Sergio Armenta - Profile on Academia.edu (original) (raw)
Papers by Sergio Armenta
Analytical and Bioanalytical Chemistry, Jul 16, 2009
A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,... more A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,6bisphosphatase with fructose 1,6-bisphosphate has been proposed. The whole procedure was done in an automated way operating in the stopped flow mode by incorporating a temperature-controlled flow cell in a sequential injection manifold. Fourier transform infrared difference spectra were evaluated for kinetic parameters, like the Michaelis-Menten constant (K M ) of the enzyme and V max of the reaction. The obtained K M of the reaction was 14±3 g L −1 (41 μM). Furthermore, inhibition by adenosine 5′-monophosphate (AMP) was evaluated, and the K M App value was determined to be 12±2 g L −1 (35 μM) for 7.5 and 15 μM AMP, respectively, with V max decreasing from 0.1±0.03 to 0.05± 0.01 g L −1 min −1 . Therefore, AMP exerted a non-competitive inhibition.
Analytical Chemistry, Apr 16, 2012
The qualitative and quantitative capabilities of ion mobility spectrometry (IMS) as a comprehensi... more The qualitative and quantitative capabilities of ion mobility spectrometry (IMS) as a comprehensive and powerful tool in workplace air monitoring have been demonstrated on the example of a Spanish pharmaceutical company. The developed IMS based procedure is capable of detecting and determining in air samples the active pharmaceutical ingredients (APIs) manipulated and/or produced in this pharmaceutical industry. Sensitivity, in the ng− pg range, selectivity, possibly to provide results in near real time, and reduction of analysis costs are the most important properties that ratify IMS as a serious alternative in occupational exposure assessment. The possibility of false positives by drift time interferences and false negatives by competitive ionization and also desorption process interferences has been deeply evaluated. Moreover, chemometric strategies based on self-modeling curve resolution (SMCR) have been applied to obtain qualitative and quantitative individual component information from overlapped peaks. The IMS procedure has been successfully applied to evaluate the concentration of APIs (nimesulide, dexketoprofen, deflazacort) handled by the pharmaceutical company employees in the making of tablets and granulates, and control measures have been suggested in accordance.
Non-chromatographic speciation
Trac, 2010
We evaluate the main strategies for screening trace-element species in most types of sample to es... more We evaluate the main strategies for screening trace-element species in most types of sample to establish their strengths and weaknesses, as they offer fast, sensitive and cheaper alternatives to classical methods involving chromatography. We consider the principles of non-chromatographic speciation analysis, based on the different behaviors of chemical species before measurement by atomic and molecular spectrometry and electroanalytical methods, so as to give an update on the literature in this field of research.
Analytica Chimica Acta, Mar 1, 2011
A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile di... more A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile dithiocarbamate compounds has been developed for determination of pesticide residues in foodstuff at low ppm levels. The method involves a selective reaction combined with liquid phase microextraction (LPME) and transmission infrared measurements. The use of a home made transmission cell improved the detection limits (LOD) compared to the use of attenuated total reflectance measurements by a factor of approximately 80. Using the most appropriate experimental conditions for the CS 2 generation and LPME preconcentration, the precision of the methodology, expressed as the relative standard deviation (RSD), was of the order of 3.1% and the absolute LOD was 0.3 g dithiocarbamate, which corresponds to 60-120 g kg −1 , for a sample mass ranging from 2.5 to 5 g. The usefulness of the methodology has been evidenced by the determination of mancozeb residues in strawberries, lettuce and corn samples at concentrations between 1 and 5 mg kg −1 , where the VP-LPME IR provided results comparable with those obtained by a head space gas chromatography mass spectrometry reference procedure.
