Simultaneous Determination of Lidocaine, Proline and Lomefloxacin in Human Urine by CE with Electrochemiluminescence Detection

A new method was developed for the simultaneous determination of lidocaine, proline and lomefloxacin in human urine by capillary electrophoresis-electrochemiluminescence detection with Ru(bpy)₃ ²⁺. Conditions of the separation and detection were investigated and optimized. It was proved that 20 mM phosphate buffer at pH 6.7 could achieve the most favorable resolution, and the high sensitivity of detection was obtained by using the detection potential at 1.15 V and 5 mM Ru(bpy)₃ ²⁺–60 mM phosphate buffer at pH 7.6 in the detection reservoir. The detection limits were 0.02 μg mL⁻¹ for lidocaine, 0.03 μg mL⁻¹ for proline and 0.06 μg mL⁻¹ for lomefloxacin. Relative standard deviations of the ECL intensity and the migration time were 3.5 and 1.1% for 6 μg mL⁻¹ lidocaine, 3.2 and 1.0% for 6 μg mL⁻¹ proline and 3.7 and 1.2% for 6 μg mL⁻¹ lomefloxacin, respectively. A baseline separation for lidocaine, proline and lomefloxacin was achieved within 360 s. The developed method was successfully applied to determine the amounts of lidocaine, proline and lomefloxacin in human urine. The recovery and RSD were in the range of 93.3–97.2 and 3.8–4.9%, respectively.     

Determination of Trihalomethanes in Drinking Water by Dispersive Liquid–Liquid Microextraction then Gas Chromatography with Electron-Capture Detection

Dispersive liquid–liquid microextraction (DLLME) has been used for preconcentration of trihalomethanes (THMs) in drinking water. In DLLME an appropriate mixture of an extraction solvent (20.0 μL carbon disulfide) and a disperser solvent (0.50 mL acetone) was used to form a cloudy solution from a 5.00-mL aqueous sample containing the analytes. After phase separation by centrifugation the enriched analytes in the settled phase (6.5 ± 0.3 μL) were determined by gas chromatography with electron-capture detection (GC–ECD). Different experimental conditions, for example type and volume of extraction solvent, type and volume of disperser solvent, extraction time, and use of salt, were investigated. After optimization of the conditions the enrichment factor ranged from 116 to 355 and the limit of detection from 0.005 to 0.040 μg L⁻¹. The linear range was 0.01–50 μg L⁻¹ (more than three orders of magnitude). Relative standard deviations (RSDs) for 2.00 μg L⁻¹ THMs in water, with internal standard, were in the range 1.3–5.9% (n = 5); without internal standard they were in the range 3.7–8.6% (n = 5). The method was successfully used for extraction and determination of THMs in drinking water. The results showed that total concentrations of THMs in drinking water from two areas of Tehran, Iran, were approximately 10.9 and 14.1 μg L⁻¹. Relative recoveries from samples of drinking water spiked at levels of 2.00 and 5.00 μg L⁻¹ were 95.0–107.8 and 92.2–100.9%, respectively. Comparison of this method with other methods indicates DLLME is a very simple and rapid (less than 2 min) method which requires a small volume of sample (5 mL).     

Determination of N-Acetylcysteine and Thioglycolic Acid in Human Urine

A method for the determination of total N-acetylcysteine and thioglycolic acid in human urine is described. Because these compounds are mainly excreted as disulfides, they are first reduced to the free thiols by treatment with tris(2-carboxyethyl)phosphine hydrochloride and then derivatized with 2-chloro-1-methylquinolinium tetrafluoroborate. Separation and quantitation of the 2-S-quinolinium derivatives of the thiols were achieved by reversed-phase ion-pair liquid chromatography with UV-detection at 355 nm. Because the method enables simultaneous determination of other endogenous urinary thiols, e.g. cysteine and cysteinylglycine, amounts of these compounds in urine were also studied. Detector responses were linear over the range covering most practical situations, with correlation coefficients for all four analytes better than 0.999. Recovery and imprecision (as RSD) were within 99.77–102.17 and 0.01–7.79%, respectively. The lower limit of detection was 0.25 μmol L⁻¹ urine for thioglycolic acid and N-acetylcysteine, and 0.12 μmol L⁻¹ urine for cysteine and cysteinylglycine. The method was used for analysis of urine samples from 29 healthy individuals to establish reference values for the thiols, normalized to creatinine. 3-Mercaptolactic acid, 2-mercaptopropionic acid, and mercaptoethanol were not present in the urine analyzed.     

