Check out our New Publishers' Select for Free Articles

Analytical and Bioanalytical Chemistry (v.376, #4)

4th Mediterranean Basin Conference on Analytical Chemistry by Marjan Veber (pp. 423-423).

The application of NMR and MS methods for detection of adulteration of wine, fruit juices, and olive oil. A review by N. Ogrinc; I. J. Košir; J. E. Spangenberg; J. Kidrič (pp. 424-430).

This review covers two important techniques, high resolution nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), used to characterize food products and detect possible adulteration of wine, fruit juices, and olive oil, all important products of the Mediterranean Basin. Emphasis is placed on the complementary use of SNIF-NMR (site-specific natural isotopic fractionation nuclear magnetic resonance) and IRMS (isotope-ratio mass spectrometry) in association with chemometric methods for detecting the adulteration.

Keywords: Nuclear magnetic resonance; Mass spectrometry; Stable isotopes; Adulteration; Wine; Fruit juices; Olive oils

The role of organic colloids in herbicide transfer to rivers: a quantitative study of triazine and phenylurea interactions with colloids by S. Irace-Guigand; J. J. Aaron (pp. 431-435).

For moderately hydrophobic compounds such as most pesticides adsorption on colloids (<0.2 µm) may play a key role in pesticide mobility as well as in their degradation by chemical and microbiological processes. However, until now, pesticide–organic colloid interactions are poorly understood. Quantitative data for sorption equilibria on colloids of two series of herbicides including triazines (atrazine, simazine, terbutylazine, prometryne, desethylatrazine, and desisopropylatrazine) and phenylureas (isoproturon, linuron, neburon, and diuron) sampled in the Seine river (urban zone) and the Marne river (agricultural zone) are presented. Partition coefficient of herbicides on colloids (K_com), were evaluated by solid-phase extraction coupled with high-performance liquid chromatography–UV diode-array detection (SPE–HPLC–UV/DAD). In the case of triazines a satisfactory log–log correlation was found between K_com and octanol–water coefficient (K_ow) values. Phenylureas did not obey this correlation, with K_com values being about two times higher than those of triazines. The existence of two distinct types of adsorption behaviour on colloids partly explains the different occurrence of triazines and phenylureas in surface waters.

Keywords: Organic colloids; Triazines; Phenylurea herbicides; Partition coefficient; Liquid chromatography (LC); Solid-phase extraction (SPE)

Characterization of carbohydrates in mucilage samples from the northern Adriatic Sea by Nunzio Penna; Samuela Capellacci; Fabio Ricci; Nives Kovac (pp. 436-439).

Carbohydrate contents in seawater, mucilage, and mucilage interstitial waters were analyzed during episodes of mucilage formation in the summers of 2000 and 2001 in the northern Adriatic Sea off Pesaro and in the Gulf of Trieste using 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and 2,4,6-tripyridyl-s-triazine (TPTZ) assays. The significant presence of polysaccharides in seawater in the presence of mucilage has an important impact on the agglomeration processes forming gelatinous material (macrogels). Characterization of oligosaccharides in the water-soluble fraction of mucilage using HPLC/RI revealed maltose and pentaose as the main components.

Keywords: Mucilage; Carbohydrates; Oligosaccharides; Adriatic Sea

Determination of methylparaben, propylparaben, triamcinolone acetonide and its degradation product in a topical cream by RP-HPLC by L. Matysová; R. Hájková; J. Šícha; P. Solich (pp. 440-443).

A novel reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of active component triamcinolone acetonide, its degradation product triamcinolone (occurring in formulation after long-term stability tests) and two preservatives presented in the cream—methylparaben and propylparaben, using hydrocortisone as an internal standard.The chromatographic separation was performed on a Supelco Discovery C18 column; the mobile phase for separation of all compounds consists of a mixture of acetonitrile and water (40:60 v/v). The analysis time was less than 9 min, at a flow rate of 0.6 mL min⁻¹ and detection at 240 nm. The method was found to be applicable for routine analysis (stability tests, homogeneity) in the pharmaceutical product topical cream Triamcinolon cream 0.1%.

