Biomedical subjects

S Muniategui-Lorenzo

Publications and source records attributed to S Muniategui-Lorenzo.

14 recordsLinked to original sources

PubMed2006

Optimisation and validation of a solid-phase microextraction method for simultaneous determination of different types of pesticides in water by gas chromatography-mass spectrometry.

A solid-phase microextraction (SPME) method for the simultaneous determination of a large number of pesticides (46) with a wide range of polarities and chemical structures (organochlorine, organophosphorous, triazines, pyrethroids and others) in water samples by GC-MS has been developed. Three different fibres and parameters that influence the extraction and desorption efficiency were studied. The selected conditions were: a 60 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre, 45 min of extraction time, sample agitation and temperature control at 60 degrees C; neither pH adjustment nor ionic strength correction were applied. Good detection limits, linearity and repeatability were obtained with this method for the 46 pesticides studied. The method was validated for 29 pesticides following the recommendations of the international norm ISO/IEC 17025 including the calculation of the uncertainties. The detection limits ranged from 4 to 17 ng l(-1). Furthermore, repeatability (6.9-20.5%) and intermediate precision (4.5-19.7%) were shown to be satisfactory. To validate matrix effects for drinking and surface water analytical recoveries were calculated for these matrices. The accuracy of the method was also evaluated by participating in a proficiency inter-laboratory test.

Gas Chromatography-Mass Spectrometry↗

PubMed2006

Evaluation of HCH isomers and metabolites in soils, leachates, river water and sediments of a highly contaminated area.

In this work we evaluate the contamination caused by HCH residues in the soil, leachates, river water and sediments of an industrial estate of the NW of Spain. We study the distribution of the isomers in the different matrices, analysing 37 soil samples, collected in eight points at several depths, six natural leachates, four river water samples and three river sediments. Soil and leachate samples present very high levels of HCH isomers, higher than the established by legislation, and some pesticides were also detected in the analysed river water whereas no pesticides were detected in the river sediments. The distribution of isomers was different depending on the matrix analysed. Some natural degradation products and also other organochlorine pesticides were detected in the samples analysed.

Environmental Monitoring↗

PubMed2005

Troubleshooting with cell blanks in PLE extraction.

The blank extracts obtained from the pressurized liquid extraction (PLE) of a 11 mL empty cell of ASE 200 were analysed by GC-FID and GC-ECD and many interfering peaks were detected, which could difficult the trace analysis of persistent organic pollutants (i.e. polycyclic aromatic hydrocarbons, aliphatic hydrocarbons and organochlorine pesticides). These interfering compounds were identified as phthalates, silicones and organic acids and their sources were established. A solution to this analytical trouble is a previous extraction step of the empty cell under the same conditions optimised for the sample extraction.

Carboxylic Acids↗

PubMed2004

Determination of 21 organochlorine pesticides in tree leaves using solid-phase extraction clean-up cartridges.

A method to determine 21 organochlorine pesticides (OCPs) in tree leaves [chestnut (Castanea sativa), hazel (Corylus avellana), oak (Quercus robur) and walnut tree (Juglans regia)] based on microwave-assisted extraction (MAE) followed by solid-phase extraction (SPE) clean-up is described. After extraction with hexane:acetone (50:50), four different sorbents (Florisil, tandem Florisil + alumina, silica and ENVI-Carb) were assayed for the clean-up step. Pesticides were eluted with 5 mL of hexane:ethyl acetate (80:20) and determined by gas chromatography and electron capture detection (GC-ECD). Carbon was the sorbent, which provided colourless eluates and chromatograms with less interferent compounds. Analytical recoveries obtained were ca. 100% for all the studied pesticides with this sorbent.

Chromatography, Gas↗

PubMed2004

C1 to C9 volatile organic compound measurements in urban air.

