DigitalUM :: Browsing by browse.metadata.contributordepartment "Química Analítica"

Browsing by browse.metadata.contributordepartment "Química Analítica"

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Open Access
A volatilomic approach using ion mobility and mass spectrometry combined with multivariate chemometrics for the assessment of lemon juice quality
(Elsevier, 2024-11-09) Giménez Campillo, Claudia; Arroyo Manzanares, Natalia; Campillo Seva, Natalia; Díaz García, Miriam Cristina; Viñas López-Pelegrin, Pilar; Química Analítica
Lemon (Citrus limon (L.) Burm.) is a citrus fruit known for its high nutritional value and potent antioxidant activity. Lemon juice, obtained by squeezing the fruit, is widely used in the kitchen for its acidic taste to flavour dishes and drinks. It has also been attributed with various medicinal properties to treat conditions such as sore throat, fever, rheumatism and hypertension. Ensuring the quality and safety of lemon juice, as well as its geographical origin, is not easy due to the scarcity of analytical methods available for this purpose, which makes it difficult to detect adulterations. To meet this challenge of testing the authenticity and safety of lemon juice, multiple physicochemical parameters need to be evaluated, which is expensive and time-consuming, so it is of great interest to develop an alternative simple method. In this research, two alternative analytical methods were developed and optimized for the analysis of lemon juice samples based on headspace gas chromatography coupled to both mass spectrometry (HS-GC-MS) or ion mobility spectrometry (HS-GC-IMS). These new methods were compared with the method currently used in the food industry for quality control of juices, which is Fourier transform near infrared spectroscopy (FT-NIR). A total of 159 samples belonging to different lemon varieties were analysed by measuring the physicochemical parameters, FT-NIR spectra and fingerprinting of the juice samples based on the total volatile compounds profile by GC-MS and GC-IMS. Partial least squares (PLS) regression models were then constructed and all models were validated by paired tests with the values measured by the reference chemical methods. The models developed confirm that both HS-GC-MS and HS-GC-IMS methods are viable alternatives for predicting physicochemical parameters and ensuring lemon juice quality. Finally, the data were used to build chemometric models using orthogonal partial least squares discriminant analysis (OPLSDA) to distinguish lemon juices according to the lemon variety used in their manufacture. Very promising models were obtained with the HS-GC-MS and HS-GC-IMS data, suggesting the potential use of the volatile profile for lemon variety confirmation. Consequently, fingerprinting represents an alternative proposal to the conventional method applied in the food industry based on the use of chemical reference parameters or the use of the NIR technique.
Open Access
Advanced materials for magnetic solid-phase extraction of mycotoxins: a review
(Elsevier, 2024-06-20) Castell Martínez, Ana; Arroyo Manzanares, Natalia; Viñas López-Pelegrin, Pilar; López García, Ignacio Francisco; Campillo Seva, Natalia; Química Analítica
Mycotoxins can occur at various stages of the food production process. Due to the toxicity of many of these compounds for human health, the development of analytical methodologies that allow their detection and remediation in food is of great interest. However, food analysis is challenging due to the complexity of the matrices, so sample treatment is a crucial step. Magnetic solid-phase extraction (MSPE) has become one of the most popular green approaches for the isolation of mycotoxins from complex matrices. Furthermore, advanced magnetic materials as molecularly imprinted polymers, metal-organic frameworks and covalent organic frameworks have emerged as promising candidates for MSPE, as they offer a simple and efficient application for mycotoxin extraction due to the possibility to modify and functionalize their surface according to specific requirements. This review provides an overview of the synthesis and recent applications of these sorbents for the MSPE isolation of mycotoxins from complex matrices.