Keywords: HPLC; Pharmaceuticals; Degradation product; Methylparaben; Propylparaben; Triamcinolone acetonide

Development and validation of HPLC method for the determination of α-tocopherol in human erythrocytes for clinical applications by Dagmar Solichová; Lucie Korecká; Iveta Svobodová; František Musil; Vladimír Bláha; Petr Žďánský; Zdeněk Zadák (pp. 444-447).

In this work, a simple isocratic reversed-phase HPLC method for determination of α-tocopherol in human erythrocytes has been developed and validated. After separation of plasma the erythrocytes were washed three times with 0.9% sodium chloride containing 0.01% butylated hydroxytoluene (BHT) as antioxidant and then were diluted 1:1 (v/v) with the same solution. In the liquid–liquid extraction (LLE) procedure, 2500 μL of n -hexane was added to 500 μL of erythrocytes. After 2 min this mixture was deproteinized by addition of cool ethanol (500 μL, 5 min) denatured with 5% methanol containing α-tocopherol acetate (20 μmol L⁻¹), as internal standard, and then extracted for 5 min by vortex mixing. After centrifugation (10 min, 1600×g) an aliquot (2000 μL) of the clean extract was separated and evaporated under nitrogen. The residue was dissolved in 400 μL methanol and analysed by reversed-phase HPLC on a 4.6 mm×150 mm, 5 μm Pecosphere C18 column; the mobile phase was 100% methanol, flow rate 1.2 mL min⁻¹. The volume injected was 100 μL and detection was by diode-array detector at a wavelength of 295 nm. The extraction recovery of α-tocopherol from human erythrocytes was 100.0±2.0%. The detection limit was 0.1 μmol L⁻¹ and a linear calibration plot was obtained in the concentration range 0.5–20.0 μmol L⁻¹. Within determination precision was 5.2% RSD (n=10), between determination precision was 6.1% RSD (n=10). The method was applied successfully in a clinical study of patients with acute pancreatitis and for determination of the reference values in the healthy Czech population.

Keywords: α-Tocopherol; HPLC; Erythrocytes; Biological membrane; Acute pancreatitis

Determination of salbutamol using on-line solid-phase extraction and sequential injection analysis. Comparison of chemiluminescence and fluorescence detection by Jitka Huclová; Dalibor Šatínský; Hana Sklenářová; Rolf Karlíček (pp. 448-454).

Determination of salbutamol using sequential injection analysis (SIA) with chemiluminescence and fluorescence detection has been devised. The chemiluminescence signal was emitted during the oxidation of salbutamol by potassium permanganate in sulfuric acid medium. Sodium polyphosphate was used as chemiluminescence enhancer. The fluorescence signal (excitation wavelength 230 nm) was also measured in sulfuric acid medium. Both detection techniques were compared with respect to the application of the methods to the determination of salbutamol in biological materials. The sample pre-treatment takes place directly in the SIA system, when salbutamol is adsorbed on the solid-phase (Baker-carboxylic acid) microcolumn integrated into the system. Sulfuric acid serves both as the reagent and the eluent. The lab-made SIA system consisted of a 2.5-mL Cavro syringe pump, ten-port Vici Valco selection valve and Spectra-Physics FS 970 fluorescence detector, which was lab-modified for chemiluminescence detection. The system was controlled by a PC using originally compiled LabVIEW^®-supported software. Concentrations, volumes of reagents and flow rates were optimised by a simplex method. Salbutamol was determined in the linear range 0.05–10 μg mL⁻¹ (RSD 1.53%), with the detection limit (3σ) 0.03 μg mL⁻¹ and sample throughput of 42 samples per hour with chemiluminescence detection in standard solutions. The fluorescence detection enabled the determination of salbutamol in standard solutions in the linear range 0.5–100 μg mL⁻¹ (RSD 2.69%), with the detection limit 0.2 μg mL⁻¹ and sample throughput of 24 h⁻¹. The proposed methods were applied to the determination of salbutamol in human serum and urine. However, serum is a very complicated matrix and the SIA–SPE analysis did not provide satisfactory results. It was possible to determine salbutamol in human urine using this technique. Better recovery was achieved with fluorescence detection.

