Rosa Garcia-Arrona

Development and application of a screening method for triazole fungicide determination in liquid and fruit samples using solid-phase microextraction and HPLC-DAD

A screening method for determination of six triazole fungicides (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole and tetraconazole) using the solid-phase microextraction (SPME) technique coupled to a high-performance liquid chromatography-diode array detector (HPLC-DAD) was developed. Experimental variables were chosen and their values were fixed according to an experimental design with the steps of screening (25−1 fractional factorial design) and optimization of the significant variables (central composite design). Using polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers, the other experimental conditions were: extraction time, 90 min; extraction temperature, 60 °C; NaCl addition, 180 g L−1; static desorption mode and desorption time, 2 min. The method showed good inter and intraday precision (RSD values less than 13.2%) and the limits of detection were from 1.5 to 5.9 μg L−1 in liquid extracts and from 0.08 to 0.3 mg kg−1 in solid products. The method was applied to grape and apple fruit samples previously sprayed with commercial products containing the analytes. Samples were taken from peel, pulp and juice following a pre-harvest interval of two weeks. Also, rain samples under the fruit trees were collected. Myclobutanil and tebuconazole were found in the peel and rain, but not in pulp and juice samples.

Optimization and validation of a nonaqueous micellar electrokinetic chromatography method for determination of polycyclic musks in perfumes

A nonaqueous micellar electrokinetic chromatography method was developed for determination of Tonalide®, Galaxolide®, and Traseolide® polycyclic musks (PCMs). These compounds are widely used as fragrance ingredients in cosmetics. The method was optimized by using a three variable Box-Behnken experimental design and response surface methodology. A modified chromatographic response function was defined in order to adequately weigh the terms in the response function. After optimization of experimental conditions, an electrolyte solution of 195 mM SDS and 40 mM NaH(2) PO(4) in formamide was selected for the separation of the three PCMs, and the applied voltage was fixed at 30 kV. The nonaqueous MEKC method was then checked in terms of linearity, limits of detection and quantification, repeatability, intermediate precision and accuracy, providing appropriate values (i.e. RSD values for precision never exceeding 7%, and accuracy 96-107%). Nonaqueous MEKC for determination of the selected compounds was successfully applied to the analysis of commercial perfume samples.

Evaluation of Soil Contamination by Polycyclic Aromatic Hydrocarbons in Gipuzkoa (Northern Spain)

Representative polycyclic aromatic hydrocarbons (PAHs) of low-medium molecular weight were determined using headspace solid-phase microextraction and gas chromatography with a flame ionization detector (HS-SPME-GC-FID) in ten surface soil samples from Gipuzkoa (Northern Spain). The sum of the PAHs ranged from 0.21 to 136.26 mg kg−1. Pyrene and chrysene were the most abundant detected PAHs with an average concentration around 3.1 mg kg−1. Pearsons correlation and PAH isomer ratios were applied to study the different origins of contamination. The results indicated that the PAH contamination in the studied area was a mixed pattern of pyrolytic and petrogenic inputs. Multivariate exploratory techniques, principal component analysis (PCA), and cluster analysis (CA) were also applied corroborating the PAH compounds patterns in the soils.

Simultaneous determination of multiclass preservatives including isothiazolinones and benzophenone-type UV filters in household and personal care products by micellar electrokinetic chromatography.

In this work, a simple and reliable micellar electrokinetic chromatography method for the separation and quantification of 14 preservatives, including isothiazolinones, and two benzophenone‐type UV filters in household, cosmetic and personal care products was developed. The selected priority compounds are widely used as ingredients in many personal care products, and are included in the European Regulation concerning cosmetic products. The electrophoretic separation parameters were optimized by means of a modified chromatographic response function in combination with an experimental design, namely a central composite design. After optimization of experimental conditions, the BGE selected for the separation of the targets consisted of 60 mM SDS, 18 mM sodium tetraborate, pH 9.4 and 10% v/v methanol. The MEKC method was checked in terms of linearity, LODs and quantification, repeatability, intermediate precision, and accuracy, providing appropriate values (i.e. R2 ≥ 0.992, repeatability RSD values ˂9%, and accuracy 90–115%). Applicability of the validated method was successfully assessed by quantifying preservatives and UV filters in commercial consumer products.

SIMULTANEOUS DETERMINATION OF COLOR ADDITIVES TARTRAZINE AND ALLURA RED IN FOOD PRODUCTS BY DIGITAL IMAGE ANALYSIS

A method based on digital image is described to quantify tartrazine (E102), yellow, and allura red (E129) colorants in food samples. HPLC is the habitual method of reference used for colorant separation and quantification, but it is expensive, time-consuming and it uses solvents, sometimes toxic. By a flatbed scanner, which can be found in most laboratories, images of mixtures of colorants can be taken in microtitration plates. Only 400 µL of sample are necessary and up to 92 samples can be measured together in the same image acquisition. A simple-to-obtain color fingerprint is obtained by converting the original RGB image into other color spaces and individual PLS models are built for each colorant. In this study, root mean square errors of 3.3 and 3.0 for tartrazine and 1.1 and 1.2 for allura red have been obtained for cross-validation and external validation respectively. Results for repeatability and reproducibility are under 12%. These results are slightly worse but comparable to the ones obtained by HPLC. The applicability of both methodologies to real food samples has proven to give the same result, even in the presence of a high concentration of an interfering species, provided that this interference is included in the image analysis calibration model. Considering the colorant content found in most samples this should not be a problem though and, in consequence, the method could be extended to different food products. Values of LODs of 1.8 mg L-1 and 0.6 mg L-1 for tartrazine and allura red have been obtained by image analysis.

Determination of food colorants in a wide variety of food matrices by microemulsion electrokinetic capillary chromatography. Considerations on the found concentrations and regulated consumption limits

Color additives are used widely by the food industry to confer a desirable appearance. Some of the most used colorants (Tartrazine (E102), Sunset Yellow (E110), Red Allure (E129) and Blue Brilliant (E133)) were determined in this study using microemulsion electrokinetic capillary chromatography (MEEKC). Regression coefficients were greater than 0.9981; intra- and inter-day precisions, in terms of percentage RSD, were less than 7.01% and 8.55%, respectively; recoveries were between 90 and 100% in most cases. LODs and LOQs ranged from 0.24 to 1.21 mg L-1 and from 0.80 to 4.03 mg L-1, respectively. Moreover, MEEKC consumed less solvent than HPLC, making the analysis more environmentally friendly. The proposed method is suitable for the determination of colorants in a wide variety of foods. Results showed that consumers should be aware of colorants to avoid consumption exceeding recommended amounts.