Open Access
Application of voltammetric techniques at microelectrodes to the study of the chemical stability of highly reactive species
(American Chemical Society (ACS), 2014-12-31) Laborda, Eduardo; Olmos, José Manuel; Torralba, Encarnación; Molina, Ángela; Química Analítica
The application of voltammetric techniques to the study of chemical speciation and stability is addressed both theoretically and experimentally in this work. In such systems, electrode reactions are coupled to homogeneous chemical equilibria (complexations, protonations, ion associations,…) that can be studied in a simple, economical and accurate way by means of electrochemical methods. These are of particular interest when some of the participating species are unstable given that the generation and characterization of the species are performed in situ and in a short time scale. With the above aim, simple explicit solutions are presented in this paper for quantitative characterization with any voltammetric technique and with the most common electrode geometries. From the theoretical results obtained, it is pointed out that the use of square wave voltammetry in combination with microelectrodes is very suitable. Finally, the theory is applied to the investigation of the ion association between the anthraquinone radical monoanion and the tetrabutylammonium cation in acetonitrile medium.
Open Access
Authentication strategy for paprika analysis according to geographical origin and study of adulteration using near infrared spectroscopy and chemometric approaches
(Elsevier, 2024-02-17) Castell, Ana; Arroyo-Manzanares, Natalia; López-García, Ignacio; Viñas, Pilar; Zapata Arráez, Félix; Química Analítica
Paprika is a spice whose composition and characteristics vary with its geographical origin and additionally is illegally adulterated with dyes to improve its appearance. This work proposes a strategy based on Fourier transform near infrared (FT-NIR) analysis and chemometric tools for its authentication and detection of fraud. A total of 115 paprika samples were analyzed, including paprika with protected designation of origin (PDO) labels from Spain, France and Hungary, and samples from China and Zambia. The proposed orthogonal partial least squares-discriminant analysis (OPLS-DA) models allow to distinguish paprika according to its PDO and variety, as well as to identify adulteration with Sudan dyes or Congo red. Partial least squares regressions allow to quantify the adulterant in paprika from 0.1 to 5 %. Chemometric models achieved high classification success rates and suitable linearities. The proposed strategy is presented as a comprehensive and effective tool to ensure paprika quality and authenticity, including the detection and quantification of adulteration with commercial dyes.
Open Access
Bioaccumulation of mycotoxins in human forensic liver and animal liver samples using a green sample treatment
(Elsevier, 2023-11-23) Castell Martínez, Ana; Arroyo Manzanares, Natalia; Campillo Seva, Natalia; Torres Sánchez, Carmen; Fenoll, José; Viñas López-Pelegrin, Pilar; Química Analítica
The investigation of the mycotoxin bioaccumulation in human and animals is of wide relevance due to the potential toxicity associated with these secondary metabolites. This study proposes an analytical methodology consisting of salting-out liquid–liquid extraction (SALLE) followed by dispersive liquid–liquid microextraction (DLLME) for the determination of 13 mycotoxins: aflatoxins (G1, G2, B1 and B2), enniatins (A, A1, B and B1), beauvericin, HT-2 and T-2 toxins, zearalenone and deoxynivalenol, in human and animal liver. A targeted analysis was performed by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), as well as the screening of derived metabolites by ultrahigh performance LC and high-resolution mass spectrometry (UHPLC-HRMS). The proposed method was in-home validated, and trueness was verified by apparent recovery studies with values between 94 and 110 %. Furthermore, suitable linearities were obtained by the proposed method for all the mycotoxins and detection and quantification limits allow the mycotoxin monitoring at the low levels expected in biological samples. Repeatability and intermediate precision were calculated at two concentration levels, obtaining values of relative standard deviation below 9.5 %. The proposed methodology allowed to study the bioaccumulation of mycotoxins in both human and animal liver, demonstrating the presence of emergent mycotoxins in all liver samples analyzed, specifically enniatins B, B1 and beauvericin were detected with concentrations up to 4.04 μg/kg.
Open Access
Casos prácticos. Criterio profesional en calibración analítica
(2026-02-27) Giménez Campillo, Claudia; García Nicolás, María; Castell Martínez, Ana; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Química Analítica; Facultades de la UMU::Facultad de Química
Formando al químico analítico del mañana: uso del aprendizaje cooperativo para comprender y aplicar los distintos modelos de calibración
Open Access
Casos prácticos. Escenarios de decisión técnica
(2026-02-27) Giménez Campillo, Claudia; García Nicolás, María; Castell Martínez, Ana; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Química Analítica
Formando al químico analítico del mañana: uso del aprendizaje cooperativo para comprender y aplicar los distintos modelos de calibración.