Environmental monitoring of phenolic pollutants in water by cloud point extraction prior to micellar electrokinetic chromatography

Many aromatic compounds can be found in the environment as a result of anthropogenic activities and some of them are highly toxic. The need to determine low concentrations of pollutants requires analytical methods with high sensitivity, selectivity, and resolution for application to soil, sediment, water, and other environmental samples. Complex sample preparation involving analyte isolation and enrichment is generally necessary before the final analysis. The present paper outlines a novel, simple, low-cost, and environmentally friendly method for the simultaneous determination of p-nitrophenol (PNP), p-aminophenol (PAP), and hydroquinone (HQ) by micellar electrokinetic capillary chromatography after preconcentration by cloud point extraction. Enrichment factors of 180 to 200 were achieved. The limits of detection of the analytes for the preconcentration of 50-ml sample volume were 0.10 μg L⁻¹ for PNP, 0.20 μg L⁻¹ for PAP, and 0.16 μg L⁻¹ for HQ. The optimized procedure was applied to the determination of phenolic pollutants in natural waters from San Luis, Argentina. Figure Schematic representation of the cloud point extraction process.     

Flow injection spectrofluorimetric determination of iron(III) in water using salicylic acid

A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed. Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used was 2 × 10⁻⁶ mol L⁻¹ salicylic acid in 0.1 mol L⁻¹ NH₄⁺/NH₃ buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L⁻¹ iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection was 0.3 μg L⁻¹ and the sampling rate was 60 h⁻¹. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully applied to the determination of low levels of iron in real samples (river, sea, and spring waters).     

Development of a novel luminol chemiluminescent method catalyzed by gold nanoparticles for determination of estrogens

It has been found that gold nanoparticles (nano-Au) enhance the chemiluminescence (CL) of the luminol–hydrogen peroxide system and that estrogens inhibit these CL signals in alkaline solution. CL spectra, UV–visible spectra, X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) were used to investigate the mechanism of the CL enhancement. On the basis of the inhibition, a flow-injection CL method has been established for determination of three natural estrogens. Under the optimized conditions, the linear range for determination of the estrogens was 0.07 to 7.0 μmol L⁻¹ for estrone, 0.04 to 10 μmol L⁻¹ for estradiol, and 0.1 to 10 μmol L⁻¹ for estriol. The detection limits were 3.2 nmol L⁻¹ for estrone, 7.7 nmol L⁻¹ for estradiol, and 49 nmol L⁻¹ for estriol, with RSD of 2.9, 2.6, and 1.8%, respectively. This method has been used for analysis of estrogens in commercial tablets and in urine samples from pregnant women.     

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.     

Determination of triazine herbicides: development of an electroanalytical method utilizing a solid amalgam electrode that minimizes toxic waste residues, and a comparative study between voltammetric and chromatographic techniques

The use of a copper solid amalgam electrode (CuSAE) for the analytical determination of triazine herbicides (atrazine and ametryne) instead of the conventional hanging mercury drop electrode (HMDE) is reported. The results obtained using electroanalytical methods utilizing each of these electrodes were also compared with those provided by the HPLC technique. The results indicated that the CuSAE electrode can be used to detect the herbicides studied, since the detection limits reached using the electrode (3.06 μg L⁻¹ and 3.78 μg L⁻¹ for atrazine and ametryne, respectively) are lower than the maximum values permitted by CONAMA (Brazilian National Council for the Environment) for wastewaters (50 μg L⁻¹) and by the US EPA (Environmental Protection Agency of the United States) in natural water samples (10.00 μg L⁻¹). An electroanalytical methodology employing CuSAE and square wave voltammetry (SWV) was successfully applied to the determination of atrazine and ametryne in natural water samples, yielding good recoveries (70.30%–79.40%). This indicates that the CuSAE provides a convenient substitute for the HMDE, particularly since the CuSAE minimizes the toxic waste residues produced by the use of mercury in HDME-based analyses.     