Searching the Most Appropriate Sample Pretreatment for the Elemental Analysis of Wines by Inductively Coupled Plasma-Based Techniques
J Agr Food Chem, 2008
Different sample preparation methods were evaluated for the simultaneous multielement analysis of... more Different sample preparation methods were evaluated for the simultaneous multielement analysis of wine samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Microwave-assisted digestion in closed vessel, thermal digestion in open reactor, and direct sample dilution were considered for the determination of Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, and Bi in 12 samples of red wine from Valencia and Utiel-Requena protected designation of origin. ICP-MS allows the determination of 17 elements in most of the samples, and using ICP-OES, a maximum of 15 elements were determined. On comparing the sample pretreatment methodology, it can be concluded that the three assayed procedures provide comparable results for the concentration of Li, Na, Mg, Al, K, Ca, Mn, Fe, Zn, and Sr by ICP-OES. Furthermore, ICP-MS data found for Cu, Pb, and Ba were comparable. Digestion treatment provides comparable values using both total decomposition in open system and microwave-assisted treatment for Cu by ICP-OES and for Cr, Ni, and Zn by ICP-MS. Open vessel total digestion provides excess values for Cr, Mn, Fe, and Zn by ICP-OES and defect values for Se. However, direct measurement of diluted wine samples provided uncomparable results with the digestion treatment for Mn, Cu, Pb, Zn, Ba, and Bi by ICP-OES and for Mg, Cr, Fe, Ni, and Zn by ICP-MS. Therefore, it can be concluded that microwave-assisted digestion is the pretreatment procedure of choice for elemental analysis of wine by ICP-based techniques.
Adulteration detection of argan oil by inductively coupled plasma optical emission spectrometry
Food Chemistry, Aug 1, 2010
The singularity of the trace element profile of argan oil has been demonstrated by means of induc... more The singularity of the trace element profile of argan oil has been demonstrated by means of inductively coupled plasma optical emission measurement in combination with different chemometric approaches. The ability of multivariate analysis methods; such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification trees using Chi-squared Automatic Interaction Detector (CHAID) and discriminant analysis (DA) to achieve edible oils
Talanta, Feb 15, 2008
The elemental composition of seasoning products, like spices garlic and onion, has been reviewed ... more The elemental composition of seasoning products, like spices garlic and onion, has been reviewed paying special attention to methods proposed in the literature to determine specific elements or as much as possible components of these products which are widespread used in food preservation or food flavouring and can contribute to the intake of both, essential and toxic elements. Sample treatment and metal speciation aspects have been critically revised concerning onion, garlic and pepper (the most commonly studied products).
Hydrodistillation�liquid-phase microextraction for infrared analysis of food
Analytical and Bioanalytical Chemistry, Jul 28, 2010
A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successf... more A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successfully developed to improve sensitivity and selectivity in attenuated total reflection (ATR) infrared determination of semivolatile organic compounds from high water content plant and food matrices contributing to solve extraction efficiency drawbacks. The HD sampling facilitates the extraction of the semivolatile analytes from the sample matrix compared to headspace sampling, while the liquid-phase microextraction using a water immiscible solvent allows analyte preconcentration prior to ATR analysis. Experimental conditions regarding temperature and time of extraction, water effect and number of consecutive extractions have been deeply studied. The qualitative and quantitative capability of the developed methodology has been evaluated through the identification of the main semivolatile substances in plant and food matrices like spices and citrus peels and the effect of different drying treatments on the volatile composition of rosemary samples was studied through the quantification of camphor and eucalyptol.
Geographical traceability of �Arr�s de Valencia� rice grain based on mineral element composition
Food Chem, 2011
The geographical traceability of rice grain samples involves the use of analytical methodologies ... more The geographical traceability of rice grain samples involves the use of analytical methodologies that allow their differentiation on the basis of the rice composition, thus confirming their authenticity. In this paper, trace element determination of rice samples by inductively coupled plasma optical emission spectroscopy (ICP-OES) has been addressed to achieve a complete geographical origin classification. Samples (107) from Spain including Valencia, Tarragona, Murcia and Extremadura, Japan, Brazil and India were employed as training set whereas the validation set was formed by 46 samples of the aforementioned geographical origins. Data were processed by linear discriminant analysis (LDA), using as analytical variable the concentration of 32 elements (Al, As, Ba, Bi, Cd, Ca, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Mo, Ni, K, Se, Na, Sr, Tl, Ti, Zn, La, Ce, Pr, Nd, Sm, Eu, Ho, Er and Yb), enabling a 91.30% of correct classification for the validation set.► Trace element composition determined by inductively coupled plasma optical emission spectroscopy has been addressed to achieve a complete geographical origin classification of rice samples. ► Data processed by linear discriminant analysis (LDA) enabled a 91.30% of prediction capability. ► Lanthanides, Cd and Co have been identified as the most influent indicators of the geographical origin of rice samples due to their different concentrations in soils and their effective uptake by plants.
