Sara Cunha | Universidade do Porto (original) (raw)
Papers by Sara Cunha
Food Chemistry, 2003
Benzoic and sorbic acids are the most commonly used preservatives in foodstuffs. They are usually... more Benzoic and sorbic acids are the most commonly used preservatives in foodstuffs. They are usually analysed by RP-HPLC. However, in view of the complexity and diversity of foodstuffs composition, appropriate sample preparation procedures are required for reliable extraction of these preservatives from the matrices. Specific extraction procedures for analysis of jams, table olives, spreadable fats, sauces, fruit juices and wines
Food Chemistry, 2009
A reliable gas chromatographic mass spectrometric method has been validated for the determination... more A reliable gas chromatographic mass spectrometric method has been validated for the determination of trace levels (<10 lgL À1 ) of patulin in apple products and quince jam. The method was based on extraction of patulin with ethyl acetate-hexane, alkalinisation and silylation with N,O-bis-trimethylsilyltrifluoroacetamide with 1% of trimethylchloro-silane. The accurate determination of patulin was achieved by employing commercial 13 C 5-7 patulin labelled as an internal standard, which allowed compensating target analyte losses and enhancement or suppression matrix effects. Limits of detection and quantification of method using real samples were 0.4 and 1.6 lgkg À1 , respectively. Recoveries of patulin from samples spiked at 8-50 lgkg À1 levels ranged between 71% and 89%. The repeatability of measurements (expressed as relative standard deviation) was lower than 16%. The method was successfully applied to the determination of patulin in apple fruit and apple products including juice, cider and baby food, and also in quince fruit and quince jam. A new PCR system for the detection of Penicillium expansum in samples containing highly degraded DNA was developed which permitted the detection of the mould in 2/3 of the samples containing patulin, including juices and jams.
Food Chemistry, 2006
This paper describes an HPLC procedure for the determination of triacylglycerol (TAG) profile in ... more This paper describes an HPLC procedure for the determination of triacylglycerol (TAG) profile in vegetable oils. Sample preparation consisted in the dissolution of the oils in acetone and filtration. The chromatographic separation was achieved using a Kromasil 100 C 18 column (at 25°C) and gradient elution with acetone and acetonitrile. Elution was performed at a solvent flow rate of 1 mL/min. Detection was accomplished with an evaporative light scattering detector (ELSD), with the following settings: evaporator temperature 40°C, air pressure 3.5 bars and photomultiplier sensitivity 6. TAG peaks were identified taking into account the logarithms of a in relation to homogeneous TAG (relative retention times to triolein) and their quantification was based on the internal normalization method.
Food Control, 2004
The present work aimed to study the quality of 18 brands of quince jam commercially available in ... more The present work aimed to study the quality of 18 brands of quince jam commercially available in the Portuguese market. Microbiological analyses included enumeration of yeasts and molds. Sugar content was determined by refractometry (°Brix), while the quantification of the preservatives benzoic and sorbic acids as well as other organic acids (citric, malic, lactic, quinic, succinic) was carried out by HPLC/UV. For sensory analysis, a panel of 10 assessors with slight training was used following the quantitative descriptive analysis methodology.
Journal of Chromatography A, 2009
A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination o... more A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 12 isoflavones in Trifolium pratense L. Dried leaf samples were blended with C 18 , placed in small columns and isoflavones extracted with dichloromethane-methanol. Analyses were performed by high performance liquid chromatography with diode array detection (HPLC-DAD) with 2-methoxyflavone as internal standard. Several dispersants, eluents and clean-up steps were tested during the optimization of the process in order to obtain the best selectivity and yields. Mean recoveries ranged from 70% to 119%, with relative standard deviations <18%. The limits of detection were between 0.006 mg/l for biochanin A and 0.108 mg/l for daidzin. The performance of the optimized method in real samples was compared with a conventional method based in solid-liquid extraction (SLE).