Cleanup strategies and advantages in the determination of several therapeutic classes of pharmaceuticals in wastewater samples by SPE–LC–MS/MS

This work describes the development and validation of an offline solid-phase extraction with simultaneous cleanup capability, followed by liquid chromatography–(electrospray ionisation)–ion trap mass spectrometry, enabling the concurrent determination of 23 pharmaceuticals of diverse chemical nature, among the most consumed in Portugal, in wastewater samples. Several cleanup strategies, exploiting the physical and chemical properties of the analytes vs. interferences, alongside with the use of internal standards, were assayed in order to minimise the influence of matrix components in the ionisation efficiency of target analytes. After testing all combinations of adsorbents (normal-phase, ion exchange and mixed composition) and elution solvents, the best results were achieved with the mixed-anion exchange Oasis MAX cartridges. They provided recovery rates generally higher than 60%. The precision of the method ranged from 2% to 18% and 4% to 19% (except for diclofenac (22%) and simvastatin (26%)) for intra- and inter-day analysis, respectively. Method detection limits varied between 1 and 20 ng L⁻¹, while method quantification limits were <85 ng L⁻¹ (both excluding ibuprofen). This analytical method was applied to gather preliminary results on influents and effluents of two wastewater treatment plants (WWTPs) located in the urban region of Porto (Portugal). Typically, paracetamol, hydrochlorothiazide, furosemide, naproxen, ibuprofen, diclofenac and bezafibrate were detected in concentrations ranging from 1 to 20 μg L⁻¹, while gemfibrozil, simvastatin, ketoprofen, azithromycin, bisoprolol, lorazepam and paroxetine were quantified in levels below 1 μg L⁻¹. These WWTPs were given particular attention since they discharge their effluents into the Douro river, where water is extracted for the production of drinking water. Some sampling spots in this river were also analysed.     

Determination of norfloxacin in human urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach that can be used to detect norfloxacin in human urine using capillary electrophoresis with end-column electrochemiluminescence (ECL) detection of is described. The separation column was a 75-μm i.d. capillary. The running buffer was 15 mmol L⁻¹ sodium phosphate (pH 8.2). The solution in the detection cell was 50 mmol L⁻¹ sodium phosphate (pH 8.0) and 5 mmol L⁻¹ The ECL intensity varied linearly with norfloxacin concentration from 0.05 to 10 μmol L⁻¹. The detection limit (S/N=3) was 0.0048 μmol L⁻¹, and the relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 μmol L⁻¹ norfloxacin (n=11) were 2.6% and 0.8%, respectively. The method was successfully applied to the determination of norfloxacin spiked in human urine without sample pretreatment. The recoveries were 92.7–97.9%.      

Determination of 2-ethylhexyl 4-(dimethylamino) benzoate using membrane-assisted liquid–liquid extraction and gas chromatography-mass spectrometric detection

A flow-cell for micro-porous membrane liquid–liquid extraction with a sheet membrane was used to extract 2-ethylhexyl 4-(dimethylamino) benzoate (EDB) from urine of solar-cream users and spiked wine samples. The cell enabled the target analyte to be extracted from 7.9 mL of donor solution into 200 μL of acceptor solution (decane). After extraction, the acceptor solution was transferred to a micro-vial for GC-MS analysis without derivation. In this work, variables affecting the enrichment factor were also studied, such as organic solvent, extraction time, recirculation flow of the donor solution through the donor chamber, presence of potassium chloride and ethanol in the donor solution and pH. The method has been evaluated in terms of linearity, sensitivity, precision, limits of detection and quantification and extraction efficiency. Limits of quantification were 1 and 3 μg L⁻¹ EDB for urine and wine, respectively. Quantitative analysis has been carried out by applying the method of standard additions. Within- and between-day relative standard deviations were lower than 12% and 20%, respectively. EDB was found in the urine of users of cream containing EDB in the concentration interval 1.2–7.2 μg L⁻¹. Therefore, this provides evidence of EDB dermal absorption and subsequent excretion through the urinary tract. EDB was not found in the analysed wine samples.     

