SEMIAUTOMATED SOLID PHASE EXTRACTION SYSTEM COUPLED TO GAS CROMATOGRAPHY-MASS SPECTROMETRY FOR THE ISOLATION AND DETECTION OF
POLYCYCLIC AROMATIC HYDROCARBONS IN CEREAL BASED FOODSTUFF
Andrés J. Rascón, Evaristo Ballesteros
Department of Physical and Analytical Chemistry, E.P.S of Linares, University of Jaén, Spain, email: [email protected]
Polycyclic aromatic hydrocarbons are one of the largest families of contaminants, they have proved carcinogenic and mutagenic properties, because of this, the European Commission and the Environmental Protection Agency (EPA) included them into the priority pollutants list. Although they are included as priority pollutants they are not regulated in some families of foodstuff, in the last revision of the European Policies the PAHs has not been assessed and either limited their presence in cereal based foodstuff since the Regulation (EC) No 1881/2006, only for infants cereal based food the allowed limit is set at 1 µg/kg for benzo(a)pyrene and 1 µg/kg for the sum of benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene and chrysene. The presence of this kind of compounds in cereal based foodstuff could be made by three main ways, first for the environmental pollution, caused by nature or by human activities like petrol fuel combustion, etc. that affect to the cereal crops, the use of contaminated water for the cultivation also could be a source. During the harvesting the use of lubricants in the machinery used for this purpose could be a source of PAHs for the grain, and as mentioned before, the use of fuel in those machines. Before their use in the food industry, the grains are treated under a dryness process applying heat to reduce their content in water and improve their lifetime, in some food this dryness is more intense than others, depending the destination of the grain, in the most extreme cases the grain is toasted, increasing their PAHs content [1]. In the food factory, the grains are transformed and processed into diverse kinds of food like bread, cereal, cookies, flour, pasta, rice, etc. depending of the product the use of different baking procedures could increase the PAHs levels in a significant way [2].
There is a needing for the assessment and knowledge about the presence of polycyclic aromatic hydrocarbons in cereal based foodstuff and provide analytical data to help to establish new regulation policies for the allowed limits by the European Regulation. The concentration levels in those kinds of food are usually low, for that reason an analyte enrichment is required before the chromatographic determination. For solid matrices, as those products are, a homogenization process is required before the extraction procedure, the presence of lipid content must be addressed because PAHs are highly soluble in fat, and a saponification step will be required. The use of solid-phase extraction (SPE) for the sample enrichment improves the analytical sensibility while reduces the sample manipulation and the risk of being contaminated. For the PAHs determination in foodstuff samples the use of gas chromatography coupled to mass spectrometry (GC-MS) is extended and has proved their great selectivity, resolution and sensitivity [3], high resolution liquid chromatography with fluorescence detector (HPLC-FLD) has been also used over this family of compounds and had demonstrated great analytical features, but some of the PAHs has not fluorescence properties and the use of GC-MS is required [4].
The proposed methodology for the isolation and determination of PAHs in cereal grain foodstuff combining a semi-automated SPE system and GC-MS for 9 PAHs (naphthalene, anthracene, fluoranthene, chrysene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene) obtained good analytical features, with low limits of detection, relative standard deviation (RSD less than 6%) and high recoveries (near to 100 %) in several samples of bread, cereal, cookies, flour, pasta and rice, reporting positive results for some of them.
[1] A. J. Alldrick, Chemical Contaminants and Residues in Food, (2012) 421–446.
[2] L. Rey-Salgueiro, E. Martínez-Carballo, M.S. García-Falcón, J. Simal-Gándara, Food Chemistry,108 (2008) 347-353. [3] I. Rozentale, D. Zacs, I. Perkons, V. Bartkevics, Food Chemistry, 221 (2016) 1291-1297.
PO-AL-06
DETERMINACIÓN DE TITANIO EN PRODUCTOS LÁCTEOS MEDIANTE ICP-MS L. Regueiro-Caamaño, E. Peña-Vazquez, M.C. Barciela-Alonso,
P. Bermejo-Barrera
Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Químicas, Universidad de Santiago de Compostela. Avenida de las Ciencias, s/n, 15782,
Santiago de Compostela.
Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Travesía da Choupana, s/n, 15706, Santiago de Compostela.
E-mail: [email protected]
El dióxido de titanio se emplea como aditivo alimentario (E-171) hasta concentraciones del 2%, por ejemplo, en las coberturas azucaradas de chicles o caramelos. En productos lácteos puede añadirse como espesante y blanqueante a yogures, helados, quesos, etc.
En este trabajo se ha determinado la concentración de titanio en diferentes productos lácteos. Para ello se realizó una digestión ácida asistida con microondas con ácido nítrico y sulfúrico de distintas muestras de productos lácteos y se determinó el titanio en los digeridos mediante Plasma de Acoplamiento Inductivo-Espectrometría de Masas (ICP-MS). Una de los principales problemas en el análisis del titanio en los productos lácteos es la presencia de calcio que interfiere en la determinación empleando el isótopo mayoritario 48Ti. Por ello se ha evaluado el empleo de otros isótopos minoritarios (47Ti y 49Ti), y de helio como gas de colisión para eliminar interferencias moleculares. La utilización de escandio, germanio o itrio como patrones internos no aportaron mejoras significativas en la determinación cuando se realizaron las medidas con 47Ti y un flujo de gas de colisión de 1 mL min-1.
Se estudiaron las características analíticas del método desarrollado. Los límites de detección y cuantificación obtenidos fueron de 0.05 y 0.17 mg/Kg, respectivamente. Los coeficientes de variación calculados al estudiar la reproducibilidad en las medidas fueron del 3%, y las recuperaciones analíticas medias fueron del 97%.
El método desarrollado se aplicó al análisis de una variedad de muestras de productos lácteos (leches, natas, yogures, quesos), y las mayores concentraciones de titanio (de hasta 70 mg/Kg) se hallaron en muestras procedentes de máquinas de venta automatizada de leche.
Agradecimientos:
Esta investigación está financiada por el Gobierno de España (Ministerio de Economía y Competitividad, proyecto CTQ2015-68094-C2-2-R). Los autores pertenecen al Grupo de Referencia Competitivo 6RC2014/2016 (Xunta de Galicia). Estos programas están cofinanciados por los fondos FEDER (UE).
PO-AL-07
DETERMINATION OF ULTRATRAZE LEVELS OF ALKYLMETHOXYPYRAZINES IN WINE