Keywords: Sequential injection analysis; Solid-phase extraction; Salbutamol; Chemiluminescence; Fluorescence; Body fluids

Application of capillary electrophoresis for inorganic selenium speciation in the frame of high-level waste management by Vladimir Sladkov; Blandine Fourest; François David; Laurent Venault; Michael Lecomte (pp. 455-459).

Capillary electrophoresis (CE) with direct UV detection is proposed for speciation of inorganic Se in high-level liquid waste. In this aim, the optimal conditions of measurements (pH, electrolyte buffer concentration) and the influence of nitrate excess on the quantitative determination of Se(IV) and Se(VI) were studied. Different electrolyte buffers were considered: carbonate, phosphate and citrate. It was found, that citrate buffer is the most suitable for the application under consideration. Under the chosen optimal conditions (20 mmol L⁻¹ citrate buffer, pH 2.5), calibration curves for Se(IV) and Se(VI) are linear in the concentration range 10⁻⁴–10⁻³ mol L⁻¹. The detection limits are 4×10⁻⁶for Se(IV) and 2×10⁻⁵ for Se(VI). The accuracy of the procedure was checked by calculating the recovery by spiking simulation solutions. Relative standard deviation (S_r) is less than 10%.

Keywords: Capillary electrophoresis; Selenium; Citrate buffer; High-level liquid waste management

Development of a new microelectrolysis system for in-situ electrodeposition of ultra-traces of gold prior to measurement by ETAAS by Nahid Mashkouri Najafi; Nastaran Manouchehri (pp. 460-466).

Electrodeposition is known to be suitable for separation and preconcentration of extremely low concentrations of analyte from bulk samples and is instrumentally is very simple. In this approach a new combined system was designed for in-situ electrodeposition of ultratrace levels of gold from micro samples on to a graphite furnace prior to determination by electrothermal atomic absorption spectrometry (ETAAS). Sediment samples were digested and traces of the gold content were extracted with boiling aqua regia. To prevent the highly corrosive effect of aqua regia media, the graphite tube surface was pre-coated by electrodeposition of ppm amounts of Pd prior to sample introduction. Separation of the analyte from the matrix was achieved by electrodeposition of the analyte in situ on the Pd/C surface of the furnace tube. Vanadium was also used as a modifier to stabilize the analyte from decomposition at charring temperatures. By using the proposed microelectrolysis preconcentration technique a considerable improvement in sensitivity and detection limit was achieved compared with conventional ETAAS. Characteristic masses for ED–ETAAS techniques in both nitric acid and aqua regia were reported to be m_o=4.1 pg, with %RSD=2.9; the calculated LOD was 0.105 ppb, and typical calibration graphs for this element in nitric acid and aqua regia for both techniques were linear up to 70 μg L⁻¹ with about 99% recovery. Six reference sediments samples were tested by the proposed technique and by the Conv-ETAAS method. The results were in agreement with recommended values (reported by a reference laboratory using UV–visible spectrometry), demonstrating the efficiency of extraction and preconcentration of ultratrace levels of gold.

Keywords: Trace elements analysis; Electrodeposition; ETAAS; Gold measurement; Sediment analysis

Chemometric investigation of the efficiency of different TiO₂-based catalysts as principal components of TOC photochemical sensors under development by Luigi Campanella; Giovanni De Angelis; Giovanni Visco (pp. 467-475).

There is an increasing demand for measurement of organic carbon in solutions both in industry and in environmental research for the purpose of continuous water-quality monitoring. Practically all the methods used are based on a catalytic system in which metal oxides play a major role. The development of a new TOC/DOC measurement system, in our work, uses a mixed anatase–rutile form of TiO₂as catalyst of the mineralisation process, and direct measurement of the CO₂ produced, by a gaseous diffusion electrode. The entire research is based on heterogeneous catalysis using an immobilised catalyst, which can offer considerable advantages over other methods of catalysis. Four different catalytic systems were analysed. Three involved thermal immobilisation of TiO₂ on glass supports (glass spheres and glassy particulates) or on an Al metal grid. One further system consisted of direct oxidation of a Ti grid at high temperatures. The system was illuminated using a 350 nm UV source (350 mW cm⁻²) contained in a home-made measurement cell. Five molecules—malic acid, pentachlorophenol, sodium dodecylsulfate, hydroquinone, and citric acid—which were deemed to be representative and had been investigated in several previous studies, were used as photodegradation targets. However, it was not possible to obtain a direct expression of "catalytic efficiency" simply by reading the data obtained, nor any indirect molecular "recalcitrancy" scale. Chemometric analysis, by principal components analysis, allows the five used catalytic systems to be easily compared each other and a single PC component is able to perform classification.