Journal of Chromatography A, 2007
Erratum to "Quantification of free and esterified sterols in Portuguese olive oils by solid-phase... more Erratum to "Quantification of free and esterified sterols in Portuguese olive oils by solid-phase extraction and gas chromatography-mass spectrometry"
Talanta, 2007
An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spe... more An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spectrometry (GC/MS) was developed for determination of phosmet residues and its metabolites (phosmet-oxon, phthalimide, N-hydroxymethylphthalimide, and phthalic acid) in olive fruits. After testing different sorbents and eluents for MSPD extraction, C 18 and acetonitrile were found to be the most appropriate for clean-up of the samples, in terms of yields and efficient removal of interfering compounds. All analytes were determined in selective ion monitoring (SIM) mode following a derivatization step with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TMCS), except for phosmet and phosmet-oxon which were analyzed directly. The method showed suitable linearity (correlation coefficients higher than 0.8919 for all the compounds) and suitable sensitivity (limit of detection lower than 0.06 mg/kg). It was successfully applied in the analysis of olive fruits collected during the preharvest interval and olive oil. Phosmet residues found in all samples were lower than the maximum residue limits established by legislation (2 mg/kg).
Journal of Chromatography A, 2009
A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensiona... more A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensional gas chromatography-mass spectrometry (MD-GC/MS) using dispersive liquid-liquid microextraction (DLLME) was developed and optimized. Several parameters of the extraction procedure such as type and volume of extraction solvent, type and volume of dispersive solvent and salt addition were evaluated to achieve the highest yield and to attain the lowest detection limits. The DLLME procedure optimized consists in the formation of a cloudy solution promoted by the fast addition to the sample (5 ml) of a mixture of carbon tetrachloride (extraction solvent, 100 l) and acetone (dispersive solvent, 400 l). The tiny droplets formed and dispersed among the aqueous sample solution are further joined and sedimented (85 l) in the bottom of the conical test tube by centrifugation. Once extracted, all the 24 pesticides were directly injected and separated by a dual GC column system, comprising a short wide-bore DB-5 capillary column with low film thickness connected by a Deans switch system to a second chromatographic narrower column, with identical stationary phase. The instrumental setting used, in combination with carefully optimized operational fast GC and MS parameters, markedly decreased the retention times of the targeted analytes. The total chromatographic run was 8 min. Mean recoveries for apple juice spiked at three concentrations ranged from 60% to 105% and the intra-repeatability ranged from 1% to 21%. The limits of detection of the 24 pesticides ranged from 0.06 to 2.20 g/L. In 2 of a total of 28 analysed samples were found residues of captan, although at levels below the maximum limit legal established.
Food Chemistry, 2007
This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, st... more This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, sterols and fatty acids) as a tool to discriminate three varietal olive oils (Cvs. Cobrançosa, Madural and Verdeal Transmontana), which are permitted cultivars for the production of ''Trás-os-Montes olive oil'', a Portuguese protected designation of origin (PDO) product. The olives were collected during the year crop 2000/2001 from the same orchard, in order to eliminate the geographical and climatic influences. Lots with different maturation indices were prepared to allow the evaluation of the ripening stage on the characteristics of varietal olive oils produced from each cultivar. Statistical methods such as multivariate analysis of variance (MANOVA), principal components analysis (PCA) and cluster analysis were used to evaluate significant differences on the studied parameters. Regarding the results, the three cultivars were clearly discriminated.
Food Chemistry, 2007
This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, st... more This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, sterols and fatty acids) as a tool to discriminate three varietal olive oils (Cvs. Cobrançosa, Madural and Verdeal Transmontana), which are permitted cultivars for the production of ''Trás-os-Montes olive oil'', a Portuguese protected designation of origin (PDO) product. The olives were collected during the year crop 2000/2001 from the same orchard, in order to eliminate the geographical and climatic influences. Lots with different maturation indices were prepared to allow the evaluation of the ripening stage on the characteristics of varietal olive oils produced from each cultivar. Statistical methods such as multivariate analysis of variance (MANOVA), principal components analysis (PCA) and cluster analysis were used to evaluate significant differences on the studied parameters. Regarding the results, the three cultivars were clearly discriminated.