Trace elemental composition of curry by inductively coupled plasma optical emission spectrometry (ICP-OES)
Food Additives and Contaminants Part B Surveillance, Dec 1, 2008
A methodology based on inductively coupled plasma optical emission spectrometry (ICP-OES) after m... more A methodology based on inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted acid digestion was developed to determine the content of traces elements in curry samples from the Spanish market. The methodology was validated in terms of accuracy by the analysis of citrus and tomato leaf reference materials achieving comparable results with the certified values. The trace metal content of curry samples was compared with data available from previously published reports concerning Indian samples, especially in terms of heavy metal composition, in order to guarantee the quality of the commercially available spices in the European countries. Values found for the analysis of arsenic, lead and cadmium were significantly lower than the maximum limit allowed by European Union statutory limits for heavy metals and lower than those obtained for Indian curry leaves reported by Indian research teams by using neutron activation and γ-ray analysis.
Determination of 3,4-methylenedioxypyrovalerone (MDPV) in oral and nasal fluids by ion mobility spectrometry
Analytical and bioanalytical chemistry, Jan 22, 2016
A fast and sensitive methodology has been developed for the evaluation of the 3,4-methylenedioxyp... more A fast and sensitive methodology has been developed for the evaluation of the 3,4-methylenedioxypyrovalerone (MDPV) consumed. Based on ion mobility spectrometry (IMS), MDPV was directly determined in nasal fluids with a limit of detection (LOD) in the order of 22 ng mL(-1), which corresponds to an absolute amount of 33 ng of MDPV per swab. MDPV was also determined after liquid-liquid microextraction (LLME) in oral fluids to avoid matrix effects, obtaining a LOD value of 4.4 ng mL(-1) in oral fluid samples. The IMS spectrum for MDPV exhibited a peak with K 0 = 1.210 ± 0.005 cm(2)V(-1) s(-1) at a drift time of 14.62 ms, the total analysis time being 4.5 min per oral fluid and 1.5 min per nasal fluid sample. Samples must be analyzed within 24 h following collection and dissolution in 2-propanol, based on the complementary stability studies. Graphical Abstract IMS procedure for the analysis of MDPV in mucus and saliva.
Detection of tetrahydrocannabinol residues on hands by ion-mobility spectrometry (IMS). Correlation of IMS data with saliva analysis
Analytical and bioanalytical chemistry, Jan 14, 2015
Ion-mobility spectroscopy (IMS) was evaluated as a high-throughput, cheap, and efficient analytic... more Ion-mobility spectroscopy (IMS) was evaluated as a high-throughput, cheap, and efficient analytical tool for detecting residues of tetrahydrocannabinol (THC) on hands. Regarding the usefulness of hand residues as potential samples for determining THC handling and abuse, we studied the correlation between data obtained from cannabis consumers who were classified as positive after saliva analysis and from those who were classified as positive on the basis of the information from hand-residue analysis. Sampling consisted of wiping the hands with borosilicate glass microfiber filters and introducing these directly into the IMS after thermal desorption. The possibility of false positive responses, resulting from the presence of other compounds with a similar drift time to THC, was evaluated and minimised by applying the truncated negative second-derivative algorithm. The possibility of false negative responses, mainly caused by competitive ionisation resulting from nicotine, was also stu...
Importance of Incorporating a Waste Detoxification Step in Analytical Methodologies
Anal. Methods, 2015
ABSTRACT The introduction of a waste detoxification step in the analytical process has been highl... more ABSTRACT The introduction of a waste detoxification step in the analytical process has been highlighted by using, as example, the determination of copper in pesticide formulations by electrogravimetry, flame atomic absorption spectroscopy (FAAS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). This quantitatively study evidenced, the improvement of the aforementioned analytical methods, from a green perspective, after addition of electrodeposition or neutralization steps to the analytical process. Based on that, the application of the eco-scale and the green certificate to the evaluation of these methodologies allows to move from B and C classes to A class of method.