Keywords: Total organic carbon; Titanium dioxide; Photocatalytic system; Chemometrics; Carbon dioxide electrode; Alternative catalyst

Development of an EnFET for the detection of organophosphorous and carbamate insecticides by Francisco Flores; Judit Artigas; Jean-Louis Marty; Francisco Valdés (pp. 476-480).

A biosensor for the detection of insecticides based on an ion-sensitive field-effect transistor (ISFET) was developed. The resulting device combines the simplicity of potentiometric sensors and the use of associated electronic systems as powerful tools for the acquisition and the processing of data. The enzyme acetylcholinesterase (AChE) was entrapped in a membrane placed on the gate of the ISFET forming an enzyme field-effect transistor (EnFET). The biosensor is applied to the determination of pesticides in spiked real samples. Organophosphorous and carbamate insecticides were measured with a detection limit of 10⁻⁸ mol L⁻¹. The measurement is based on the production of hydrogen ions due to the hydrolysis of acetylthiocholine by the enzyme. The resulting local pH change is picked up by the underlying pH-sensitive ISFET and transduced as potential variations. The preparation of the membrane is simple and reproducible. The analysis in spiked real samples was performed in tap water and showed detection limits comparable to those obtained by other researchers.

Keywords: EnFET; Organophosphorous; Carbamates; Pesticide analysis

Electrochemical immunosensor for Forest-Spring encephalitis based on protein A labeled with colloidal gold by Khiena Brainina; Alisa Kozitsina; Jakov Beikin (pp. 481-485).

An electrochemical immunosensor for diagnosis of Forest-Spring encephalitis has been proposed. It comprises a screen-printed thick-film graphite electrode serving as the transducer and a layer of the Forest-Spring encephalitis antigen immobilized on the electrode and functioning as the biorecognition substance. The procedure includes formation of an antigen–antibody immune complex, localization of colloidal gold-labeled protein A on the complex, and recording of gold oxidation voltammogram, which provides information about the presence and the concentration of antibodies in blood serum. The response is proportional to the concentration of antibodies over the interval from 10⁻⁷ to 10⁻² mg mL⁻¹. The detection limit is 10⁻⁷ mg mL⁻¹.

Keywords: Immunosensor; Protein A; Gold; Voltammetry; Forest-Spring encephalitis

¹⁵N isotopic analyses: a powerful tool to establish links between seized 3,4-methylenedioxymethamphetamine (MDMA) tablets by Fabien Palhol; Catherine Lamoureux; Norbert Naulet (pp. 486-490).

In this study the ¹⁵N/¹⁴N isotopic ratios of 43 samples of 3,4-methylenedioxymethamphetamine (MDMA) samples were measured using Gas Chromatography–Combustion–Isotope-Ratio Mass Spectrometry (GC–C–IRMS). The results show a large discrimination between samples with a range of δ¹⁵N values between −16 and +19‰. Comparison between δ¹⁵N values and other physical and chemical parameters shows a strong relationship between δ¹⁵N and brand logo or composition. Thus, it could be assumed that tablets from different seizures probably originated from the same clandestine manufacturing source. Hence, ¹⁵N isotopic parameters provide an important additional tool to establish common origins between seizures of clandestine synthetic drugs.

Keywords: Nitrogen isotopic abundance measurement; Gas chromatography–combustion–isotope-ratio mass spectrometry; 3,4-Methylenedioxymethamphetamine; Designer drugs; Seizures comparisons

Clean-up of triazines in vegetable extracts by molecularly-imprinted solid-phase extraction using a propazine-imprinted polymer by C. Cacho; E. Turiel; A. Martín-Esteban; C. Pérez-Conde; C. Cámara (pp. 491-496).