Food Control
Dispersive liquid-liquid microextraction based on solidification of floating organic droplet Poly... more Dispersive liquid-liquid microextraction based on solidification of floating organic droplet Polycyclic aromatic hydrocarbons Liquid chromatography 1-Dodecanol a b s t
Journal of Agricultural and Food Chemistry, 2006
The oil of several hazelnut (Corylus avellana L.) samples was extracted and evaluated for their t... more The oil of several hazelnut (Corylus avellana L.) samples was extracted and evaluated for their triacylglycerol (TAG) composition. Trials were conducted in two Portuguese localities (Vila Real and Felgueiras) during three consecutive years and involved a total of 19 cultivars. The samples were analyzed by reversed-phase high-performance liquid chromatography with evaporative light-scattering detection. Sample preparation was fast and simple, consisting only of the dissolution of the oil in acetone, homogenization, and filtration, allowing this technique to be suitable for routine analyses. All samples presented a similar qualitative profile composed of eleven compounds: LLL, OLL, PLL, OOL, POL, PPL, OOO, POO, PPO, SOO and PSO (P, palmitoyl; S, stearoyl; O, oleoyl; and L, linoleoyl). The main components were OOO, LOO, and POO, reflecting the high content of oleic acid in hazelnut oils. A total of 79 different samples were studied, and the obtained data were statistically analyzed. Significant differences were verified in canonical variate plots when cultivars were grouped by country of origin. In general, the American cultivars were richer in TAGs with saturated fatty acids moieties, and the group of French, German, and English cultivars was richer in TAGs containing linoleic acid moieties. Differences were also significant when cultivars were grouped by year of production, showing that besides genetic factors, the TAG composition can be influenced by environmental factors.
Journal of Separation Science, 2007
This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) meth... more This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and cleanup of 16 pesticide residues of interest in olives and olive oil. These products contain a high lipid content, which can adversely affect pesticide recoveries and harm traditional chromatographic systems. For extraction, the main factors (oil and water content) were studied and optimized in experiments to maximize pesticide recoveries. Dispersive SPE with different sorbents was also investigated to minimize matrix coextractives and interferences. For analysis, a new automated DSI device was tested in GC-MS to avoid nonvolatile coextractives from contaminating the instrument. LC-MS/MS with positive ESI was used for those pesticides that were difficult to detect by GC-MS. The final method was validated for olives in terms of recoveries, repeatabilities, and reproducibilities using both detection techniques. The results demonstrated that the method achieved acceptable quantitative recoveries of 70–109% with RSDs <20% for DSI-GC-MS and 88–130% with RSDs <10% for LC-MS/MS, and LOQ at or below the regulatory maximum residue limits for the pesticides were achieved.
Ciencia Y Tecnologia Alimentaria, 2002
Ciencia y Tecnología Alimentaria Sociedad Mexicana de Nutrición y Tecnología de Alimentos somenta... more Ciencia y Tecnología Alimentaria Sociedad Mexicana de Nutrición y Tecnología de Alimentos somenta@gmail.com ISSN (Versión impresa): 1135-8122 ISSN (Versión en línea): 1696-2443 MÉXICO 2002 SC Cunha / JO Fernandes / MA Faria / IMPLVO Ferreira / MA Ferreira ...
Food Additives & Contaminants: Part A, 2011
The purpose of this study was to establish a reliable, cost-effective, fast and simple method to ... more The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was <15%. The limits of detection (LOD) in canned beverages were 5.0 and 2.0 ng l(-1) for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0 ng l(-1), respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0 ng l-1 for BPA and BPB, respectively, whereas LOQ in powdered infant formula were 200.0 and 100.0 ng l(-1), respectively. BPA was detected in 21 of 30 canned beverages (ranging from 0.03 to 4.70 µg l(-1)) and in two of seven powdered infant formula samples (0.23 and 0.40 µg l(-1)) collected in Portugal. BPB was only detected in canned beverages being positive in 15 of 30 samples analysed (ranging from 0.06 to 0.17 µg l(-1)). This is the first report about the presence of BPA and BPB in canned beverages and powdered infant formula in the Portuguese market.
Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2006
An improved GC-MS method to determine acrylamide (AA) in coffee and coffee 10 products was develo... more An improved GC-MS method to determine acrylamide (AA) in coffee and coffee 10 products was developed. The method was based in two main purification steps, the first 11 one with ethanol and Carrez solutions in order to precipitate polysaccharides and 12 proteins, respectively, and the second with a layered solid phase extraction (SPE) 13 column which proved to be efficient to eliminate the main chromatographic 14 interferences. The method is applicable to a wide range of coffee products. Twenty six 15 samples of different coffee products were analysed. The levels of AA were in the range 16 of 11.4 -36.2 µg L -1 for "espresso coffee" and 200.8 -229.4 µg L -1 for coffee blends 17 with cereals. The results indicated that the presence of cereals significantly increased 18 the levels of AA. 19 20
Journal of Liquid Chromatography & Related Technologies, 2001
Food Chemistry, 2003
Benzoic and sorbic acids are the most commonly used preservatives in foodstuffs. They are usually... more Benzoic and sorbic acids are the most commonly used preservatives in foodstuffs. They are usually analysed by RP-HPLC. However, in view of the complexity and diversity of foodstuffs composition, appropriate sample preparation procedures are required for reliable extraction of these preservatives from the matrices. Specific extraction procedures for analysis of jams, table olives, spreadable fats, sauces, fruit juices and wines
Food Chemistry, 2009
A reliable gas chromatographic mass spectrometric method has been validated for the determination... more A reliable gas chromatographic mass spectrometric method has been validated for the determination of trace levels (<10 lgL À1 ) of patulin in apple products and quince jam. The method was based on extraction of patulin with ethyl acetate-hexane, alkalinisation and silylation with N,O-bis-trimethylsilyltrifluoroacetamide with 1% of trimethylchloro-silane. The accurate determination of patulin was achieved by employing commercial 13 C 5-7 patulin labelled as an internal standard, which allowed compensating target analyte losses and enhancement or suppression matrix effects. Limits of detection and quantification of method using real samples were 0.4 and 1.6 lgkg À1 , respectively. Recoveries of patulin from samples spiked at 8-50 lgkg À1 levels ranged between 71% and 89%. The repeatability of measurements (expressed as relative standard deviation) was lower than 16%. The method was successfully applied to the determination of patulin in apple fruit and apple products including juice, cider and baby food, and also in quince fruit and quince jam. A new PCR system for the detection of Penicillium expansum in samples containing highly degraded DNA was developed which permitted the detection of the mould in 2/3 of the samples containing patulin, including juices and jams.
Food Chemistry, 2006
This paper describes an HPLC procedure for the determination of triacylglycerol (TAG) profile in ... more This paper describes an HPLC procedure for the determination of triacylglycerol (TAG) profile in vegetable oils. Sample preparation consisted in the dissolution of the oils in acetone and filtration. The chromatographic separation was achieved using a Kromasil 100 C 18 column (at 25°C) and gradient elution with acetone and acetonitrile. Elution was performed at a solvent flow rate of 1 mL/min. Detection was accomplished with an evaporative light scattering detector (ELSD), with the following settings: evaporator temperature 40°C, air pressure 3.5 bars and photomultiplier sensitivity 6. TAG peaks were identified taking into account the logarithms of a in relation to homogeneous TAG (relative retention times to triolein) and their quantification was based on the internal normalization method.
Food Control, 2004
The present work aimed to study the quality of 18 brands of quince jam commercially available in ... more The present work aimed to study the quality of 18 brands of quince jam commercially available in the Portuguese market. Microbiological analyses included enumeration of yeasts and molds. Sugar content was determined by refractometry (°Brix), while the quantification of the preservatives benzoic and sorbic acids as well as other organic acids (citric, malic, lactic, quinic, succinic) was carried out by HPLC/UV. For sensory analysis, a panel of 10 assessors with slight training was used following the quantitative descriptive analysis methodology.
Journal of Chromatography A, 2009
A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination o... more A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 12 isoflavones in Trifolium pratense L. Dried leaf samples were blended with C 18 , placed in small columns and isoflavones extracted with dichloromethane-methanol. Analyses were performed by high performance liquid chromatography with diode array detection (HPLC-DAD) with 2-methoxyflavone as internal standard. Several dispersants, eluents and clean-up steps were tested during the optimization of the process in order to obtain the best selectivity and yields. Mean recoveries ranged from 70% to 119%, with relative standard deviations <18%. The limits of detection were between 0.006 mg/l for biochanin A and 0.108 mg/l for daidzin. The performance of the optimized method in real samples was compared with a conventional method based in solid-liquid extraction (SLE).