Open Access
Comparison of two derivatizing agents for the simultaneous determination of selenite and organoselenium species by gas chromatography and atomic emission detection after preconcentration using solid-phase microextraction
(ELSEVIER, 2007-09-21) Campillo Seva, Natalia; Peñalver Soler, Rosa María; Hernández Córdoba, Manuel; Pérez-Sirvent, Carmen; Martínez Sánchez, María José; Química Analítica
Two methods for the simultaneous determination of selenite and two organoselenium compounds, dimethylselenide (DMSe) and dimethyldiselenide (DMDSe), are proposed. Both methods involve sample preconcentration by solid-phase microextraction (SPME) and capillary gas chromatography coupled to atomic emission detection (GC-AED). The main difference between the methods is the derivatizing agent used to complex the inorganic species: sodium tetraethylborate and 4,5-dichloro-1,2-phenylenediamine. The parameters affecting the derivatization and preconcentration steps, chromatographic separation as well as detection of the compounds were optimized. Direct immersion (DI) mode and a relatively long extraction time were selected for the method involving the formation of the piazselenol complex, better sensitivity being achieved for the three analytes under study. In this case, detection limits ranged between 3 to 25 ng L-1, depending on the compound. Headspace mode (HS) and extraction times of 20 min were selected for the method involving tetraalkylborate, and detection limits of between 7.3 and 55 ng L-1 were obtained. DMSe and Se(IV) were found in several of the water samples analyzed at concentrations of 0.07-1.0 ng mL-1.
Restricted
Complete and simultaneous removal of ionic silver and silver nanoparticles by using an ionic liquid supported on a magnetic nanoparticle core
(Elsevier, 2022-08-11) Vicente Martínez, Yésica; Sandoval Muñoz, Maria José; Caravaca, Manuel; Hernández Córdoba, Manuel; López-García, Ignacio; Química Analítica
The global pandemic situation due to COVID-19 has given rise to the massive use of disinfectant products, many of them based on silver atoms. After the use of these products, the silver passes into the aqueous effluents, becoming an emerging contaminant in waters. In this work, a novel procedure for the total and simultaneous removal of ionic and nanomeric silver in aqueous samples is introduced, employing magnetic nanoparticles wrapped with an ionic liquid (Fe3O4@IL) as a removal agent. Experimental variables such as pH, contact time, temperature, as well as pollutant and removal agent doses were studied to achieve the total elimination, exhibiting exceptional conditions for the removal of different concentrations of silvers species in water. The approach achieves 100% removal efficiency for the simultaneous removal of both silver species, goal not achieved previously. Also, 100% removal efficiency is reached for the both species separately, since ionic silver is adsorbed onto the Fe3O4, while nanomeric silver is extracted in the IL. Particularly, for concentrations within the range 50–200 μg L−1, total removal efficiency was reached for a wide range of temperatures and a pH range 7–9, achieved in just 15 min, for all cases. Additionally, the doses of Fe3O4@IL employed to remove all concentrations of silver were 13.7 mg. Characterization of Fe3O4@IL surfaces before and after the process was performed by means of Field Effect Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy. Fe3O4@IL was recycled by employing 100 μL of 1% HNO3 solution, allowing its use for 10 additional silver removal cycles without loss of efficiency. The study of adsorption kinetics and equilibrium isotherms reveal a Freundlich-type adsorption, which suggests affinity between sites in the complex surface of Fe3O4@IL, and Elovich kinetics, indicative of chemisorption onto a heterogeneous surface, while the temperature shows no effect on the results.
Open Access
Controlando la variabilidad analítica. Estándar interno
(2026-02-27) Giménez Campillo, Claudia; García Nicolás, María; Castell Martínez, Ana; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Química Analítica; Facultades de la UMU::Facultad de Química
Técnica de corrección en tiempo real que compensa errores aleatorios y sistemáticos mediante la medida simultánea de un estándar interno (EI) o de referencia añadido a todas las muestras y estándares analíticos.
