接进样对比,联用系统对5种检测对象表现出优良的富集能力。5种苯氧羧酸类除草剂的回收率在79.0%~98.0%之间(RSD≤3.9%)。该方法成功应用于水样中5种苯氧羧酸类除草剂的检测,结果令人满意。     

Chiral separation of amide conjugates of jasmonic acid by liquid chromatography

Summary Synthetic amide conjugates of (−)-jasmonic acid and its (+)-enantiomer were resolved by means of chiral liquid chromatography. The diastereomeric pairs prepared by chemical reaction of (±)-jasmonic acid with a series of (S)- or (R)-amino acids and with some (S)-amino acid alcohols were completely separated on Chiralpak AS using a mixture of n-hexane/2-propanal as mobile phase. The retention data indicate that the (−)-jasmonic acid conjugates eluted faster than those of the (+)-enantiomer, independent on the configuration of the bound amino acid. Likewise, enantiomeric derivatives of (±)-jasmonic acid and non-chiral amino acids were completely separated on the chiral stationary phase and showed the same elution sequence. The resolution factors,Rs, were found to range between 1.13 and 6.64. The separated compounds were chiropatically analyzed by measurement of the circular dichroism. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

New derivatives of cyclodextrins as chiral selectors for the capillary electrophoretic separation of dichlorprop enantiomers

-, β- and γ-cyclodextrins (CDs), as well as some of their chemical derivatives, have been tested as chiral resolving agents for the capillary zone electrophoretic resolution of the racemic herbicide dichlorprop, (±)-2-(2,4-dichlorophenoxy)propionic acid, of which only the (+)-isomer is herbicidally active. The complexation constants of the herbicide enantiomers with the cyclodextrin host molecules have been calculated from the electrophoretic migration time data at variable cyclodextrin concentration. The experimental results showed that several of the investigated CDs allowed dichlorprop enantiomer resolution. In particular, a newly synthesised ethylcarbonate derivative of β-CD showed the best enantiomer resolution properties among the tested compounds, while the remaining ones showed inferior or no performances at all. The calculated inclusion constants allowed identification of the best conditions for enantioresolution, and an explanation of the different complexation properties of the investigated compounds has been proposed on the basis of molecular modeling.     

Enantioselective stable isotope analysis (ESIA) of polar herbicides

Assessing the environmental fate of chiral micropollutants such as herbicides is challenging. The complexity of aquatic systems often makes it difficult to obtain hydraulic mass balances, which is a prerequisite when assessing degradation based on concentration data. Elegant alternatives are concentration-independent approaches like compound-specific isotope analysis or enantiospecific concentration analysis. Both detect degradation-induced changes from ratios of molecular species, either isotopologues or enantiomers. A combination of both—enantioselective stable isotope analysis (ESIA)—provides information on ¹³C/¹²C ratios for each enantiomer separately. Recently, Badea et al. demonstrated for the first time ESIA for the insecticide α-hexachlorocyclohexane. The present study enlarges the applicability of ESIA to polar herbicides such as phenoxy acids: 4-CPP ((RS)-2-(4-chlorophenoxy)-propionic acid), mecoprop (2-(4-chloro-2-methylphenoxy)-propionic acid), and dichlorprop (2-(2,4-dichlorophenoxy)-propionic acid). Enantioselective gas chromatography–isotope ratio mass spectrometry was accomplished with derivatization prior to analysis. Precise carbon isotope analysis (2σ?≤?0.5‰) was obtained with ≥7 ng C on column. Microbial degradation of dichlorprop, 2-(2,4-dichlorophenoxy)-propionic acid by Delftia acidovorans MC1 showed pronounced enantiomer fractionation, but no isotope fractionation. In contrast, Badea et al. observed isotope fractionation, but no enantiomeric fractionation. Hence, the two lines of evidence appear to complement each other. They may provide enhanced insight when combined as ESIA.     

Meldrum ’s acid in heterocyclic synthesis: azoles incorporating a 2,4-dichlorophenoxy moiety with anticipated molluscicidal activity

Synthesis of the title ring system is described using ethyl 4-(2,4-dichlorophenoxy)-3-oxobutanoate as starting material. The latter was prepared through acylating Meldrum’s acid with the phenoxy acid chloride derivative.     