Mineral content of seasonings, salt and vinegar
de la Guardia/Handbook of Mineral Elements in Food, 2015
Vibrational spectroscopy has become one of the key techniques for the structural recognition of m... more Vibrational spectroscopy has become one of the key techniques for the structural recognition of molecular systems and measuring their interactions. Its spectral range, corresponding to vibrational transitions, leads to knowledge of the functional groups of the analyzed systems. Since the discovery of infrared radiation, two centuries ago, then Raman scattering a century later, these techniques have undergone extraordinary breakthrough to a variety of applications on small molecules and on macromolecules alike. Due to recent wide applications, we have encouraged our peers to contribute either original research or review articles that will recapitulate the continuing advancement to interpret molecular and even material structure using vibrational spectroscopy mainly infrared absorption.
Detection and characterization of emerging psychoactive substances by ion mobility spectrometry
Drug Testing and Analysis, 2014
Rapid detection and identification of novel psychoactive substances (NPS) continues to present si... more Rapid detection and identification of novel psychoactive substances (NPS) continues to present significant analytical challenges to forensic and analytical chemists. Ion mobility spectrometry (IMS) has been traditionally considered as the analytical technique of choice to detect illicit drugs in security points in airports, borderlines and customs. Databases of the reduced mobility (K0 ) values of illicit drugs are available in the scientific literature and they should be completed with data of emerging designer drugs. In this paper, we have evaluated the effect of different measurement conditions and determined the K0 values of an important number of NPS including different families; such as phenethylamines, cathinones, synthetic cannabinoids and tryptamines among others to be incorporated to the existing data to provide a rapid detection and identification of this emerging threat. Copyright © 2014 John Wiley & Sons, Ltd.
Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid–liquid extraction
Journal of Chromatography A, 2015
We developed and evaluated two different strategies for determining abuse drugs based on (i) the ... more We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid-liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160μgL(-1), requires adding 0.2M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spectroscopy after LLME provides an LOD of 11μgL(-1) with the former technique and 800μgL(-1) with the latter, in addition to a limit of confirmation (LOC) of 1.5mgL(-1). Using IMS after thermal desorption simplifies the operational procedure, and using it jointly with IR spectroscopy after LLME allows double confirmation of MDMA abuse with two techniques based on different principles (viz., IMS drift times and IR spectra). Also, it affords on-site analyses, albeit at a lower throughput.
Talanta, 2014
An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocai... more An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 735 ng m À 3 of a normal day to 10,000 ng m À 3 during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the evaluation of the health effects of continuous exposition to very small doses of cocaine. Cocaine was also found in almost all the analyzed sample surfaces and also was found in nasal mucus of the police officers that were present during the manipulation of cocaine seizures without using a face mask. In summary, cocaine concentrations could present a health hazard to the employees and therefore warrants remediation and some modifications of the manipulation operations have been proposed.
Non-chromatographic speciation
TrAC Trends in Analytical Chemistry, 2010
... Absence of gradient and Nernstian equilibrium stripping (AGNES) is a new electrochemical tech... more ... Absence of gradient and Nernstian equilibrium stripping (AGNES) is a new electrochemical technique specifically designed for determination of the concentration of free metal ions [M]. It can be an alternative to other existing techniques, especially for those metal ions (eg, Zn ...
Trace-element composition and stable-isotope ratio for discrimination of foods with Protected Designation of Origin
TrAC Trends in Analytical Chemistry, 2009
ABSTRACT We review the literature on authentication of foods with Protected Designation of Origin... more ABSTRACT We review the literature on authentication of foods with Protected Designation of Origin (PDO) from their trace-element composition or stable-isotope ratios in order to evaluate the state of the art of this field and to identify the main parameters of analytical techniques and chemometric-data treatments that permit accurate discrimination of samples of different geographical origins and with different characteristics.