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Degradation of imidacloprid in water by photo-Fenton process using UV-LED lamps at neutral pH: Study of intermediate products by liquid chromatography mass spectrometry after dispersive liquid–liquid microextraction
(Elsevier, 2024-03-01) Martínez Escudero, Carmen Maria; Garrido, Isabel; Contreras, Fulgencio; Hellín, Pilar; Flores, Pilar; Arroyo Manzanares, Natalia; Campillo Seva, Natalia; Pastor Belda, Marta; Viñas López-Pelegrin, Pilar; Fenoll, José; León Morán, Lixy Olinda; Química Analítica
In the present study, a suitable analytical method to determine imidacloprid (IMI) and its main transformation products (TPs) in water by means of dispersive liquid–liquid microextraction (DLLME) combined with liquid chromatography coupled to mass spectrometry (LC-MS), using both quadrupole-time-of-flight (QTOF) and triple quadrupole (QqQ) analysers, has been developed. In addition, the structures of major products formed when IMI is photo-oxidized using ultraviolet A (UVA) irradiation with light emitting diode (LED) lamps were established. Finally, the behaviour of IMI and its main TPs generated in water during photo-Fenton processes at neutral pH using two ferric iron complexes, with ethylenediamine-N,N-disuccinic acid (EDDS) and nitrilotriacetic acid (NTA) as chelating agents, was studied. DLLME was found to efficiently preconcentrate IMI and IMI TPs from the water matrix using chloroform (as extractant solvent) and acetonitrile (as dispersant solvent) in a simple step. The selectivity of the used techniques provided unequivocal identification of IMI and its TPs and their quantification with high sensitivity during the photo-Fenton treatments. In addition, the photo-Fenton treatment using EDDS exhibited higher degradation rate than photo-Fenton treatment using NTA.
Open Access
Determination of nitrophenols in environmental samples using stir bar sorptive extraction coupled to thermal desorption gas chromatography-mass spectrometry
(Elsevier, 2018-07) Pastor Belda, Marta; Sanchez-López, María José; Campillo Seva, Natalia; Viñas López-Pelegrín, Pilar; Hernández Córdoba, Manuel; Química Analítica
This paper presents a procedure for the determination of seven nitrophenols (NPs) in water and soil samples using stir bar sorptive extraction (SBSE) coupled to gas chromatography with mass spectrometry (GC-MS) by means of a thermal desorption unit (TDU). Microwave assisted extraction (MAE) is proposed to release the NPs from the soil matrices into an aqueous phase, prior to their acetylation. The different variables affecting the preconcentration efficiency of SBSE, during both the adsorption and the thermal desorption steps, are studied. As regards the analytical characteristics of the method, the accuracy was measured through recovery studies, re covery percentages in all cases being in the 79–120% range, as well as by analyzing a certified reference ma terial. The precision was evaluated in terms of relative standard deviation, which provided values lower than 15% for both repeatability and reproducibility. The limits of detection were between 0.001 and 0.031 µg L−1 for water and 0.020–0.107 ng g−1 for soil samples. When environmental samples of different origins were analyzed, contents in the 0.01–1.0 µg L−1 and 0.7–40 ng g−1 ranges were obtained for waters and soils, respectively.
Open Access
Determination of nitrophenols in environmental samples using stir bar sorptive extraction coupled to thermal desorption gas chromatography-mass spectrometry
(Elsevier, 2018-11-01) Pastor-Belda, M.; Sánchez-López, M.J.; Campillo, N.; Viñas López-Pelegrín, Pilar; Hernández Córdoba, Manuel; Química Analítica
This paper presents a procedure for the determination of seven nitrophenols (NPs) in water and soil samples using stir bar sorptive extraction (SBSE) coupled to gas chromatography with mass spectrometry (GC-MS) by means of a thermal desorption unit (TDU). Microwave assisted extraction (MAE) is proposed to release the NPs from the soil matrices into an aqueous phase, prior to their acetylation. The different variables affecting the preconcentration efficiency of SBSE, during both the adsorption and the thermal desorption steps, are studied. As regards the analytical characteristics of the method, the accuracy was measured through recovery studies, recovery percentages in all cases being in the 79–120% range, as well as by analyzing a certified reference material. The precision was evaluated in terms of relative standard deviation, which provided values lower than 15% for both repeatability and reproducibility. The limits of detection were between 0.001 and 0.031 μg L−1 for water and 0.020–0.107 ng g−1 for soil samples. When environmental samples of different origins were analyzed, contents in the 0.01–1.0 μg L−1 and 0.7–40 ng g−1 ranges were obtained for waters and soils, respectively.
