Lúcia Santos - Academia.edu (original) (raw)

Papers by Lúcia Santos

Analytica Chimica Acta, 2006

As the performances of analytical instrumentation are being gradually enhanced, the limits of det... more As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens.

Journal of Chromatography A, 2000

Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as we... more Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as well as other specific trace organic compounds like organochlorine pesticides. In this study a simple and reliable methodology was improved to detect organochlorine pesticides in leachate samples by using a previous solid-phase microextraction procedure [with a 100 mm poly(dimethylsiloxane) fiber] and chromatographic analysis by GC-electron-capture detection. The extraction time, temperature, ionic strength of the solution and sampling of the headspace were the parameters studied. Reproducibility achieved values below 20% RSD, and standard addition was used for pesticides confirmation.

Industrial & Engineering Chemistry Research, 2006

An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichloroph... more An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichlorophenol (2, 4-DCP) oxidation using Fenton's reagent. This multivariable and multilevel approach allowed us to investigate the effects between the experimental ...

Journal of Chromatography A, 2002

Landfill leachates represent a serious environmental concern with regard to trace priority pollut... more Landfill leachates represent a serious environmental concern with regard to trace priority pollutants introduced into the aquatic environment. From the analytical point of view, they constitute complex matrices because of their high organic matter content and competition with the trace analytes in the extraction procedure. Although the use of SPME to extract chlorophenols in leachates has already been described in several publications, the limited number of chlorophenols restricts this analysis field of application. This paper presents a new analytical methodology to determine 13 chlorophenols and phenol by SPME-GC-MS in landfill leachates. The overall analysis was performed in 90 min and the detection limits range from 0.005 mg / l (pentachlorophenol) to 2.5 mg / l (phenol). Reproducibility, expressed by the coefficient of variation of repeated extractions at different concentration levels of the analytes, was on average inferior to 10%. Recovery, evaluated by standard addition to leachates, was 86.2% on average. Pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,4,6-tetrachlorophenol were the sole analytes detected at nanogram level in the landfill leachates analysed. 

Analytical and Bioanalytical Chemistry, 2006

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assiste... more A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p′-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005

The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups us... more The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid-liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073 mg kg(-1), a precision not exceeding 10.0% and an average recovery of 93% +/- 38.

Environmental Science & Technology, 1999

Pesticides belong to a chemical family that calls our attention because of its hazardous effects ... more Pesticides belong to a chemical family that calls our attention because of its hazardous effects in the environment. The organochlorine pesticides were strongly used in the past, but their persistency and bioaccumulation make them an actual problem. Common wastewater treatment methods, like activated carbon sorption, mean expensive investment and operating costs. Pine bark is a wood industry byproduct and has a high affinity with hydrophobic compounds because of its organic composition. The aim of this work is to test the capability of this material to remove organochlorine pesticides from water solutions. This capability was quantified by studying the best operating conditions for pine bark fixed bed mini-columns, the yield of removal from spiked water solutions, and the saturation parameters. The yield of removal from spiked organochlorine water solutions ranging from 1 to 10 µg/L, was 97% on average, for heptachlor, aldrin, endrin, dieldrin, DDD, DDT, and DDE. Lindane could not be efficiently adsorbed by this methodology (38% for yield of removal). Saturation studies, performed until 60.00 L of spiked solution/g of adsorbent was reached, did not reveal system rupture. When compared with activated carbon, pine bark displays analogous response, suggesting that for compounds with similar physicochemical characteristics pine bark will play a significant role.

Analytica Chimica Acta, 2006

As the performances of analytical instrumentation are being gradually enhanced, the limits of det... more As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens.

Journal of Chromatography A, 2000

Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as we... more Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as well as other specific trace organic compounds like organochlorine pesticides. In this study a simple and reliable methodology was improved to detect organochlorine pesticides in leachate samples by using a previous solid-phase microextraction procedure [with a 100 mm poly(dimethylsiloxane) fiber] and chromatographic analysis by GC-electron-capture detection. The extraction time, temperature, ionic strength of the solution and sampling of the headspace were the parameters studied. Reproducibility achieved values below 20% RSD, and standard addition was used for pesticides confirmation.

Industrial & Engineering Chemistry Research, 2006

An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichloroph... more An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichlorophenol (2, 4-DCP) oxidation using Fenton's reagent. This multivariable and multilevel approach allowed us to investigate the effects between the experimental ...

Journal of Chromatography A, 2002

Landfill leachates represent a serious environmental concern with regard to trace priority pollut... more Landfill leachates represent a serious environmental concern with regard to trace priority pollutants introduced into the aquatic environment. From the analytical point of view, they constitute complex matrices because of their high organic matter content and competition with the trace analytes in the extraction procedure. Although the use of SPME to extract chlorophenols in leachates has already been described in several publications, the limited number of chlorophenols restricts this analysis field of application. This paper presents a new analytical methodology to determine 13 chlorophenols and phenol by SPME-GC-MS in landfill leachates. The overall analysis was performed in 90 min and the detection limits range from 0.005 mg / l (pentachlorophenol) to 2.5 mg / l (phenol). Reproducibility, expressed by the coefficient of variation of repeated extractions at different concentration levels of the analytes, was on average inferior to 10%. Recovery, evaluated by standard addition to leachates, was 86.2% on average. Pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,4,6-tetrachlorophenol were the sole analytes detected at nanogram level in the landfill leachates analysed. 