Analytical and Bioanalytical Chemistry, Jul 16, 2009
A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,... more A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,6bisphosphatase with fructose 1,6-bisphosphate has been proposed. The whole procedure was done in an automated way operating in the stopped flow mode by incorporating a temperature-controlled flow cell in a sequential injection manifold. Fourier transform infrared difference spectra were evaluated for kinetic parameters, like the Michaelis-Menten constant (K M ) of the enzyme and V max of the reaction. The obtained K M of the reaction was 14±3 g L −1 (41 μM). Furthermore, inhibition by adenosine 5′-monophosphate (AMP) was evaluated, and the K M App value was determined to be 12±2 g L −1 (35 μM) for 7.5 and 15 μM AMP, respectively, with V max decreasing from 0.1±0.03 to 0.05± 0.01 g L −1 min −1 . Therefore, AMP exerted a non-competitive inhibition.
Analytical Chemistry, Apr 16, 2012
The qualitative and quantitative capabilities of ion mobility spectrometry (IMS) as a comprehensi... more The qualitative and quantitative capabilities of ion mobility spectrometry (IMS) as a comprehensive and powerful tool in workplace air monitoring have been demonstrated on the example of a Spanish pharmaceutical company. The developed IMS based procedure is capable of detecting and determining in air samples the active pharmaceutical ingredients (APIs) manipulated and/or produced in this pharmaceutical industry. Sensitivity, in the ng− pg range, selectivity, possibly to provide results in near real time, and reduction of analysis costs are the most important properties that ratify IMS as a serious alternative in occupational exposure assessment. The possibility of false positives by drift time interferences and false negatives by competitive ionization and also desorption process interferences has been deeply evaluated. Moreover, chemometric strategies based on self-modeling curve resolution (SMCR) have been applied to obtain qualitative and quantitative individual component information from overlapped peaks. The IMS procedure has been successfully applied to evaluate the concentration of APIs (nimesulide, dexketoprofen, deflazacort) handled by the pharmaceutical company employees in the making of tablets and granulates, and control measures have been suggested in accordance.
Non-chromatographic speciation
Trac, 2010
We evaluate the main strategies for screening trace-element species in most types of sample to es... more We evaluate the main strategies for screening trace-element species in most types of sample to establish their strengths and weaknesses, as they offer fast, sensitive and cheaper alternatives to classical methods involving chromatography. We consider the principles of non-chromatographic speciation analysis, based on the different behaviors of chemical species before measurement by atomic and molecular spectrometry and electroanalytical methods, so as to give an update on the literature in this field of research.
Analytica Chimica Acta, Mar 1, 2011
A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile di... more A methodology based on the vapour phase (VP) generation of carbon disulphide from non-volatile dithiocarbamate compounds has been developed for determination of pesticide residues in foodstuff at low ppm levels. The method involves a selective reaction combined with liquid phase microextraction (LPME) and transmission infrared measurements. The use of a home made transmission cell improved the detection limits (LOD) compared to the use of attenuated total reflectance measurements by a factor of approximately 80. Using the most appropriate experimental conditions for the CS 2 generation and LPME preconcentration, the precision of the methodology, expressed as the relative standard deviation (RSD), was of the order of 3.1% and the absolute LOD was 0.3 g dithiocarbamate, which corresponds to 60-120 g kg −1 , for a sample mass ranging from 2.5 to 5 g. The usefulness of the methodology has been evidenced by the determination of mancozeb residues in strawberries, lettuce and corn samples at concentrations between 1 and 5 mg kg −1 , where the VP-LPME IR provided results comparable with those obtained by a head space gas chromatography mass spectrometry reference procedure.
