Analysis of endocrine disrupting pesticides by capillary GC with mass spectrometric detection.

Endocrine disrupting chemicals, among them many pesticides, alter the normal functioning of the endocrine system of both wildlife and humans at very low concentration levels. Therefore, the importance of method development for their analysis in food and the environment is increasing. This also covers contributions in the field of ultra-trace analysis of multicomponent mixtures of organic pollutants in complex matrices.

Analysis of pesticide residues by fast gas chromatography in combination with negative chemical ionization mass spectrometry.

A combination of fast GC with narrow-bore column and bench top quadrupole mass spectrometer (MS) detector in negative chemical ionization (NCI) mode (with methane as reagent gas) is set up and utilized for the ultratrace analysis of 25 selected pesticides. The observed pesticides, belonging to the endocrine disrupting chemicals (EDCs), were from different chemical classes. A comparative study with electron impact (EI) ionization was also carried out (both techniques in selected ion monitoring (SIM) mode).

Comparison of negative chemical ionization and electron impact ionization in gas chromatography-mass spectrometry of endocrine disrupting pesticides.

The study of pesticide residues belonging to endocrine disrupting chemicals (EDCs) (23 analytes of different chemical classes--organochlorines, organophosphates, pyrethroids, dicarboximides, phtalamides, dinitroanilines, pyrazole, triazinone) in apple matrix with conventional capillary GC-NCI-MS (with methane as reagent gas) in comparison to EI ionization is presented. For sample preparation QuEChERS method was applied. The lowest calibration levels (LCLs) for all pesticides were determined in both modes.

Fast gas chromatography for pesticide residues analysis.

The importance of method development in the area of pesticide residues analysis is apparent from legislative requirements continuously decreasing the maximum acceptable concentration levels in food and water. This covers also contribution in the science in the field of ultra-trace analysis of organic pollutants in complex mixtures. Analysis time is one of the most important aspects that should be considered in the choice of analytical methods for routine application.

Fast gas chromatography for pesticide residues analysis using analyte protectants.

Fast GC-MS with narrow-bore columns combined with effective sample preparation technique (QuEChERS method) was used for evaluation of various calibration approaches in pesticide residues analysis. In order to compare the performance of analyte protectants (APs) with matrix-matched standards calibration curves of selected pesticides were searched in terms of linearity of responses, repeatability of measurements and reached limit of quantifications utilizing the following calibration standards in the concentration range 1-500 ng mL(-1)(the equivalent sample concentration 1-500 microg kg(-1)): in neat solvent (acetonitrile) with/without addition of APs, matrix-matched standards with/without addition of APs. For APs results are in a good agreement with matrix-matched standards.

Sample preparation methods in the analysis of pesticide residues in baby food with subsequent chromatographic determination.

Pesticides are widely utilized at various stages of cultivation and during postharvest storage to protect plants against a range of pests and/or to provide quality preservation. Reliable confirmatory methods are required to monitor pesticide residues in baby foods and to ensure the safety of baby food supply. This review covers methods in which pesticide residues have been determined in baby food by the use of a wide range of chromatographic techniques after various sample preparation steps.

Comparison of sample preparation methods combined with fast gas chromatography-mass spectrometry for ultratrace analysis of pesticide residues in baby food.

Four sample preparation techniques were compared for the ultratrace analysis of pesticide residues in baby food: (a) modified Schenck's method based on ACN extraction with SPE cleaning; (b) quick, easy, cheap, effective, rugged, and safe (QuEChERS) method based on ACN extraction and dispersive SPE; (c) modified QuEChERS method which utilizes column-based SPE instead of dispersive SPE; and (d) matrix solid phase dispersion (MSPD). The methods were combined with fast gas chromatographic-mass spectrometric analysis. The effectiveness of clean-up of the final extract was determined by comparison of the chromatograms obtained.

Possibilities and limitations of fast GC with narrow-bore columns.