Urban atmospheric samples were collected in A Coruna (NW Spain) and analysed for volatile organic compounds. One hundred and twenty one hour samples were collected in winter 2000. The ambient air was rich in benzene, toluene, ethyl-benzene and xylenes (BTEX) and especially toluene (mean: 23.6 microg m(-3), median: 14.66 microg m(-3)), but the presence of chlorinated compounds was also notable. High concentrations of 1,4-dichlorobenzene (mean: 11.4 microg m(-3), max: 90.4 microg m(-3)) were recorded. Multivariate analysis of VOC, trace gases (NO(x), NO(2), NO, SO(2) and O(3)) and meteorological variables (temperature, wind direction and speed, precipitation and radiation) was applied and correlations between VOC were also studied. Principal component analysis and correlation analysis confirm traffic as the main source of VOC in the area, although the importance of evaporative sources is also reflected. Three groups of samples were obtained by cluster analysis; these groups are formed depending on the content of aromatics and ozone and, in many cases, on the sampling hour.

Journal Article↗

PubMed2004

Assessment of methodologies for airborne BaP analysis.

Very sensitive analytical methods will be required to assess airborne contaminants with the implementation of new EC Directives. In this work, Soxhlet, ultrasonic and microwave-assisted extraction (MAE) were applied to two airborne standard reference materials (SRM) 1648 "Urban Particulate Matter" and SRM 1649a "Urban Dust". All three techniques afforded satisfactory results, but MAE was preferred due to its low solvent requirement and speed of analysis. In addition, high performance liquid chromatography (HPLC) with ultraviolet and fluorescence detection was compared to gas chromatography (GC)-flame ionisation detection (FID) with programmed split-splitless injection (PSS) and GC-mass spectrometry (MS) with programmed temperature vaporiser (PTV) injection. The HPLC method proved far more sensitive than the GC techniques (four and three orders of magnitude, respectively). Real atmospheric particulate samples were taken at A Coruna (Spain). Different sampling devices were used to collect PM(10), PM(2.5), PM(1), cascade impactor and TSP/gas phase samples. BaP concentrations quantified in the samples are similar to those reported for other cities.

Journal Article↗

PubMed2004

Development of pressurized liquid extraction and cleanup procedures for determination of organochlorine pesticides in soils.

The scope of this work is the development of a rapid, reliable and sensitive method for the analysis of organochlorine pesticides from soils by pressurized liquid extraction (PLE). The effect of four parameters (temperature, pressure, static time and cell volume) on the extraction efficiency was studied. The great extracting power of the PLE causes the extraction of numerous interfering substances, so a more efficient purification of this extract was necessary. In this work several sorbents have also been assayed to carry out the purification of soil samples: Florisil, silica, alumina, carbon, as well as combinations of them. Finally, the proposed analytical method was validated using a certified reference soil material (CRM804-050) and the results were compared with those obtained by other extraction techniques (Soxhlet and microwave-assisted extraction).

Animals↗

PubMed2004

Improvement of sensitivity in the determination of organochlorine pesticides using a PSS injector with GC-ECD.

This paper describes the optimisation of a PSS injector in a gas chromatograph with a programmed pneumatic control (PPC) for the determination of 21 organochlorine pesticides. The injection of high volumes of sample (20 microl) improves the detection limits and allows a reduction in the amount of sample processed. The injection conditions were selected by a Plackett-Burman design followed by a central composite design. The LODs obtained in the optimum conditions were compared with those obtained with splitless/ECD. Finally, the method was successfully applied to the analysis of a leachate and vegetable samples.

Chromatography, Gas↗

PubMed2004

First assessment of dioxin emissions from coal-fired power stations in Spain.

In this work, the findings of the first assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in emissions releases to the atmosphere from coal-fired power plants are given. A total of five plants were selected for the study located at different provinces in Spain. In all the cases, the results revealed very low levels, in the range of 0.41 pg I-TEQ/Nm(3). The profile indicated in the majority of the cases predominance of highly chlorinated congeners being OCDD the most important contributor. The findings were also used to estimate contribution of PCDDs/PCDFs emitted from coal-fired power plants in Spain. Individual plant results revealed values below 0.02 g I-TEQ per year and plant. Nevertheless, considering the total coal consumption in Spain in 1997, the values are comparable to those reported in other countries in the range of 0.6-0.7 g I-TEQ per year. Moreover, emission factors were determined considering operating conditions of evaluated plants. In general, large variability was observed and values below 1-5 pg I-TEQ/kg coal were early reached.