Searching the Most Appropriate Sample Pretreatment for the Elemental Analysis of Wines by Inductively Coupled Plasma-Based Techniques
J Agr Food Chem, 2008
Different sample preparation methods were evaluated for the simultaneous multielement analysis of... more Different sample preparation methods were evaluated for the simultaneous multielement analysis of wine samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Microwave-assisted digestion in closed vessel, thermal digestion in open reactor, and direct sample dilution were considered for the determination of Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, and Bi in 12 samples of red wine from Valencia and Utiel-Requena protected designation of origin. ICP-MS allows the determination of 17 elements in most of the samples, and using ICP-OES, a maximum of 15 elements were determined. On comparing the sample pretreatment methodology, it can be concluded that the three assayed procedures provide comparable results for the concentration of Li, Na, Mg, Al, K, Ca, Mn, Fe, Zn, and Sr by ICP-OES. Furthermore, ICP-MS data found for Cu, Pb, and Ba were comparable. Digestion treatment provides comparable values using both total decomposition in open system and microwave-assisted treatment for Cu by ICP-OES and for Cr, Ni, and Zn by ICP-MS. Open vessel total digestion provides excess values for Cr, Mn, Fe, and Zn by ICP-OES and defect values for Se. However, direct measurement of diluted wine samples provided uncomparable results with the digestion treatment for Mn, Cu, Pb, Zn, Ba, and Bi by ICP-OES and for Mg, Cr, Fe, Ni, and Zn by ICP-MS. Therefore, it can be concluded that microwave-assisted digestion is the pretreatment procedure of choice for elemental analysis of wine by ICP-based techniques.
Adulteration detection of argan oil by inductively coupled plasma optical emission spectrometry
Food Chemistry, Aug 1, 2010
The singularity of the trace element profile of argan oil has been demonstrated by means of induc... more The singularity of the trace element profile of argan oil has been demonstrated by means of inductively coupled plasma optical emission measurement in combination with different chemometric approaches. The ability of multivariate analysis methods; such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification trees using Chi-squared Automatic Interaction Detector (CHAID) and discriminant analysis (DA) to achieve edible oils
Talanta, Feb 15, 2008
The elemental composition of seasoning products, like spices garlic and onion, has been reviewed ... more The elemental composition of seasoning products, like spices garlic and onion, has been reviewed paying special attention to methods proposed in the literature to determine specific elements or as much as possible components of these products which are widespread used in food preservation or food flavouring and can contribute to the intake of both, essential and toxic elements. Sample treatment and metal speciation aspects have been critically revised concerning onion, garlic and pepper (the most commonly studied products).
Hydrodistillation�liquid-phase microextraction for infrared analysis of food
Analytical and Bioanalytical Chemistry, Jul 28, 2010
A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successf... more A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successfully developed to improve sensitivity and selectivity in attenuated total reflection (ATR) infrared determination of semivolatile organic compounds from high water content plant and food matrices contributing to solve extraction efficiency drawbacks. The HD sampling facilitates the extraction of the semivolatile analytes from the sample matrix compared to headspace sampling, while the liquid-phase microextraction using a water immiscible solvent allows analyte preconcentration prior to ATR analysis. Experimental conditions regarding temperature and time of extraction, water effect and number of consecutive extractions have been deeply studied. The qualitative and quantitative capability of the developed methodology has been evaluated through the identification of the main semivolatile substances in plant and food matrices like spices and citrus peels and the effect of different drying treatments on the volatile composition of rosemary samples was studied through the quantification of camphor and eucalyptol.
Geographical traceability of �Arr�s de Valencia� rice grain based on mineral element composition
Food Chem, 2011
The geographical traceability of rice grain samples involves the use of analytical methodologies ... more The geographical traceability of rice grain samples involves the use of analytical methodologies that allow their differentiation on the basis of the rice composition, thus confirming their authenticity. In this paper, trace element determination of rice samples by inductively coupled plasma optical emission spectroscopy (ICP-OES) has been addressed to achieve a complete geographical origin classification. Samples (107) from Spain including Valencia, Tarragona, Murcia and Extremadura, Japan, Brazil and India were employed as training set whereas the validation set was formed by 46 samples of the aforementioned geographical origins. Data were processed by linear discriminant analysis (LDA), using as analytical variable the concentration of 32 elements (Al, As, Ba, Bi, Cd, Ca, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Mo, Ni, K, Se, Na, Sr, Tl, Ti, Zn, La, Ce, Pr, Nd, Sm, Eu, Ho, Er and Yb), enabling a 91.30% of correct classification for the validation set.► Trace element composition determined by inductively coupled plasma optical emission spectroscopy has been addressed to achieve a complete geographical origin classification of rice samples. ► Data processed by linear discriminant analysis (LDA) enabled a 91.30% of prediction capability. ► Lanthanides, Cd and Co have been identified as the most influent indicators of the geographical origin of rice samples due to their different concentrations in soils and their effective uptake by plants.