An analytical methodology based on a molecularly imprinted solid-phase extraction (MISPE) procedure was developed for the determination of several triazines (atrazine, simazine, desethylatrazine (DEA), desisopropylatrazine (DIA), and propazine) in vegetable samples. A methacrylic acid-based imprinted polymer was prepared by precipitation polymerisation using propazine as template and toluene as porogen. After removal of the template by Soxhlet extraction, the optimum loading, washing, and elution conditions for MISPE of the selected triazines were established. The optimised MISPE procedure was applied to the extraction of the selected triazines in pea, potato, and corn sample extracts and a high degree of clean-up was obtained. However, some remaining interferences, non-specifically and strongly bound to the polymeric matrix, appeared in the chromatogram, preventing quantification of DIA in potatoes and DIA, DEA, and propazine in corn samples. Thus, a new clean-up protocol based on the use of a non-imprinted polymer for removal of these interferences prior to the MISPE step was developed. By following the new two-step MISPE procedure, the matrix compounds were almost completely removed, allowing the determination of all the triazines selected at concentration levels below the established maximum residue limits, making the developed procedure suitable for monitoring these analytes in vegetable samples.

Keywords: Molecularly-imprinted solid-phase extraction; Vegetable samples; Triazines; Propazine-imprinted polymer

Fast screening method for determining 2,4,6-trichloroanisole in wines using a headspace–mass spectrometry (HS–MS) system and multivariate calibration by M. P. Martí; R. Boqué; M. Riu; O. Busto; J. Guasch (pp. 497-501).

The system based on coupling a headspace sampler to a mass spectrometer (HS–MS), which is considered one kind of electronic nose, is an emergent technique for ensuring and controlling quality in industry. It involves injecting the headspace of the sample into the ionization chamber of the mass spectrometer where the analytes are fragmented. The result is a complex mass spectrum for each sample analyzed. When several samples are analyzed the data matrix generated is processed with chemometric techniques to compare and classify the substances from their volatile composition, in other words, to compare and classify their flavor. So far, information from electronic nose applications has mainly been qualitative. In this paper we present a quantitative study that uses a multivariate calibration. We analyzed several white wines using HS–MS to determine 2,4,6-tricholoranisole (TCA). This is an off-flavor that is a serious problem for the wine industry. The method is simple because it does not require sample preparation, only addition of sodium chloride being necessary for sample conditioning. Also, it provides a fast screening (10 min/sample) of the quantity of TCA in wines at ultratrace (sub μg L⁻¹) levels.

Keywords: Wine; Off-flavour; 2,4,6-Trichloroanisole; HS–MS; Multivariate calibration; Electronic nose

Application of solid-phase microextraction for the determination of pyrethroid residues in vegetable samples by GC-MS by J. Beltran; A. Peruga; E. Pitarch; F. J. López; F. Hernández (pp. 502-511).

A solid-phase microextraction (SPME) method has been developed for the determination of 7 pyrethroid insecticides (bifenthrin, lambda-cyhalothrin, permethrin, cyfluthrin, cypermethrin, fenvalerate, and tau-fluvalinate) in water, vegetable (tomato), and fruit (strawberry) samples, based on direct immersion mode and subsequent desorption into the injection port of a GC/MS. The SPME procedure showed linear behavior in the range tested (0.5–50 μg L⁻¹ in water and 0.01–0.1 mg kg⁻¹ in tomato) with r ² values ranging between 0.97 and 0.99. For water samples limits of detection ranged between 0.1 and 2 μg L⁻¹with relative standard deviations lower than 20%. Detection limits for tomato samples were between 0.003 and 0.025 mg kg⁻¹ with relative standard deviations around 25%. Finally, the SPME procedure has been applied to vegetable (tomato) and fruit (strawberry) samples obtained from an experimental plot treated with lambda-cyhalothrin, and in both cases the analyte was detected and quantified using a calibration curve prepared using blank matrix. SPME has been shown to be a simple extraction technique which has a number of advantages such as solvent-free extraction, simplicity, and compatibility with chromatographic analytical systems. Difficulties with the correct quantification in a complex matrix are also discussed.

Keywords: SPME; Pyrethroids; Vegetable samples; GC/MS

Structure of silica in Equisetum arvense by G. Holzhüter; K. Narayanan; T. Gerber (pp. 512-517).