Air Pollutants↗

PubMed2003

Microwave-assisted extraction versus Soxhlet extraction in the analysis of 21 organochlorine pesticides in plants.

A method to determine 21 organochlorine pesticides in vegetation samples using microwave-assisted extraction (MAE) is described and compared with Soxhlet extraction. Samples were extracted with hexane-acetone (1:1, v/v) and the extracts were cleaned using solid-phase extraction with Florisil and alumine as adsorbents. Pesticides were eluted with hexane-ethyl acetate (80:20, v/v) and determined by gas chromatography and electron-capture detection. Recoveries obtained (75.5-132.7% for Soxhlet extraction and 81.5-108.4% for MAE) show that both methods are suitable for the determination of chlorinated pesticides in vegetation samples. The method using microwave energy was applied to grass samples from parks of A Coruña (N.W. Spain) and to vegetation from the contaminated industrial area of Torneiros (Pontevedra, N.W. Spain).

Chromatography, Gas↗

PubMed2003

Microwave extraction of organochlorine pesticides from soils.

The purpose of this work was to develop a rapid, reliable and sensitive method for the extraction of organochlorine pesticides from soils using microwave energy with closed vessel technology. Three oven programs were assayed with two different solvent mixtures in order to achieve adequate experimental conditions for the complete extraction of organochlorine pesticides from the matrix. The method was validated using a certified reference soil material (CRM804-050).

Journal Article↗

PubMed2002

Optimisation of a programmed split-splitless injector in the gas chromatographic-mass spectrometric determination of organochlorine pesticides.

Large-volume injection techniques in gas chromatography are used to compensate for the at times limited detection sensitivity of mass spectrometric detection. In this work a programmed split-splitless injector in solvent split mode was employed to determine organochlorine pesticides in environmental samples. The injection conditions were selected by a Plackett-Burman design followed by a central composite design. The LODs obtained in the optimum conditions were compared with those obtained with splitless-MS and splitless-ECD. Finally, the method was applied to a soil sample.

Gas Chromatography-Mass Spectrometry↗

PubMed2001

Determination of volatile organic compounds in emissions by coal-fired power stations from Spain.

This study concerns the emissions of volatile organic compounds (VOCs) by coal fired power stations. The main compounds are monoaromatic hydrocarbons and aliphatic hydrocarbons, chlorinated compounds have less importance. The influence of combustion parameters can not be clearly established. Emissions factors were calculated and they are smaller than those of other anthropogenic combustions. A comparative study of two sources of VOCs, power stations and motor vehicles, indicates that the environmental impact of the latter are most important.

Air Pollutants↗

PubMed2000

Microwave assisted extraction of polycyclic aromatic hydrocarbons from atmospheric particulate samples.

For several years, microwave assisted extraction (MAE) was applied to extract organic compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, etc., from soils, sediments and standard reference materials. Very few authors applied this methodology for the extraction of PAHs from atmospheric particulate matter. In the present study, MAE of polycyclic aromatic hydrocarbons with hexane/acetone (1:1) from real atmospheric particulate samples was investigated and the effect of microwave energy and irradiation time studied. The yields of extracted compounds obtained by microwave irradiation were compared with those obtained using traditional Soxhlet extraction. MAE was evaluated using spiked real atmospheric particulate samples and two standard reference materials. Analytical determinations of PAHs were carried out by high performance liquid chromatography (HPLC) with ultraviolet and fluorescence detection. The best recoveries were achieved with a microwave energy of 400 W and an irradiation time of 20 min.

Air Pollutants↗