Analytical and Bioanalytical Chemistry, 2006

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assiste... more A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p′-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005

The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups us... more The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid-liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073 mg kg(-1), a precision not exceeding 10.0% and an average recovery of 93% +/- 38.

Environmental Science & Technology, 1999

Pesticides belong to a chemical family that calls our attention because of its hazardous effects ... more Pesticides belong to a chemical family that calls our attention because of its hazardous effects in the environment. The organochlorine pesticides were strongly used in the past, but their persistency and bioaccumulation make them an actual problem. Common wastewater treatment methods, like activated carbon sorption, mean expensive investment and operating costs. Pine bark is a wood industry byproduct and has a high affinity with hydrophobic compounds because of its organic composition. The aim of this work is to test the capability of this material to remove organochlorine pesticides from water solutions. This capability was quantified by studying the best operating conditions for pine bark fixed bed mini-columns, the yield of removal from spiked water solutions, and the saturation parameters. The yield of removal from spiked organochlorine water solutions ranging from 1 to 10 µg/L, was 97% on average, for heptachlor, aldrin, endrin, dieldrin, DDD, DDT, and DDE. Lindane could not be efficiently adsorbed by this methodology (38% for yield of removal). Saturation studies, performed until 60.00 L of spiked solution/g of adsorbent was reached, did not reveal system rupture. When compared with activated carbon, pine bark displays analogous response, suggesting that for compounds with similar physicochemical characteristics pine bark will play a significant role.

Journal of The American Chemical Society, 1989

subsequent loss o f t h e metal cation to the oxidant) isslow compared to the rate of the couplin... more subsequent loss o f t h e metal cation to the oxidant) isslow compared to the rate of the coupling reaction.

A arquitetura Gótica no Norte da França teve um lenta recepção, de forma gradual esta foi-se inst... more A arquitetura Gótica no Norte da França teve um lenta recepção, de forma gradual esta foi-se instalando, o que levou a crer que que o Gótico, era uma criação alemã.

Analytica Chimica Acta, 2006

As the performances of analytical instrumentation are being gradually enhanced, the limits of det... more As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens.

Journal of Chromatography A, 2000

Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as we... more Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as well as other specific trace organic compounds like organochlorine pesticides. In this study a simple and reliable methodology was improved to detect organochlorine pesticides in leachate samples by using a previous solid-phase microextraction procedure [with a 100 mm poly(dimethylsiloxane) fiber] and chromatographic analysis by GC-electron-capture detection. The extraction time, temperature, ionic strength of the solution and sampling of the headspace were the parameters studied. Reproducibility achieved values below 20% RSD, and standard addition was used for pesticides confirmation.

Industrial & Engineering Chemistry Research, 2006

An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichloroph... more An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichlorophenol (2, 4-DCP) oxidation using Fenton's reagent. This multivariable and multilevel approach allowed us to investigate the effects between the experimental ...

Journal of Chromatography A, 2002

Landfill leachates represent a serious environmental concern with regard to trace priority pollut... more Landfill leachates represent a serious environmental concern with regard to trace priority pollutants introduced into the aquatic environment. From the analytical point of view, they constitute complex matrices because of their high organic matter content and competition with the trace analytes in the extraction procedure. Although the use of SPME to extract chlorophenols in leachates has already been described in several publications, the limited number of chlorophenols restricts this analysis field of application. This paper presents a new analytical methodology to determine 13 chlorophenols and phenol by SPME-GC-MS in landfill leachates. The overall analysis was performed in 90 min and the detection limits range from 0.005 mg / l (pentachlorophenol) to 2.5 mg / l (phenol). Reproducibility, expressed by the coefficient of variation of repeated extractions at different concentration levels of the analytes, was on average inferior to 10%. Recovery, evaluated by standard addition to leachates, was 86.2% on average. Pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,4,6-tetrachlorophenol were the sole analytes detected at nanogram level in the landfill leachates analysed. 

Analytical and Bioanalytical Chemistry, 2006

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assiste... more A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p′-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005

The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups us... more The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid-liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073 mg kg(-1), a precision not exceeding 10.0% and an average recovery of 93% +/- 38.

