Development and validation of a new method for the simultaneous determination of PAHs and NDL-PCBs in fish by GC-SQ-MS.

A new method for the simultaneous determination of PAHs and NDL-PCBs in fish and fish products was developed and validated using a GC-SQ-MS system. The efficacy of different solvents for a quantitative extraction was studied, as was the efficacy of different sorbents for sample clean up. The developed method, which includes extraction by DCM and sample clean up by SPE using Isolute® SI cartridges, was statistically validated at two concentration levels by assessing: accuracy, precision, limit of quantification, limit of detection and matrix effect.

Liquid Chromatographic Determination of Biogenic Amines in Fish Based on Pyrene Sulfonyl Chloride Pre-Column Derivatization.

Monitoring of biogenic amines in food is important for quality control, in terms of freshness evaluation and even more for food safety. A novel and cost-effective method was developed and validated for the determination of the main biogenic amines: histamine, putrescine, cadaverine, spermidine and spermine in fish tissues. The method includes extraction of amines with perchloric acid, pre-column derivatization with Pyrene Sulfonyl Chloride (PSCl), extraction of derivatives with toluene, back-dissolution in ACN after evaporation and determination by reversed phase high performance liquid chromatography with UV and intramolecular excimer fluorescence detection.

Determination of bisphenol A in canned food by microwave assisted extraction, molecularly imprinted polymer-solid phase extraction and liquid chromatography-mass spectrometry.

Bisphenol A (BPA), a known potential endocrine disrupting compound (EDC) is expected to be present in low quantities in canned food due to its migration from the inner surface coating of cans made of epoxy resins. A selective and confirmatory analytical method, based on microwave assisted extraction (MAE), molecularly imprinted solid phase extraction (MISPE) using a polymer prepared by a non-covalent molecular imprinting technique and liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI/MS) was developed for the determination of BPA in canned pineapple, tuna and mushrooms. First, the effect of the loading medium of hydro- organic solutions on the binding of BPA and its deuterated analogue on the MISPE sorbent was investigated.

A novel derivatization method for the determination of Fosfomycin in human plasma by liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection via phase transfer catalyzed derivatization.

An analytical method employing novel sample preparation and liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection (LC-APCI/MS) was developed for the determination of fosfomycin in human plasma. Sample preparation involves derivatization through phase transfer catalysis (PTC) which offers multiple advantages due to the simultaneous extraction, preconcentration and derivatization of the analyte. Using a PT catalyst, fosfomycin was extracted from plasma in an organic phase and, then converted to a pentafluorobenzyl ester with the use of pentafluorobenzyl bromide (PFBBr) derivatization reagent.

A generic screening methodology for horse doping control by LC-TOF-MS, GC-HRMS and GC-MS.

In the present study a general screening protocol was developed to detect prohibited substances and metabolites for doping control purposes in equine sports. It was based on the establishment of a unified sample preparation and on the combined implementation of liquid and gas chromatographic MS analysis. The sample pretreatment began with two parallel procedures: enzymatic hydrolysis of sulfate and glucuronide conjugates, and methanolysis of the 17β-sulfate steroid conjugates.

Optimization and comparison of ESI and APCI LC-MS/MS methods: a case study of Irgarol 1051, Diuron, and their degradation products in environmental samples.

A systematic and detailed optimization strategy for the development of atmospheric pressure ionization (API) LC-MS/MS methods for the determination of Irgarol 1051, Diuron, and their degradation products (M1, DCPMU, DCPU, and DCA) in water, sediment, and mussel is described. Experimental design was applied for the optimization of the ion sources parameters. Comparison of ESI and APCI was performed in positive- and negative-ion mode, and the effect of the mobile phase on ionization was studied for both techniques.

Recent trends in biomonitoring of bisphenol A, 4-t-octylphenol, and 4-nonylphenol.

Bisphenol A (BPA), 4-t-octylphenol (4-t-OP), and 4-nonylphenol (4-NP) are man-made alkylphenolic environmental contaminants possessing controversial endocrine disruption properties. Nowadays, an increased interest is raised for their accurate determination in biological media in order to estimate the exposure to these compounds and the associated health risk. The aim of this review is to present the available analytical methodologies for biomonitoring these three EDCs in human population.

Stabilization of human urine doping control samples: a current opinion.

Transportation of doping control urine samples from the collection sites to the World Anti-doping Agency (WADA) Accredited Laboratories is conducted under ambient temperatures. When sample delivery is not immediate, microbial contamination of urine, especially in summer, is a common phenomenon that may affect sample integrity and may result in misinterpretation of analytical data. Furthermore, the possibility of intentional contamination of sports samples during collection with proteolytic enzymes, masking the abuse of prohibited proteins such as erythropoietin (EPO) and peptide hormones, is a practice that has already been reported.