Open Access
Dilute-and-shoot-liquid chromatography-quadrupole time of flight-mass spectrometry for pteridine profiling in human urine and its association with different pathologies
(MDPI, 2023-06-01) Giménez Campillo, Claudia; Pastor Belda, Marta; Arroyo Manzanares, Natalia; Campillo Seva, Natalia; Val Oliver, Blanca del; Zarauz García, José; Sáenz, Luis; Viñas López-Pelegrin, Pilar; Química Analítica
Pteridines are a group of compounds synthesised by many living organisms that are involved in the metabolism of many cofactors and vitamins. Their concentration in biological fluids may be altered by various pathologies such as cancer or inflammatory bowel disease, urine being the main route of excretion. In this study, three lumazines and ten pterins were analysed in their native oxidation state using high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Their high concentration in urine samples and their good ionisation behaviour allow the use of the dilute-and-shoot method by simple filtration of the urine prior to chromatographic analysis. The final method offers excellent linearity, sensitivity and precision parameters, and a total of 135 urine samples were analysed from patients with some relevant information such as faecal calprotectin (FCP) levels, common diseases such as diabetes, hypertension and dyslipidaemia and immunological diseases such as inflammatory bowel disease (IBD). The pteridine profile was related to FCP levels without showing any correlation. In addition, pteridine levels were compared between healthy subjects and IBD, diabetic, hypertensive and dyslipidaemic patients, and significant differences were found between the two groups for some of the pteridines.
Open Access
Discrimination of the geographical origin of peaches by the monitoring of volatile organic compounds by gas chromatography with mass spectrometry and chemometric tools
(Elsevier, 2024-02-24) Giménez Campillo, Claudia; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Campillo Seva, Natalia; Viñas López-Pelegrin, Pilar; Química Analítica
The peach is one of the most popular and widely consumed fruits in Europe. Spain is the largest peach-producing country in the world with several growing areas recognised by consumers. This work focuses on the development, optimisation and validation of a non-targeted metabolomics strategy for the determination of peach volatile organic compounds from different origins by headspace gas chromatography coupled to mass spectrometry (HS–GC–MS). The volatil profile found in each sample is used to classify peaches according to their origin. The results obtained were processed using MS-DIAL software and 279 features were detected, of which 102 volatile compounds were tentatively identified and 30 of them could also be quantified. In addition, the areas of all the features were used to build models based on orthogonal partial least squares discriminant analysis (OPLS-DA) to differentiate peaches according to their geographical origin. A very promising model was obtained, with a validation rate of 90.32%, which means that it could be used to guarantee the Protected Designation of Origin of different peaches with a simple analysis.
Open Access
Effects of unequal diffusion coefficients and coupled chemical equilibria on square wave voltammetry at disc and hemispherical microelectrodes
(Elsevier, 2015) Olmos Martínez, José Manuel; Molina Gómez, María de los Ángeles; Laborda Ochando, Eduardo; Martínez-Ortíz, Francisco Asís; Química Analítica
Square wave voltammetry (SWV) at disc and hemispherical microelectrodes is studied when the electroactive species show different diffusivities and/or take part in chemical equilibria in solution, under both transient and steady state conditions. Despite the use of microelectrodes, experiments in pulse techniques such as SWV frequently correspond to transient conditions since the pulse duration are typically very short (<100ms, f>5Hz). As will be shown, under such conditions the case of unequal diffusion coefficients gives rise to a complex behaviour of the SWV peak, the features of which deviate from the theory and criteria already established under the assumption of equal diffusion coefficients. Also, the theoretical treatment is notably more difficult and no analytical solution has been deduced for multipulse techniques.The effects of coupled chemical equilibria and, particularly, of unequal diffusion coefficients on SWV will be described in depth as a function of the electrode size and shape and they will be compared with those observed in differential double pulse voltammetry (DDPV). The main discrepancies in the peak height, width and position with respect to the case of equal diffusion coefficients will be studied. Also, appropriate methodologies and experimental conditions will be discussed for the determination of, formal potentials and equilibrium constants.
