Laura Rubio

Standard addition method based on four-way PARAFAC decomposition to solve the matrix interferences in the determination of carbamate pesticides in lettuce using excitation-emission fluorescence data.

The simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of PARAFAC decomposition and excitation-emission fluorescence matrices. A standard addition method for a calibration based on four-way data was applied using different dilutions of the extract from iceberg lettuce as a fourth way that provided the enough variation of the matrix to carry out the four-way analysis. A high fluorescent overlapping existed between the three analytes and the fluorophores of the matrix. The identification of two fluorescent matrix constituents through the four-way model enabled to know the matrix contribution in each dilution of the extract. This contribution was subtracted from the previous signals and a subsequent three-way analysis was carried out with the tensors corresponding to each dilution. The PARAFAC decomposition of these resulting tensors showed a CORCONDIA index equal to 99%. For the identification of the analytes, the correlation between the PARAFAC spectral loadings and the reference spectra has been used. The trueness of the method, in the concentration range studied, was guaranteed because there was neither constant nor proportional bias according to the appropriate hypothesis tests. The best recovery percentages were obtained with the data from the most diluted extract, being the results: 127.6% for carbaryl, 125.55% for carbendazim and 87.6% for 1-naphthol. When the solvent calibration was performed, the decision limit (CCα) and the capability of detection (CCβ) values, in x0=0, were 2.21 and 4.38 μg L(-1) for carbaryl, 4.87 and 9.64 μg L(-1) for carbendazim; and 3.22 and 6.38 μg L(-1) for 1-naphthol, respectively, for probabilities of false positive and false negative fixed at 0.05. However, these values were 5.30 and 10.49 μg L(-1) for carbaryl, 18.05 and 35.73 μg L(-1) for carbendazim; and 1.92 and 3.79 μg L(-1) for 1-naphthol, respectively, when the matrix-matched calibration using the most diluted extract was carried out in the recovery study.

Coping: Impact of Gender and Stressful Life Events in Middle and in Old Age

ABSTRACT Objectives: This study seeks to identify different life events that participants considered stressful and to study the joint effect of gender, age group, and main stressful life events on the use of different coping strategies.Methods: The sample comprised 243 men and women, 55 to 99 years old, who attended senior activity centers. Analyses were conducted using multivariate analysis of variance (MANOVA).Results: Three main categories of stressful life events were identified: health problems, family problems, and other problems. Significant main effects of gender and stressful life events, and marginal effects of age group on coping strategies were found. Furthermore, an interaction between gender and age group, and also between gender and stressful life events emerged in some of the coping strategies analyzed.Conclusions: Age, gender or type of stressful situation impact on the coping strategies used by older people. Older men and women were found to use different strategies depending upon the situation they are facing and upon their age group. The results may prove useful to practitioners and clinicians who directly work with older people and may help clinicians provide effective coping strategies to address the specific life events that older adults find stressful.

Dealing with the ubiquity of phthalates in the laboratory when determining plasticizers by gas chromatography/mass spectrometry and PARAFAC

Determining plasticizers and other additives migrated from plastic materials becomes a hard task when these substances are already present in the laboratory environment. This work dealt with this drawback in the multiresidue determination of four plasticizers (2,6-di-tert-butyl-4-methyl-phenol (BHT), diisobutyl phthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and diisononyl phthalate (DiNP)) and a UV stabilizer (benzophenone (BP)) by gas chromatography/mass spectrometry (GC/MS) using DiBP-d4 as internal standard. The ubiquity of DiBP by a non-constant leaching process in the laboratory was detected, which could not guarantee the achievement of a trustworthy quantification. To handle this, the assessment of the level of DiBP in solvent blanks having fixed the probabilities of false non-compliance (α) and false compliance (β) at 0.01 was performed. On the other hand, another special case was that of DiNP, in whose chromatogram finger peaks appear because of an array of possible C9 isomers. PARAFAC, used for the identification and quantification of all the substances, is a useful chemometric tool that enabled a more reliable determination of this analyte since no peak areas were considered but chromatographic and spectral loadings. Since phthalates may migrate from rubber latex items, an evaluation of the existence of matrix effects on the determination of the five analytes was conducted prior to an extraction with hexane from a dummy for infants. As matrix effects were present, the quantification of the compounds under study was performed following the standard addition method using PARAFAC sample loadings as response variable. As a result, the presence of BHT was confirmed, being its concentration equal to 37.87μgL(-1). Calibrations based on PARAFAC yielded the following values for the decision limit (CCα): 1.16μgL(-1) for BHT, 1.34μgL(-1) for BP, 1.84μgL(-1) for DEHA and 51.42μgL(-1) for DiNP(for α=0.05 and two replicates).