In this work, two narrow-bore capillary columns with different internal diameters (I.D.) 0.

Application of large volume injection GC-MS to analysis of organic compounds in the extracts and leachates of municipal solid waste incineration fly ash.

Organic solvent and water extracts of fly ash from a Milan (Italy) municipal solid waste incinerator (MSWI) were analyzed by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) with programmable temperature vaporizer (PTV). Using injection volumes of 10-100 microl, typically over a hundred compounds were detected in organic solvent extracts and ca. 35% of them could be tentatively identified from their electron impact ionization mass spectra.

Possibilities and limitations of quadrupole mass spectrometric detector in fast gas chromatography.

In this work the application and limitations of a common bench top quadrupole mass spectrometer was evaluated for the qualitative and quantitative measurement of n-alkanes and pesticides of a wide range of volatilities and polarities with fast GC separations using 0.15 mm I.D.

Search on ruggedness of fast gas chromatography-mass spectrometry in pesticide residues analysis.

In this study, suitability of fast gas chromatography-mass spectrometry (GC-MS) on a narrow-bore column with a programmed temperature vaporizer for the analysis of pesticide residues in non-fatty food was evaluated. The main objectives were ruggedness and stability of chromatographic system with regards to co-extractives injected. The chromatographic matrix induced response enhancement was found to be strongly dependent on the concentration of residues and is reaching up to 700% compared to the pesticides solutions in a neat solvent.

Fast gas chromatography with solid phase extraction clean-up for ultratrace analysis of pesticide residues in baby food.

A sample preparation method based on single solvent phase extraction and solid-phase extraction (SPE-NH2) clean-up is studied in combination with fast capillary gas chromatography (GC) to determine 18 selected pesticides belonging to various chemical classes in apples, the common raw material for baby food production and baby food, at the concentration level < or = 10 microg/kg maximum residual limit (MRL). Possibilities of mass spectrometry (MS) detector and electron capture detector (ECD) in fast gas chromatography (GC) of samples with complex matrice at ultra trace levels of pesticide residues were studied and compared. MS detection in single ion monitoring (SIM) mode provided higher selectivity compared to ECD.

Optimization of conditions for PTV large-volume injection combined with fast GC-MS.

Large-volume injection utilizing programmable temperature vaporizer in solvent vent mode is combined with fast capillary gas chromatography and mass spectrometric detection. Optimized injection and chromatographic conditions made possible manual injection of a 20-microL ethyl acetate extract containing 15 organochlorine pesticides and their separation on a short, 0.1-mm-i.

Practical aspects of splitless injection of semivolatile compounds in fast gas chromatography.

Possibilities and practical aspects of implementation of splitless injection of larger volumes for fast GC purposes utilizing narrow-bore column, hydrogen as carrier gas, fast temperature programming under programmed flow conditions and commercial instrumentation were searched. As a model sample semivolatile compounds of a broad range of volatility and polarity (7 n-alkanes and 19 pesticides) were chosen. Peak shapes, peak broadening and peak areas and its repeatability were evaluated under various experimental set-ups (liner/injection technique combinations).

Fast gas chromatography and its use in trace analysis.

There is revived interest in the development and implementation of methods of faster GC. The paper summarises the advantages of faster GC analysis, general approaches to faster GC method development and practical aspects of fast gas chromatography with the utilisation of open tubular capillary columns with the stress on trace analysis. There are a number of ways to take the advantage of the improved speed of analysis by faster GC.

Optimisation of solid-phase microextraction of volatiles.

The results of a systematic study on the precision and repeatability of measurements of the headspace solid phase micro-extraction (SPME) with open-cap vials in combination with capillary gas chromatography in comparison with septum-sealed vials are reported. Benzene, toluene, ethylbenzene, and xylene isomers (BTEX) were used as the target analytes in the investigation of spiked water samples at concentration levels of 42.5 microg l(-1).