Open Access
El desafío de la matriz. Adiciones estándar.
(2026-02-27) García Nicolás, María; Giménez Campillo, Claudia; Castell Martínez, Ana; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Química Analítica; Facultades de la UMU::Facultad de Química
Estrategia de cuantificación diseñada para muestras complejas donde la matriz altera la respuesta del analito, invalidando el uso de una calibración externa convencional.
Open Access
El estándar perfecto. Calibración externa
(2026-02-27) Giménez Campillo, Claudia; García Nicolás, María; Castell Martínez, Ana; Arroyo Manzanares, Natalia; Pastor Belda, Marta; Química Analítica; Facultades de la UMU::Facultad de Química
Relaciona la señal instrumental de una muestra desconocida con la de patrones de concentración conocida para cuantificar el analito.
Open Access
Evaluation of distribution of emerging mycotoxins in human tissues: applications of dispersive liquid–liquid microextraction and liquid chromatography‑mass spectrometry
(Springer, 2023-11-21) Castell Martínez, Ana; Arroyo Manzanares, Natalia; Palma Manrique, Rosa; Campillo Seva, Natalia; Torres, Carmen; Fenoll, José; Viñas López-Pelegrin, Pilar; Química Analítica
In this work, a complete study of the distribution of emerging mycotoxins in the human body has been carried out. Specifically, the presence of enniatins (A, A1, B, B1) and beauvericin has been monitored in brain, lung, kidney, fat, liver, and heart samples. A unique methodology based on solid–liquid extraction (SLE) followed by dispersive liquid–liquid microextraction (DLLME) was proposed for the six different matrices. Mycotoxin isolation was performed by adding ultrapure water, acetonitrile, and sodium chloride to the tissue sample for SLE, while the DLLME step was performed using chloroform as extraction solvent. Subsequently, the analysis was carried out by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC–MS/MS). The proposed method allowed limits of quantification (LOQs) to be obtained in a range of 0.001–0.150 ng/g, depending on the tissue and mycotoxin. The precision was investigated intraday and interday, not exceeding of 9.8% of relative standard deviation. In addition, trueness studies achieved 75 to 115% at a mycotoxin concentration of 25 ng/g and from 82 to 118% at 5 ng/g. The application of this methodology to 26 forensic autopsies demonstrated the bioaccumulation of emerging mycotoxins in the human body since all mycotoxins were detected in tissues. Enniatin B (ENNB) showed a high occurrence, being detected in 100% of liver (7 ± 13 ng/g) and fat samples (0.2 ± 0.8 ng/g). The lung had a high incidence of all emerging mycotoxins at low concentrations, while ENNB, ENNB1, and ENNA1 were not quantifiable in heart samples. Co-occurrence of mycotoxins was also investigated, and statistical tests were applied to evaluate the distribution of these mycotoxins in the human body.
Open Access
Evaluation of solid-phase microextraction conditions for the determination of chlorophenols in honey samples using gas chromatography
(ELSEVIER, 2006-08-25) Campillo Seva, Natalia; Peñalver Soler, Rosa María; Hernández Córdoba, Manuel; Química Analítica
A rapid and solvent-free method for the determination of nine chlorophenol compounds (CPs) in honey samples using headspace solid-phase microextraction (HS-SPME) and gas chromatography with atomic emission detection (GC-AED) is developed. The different factors affecting the efficiency of the extraction and derivatization steps were carefully optimized. The polydimethylsiloxane-divinylbenzene (PDMS/DVB) fiber was the most suitable for preconcentrating the analytes from the headspace of an aqueous solution containing the dissolved honey samples where the chlorophenols had been submitted to acetylation. When the matrix effect was evaluated for different samples, it was concluded that standard addition calibration was required for quantification purposes. Detection limits roughly ranged from 0.1 to 2.4 ng g-1, depending on the compound and the honey sample analyzed, with a fiber time exposure of only 15 min at 75 °C. The optimized method was successfully applied to different samples, some of the studied chlorophenols being detected in some of the analyzed honeys at concentration levels 0.6-9.4 ng g-1.