Synthesis of polynucleotide analogs by grafting optically active adenine,cytosine, and hypoxanthine derivatives onto polytrimethylenimine

A new family of polynucleotide analogs were prepared by grafting nucleic acid base derivatives onto polytrimethylenimine. Several new optically pure α-nucleic acid base substituted propanoic acids were prepared as pendant groups. The (R)-ethyl adeninylpropanoate was obtained from adenine and (S)-ethyl lactate by utilizing a diethyl azodicarboxylate-triphenyl phosphine method. Subsequent hydrolysis of the ester in aqueous acid gave the (R)-adeninylpropanoic acid without racemization. The reaction of cytosine sodium salt with (S)-ethyl 2-[(methylsulfonyl)oxy] propanoate produced the 20% racemized (R)-ethyl 2-(cytosin-1-yl)propanoate. The optically pure ester was obtained by recrystallization from ethyl alcohol, which was hydrolyzed in aqueous acid to give the (R)-acid with 66% enantiomeric excess. The (R)-2-(hypoxanthin-9-yl)propanoic acid was prepared by reaction of (R)-2-(adenin-9-yl)propanoic acid with sodium nitrite. The pendant groups were allowed to react with N-hydroxy compounds in the presence of dicyclohexylcarbodiimide to give the active esters. These active esters underwent reaction with N,N-dipropylamine to provide monomer model compounds. The pendant groups were grafted onto polytrimethylenimine by using the active ester method. The racemization reactions were observed in the grafting reactions. The resulting polymers showed a range of percent grafting from 60 to 80%.     

Chiral separation of ephedrine alkaloids from <Emphasis Type="Italic">Ephedra sinica</Emphasis> extract and its medicinal preparation using cyclodextrin-modified capillary zone electrophoresis

A fast capillary zone electrophoresis (CZE) method using dimethyl-β-cyclodextrin (DM-β-CD) as modifier with tetrabutylammonium chloride (TBAC) as addition has been developed for the chiral separation of (±)-ephedrine ((±)-EP), (±)-pseudoephedrine ((±)-PP), (±)-N-methylephedrine ((±)-MP), and (±)-norephedrine ((±)-NP). The electrophoretic separation was performed using a 35-cm × 50 μm I.D. (30-cm effective length) fused silica capillary. Samples were introduced under electromigrated injection at 5 kV for 4 s, and the running voltage was 15 kV at the injector end of the capillary. Within 19 min, eight ephedrine compounds were separated and detected at 210 nm. The method was successively applied to the determination of the ephedrine enantiomers in the Chinese herbal extract from Ephedra sinica and its medicinal preparation (Xiaoerqing feiwan). Parameters affecting the resolution between (+) and (-)-enantiomers, such as pH, cyclodextrin type and concentration, organic modifier, and tetraalkylammonium reagents, were reported. The text was submitted by the authors in English.     

Determination of phenoxy herbicides in water samples using phase transfer microextraction with simultaneous derivatization followed by GC‐MS analysis

A sensitive and accurate method for the determination of two model phenoxy herbicides, 4‐chloro‐2‐methylphenoxy acetic acid and 4‐chloro‐2‐methylphenoxy propanoic acid, in water is explained. This method utilizes a simple phase transfer catalyst‐assisted microextraction with simultaneous derivatization. Factors affecting the performance of this method including pH of the aqueous matrix, temperature, extraction duration, type and amount of derivatization reagents, and type and amount of the phase transfer catalyst are examined. Derivatization and the use of phase transfer catalyst have proven to be especially vital for the resolution of the analytes and their sensitive determination, with an enrichment factor of 288‐fold for catalyzed over noncatalyzed procedure. Good linearity ranging from 0.1 to 80 μg L^?1 with correlation of determination (r²) between 0.9890 and 0.9945 were obtained. Previous reported detection limits are compared with our new current method. The low LOD for the two analytes (0.80 ng L^?1 for 4‐chloro‐2‐methylphenoxy propanoic acid and 3.04 ng L^?1 for 4‐chloro‐2‐methylphenoxy acetic acid) allow for the determination of low concentrations of these analytes in real samples. The absence of matrix effect was confirmed through relative recovery calculations. Application of the method to seawater and tap water samples was tested, but only 4‐chloro‐2‐methylphenoxy propanoic acid at concentrations between 0.27 ± 0.01 and 0.84 ± 0.06 μg L^?1 was detected in seawater samples.     