Journal of Chromatography A, 2007
Erratum to "Quantification of free and esterified sterols in Portuguese olive oils by solid-phase... more Erratum to "Quantification of free and esterified sterols in Portuguese olive oils by solid-phase extraction and gas chromatography-mass spectrometry"
Talanta, 2007
An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spe... more An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spectrometry (GC/MS) was developed for determination of phosmet residues and its metabolites (phosmet-oxon, phthalimide, N-hydroxymethylphthalimide, and phthalic acid) in olive fruits. After testing different sorbents and eluents for MSPD extraction, C 18 and acetonitrile were found to be the most appropriate for clean-up of the samples, in terms of yields and efficient removal of interfering compounds. All analytes were determined in selective ion monitoring (SIM) mode following a derivatization step with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TMCS), except for phosmet and phosmet-oxon which were analyzed directly. The method showed suitable linearity (correlation coefficients higher than 0.8919 for all the compounds) and suitable sensitivity (limit of detection lower than 0.06 mg/kg). It was successfully applied in the analysis of olive fruits collected during the preharvest interval and olive oil. Phosmet residues found in all samples were lower than the maximum residue limits established by legislation (2 mg/kg).
Journal of Chromatography A, 2009
A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensiona... more A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensional gas chromatography-mass spectrometry (MD-GC/MS) using dispersive liquid-liquid microextraction (DLLME) was developed and optimized. Several parameters of the extraction procedure such as type and volume of extraction solvent, type and volume of dispersive solvent and salt addition were evaluated to achieve the highest yield and to attain the lowest detection limits. The DLLME procedure optimized consists in the formation of a cloudy solution promoted by the fast addition to the sample (5 ml) of a mixture of carbon tetrachloride (extraction solvent, 100 l) and acetone (dispersive solvent, 400 l). The tiny droplets formed and dispersed among the aqueous sample solution are further joined and sedimented (85 l) in the bottom of the conical test tube by centrifugation. Once extracted, all the 24 pesticides were directly injected and separated by a dual GC column system, comprising a short wide-bore DB-5 capillary column with low film thickness connected by a Deans switch system to a second chromatographic narrower column, with identical stationary phase. The instrumental setting used, in combination with carefully optimized operational fast GC and MS parameters, markedly decreased the retention times of the targeted analytes. The total chromatographic run was 8 min. Mean recoveries for apple juice spiked at three concentrations ranged from 60% to 105% and the intra-repeatability ranged from 1% to 21%. The limits of detection of the 24 pesticides ranged from 0.06 to 2.20 g/L. In 2 of a total of 28 analysed samples were found residues of captan, although at levels below the maximum limit legal established.
Food Chemistry, 2007
This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, st... more This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, sterols and fatty acids) as a tool to discriminate three varietal olive oils (Cvs. Cobrançosa, Madural and Verdeal Transmontana), which are permitted cultivars for the production of ''Trás-os-Montes olive oil'', a Portuguese protected designation of origin (PDO) product. The olives were collected during the year crop 2000/2001 from the same orchard, in order to eliminate the geographical and climatic influences. Lots with different maturation indices were prepared to allow the evaluation of the ripening stage on the characteristics of varietal olive oils produced from each cultivar. Statistical methods such as multivariate analysis of variance (MANOVA), principal components analysis (PCA) and cluster analysis were used to evaluate significant differences on the studied parameters. Regarding the results, the three cultivars were clearly discriminated.
Food Chemistry, 2007
This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, st... more This paper evaluates the usefulness of three chemical parameters (compositions on tocopherols, sterols and fatty acids) as a tool to discriminate three varietal olive oils (Cvs. Cobrançosa, Madural and Verdeal Transmontana), which are permitted cultivars for the production of ''Trás-os-Montes olive oil'', a Portuguese protected designation of origin (PDO) product. The olives were collected during the year crop 2000/2001 from the same orchard, in order to eliminate the geographical and climatic influences. Lots with different maturation indices were prepared to allow the evaluation of the ripening stage on the characteristics of varietal olive oils produced from each cultivar. Statistical methods such as multivariate analysis of variance (MANOVA), principal components analysis (PCA) and cluster analysis were used to evaluate significant differences on the studied parameters. Regarding the results, the three cultivars were clearly discriminated.