Electrochemical determination of muscle relaxant drug tetrazepam in bulk form,pharmaceutical formulation,and human serum

Tetrazepam dissolved in the Britton-Robinson universal buffer of various pH values (2.5–11.5) containing 10 vol. % of ethanol was reduced at the mercury electrode in a single 2-electron irreversible step due to reduction of the 4,5 C=N double bond of the seven-membered ring. Differential pulse polarography (DPP) and adsorptive cathodic stripping voltammetry (AdCSV) techniques (Linear sweep LS, differential pulse DP and square-wave SW modes) for quantification of tetrazepam in bulk form and in myolastan tablets are presented. Moreover, the described linear sweep, differential pulse, and square-wave adsorptive cathodic stripping voltammetry was successfully applied in quantification of tetrazepam in spiked human serum without any prior extraction of the drug. The obtained results showed an increased sensitivity of the described electro-analytical procedures for the quantification of tetrazepam in the following order DPP, DP-AdCSV, LS-AdCSV, and SW-AdCSV, since the observed limits of tetrazepam quantitation by these electroanalytical techniques were 5 × 10⁻⁶ mol L⁻¹, 3 × 10⁻⁷ mol L⁻¹, 1 × 10⁻⁸ mol L⁻¹, and 3 × 10⁻⁹ mol L⁻¹, respectively.     

Capillary electrophoretic speciation of Cu(II) and Co(III) in the electroless copper plating baths

Summary A capillary electrophoretic method for the determination of Cu(II) and Co(III) chelates with ethylenediamine in electroless copper plating baths has been developed. The influence of carrier electrolyte parameters such as nature of counter-ion and pH were studied and discussed. The optimised separations were carried out in a fused silica capillary (57 cm × 75 μm I.D.) filled with an ethylenediamine sulfate electrolyte (20 mol L⁻¹ ethylendiamine, pH7.0 with H₂SO₄; applied voltage, +25 kV) using direct UV detection at 214 nm. The detection limits for a signalto-noise ratio of 3 and 10s hydrodynamic injection were 5×10⁻⁶ mol L⁻¹ for Cu(II) and 1×10⁻⁶ mol L⁻¹ for Co(III). The relative standard deviations of the peak areas for Cu(II) and Co(III) were found to be 1.5% and 2.4%, respectively, with five consecutive injections of standard solution containing 5×10⁻⁵ mol L⁻¹ of each metal ion. Application of the method to the speciation of Cu(II) and Co(III) complexes in copper plating bath samples is also demonstrated.     

Determination of glyphosate and AMPA in surface and waste water using high-performance ion chromatography coupled to inductively coupled plasma dynamic reaction cell mass spectrometry (HPIC–ICP–DRC–MS)

A novel method employing high-performance cation chromatography in combination with inductively coupled plasma dynamic reaction cell mass spectrometry (ICP–DRC–MS) for the simultaneous determination of the herbicide glyphosate (N-phosphonomethylglycine) and its main metabolite aminomethyl phosphonic acid (AMPA) is presented. P was measured as ³¹P¹⁶O⁺ using oxygen as reaction gas. For monitoring the stringent target value of 0.1 μg L⁻¹ for glyphosate, applicable for drinking and surface water within the EU, a two-step enrichment procedure employing Chelex 100 and AG1-X8 resins was applied prior to HPIC–ICP–MS analysis. The presented approach was validated for surface water, revealing concentrations of 0.67 μg L⁻¹ glyphosate and 2.8 μg L⁻¹ AMPA in selected Austrian river water samples. Moreover, investigations at three waste water-treatment plants showed that elimination of the compounds at the present concentration levels was not straightforward. On the contrary, all investigated plant effluents showed significant amounts of both compounds. Concentration levels ranged from 0.5–2 μg L⁻¹ and 4–14 μg L⁻¹ for glyphosate and AMPA, respectively.     