Silicified regions in the stem and leaf of the horsetail Equisetum arvense were studied by scanning and transmission electron microscopy. The silica was present as a thin layer on the outer surface with variation in the size of this layer depending on the part investigated. There was a dense arrangement of silica spheres with some density fluctuations. A loose arrangement of silica particles with variation in their size was found beneath this dense arrangement suggesting the agglomeration of silica. An electron diffraction pattern showed the presence of amorphous silica, with the short range order being comparable to that of silica from other chemical sources. The medium range order shows the presence of silica with a high inner surface. SAXS measurements correlate with the particle size observed in TEM, and provide values for surface fractals. A new method of plasma ashing to remove the organics is also described.

Keywords: Silica; Horsetail; Biomineralisation; Electron microscopy; SAXS

Analytical procedure for the simultaneous voltammetric determination of toxic metals in dialysis fluids by Clinio Locatelli (pp. 518-523).

A new analytical voltammetric procedure for the simultaneous determination of copper(II), lead(II), cadmium(II), zinc(II), chromium(VI), and manganese(II) in two kinds of dialysis fluid (peritoneal and haemodialysis fluids) is described. The voltammetric measurements were performed using, as working electrode, a stationary mercury electrode, and a platinum electrode and a Ag∣AgCl∣KCl _(sat.) electrode as auxiliary and reference electrodes, respectively, employing 0.1 mol L⁻¹ dibasic ammonium citrate solution pH 6.9 as supporting electrolyte. For all the elements, the accuracy, expressed as relative recovery R%, was very satisfactory being in the range 94–105%, the precision, expressed as relative standard deviation s_r%, was lower than 6%, while the limits of detection were of the order of a few units of μg L⁻¹. The analytical voltammetric procedure has been validated by comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements.

Keywords: Toxic metals; Voltammetry; Dialysis fluids

Improved selectivity and detection limit of the carbonate-selective electrode by Magdalena Maj-Żurawska; Dorota Ziemianek; Agnieszka Mikołajczuk; Józef Mieczkowski; Andrzej Lewenstam; Adam Hulanicki; Tomasz Sokalski (pp. 524-526).

The properties of the carbonate neutral carrier 4-(n-hexadecyl)-3-nitro-1-trifluoroacetylbenzene were compared with those of a similar carrier, without a nitro group, studied previously. In spite of differences in the Hammett constant of the carbonyl group responsible for interaction with the analyte, the analytical characteristics of both carriers, measured under the same conditions, were comparable. Special care was taken to avoid the presence of an excessive carbon dioxide level in the diffusion layer at the membrane–solution interface. The internal reference solution was prepared without carbonate components; the external solution was protected from contact with atmospheric carbon dioxide. Under such conditions the detection limit of both electrodes was extended to 10⁻¹¹mol L⁻¹, and the selectivity towards salicylate, chloride, and acetate was significantly improved.

Keywords: Carbonate; 4-(n-Hexadecyl)-3-nitro-1-trifluoroacetylbenzene; Ion-selective electrode; Selectivity; Detection limit

New contributions to the field of bead-injection spectroscopy—flow-injection analysis: determination of cobalt by M. J. Ruedas Rama; A. Ruiz Medina; A. Molina Díaz (pp. 527-533).

A bead-injection spectroscopy–flow-injection analysis (BIS–FIA) system with spectrophotometric detection has been developed for the determination of cobalt. A homogeneous bead suspension of Dowex 50 W resin (600 μL) previously loaded with the chromogenic reagent 1-(2-pyridylazo)-2-naphthol (PAN) was injected to fill the flow-cell. Co is injected into the carrier (pyrophosphate, pH 5) and reacts with the immobilized chromogenic reagent to form a green chelate. The analytical signal corresponds to the formation of the Co-PAN complex on the solid surface. At the end of the analysis, the beads are discarded by reversing the flow and instantaneously transported out of the system. The sensor shows both excellent selectivity, which could also be increased with a simple on-line modification to avoid interferences from Ni(II), Zn(II) and Cu(II), and good sensitivity; the detection limit was 19 ng mL⁻¹, the linear range 50–2000 ng mL⁻¹ and the RSD (%) 4.16. The method was satisfactorily applied to the determination of Co in waters, pharmaceuticals and alloy steels.