Trace elemental composition of curry by inductively coupled plasma optical emission spectrometry (ICP-OES)
Food Additives and Contaminants Part B Surveillance, Dec 1, 2008
A methodology based on inductively coupled plasma optical emission spectrometry (ICP-OES) after m... more A methodology based on inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted acid digestion was developed to determine the content of traces elements in curry samples from the Spanish market. The methodology was validated in terms of accuracy by the analysis of citrus and tomato leaf reference materials achieving comparable results with the certified values. The trace metal content of curry samples was compared with data available from previously published reports concerning Indian samples, especially in terms of heavy metal composition, in order to guarantee the quality of the commercially available spices in the European countries. Values found for the analysis of arsenic, lead and cadmium were significantly lower than the maximum limit allowed by European Union statutory limits for heavy metals and lower than those obtained for Indian curry leaves reported by Indian research teams by using neutron activation and γ-ray analysis.
Determination of 3,4-methylenedioxypyrovalerone (MDPV) in oral and nasal fluids by ion mobility spectrometry
Analytical and bioanalytical chemistry, Jan 22, 2016
A fast and sensitive methodology has been developed for the evaluation of the 3,4-methylenedioxyp... more A fast and sensitive methodology has been developed for the evaluation of the 3,4-methylenedioxypyrovalerone (MDPV) consumed. Based on ion mobility spectrometry (IMS), MDPV was directly determined in nasal fluids with a limit of detection (LOD) in the order of 22 ng mL(-1), which corresponds to an absolute amount of 33 ng of MDPV per swab. MDPV was also determined after liquid-liquid microextraction (LLME) in oral fluids to avoid matrix effects, obtaining a LOD value of 4.4 ng mL(-1) in oral fluid samples. The IMS spectrum for MDPV exhibited a peak with K 0 = 1.210 ± 0.005 cm(2)V(-1) s(-1) at a drift time of 14.62 ms, the total analysis time being 4.5 min per oral fluid and 1.5 min per nasal fluid sample. Samples must be analyzed within 24 h following collection and dissolution in 2-propanol, based on the complementary stability studies. Graphical Abstract IMS procedure for the analysis of MDPV in mucus and saliva.
Detection of tetrahydrocannabinol residues on hands by ion-mobility spectrometry (IMS). Correlation of IMS data with saliva analysis
Analytical and bioanalytical chemistry, Jan 14, 2015
Ion-mobility spectroscopy (IMS) was evaluated as a high-throughput, cheap, and efficient analytic... more Ion-mobility spectroscopy (IMS) was evaluated as a high-throughput, cheap, and efficient analytical tool for detecting residues of tetrahydrocannabinol (THC) on hands. Regarding the usefulness of hand residues as potential samples for determining THC handling and abuse, we studied the correlation between data obtained from cannabis consumers who were classified as positive after saliva analysis and from those who were classified as positive on the basis of the information from hand-residue analysis. Sampling consisted of wiping the hands with borosilicate glass microfiber filters and introducing these directly into the IMS after thermal desorption. The possibility of false positive responses, resulting from the presence of other compounds with a similar drift time to THC, was evaluated and minimised by applying the truncated negative second-derivative algorithm. The possibility of false negative responses, mainly caused by competitive ionisation resulting from nicotine, was also stu...
Importance of Incorporating a Waste Detoxification Step in Analytical Methodologies
Anal. Methods, 2015
ABSTRACT The introduction of a waste detoxification step in the analytical process has been highl... more ABSTRACT The introduction of a waste detoxification step in the analytical process has been highlighted by using, as example, the determination of copper in pesticide formulations by electrogravimetry, flame atomic absorption spectroscopy (FAAS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). This quantitatively study evidenced, the improvement of the aforementioned analytical methods, from a green perspective, after addition of electrodeposition or neutralization steps to the analytical process. Based on that, the application of the eco-scale and the green certificate to the evaluation of these methodologies allows to move from B and C classes to A class of method.