A porous graphitized carbon column HPLC method for the quantification of paracetamol, pseudoephedrine, and chlorpheniramine in a pharmaceutical formulation.

A simple, rapid, and stability-indicating HPLC method has been developed, fully validated, and applied to the quantification of paracetamol, pseudoephedrine hydrochloride, and chlorpheniramine maleate in a pharmaceutical formulation, using hydrochlorothiazide as an internal standard. Chromatographic separation was achieved isocratically on an RP porous graphitized carbon analytical column (125 x 2.1 mm id, particle size 5 microm) using 5.

Stabilization of human urine doping control samples: IV. Human chorionic gonadotropin.

The presence of proteolytic enzymes in urine samples, coming from exogenous or endogenous sources, enhances the cleavage of human chorionic gonadotropin (hCG). Moreover, elevated temperatures occurring occasionally during the delayed transportation of sport urine samples, favor the nicking of the hCG molecule. The aim of the current study, funded by the World Anti-Doping Agency (WADA), was the application of a stabilization mixture in athletes' urine samples to chemically inactivate proteolytic enzymes coming from exogenous or endogenous sources so as to prevent the degradation of hCG.

Hydrophilic interaction vs ion pair liquid chromatography for the determination of streptomycin and dihydrostreptomycin residues in milk based on mass spectrometric detection.

Streptomycin (STR) and dihydrostreptomycin (DHSTR) are two of the most common aminoglycoside antibiotics used in veterinary medicine. The physicochemical properties of both substances, make their determination challenging. In the present study the development of methods based on ion-pair chromatography (IPC) and on hydrophilic interaction chromatography (HILIC), for the determination of the above mentioned aminoglycosides in the range of 100-1000 μg L(-1) is described.

Development of a fast and selective method for the sensitive determination of anatoxin-a in lake waters using liquid chromatography-tandem mass spectrometry and phenylalanine-d5 as internal standard.

Anatoxin-a is a potent alkaloid neurotoxin produced by a number of cyanobacterial species and released in freshwaters during cyanobacterial blooms. Its high toxicity is responsible for several incidents of lethal intoxications of birds and mammals around the world; therefore anatoxin-a has to be regarded as a health risk and its concentration in lakes and water reservoirs should be monitored. Phenylalanine is a natural amino acid, also present in freshwaters, isobaric to anatoxin-a, with a very similar fragmentation pattern and LC retention.

Effect of suppressor current intensity on the determination of glyphosate and aminomethylphosphonic acid by suppressed conductivity ion chromatography.

This paper presents the application of ion chromatography with electrolytic eluent generation and mobile phase suppression for the direct conductimetric detection of glyphosate and its degradation product aminomethylphosphonic acid (AMPA). The compounds were separated on a Dionex AS18 anion exchange column with a 12-40 mM KOH step gradient from 9 to 9.5 min.

Determination of trace cobalt(II) by adsorptive stripping voltammetry on disposable microfabricated electrochemical cells with integrated planar metal-film electrodes.

This work reports the determination of trace Co(II) by adsorptive stripping voltammetry on disposable three-electrode cells with on-chip metal-film electrodes. The heart of the sensors was a bismuth-film electrode (BiFE) with Ag and Pt planar strips serving as the reference and counter electrodes, respectively. Metals were deposited on a silicon chip by sputtering while the areas of the electrodes were patterned via a metal mask.

A novel photometric method for evaluation of the oxidative stability of virgin olive oils.

The Oxitester method, a novel, simple, and fast photometric method for the evaluation of the antioxidant capacity of olive oils, was validated and compared to the official oil stability index (Rancimat) method. The Oxitester method appeared to be a good alternative to the Rancimat method with adequate correlation for a wide range of virgin olive oil samples, including extrissima virgin olive oils (correlation coefficient 0.88), and extra virgin olive oils of increased acidity (free fatty acids >0.

Direct determination of the estrogenic compounds 8-prenylnaringenin, zearalenone, alpha- and beta-zearalenol in beer by liquid chromatography-mass spectrometry.

A novel LC-ESI-MS method for the simultaneous determination of four of the most significant estrogenic compounds naturally occurring in beer, 8-prenylnaringenin (8-PN), zearalenone (ZON), alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL) which requires minimal sample preparation was developed using a chemometric approach. Experimental design was applied to assess the effects of the LC-ESI-MS parameters (mobile phase flow rate, drying gas flow, nebuliser pressure and capillary potential) on the obtained signal and to optimize the values in order to provide maximum sensitivity and detectability. The proposed method is simple, consisting only of degassing the beer and diluting with water (1:1, v/v) before injection.

Molecularly imprinted polymers for bisphenol A for HPLC and SPE from water and milk.

Molecularly imprinted polymers (MIPs) for bisphenol A (BPA) were prepared by two synthetic routes: semi-covalent and noncovalent methodology. The molecular imprinting effect was evaluated using the polymers in HPLC and SPE. Polymers prepared with noncovalent mode were proven more effective.