Food Control
Dispersive liquid-liquid microextraction based on solidification of floating organic droplet Poly... more Dispersive liquid-liquid microextraction based on solidification of floating organic droplet Polycyclic aromatic hydrocarbons Liquid chromatography 1-Dodecanol a b s t
Journal of Agricultural and Food Chemistry, 2006
The oil of several hazelnut (Corylus avellana L.) samples was extracted and evaluated for their t... more The oil of several hazelnut (Corylus avellana L.) samples was extracted and evaluated for their triacylglycerol (TAG) composition. Trials were conducted in two Portuguese localities (Vila Real and Felgueiras) during three consecutive years and involved a total of 19 cultivars. The samples were analyzed by reversed-phase high-performance liquid chromatography with evaporative light-scattering detection. Sample preparation was fast and simple, consisting only of the dissolution of the oil in acetone, homogenization, and filtration, allowing this technique to be suitable for routine analyses. All samples presented a similar qualitative profile composed of eleven compounds: LLL, OLL, PLL, OOL, POL, PPL, OOO, POO, PPO, SOO and PSO (P, palmitoyl; S, stearoyl; O, oleoyl; and L, linoleoyl). The main components were OOO, LOO, and POO, reflecting the high content of oleic acid in hazelnut oils. A total of 79 different samples were studied, and the obtained data were statistically analyzed. Significant differences were verified in canonical variate plots when cultivars were grouped by country of origin. In general, the American cultivars were richer in TAGs with saturated fatty acids moieties, and the group of French, German, and English cultivars was richer in TAGs containing linoleic acid moieties. Differences were also significant when cultivars were grouped by year of production, showing that besides genetic factors, the TAG composition can be influenced by environmental factors.
Journal of Separation Science, 2007
This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) meth... more This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and cleanup of 16 pesticide residues of interest in olives and olive oil. These products contain a high lipid content, which can adversely affect pesticide recoveries and harm traditional chromatographic systems. For extraction, the main factors (oil and water content) were studied and optimized in experiments to maximize pesticide recoveries. Dispersive SPE with different sorbents was also investigated to minimize matrix coextractives and interferences. For analysis, a new automated DSI device was tested in GC-MS to avoid nonvolatile coextractives from contaminating the instrument. LC-MS/MS with positive ESI was used for those pesticides that were difficult to detect by GC-MS. The final method was validated for olives in terms of recoveries, repeatabilities, and reproducibilities using both detection techniques. The results demonstrated that the method achieved acceptable quantitative recoveries of 70–109% with RSDs <20% for DSI-GC-MS and 88–130% with RSDs <10% for LC-MS/MS, and LOQ at or below the regulatory maximum residue limits for the pesticides were achieved.
Ciencia Y Tecnologia Alimentaria, 2002
Ciencia y Tecnología Alimentaria Sociedad Mexicana de Nutrición y Tecnología de Alimentos somenta... more Ciencia y Tecnología Alimentaria Sociedad Mexicana de Nutrición y Tecnología de Alimentos somenta@gmail.com ISSN (Versión impresa): 1135-8122 ISSN (Versión en línea): 1696-2443 MÉXICO 2002 SC Cunha / JO Fernandes / MA Faria / IMPLVO Ferreira / MA Ferreira ...
Food Additives & Contaminants: Part A, 2011
The purpose of this study was to establish a reliable, cost-effective, fast and simple method to ... more The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was <15%. The limits of detection (LOD) in canned beverages were 5.0 and 2.0 ng l(-1) for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0 ng l(-1), respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0 ng l-1 for BPA and BPB, respectively, whereas LOQ in powdered infant formula were 200.0 and 100.0 ng l(-1), respectively. BPA was detected in 21 of 30 canned beverages (ranging from 0.03 to 4.70 µg l(-1)) and in two of seven powdered infant formula samples (0.23 and 0.40 µg l(-1)) collected in Portugal. BPB was only detected in canned beverages being positive in 15 of 30 samples analysed (ranging from 0.06 to 0.17 µg l(-1)). This is the first report about the presence of BPA and BPB in canned beverages and powdered infant formula in the Portuguese market.
Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2006
An improved GC-MS method to determine acrylamide (AA) in coffee and coffee 10 products was develo... more An improved GC-MS method to determine acrylamide (AA) in coffee and coffee 10 products was developed. The method was based in two main purification steps, the first 11 one with ethanol and Carrez solutions in order to precipitate polysaccharides and 12 proteins, respectively, and the second with a layered solid phase extraction (SPE) 13 column which proved to be efficient to eliminate the main chromatographic 14 interferences. The method is applicable to a wide range of coffee products. Twenty six 15 samples of different coffee products were analysed. The levels of AA were in the range 16 of 11.4 -36.2 µg L -1 for "espresso coffee" and 200.8 -229.4 µg L -1 for coffee blends 17 with cereals. The results indicated that the presence of cereals significantly increased 18 the levels of AA. 19 20
Journal of Liquid Chromatography & Related Technologies, 2001