Mineral content of seasonings, salt and vinegar
de la Guardia/Handbook of Mineral Elements in Food, 2015
Vibrational spectroscopy has become one of the key techniques for the structural recognition of m... more Vibrational spectroscopy has become one of the key techniques for the structural recognition of molecular systems and measuring their interactions. Its spectral range, corresponding to vibrational transitions, leads to knowledge of the functional groups of the analyzed systems. Since the discovery of infrared radiation, two centuries ago, then Raman scattering a century later, these techniques have undergone extraordinary breakthrough to a variety of applications on small molecules and on macromolecules alike. Due to recent wide applications, we have encouraged our peers to contribute either original research or review articles that will recapitulate the continuing advancement to interpret molecular and even material structure using vibrational spectroscopy mainly infrared absorption.
Detection and characterization of emerging psychoactive substances by ion mobility spectrometry
Drug Testing and Analysis, 2014
Rapid detection and identification of novel psychoactive substances (NPS) continues to present si... more Rapid detection and identification of novel psychoactive substances (NPS) continues to present significant analytical challenges to forensic and analytical chemists. Ion mobility spectrometry (IMS) has been traditionally considered as the analytical technique of choice to detect illicit drugs in security points in airports, borderlines and customs. Databases of the reduced mobility (K0 ) values of illicit drugs are available in the scientific literature and they should be completed with data of emerging designer drugs. In this paper, we have evaluated the effect of different measurement conditions and determined the K0 values of an important number of NPS including different families; such as phenethylamines, cathinones, synthetic cannabinoids and tryptamines among others to be incorporated to the existing data to provide a rapid detection and identification of this emerging threat. Copyright © 2014 John Wiley & Sons, Ltd.
Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid–liquid extraction
Journal of Chromatography A, 2015
We developed and evaluated two different strategies for determining abuse drugs based on (i) the ... more We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid-liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160μgL(-1), requires adding 0.2M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spectroscopy after LLME provides an LOD of 11μgL(-1) with the former technique and 800μgL(-1) with the latter, in addition to a limit of confirmation (LOC) of 1.5mgL(-1). Using IMS after thermal desorption simplifies the operational procedure, and using it jointly with IR spectroscopy after LLME allows double confirmation of MDMA abuse with two techniques based on different principles (viz., IMS drift times and IR spectra). Also, it affords on-site analyses, albeit at a lower throughput.
Talanta, 2014
An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocai... more An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 735 ng m À 3 of a normal day to 10,000 ng m À 3 during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the evaluation of the health effects of continuous exposition to very small doses of cocaine. Cocaine was also found in almost all the analyzed sample surfaces and also was found in nasal mucus of the police officers that were present during the manipulation of cocaine seizures without using a face mask. In summary, cocaine concentrations could present a health hazard to the employees and therefore warrants remediation and some modifications of the manipulation operations have been proposed.
Non-chromatographic speciation
TrAC Trends in Analytical Chemistry, 2010
... Absence of gradient and Nernstian equilibrium stripping (AGNES) is a new electrochemical tech... more ... Absence of gradient and Nernstian equilibrium stripping (AGNES) is a new electrochemical technique specifically designed for determination of the concentration of free metal ions [M]. It can be an alternative to other existing techniques, especially for those metal ions (eg, Zn ...
Trace-element composition and stable-isotope ratio for discrimination of foods with Protected Designation of Origin
TrAC Trends in Analytical Chemistry, 2009
ABSTRACT We review the literature on authentication of foods with Protected Designation of Origin... more ABSTRACT We review the literature on authentication of foods with Protected Designation of Origin (PDO) from their trace-element composition or stable-isotope ratios in order to evaluate the state of the art of this field and to identify the main parameters of analytical techniques and chemometric-data treatments that permit accurate discrimination of samples of different geographical origins and with different characteristics.