Stereospecific analysis of flurbiprofen and its major metabolites in plasma and urine by chiral-phase liquid chromatography

Summary Direct chiral-phase HPLC methods have been developed for the determination of flurbiprofen and its major metabolites, namely 4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen, in biological fluids using a derivatized amylose chiral stationary phase (CSP; Chiral-pak AD). Quantification of all three analytes, both free and conjugated, in urine was carried out following liquid-liquid extraction using tandem ultraviolet (UV) and fluorescence detection. Determination of flurbiprofen and the 4′-hydroxy-metabolite in plasma utilized the same CSP but required modification in the mobile phase composition and sole use of fluorescence detection. The urine assay was linear (r>0.998) between 0.05–10 μg mL⁻¹, 0.1–20 μg mL⁻¹ and 0.01–2 μg mL⁻¹ for the enantiomers of flurbiprofen, 4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen respectively. The plasma assay was linear (r>0.997) between 0.1–6 μg mL⁻¹ and 0.01–0.6 μg mL⁻¹ for the enantiomers of flurbiprofen and 4′-hydroxyflurbiprofen respectively. Both assays, typically yielded within- and between-day imprecision and accuracy values less than 10% for the enantiomers of the different analytes. Initial volunteer studies suggest that the disposition of flurbiprofen displays modest enantioselectivity in humans.     

Reversed Capillary Electrochromatography: Investigation of Peak Symmetry for Eluting Curves of Solutes

Summary A clean method without use of organic solvents has been developed for isolation and high-performance liquid chromatographic (HPLC) determination of oxytetracycline (OTC) and sulphadimidine (SDD) in cow's milk. Isolation is rapid and simple—homogenization with an inorganic acid solution by means of a handy ultrasonic homogenizer, which is easy-to-use and portable, followed by centrifugation. Reversed-phase HPLC was performed on a C₄ column, with 1.25 mmol L⁻¹ succinic acid solution as mobile phase, and identification was by means of a photodiode-array detector. Separation of the analytes was achieved in less than 8 min. Significant linearity was established over the concentration range of 0.1–1.0 μg mL⁻¹ for both target compounds (r>0.99,P<0.01). Average recoveries of OTC and SDD (each spiked at 0.1–1.0 μg mL⁻¹) were ≥88.8, and inter- and intra-assay variability was ≤2.8%. The total time required for analysis of one sample was <20 min. The limits of quantitation of the method (μg mL⁻¹ in milk) were 0.044 for OTC and 0.023 for SDD. No organic solvent was used at any stage of the analysis.     

Fast CE Determination of d-Amphetamine and Diphenhydramine in Quick-Acting Anti-Motion Capsules

The quick separation and simultaneous determination of d-amphetamine and diphenhydramine in the quick-acting anti-motion capsules was investigated by capillary zone electrophoresis. The influence of different parameters (internal standard, injection modes, pH, concentration of the running buffer and applied voltage) was systematically studied. The two compounds could be well separated within 2.0 min in a 40.2 cm fused-silica capillary at a separation voltage of 20 kV in a 50 mM phosphate–12.5 mM borate buffer adjusted to pH 5.5. Correlation coefficients for calibration curves in the range 0.50–1.50 μg mL⁻¹ for d-amphetamine and 2.75–8.25 μg mL⁻¹ for diphenhydramine were higher than 0.999. The limits of detection of d-amphetamine and diphenhydramine were 10.0 and 5.5 ng mL⁻¹ and the recoveries of the compounds in the QAAMC were 99.80 and 99.85%, respectively. The authors L. Zhang and Y. Chen equally contributed to this work.     