Application of porous carbon for solid-phase extraction of dicarboxyimide fungicide residues from wines in combination with high-resolution capillary gas chromatography and gas chromatography-mass spectrometry.

Solid-phase extraction with a novel porous carbon sorbent CARB GR was used for the clean-up step of dicarboxyimide fungicides residues from variety of Slovak grape wines with subsequent capillary gas chromatography-flame ionization detection, -electron-capture detection (ECD) and -mass spectrometry-ion-trap detection (MS-ITD) analysis. Recovery was tested at various concentration levels of vinclozolin and iprodione in standard solutions (R = 80-97%, R.S.

Analysis of metalaxyl residues in wines by SPE in combination with HRCGC and GC/MS.

Solid phase extraction (SPE) with the porous carbon sorbent CARB GR was used for the preconcentration of metalaxyl residues from a variety of Slovak grape wines with subsequent capillary GC and GC/MS analysis. Recovery was tested at various concentrations of metalaxyl in standard solutions (recovery, R > or = 92%, relative standard deviation RSD < or = 4.3%) and in wines.

Stability study of novel zinc complexes of pharmaceutical relevance by CE.

CE was used as a stability-indicating assay for zinc mixed-ligand complexes with promised biological activity. CE measurements indicated that Zn(RCOO)2Ln compounds (where R = H, CH3, C2H5, or C3H7; L = caffeine, nicotinic acid, thiourea, or phenazone; and n = 1 or 2) in water tend to decompose at room temperature. For thiourea and phenazone compounds, the degradation products (free zinc ion, carboxylate anion, and the corresponding neutral ligand) were found to increase within a few hours of storage in water.

Determination of tetracycline antibiotics in animal tissues of food-producing animals by high-performance liquid chromatography using solid-phase extraction.

A high-performance liquid chromatographic (HPLC) method was developed for the determination of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) residues in bovine and porcine muscles. The method involved the homogenization of the sample in EDTA-McIlvaine buffer with added n-hexane and dichloromethane, centrifugation, precipitation of the supernatant using trichloroacetic acid and filtration. Preconcentration on Separcol SI C18 cartridges improved the clean-up and the recovery of tetracyclines that were separated by HPLC using the optimized mobile phase of 0.

Determination of ethylenethiourea in grapes and wine.

Residues of ethylenethiourea (ETU) in grapes and wine were determined by capillary gas chromatography and paper chromatography, without a cleanup step, and after derivatization to S-benzyl-ETU. The detection limit was 0.0002 mg/kg for flame ionization detection, 0.

Some properties of the adenosine triphosphatase associated with herpes simplex virus and nuclear membrane of host cells.

An enzyme capable to split adenosine triphosphate (ATP) was shown to be firmly associated with mature herpes simplex virus particles purified from infected rabbit lung (ZP) cells. The enzyme localized in the viral envelope was markedly activated by bivalent cations, to the largest degree by Mg2+ at a pH optimum of 7.8--8.

Capillary gas chromatography of s-triazines.

In order to achieve better resolution and lower detection limits for s-triazines, glass capillary columns made of soft soda-lime glass and etched with gaseous hydrogen chloride have been introduced. Columns with non-polar (OV-101, SE-30) mixed (Carbowax 20M + SE-30) and polar stationary liquids (Carbowax 20M) were used. The thickness of the ultra-thin film columns was determined by weighing the capillaries before and after coating of the capillary with stationary phase and conditioning, and varied from 0.

Purification and separation of enveloped and unenveloped herpes simplex virus particles.

Enveloped and unenveloped forms of herpes simplex virus (HSV) occurring in infected rabbit lung (ZP line) cells were purified by differential and discontinuous Ficoll density gradient centrifugation. Then the viral particles were separated in a sucrose-D2O density gradient. In the course of the procedures, both virus preparations were freed of Mg2+-dependent Na+ plus K+-stimulated adenosine triphosphatase (ATPase), 5'-nucleotidase, and glucose-6-phosphatase activities.