Keywords: Bead-injection spectroscopy; Flow-injection analysis; Cobalt; Pharmaceuticals; Waters; Alloy steels

Liquid chromatography–fluorescence detection for simultaneous analysis of sulfonamide residues in honey by Guo-Fang Pang; Yan-Zhong Cao; Chun-Lin Fan; Jin-Jie Zhang; Xue-Min Li; Zeng-Yin Li; Guang-Qun Jia (pp. 534-541).

A rapid, accurate LC analytical method has been developed for determination of eight sulfonamides (sulfacetamide, sulfapyridine, sulfamerazine, sulfamethoxypyridazine, sulfameter, sulfachloropyridazine, sulfamethoxazole and sulfadimethoxine) in honey. The sample was dissolved in phosphoric acid solution (pH 2). After filtration, the sample solution was cleaned by use of two solid-phase extraction (SPE) cartridges—an aromatic sulfonic cation-exchange cartridge and an Oasis HLB cartridge. The eight sulfonamides were then derivatized with fluorescamine and the derivatives were determined by LC with fluorescence detection at excitation and emission wavelengths of 405 and 495 nm, respectively. Average recoveries at three fortification levels in the range 0.02–0.50 mg kg⁻¹ in twelve different kinds of honey were 73.5–94.1% with coefficients of variation of 4.35–16.60%. The limit of detection (LOD) was 0.002 mg kg⁻¹ for sulfacetamide, sulfapyridine, sulfamerazine, and sulfamethoxypyridazine; that for sulfameter, sulfachloropyridazine, sulfamethoxazole and sulfadimethoxine was 0.005 mg kg⁻¹. The limit of quantitation (LOQ) was 0.005 mg kg⁻¹ for sulfacetamide, sulfapyridine, sulfamerazine, and sulfamethoxypyridazine; that for sulfameter, sulfachloropyridazine, sulfamethoxazole, and sulfadimethoxine was 0.010 mg kg⁻¹. The method is suitable for determination of multiresidue sulfonamides in the various kinds of honey.

Keywords: Liquid chromatography; Fluorescence detection; Fluorescamine derivatization; Solid-phase extraction; Honey; Sulfonamides

Morin applied in speciation of aluminium in natural waters and biological samples by reversed-phase high-performance liquid chromatography with fluorescence detection by Hong-zhen Lian; Yu-fen Kang; Shu-ping Bi; Arkin Yasin; Da-lin Shao; Yi-jun Chen; Le-mei Dai; Li-ching Tian (pp. 542-548).

A reversed-phase high-performance liquid chromatographic method with fluorescence detection for the determination of labile monomeric aluminium has been developed through pre-column complexation using morin as the analytical reagent. The highly fluorescent aluminium–morin complex (excitation wavelength 418 nm, emission wavelength 490 nm) was separated on a Spherisorb ODS 2 column with an eluent consisting of 30% methanol and 70% water (pH 1.0 with perchloric acid). The most remarkable point of this protocol was that only the most toxic aluminium species, that is, free aqua-aluminium ion and its monomeric hydroxo complex ions, selectively respond among various aluminium complexes. This strategy has been successfully applied to direct fractionation of the toxic aluminium in natural waters and biological samples without any pretreatment.

Keywords: Aluminium; Speciation; HPLC; Morin

Three-phase plasma arc atomic-emission spectrometric analysis of environmental samples using an ultrasonic nebulizer by Zekry F. Ghatass; Gamal D. Roston; Moustafa M. Mohamed (pp. 549-553).

Combination of an ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample throughput, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytical capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three-phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, an ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn, and detection limits have been calculated. The present technique is used to determine the concentration of the elements Ca, Cr, Fe, Mg and Mn in airborne samples.

Keywords: Three-phase plasma; Atomic emission spectroscopy; Air pollution; Heavy metals

Sections

Personal tools

Analytical and Bioanalytical Chemistry (v.376, #4)

Sections

Personal tools

Local resources

Analytical and Bioanalytical Chemistry (v.376, #4)