Simultaneous determination of phenylenediamine isomers and dihydroxybenzene isomers in hair dyes by capillary zone electrophoresis coupled with amperometric detection

The simultaneous determination of three isomers of phenylenediamines (o, m, and p-phenylenediamine) and two isomers of dihydroxybenzenes (catechol and resorcinol) in hair dyes was performed by capillary zone electrophoresis coupled with amperometric detection (CZE–AD). The effects of working electrode potential, pH and concentration of running buffer, separation voltage, and injection time on CZE–AD were investigated. Under the optimum conditions the five analytes could be perfectly separated in 0.30 mol L⁻¹ borate–0.40 mol L⁻¹ phosphate buffer (pH 5.8) within 15 min. A 300 μm diameter platinum electrode had good responses at +0.85 V (versus SCE) for the five analytes. Their linear ranges were from 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹ and the detection limits were as low as 10⁻⁷ mol L⁻¹ (S/N = 3). This working electrode was successfully used to analyze eight kinds of hair dye sample with recoveries in the range 91.0–108.0% and RSDs less than 5.0%. These results demonstrated that capillary zone electrophoresis coupled with electrochemical detection using a platinum working electrode as detector was convenient, highly sensitive, highly repeatable and could be used in the rapid determination of practical samples. Figure Electropherograms obtained from 10 mg mL⁻¹ hair dye sample solutions at a platinum working electrode under optimum CZE–AD conditions: (a) natural black (I), (b) golden: (1) p-phenylenediamine, (2) m-phenylenediamine, (3) o-phenylenediamine, (4) resorcinol, and (5) catechol     

Dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry for the rapid and sensitive determination of UV filters in environmental water samples

The performance of the dispersive liquid–liquid microextraction (DLLME) technique for the determination of eight UV filters and a structurally related personal care species, benzyl salicylate (BzS), in environmental water samples is evaluated. After extraction, analytes were determined by gas chromatography combined with mass spectrometry detection (GC-MS). Parameters potentially affecting the performance of the sample preparation method (sample pH, ionic strength, type and volume of dispersant and extractant solvents) were systematically investigated using both multi- and univariant optimization strategies. Under final working conditions, analytes were extracted from 10 mL water samples by addition of 1 mL of acetone (dispersant) containing 60 μL of chlorobenzene (extractant), without modifying either the pH or the ionic strength of the sample. Limits of quantification (LOQs) between 2 and 14 ng L⁻¹, inter-day variability (evaluated with relative standard deviations, RSDs) from 9% to 14% and good linearity up to concentrations of 10,000 ng L⁻¹ were obtained. Moreover, the efficiency of the extraction was scarcely affected by the type of water sample. With the only exception of 2-ethylhexyl-p-dimethylaminobenzoate (EHPABA), compounds were found in environmental water samples at concentrations between 6 ± 1 ng L⁻¹ and 26 ± 2 ng mL⁻¹.     

Analysis of Terbumeton and its Major Metabolites by SPE and DAD-HPLC in Soil Bulk Water

A rapid and inexpensive method for simultaneous quantification of terbumeton (TER), and its major potential metabolites (TED; terbumeton-desethyl, TOH; terbumeton-2-hydroxy and TID; terbumeton-deisopropyl) in soil bulk water (SBW) samples is proposed. The analytical method involves extraction–concentration from SBW samples using a graphitized carbon black (GCB) cartridge followed by their separation–detection by reversed-phase high-performance liquid chromatography analysis using a C₁₈ column and a diode array detector. A mobile phase of acetonitrile−0.005 mol L⁻¹ phosphate buffer (pH 7.0) (35:65, v/v) at a flow rate of 0.8 mL min⁻¹ in isocratic elution mode has been used. After optimization of the extraction and separation conditions, this method can be used for the simultaneous determination of investigated compounds in the range of the international limits of 0.1 μg L⁻¹. For TER the detection limit was 0.009 μg L⁻¹ and it was 0.100, 0.550, and 0.480 μg L⁻¹ for TED, TOH, and TID, respectively. The recoveries of TER, TED, TOH, and TID from SBW samples, measured at three levels of concentration range, were found to be between 48.0 and 102.0%. The intra-day precision measured by relative standard deviation (RSD) was always lower than 9.0%.