Environmental Science & Technology, 1999

Pesticides belong to a chemical family that calls our attention because of its hazardous effects ... more Pesticides belong to a chemical family that calls our attention because of its hazardous effects in the environment. The organochlorine pesticides were strongly used in the past, but their persistency and bioaccumulation make them an actual problem. Common wastewater treatment methods, like activated carbon sorption, mean expensive investment and operating costs. Pine bark is a wood industry byproduct and has a high affinity with hydrophobic compounds because of its organic composition. The aim of this work is to test the capability of this material to remove organochlorine pesticides from water solutions. This capability was quantified by studying the best operating conditions for pine bark fixed bed mini-columns, the yield of removal from spiked water solutions, and the saturation parameters. The yield of removal from spiked organochlorine water solutions ranging from 1 to 10 µg/L, was 97% on average, for heptachlor, aldrin, endrin, dieldrin, DDD, DDT, and DDE. Lindane could not be efficiently adsorbed by this methodology (38% for yield of removal). Saturation studies, performed until 60.00 L of spiked solution/g of adsorbent was reached, did not reveal system rupture. When compared with activated carbon, pine bark displays analogous response, suggesting that for compounds with similar physicochemical characteristics pine bark will play a significant role.

Analytica Chimica Acta, 2006

As the performances of analytical instrumentation are being gradually enhanced, the limits of det... more As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens.

Journal of Chromatography A, 2000

Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as we... more Landfill leachates contain significant amounts of organic carbon, nitrogen and heavy metals as well as other specific trace organic compounds like organochlorine pesticides. In this study a simple and reliable methodology was improved to detect organochlorine pesticides in leachate samples by using a previous solid-phase microextraction procedure [with a 100 mm poly(dimethylsiloxane) fiber] and chromatographic analysis by GC-electron-capture detection. The extraction time, temperature, ionic strength of the solution and sampling of the headspace were the parameters studied. Reproducibility achieved values below 20% RSD, and standard addition was used for pesticides confirmation.

Industrial & Engineering Chemistry Research, 2006

An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichloroph... more An experimental design methodology has been drawn regarding the model contaminant 2, 4-dichlorophenol (2, 4-DCP) oxidation using Fenton's reagent. This multivariable and multilevel approach allowed us to investigate the effects between the experimental ...

Journal of Chromatography A, 2002

Landfill leachates represent a serious environmental concern with regard to trace priority pollut... more Landfill leachates represent a serious environmental concern with regard to trace priority pollutants introduced into the aquatic environment. From the analytical point of view, they constitute complex matrices because of their high organic matter content and competition with the trace analytes in the extraction procedure. Although the use of SPME to extract chlorophenols in leachates has already been described in several publications, the limited number of chlorophenols restricts this analysis field of application. This paper presents a new analytical methodology to determine 13 chlorophenols and phenol by SPME-GC-MS in landfill leachates. The overall analysis was performed in 90 min and the detection limits range from 0.005 mg / l (pentachlorophenol) to 2.5 mg / l (phenol). Reproducibility, expressed by the coefficient of variation of repeated extractions at different concentration levels of the analytes, was on average inferior to 10%. Recovery, evaluated by standard addition to leachates, was 86.2% on average. Pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,4,6-tetrachlorophenol were the sole analytes detected at nanogram level in the landfill leachates analysed. 

Analytical and Bioanalytical Chemistry, 2006

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assiste... more A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p′-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005

The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups us... more The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid-liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073 mg kg(-1), a precision not exceeding 10.0% and an average recovery of 93% +/- 38.

Environmental Science & Technology, 1999

Pesticides belong to a chemical family that calls our attention because of its hazardous effects ... more Pesticides belong to a chemical family that calls our attention because of its hazardous effects in the environment. The organochlorine pesticides were strongly used in the past, but their persistency and bioaccumulation make them an actual problem. Common wastewater treatment methods, like activated carbon sorption, mean expensive investment and operating costs. Pine bark is a wood industry byproduct and has a high affinity with hydrophobic compounds because of its organic composition. The aim of this work is to test the capability of this material to remove organochlorine pesticides from water solutions. This capability was quantified by studying the best operating conditions for pine bark fixed bed mini-columns, the yield of removal from spiked water solutions, and the saturation parameters. The yield of removal from spiked organochlorine water solutions ranging from 1 to 10 µg/L, was 97% on average, for heptachlor, aldrin, endrin, dieldrin, DDD, DDT, and DDE. Lindane could not be efficiently adsorbed by this methodology (38% for yield of removal). Saturation studies, performed until 60.00 L of spiked solution/g of adsorbent was reached, did not reveal system rupture. When compared with activated carbon, pine bark displays analogous response, suggesting that for compounds with similar physicochemical characteristics pine bark will play a significant role.

Journal of The American Chemical Society, 1989

subsequent loss o f t h e metal cation to the oxidant) isslow compared to the rate of the couplin... more subsequent loss o f t h e metal cation to the oxidant) isslow compared to the rate of the coupling reaction.

A arquitetura Gótica no Norte da França teve um lenta recepção, de forma gradual esta foi-se inst... more A arquitetura Gótica no Norte da França teve um lenta recepção, de forma gradual esta foi-se instalando, o que levou a crer que que o Gótico, era uma criação alemã.