Studies on the syntheses of analgesics. Part 50. Synthesis of optically active 2-[4-(1-oxo-2-isoindolinyl)phenyl]propanoic acid. [Studies on the syntheses of heterocyclic compounds. Part 742]

2-[4-(1-Oxo-2-isoindolinyl)phenyl]propanoic acid ( 1 ) having a potent analgesic and anti-inflammatory activity could be obtained by three methods, which were found to provide extremely useful ways for the synthesis of 1 from the industrial point of view. (E)- and (Z)-Isomers of 2-butenoic acid and oxiranecarboxylic acid derivatives as the intermedaites in the synthesis of 1 were separated and characterized. Furthermore, the optical resolution of (±)-2-[4-(1-oxo-2-isoindolinyl)phenyl]propanoic acid was successfully achieved using cinchonidine as a resolution reagent.     

Synthesis,anti-inflammatory and analgesic activity of 2-[4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid derivatives

The title compounds 3a–l have been synthesized by the reaction of thiocarbohydrazide with substituted phenoxy acetic acid to obtained substituted 1,2,4-triazoles (1). Compound 1 was treated with various substituted aromatic aldehydes which results in 4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-2H-1,2,4-triazol-3(4H)-thiones (2a–g), further 2a–g is converted to 2-[4-(substituted benzylideneamino)-5-(substituted phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3a–l) derivatives by the reaction with chloroacetic acid. All the newly synthesized compounds were evaluated for in vivo anti-inflammatory and analgesic activities. Among the series 2-[4-(2,4-dichlorobenzylideneamino)-5-(phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3d), 2-[4-(4-dichlorobenzylideneamino)-5-(phenoxymethyl)-4H-1,2,4-triazol-3-yl thio] acetic acid (3e), 2-[4-(2,4-dichlorobenzylideneamino)-5-[(2,4-dichlorophenoxy)methyl]-4H-1,2,4-triazol-3-yl thio] acetic acid (3j) and 2-[5-[(2,4-dichlorophenoxy)methyl)]-4-(4-chlorobenzylideneamino)-4H-1,2,4-triazol-3-yl thio] acetic acid (3k) showed significant anti-inflammatory activity with P < 0.001 (63.4%, 62.0%, 64.1% and 62.5% edema inhibition, respectively), as compared to the standard drug diclofenac (67.0%) after third hour respectively and also compounds 3j, 3k exhibited significant analgesic activity with P < 0.001 (55.9% and 54.9% protection, respectively) and less ulcerogenic activity as compared with standard drug aspirin (57.8%).     

<Emphasis Type="Italic">Meldrum</Emphasis>’s acid in heterocyclic synthesis: azoles incorporating a 2,4-dichlorophenoxy moiety with anticipated molluscicidal activity

Synthesis of the title ring system is described using ethyl 4-(2,4-dichlorophenoxy)-3-oxobutanoate as starting material. The latter was prepared through acylating Meldrum’s acid with the phenoxy acid chloride derivative. Correspondence: Emad M. El-Telbani, Pesticides Department, National Research Centre, Dokki, 12622 Cairo, Egypt.     

Chemical release control: Carbamates of 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols

Polymerizable carbamates were synthesized from 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols, such as 2-phenethyl alcohol, citronellol, geraniol, 1-menthol, borneol, and 2-(2,4-dichlorophenoxy)- and 2-(2,4,5-trichlorophenoxy)ethyl alcohols. Copolymerization of these carbamate monomers and N-vinyl-2-pyrrolidone with AIBN in dioxane gave respective copolymers. Hydrolyses of both monomers and copolymers, however, required severe acid conditions, although different chemical structures gave different hydrolytic behaviors.     

Analysis of some chlorophenoxy acids and carbamate herbicides in water and soil as amide derivatives using gas chromatography-mass spectrometry

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).