Realización de actividades y extraversión como variables predictoras del bienestar psicológico en personas mayores

INTRODUCTION The relationship between extraversion and wellbeing has been discussed in the literature, however, the impact that this trait has on the wellbeing of older people has been studied to a lesser extent. The relationship between extraversion, participation in activities and psychological wellbeing in older people is analysed in this study. MATERIAL AND METHODS The sample comprised 139 individuals over 55 years from rural and urban areas of the province of Granada who completed the extraversion subscale of the NEO-FFI and the Ryff Scales of the Psychological Wellbeing, as well as responding to questions that evaluated their social participation. RESULTS A greater social participation was found in rural areas and among women. The activities more frequently performed by the participants were educational and religious activities, walking, everyday chores, crafts, and home improvements. A low positive correlation between extraversion and wellbeing was observed. The multiple regression analysis revealed that extraversion explained 19.9% of the variance in psychological wellbeing, which increased to 25.3% when social participation, gender, and the origin of the sample were considered. CONCLUSIONS Psychological wellbeing appears to be associated with personality traits, such as extraversion. In addition this personality trait is linked to the number and type of activities the elderly perform which also contributes to wellbeing in old age.

Desirability functions as response in a d-optimal design for evaluating the extraction and purification steps of six tranquillizers and an anti-adrenergic by liquid chromatography-tandem mass spectrometry

Internal standards can be added at different stages of an analytical procedure. When they are added at the beginning of a multiresidue method and their behavior is not exactly the same as that of the analytes, the intended correction for small variations within the analytical process could not be achieved. Because of this, in the present work, the use of d‐optimal designs together with desirability functions is proposed to state the experimental response under study. The overall desirability function used relates two analytical criteria: to assess a similar chemical behavior of each analyte in relation to its internal standard and to avoid a significant reduction of the absolute peak area of the internal standards. This strategy has been applied to the analysis of the effect of four factors related to the extraction and purification steps of six tranquillizers and a β‐blocker from pig muscle analyzed by liquid chromatography–tandem mass spectrometry. The effect of those factors has been evaluated by means of an ad hoc d‐optimal design consisting of only 11 experiments. The resulting levels of the four factors that enable to achieve the greatest overall desirability have also been compared with those obtained when either the standardized or absolute peak area has been considered as response. Differences in both the significant factors and their optimum levels have been observed. It is noticeable that the experimental effort necessary to study the effect of the factors has been reduced by more than 50% thanks to the d‐optimal design. Copyright

Effect of the cleaning procedure of Tenax on its reuse in the determination of plasticizers after migration by gas chromatography/mass spectrometry

This paper presents the simultaneous determination of a UV stabilizer (benzophenone (BP)) together with four plasticizers (butylated hydroxytoluene (BHT), diisobutyl phthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and diisononyl phthalate (DiNP)) in Tenax by gas chromatography/mass spectrometry and PARAFAC, using DiBP-d4 as internal standard. Regulation (EU) No. 10/2011 establishes Tenax as food simulant E for testing specific migration from plastics into dry foodstuffs. This simulant must be cleaned before its use to eliminate impurities. Tenax is expensive, so its reuse would save costs. A two-way ANOVA was used to study some parameters affecting the cleaning and the extraction of Tenax. The most adequate conditions were chosen taking the values of the coefficient of variation and the average recovery rates of spiked Tenax samples into account. A study to determine if some analytes remain in Tenax when it is reused and the effect that the cleaning procedure may have in the adsorption capability of Tenax was proposed. This study led to the conclusion that Tenax could not be reused in this multiresidue determination. All the analytes were unequivocally identified in all the stages of this work and trueness was verified at a 95% confidence level in all cases. A calibration based on PARAFAC provided the following values of capability of detection (CCβ): 2.28 µg L-1 for BHT, 10.57 µg L-1 for BP, 7.87 µg L-1 for DiBP, 3.04 µg L-1 for DEHA and 124.8 µg L-1 for DiNP, with the probabilities of false positive and false negative fixed at 0.05. The migration of the analytes from a printed paper sample into Tenax was also studied. The presence of BHT in the food simulant was confirmed and the amount released of this analyte from the paper was 2.56 μg L-1.