Migration of bisphenol A from polycarbonate baby bottles under real use conditions.

Migration of the potential endocrine disrupter, bisphenol A (BPA), from 31 polycarbonate (PC) baby bottles into aqueous food simulants was studied under real repetitive use, using a sensitive and fully validated liquid chromatographic method with fluorescence detection. Confirmation of the presence of BPA was performed by liquid chromatography-mass spectrometry (LC-MS). The effects of cleaning in a dishwasher or with a brush, sterilization with boiling water and the temperature of migration were examined.

Development of a novel liquid chromatography--evaporative light scattering detection method for bacitracins and applications to quality control of pharmaceuticals.

A novel liquid chromatography method for the direct determination of bacitracin main components (Bc-A, -B1, -B2 and -B3), a basic, cyclic polypeptide antibiotic, was developed and validated, based on ion pairs formation with trifluoroacetic acid (TFA) and evaporative light scattering detection (ELSD). The selected analytical column was the Waters Nova-pak C8 (3.9 x 150 mm), for which the optimum (using modified Simplex algorithm) mobile phase was H2O-ACN (73:27, v/v) containing 0.

Simultaneous liquid chromatographic determination of metals and organic compounds in pharmaceutical and food-supplement formulations using evaporative light scattering detection.

A novel method for the non-derivatization liquid chromatographic determination of metals (potassium, aluminium, calcium and magnesium) and organic compounds (ascorbate and aspartate) was developed and validated based on evaporative light scattering detection (ELSD). Separation of calcium, magnesium and aluminium was achieved by the cation exchange column Dionex CS-14 and an aqueous TFA mobile phase according to the following time program: 0-6 min TFA 0.96 mL L(-1), 6-7 min linear gradient from TFA 0.

Determination of catalase-like activity in plants based on the amperometric monitoring of hydrogen peroxide consumption using a carbon paste electrode modified with ruthenium(IV) Oxide.

A carbon paste electrode containing ruthenium(IV) oxide as a modifier was tested as an effective hydrogen peroxide amperometric sensor in bulk measurements (hydrodynamic amperometry). Factors that influence its overall analytical perform ance, such as pH and the applied potential, were examined. The RuO2-modified electrode displayed high sensitivity towards hydrogen peroxide, with detection limits as low as 0.

Determination of bisphenol A in milk by solid phase extraction and liquid chromatography-mass spectrometry.

A simple and reliable analytical method based on solid phase extraction (SPE) and liquid chromatography coupled with electrospray ionization mass spectrometry was developed for the determination of bisphenol A (BPA) in milk. The effects of the experimental parameters of the LC-ESI-MS system (mobile phase and additives, flow rate, temperature of the ionization source, cone voltage and capillary potential) on the obtained signal were assessed and the parameters were optimized to provide maximum sensitivity and detectability. In addition, the performance of three commercial SPE sorbents (C18, PS-DVB and hydroxylated PS-DVB) was evaluated using spiked water and milk, diluted with a mixture of water-methanol (8:1).

Development of a novel method based on liquid chromatography-evaporative light scattering detection for the direct determination of streptomycin and dihydrostreptomycin in raw materials, pharmaceutical formulations, culture media and plasma.

A novel method for the non-derivatization liquid chromatographic determination of streptomycin (STR) and dihydrostreptomycin (DHSTR) was developed and validated based on evaporative light scattering detection (ELSD). Utilizing a ThermoHypersil BetaBasic C18 analytical column, evaporation temperature of 50 degrees C and pressure of nebulizing gas (nitrogen) of 3.5 bar, the optimized mobile phase was 1.

Development and validation of a novel LC non-derivatization method for the determination of amikacin in pharmaceuticals based on evaporative light scattering detection.

A novel method for the direct determination of the aminoglycoside antibiotic amikacin and its precursor component kanamycin was developed and validated, based on reversed phase LC with evaporative light scattering detector (ELSD). ELSD response to amikacin was found to be enhanced by: (a) use of ion-pairing acidic reagents of increased molecular mass, (b) increase of mobile phase volatility and (c) decrease of peak width and asymmetry (obtained by controlling the mobile phase acidity and/or ratio of organic solvent to water). Utilizing a Thermo Hypersil BetaBasic C(18) column, the selected optimized mobile phase was water-methanol (60:40, v/v), containing 3.

Metabolism of isometheptene in human urine and analysis by gas chromatography-mass spectrometry in doping control.

A study of the metabolism of isometheptene, an antispasmodic drug, in man and comparison with heptaminol metabolism, is presented in this paper. Isometheptene and two metabolites were detected in human urine after oral administration of a tablet containing isometheptene mucate. The urine level of the parent drug, which is excreted during the first 24 h, was determined using gas chromatography-mass spectrometry, after alkaline extraction with organic solvent.