Micro-focused ultrasonic solid-liquid extraction (muFUSLE) combined with HPLC and fluorescence detection for PAHs determination in sediments: optimization and linking with the analytical minimalism concept.

Analytical minimalism is a concept that deals with the optimization of all stages of an analytical procedure so that it becomes less time, cost, sample, reagent and energy consuming. The guide-lines provided in the USEPA extraction method 3550B recommend the use of focused ultrasound (FU), i.e., probe sonication, for the solid-liquid extraction of Polycyclic Aromatic Hydrocarbons, PAHs, but ignore the principle of analytical minimalism. The problems related with the dead sonication zones, often present when high volumes are sonicated with probe, are also not addressed. In this work, we demonstrate that successful extraction and quantification of PAHs from sediments can be done with low sample mass (0.125g), low reagent volume (4ml), short sonication time (3min) and low sonication amplitude (40%). Two variables are here particularly taken into account for total extraction: (i) the design of the extraction vessel and (ii) the solvent used to carry out the extraction. Results showed PAHs recoveries (EPA priority list) ranged between 77 and 101%, accounting for more than 95% for most of the PAHs here studied, as compared with the values obtained after soxhlet extraction. Taking into account the results reported in this work we recommend a revision of the EPA guidelines for PAHs extraction from solid matrices with focused ultrasound, so that these match the analytical minimalism concept.

Effect of an aerobic training on magnesium, trace elements and antioxidant systems in a Down syndrome population.

The aim of the present study was to determine the effect of an aerobic training on plasma and red blood cells' levels of magnesium, copper, selenium and zinc and on some oxidative stress parameters in a Down syndrome (DS) sample population. Sixteen young male adults with DS participated in the protocol. Among them, eight were randomly assigned to the control group and the remaining eight participated in a 16 week training programme consisting of 10 min warm-up followed by an aerobic session at a work intensity of 60 to 75 per cent of VO2 peak lasting from 15 to 25 min, increasing 5 min every 5 weeks and by a 5 min cool-down period, 3 days/week. Blood was withdrawn by butterfly from antecubital vein of each subject at fast, 2 days before the beginning of the programme and 2 days after its ending. Before the training period, when comparing the two groups, no significant differences were observed in the evaluated parameters. However, when comparing with a healthy population, red blood cells magnesium and plasma and red blood cells selenium mean values were low in both groups and mean SOD activity was 1.4 times higher. After the protocol the mean values of the minerals studied did not show significant differences between groups except for plasma zinc that was lower (p = 0.029) in the trained group. Plasma TBARS increase was significant in the trained group (p = 0.034) but not in the control group and plasma GSH of the trained group had a significantly higher increase than the control group (p = 0.003). The levels of plasma TBARS after the training programme that were inversely correlated with red blood cells GSSG levels (p = 0.023) and the higher increase of plasma GSH mean values observed, may be explained by the effect of the exercise period on the peroxidation and reduction of glutathione and also on the synthesis and efflux of GSH. Red blood cells magnesium levels remained low after the training programme which is in accordance with other studies. Plasma zinc decreased during the programme could be related to the activated expression of antioxidant mechanisms after the training.

Preliminary study of the relationship between plasma and erythrocyte magnesium variations and some circulating pro-oxidant and antioxidant indices in a standardized physical effort.

The aim of this preliminary study was to determine the relationship between exercise, magnesium (Mg) status, oxidative stress, and antioxidant defence systems. Some corresponding indices have been evaluated: plasma Mg, ascorbate, uric acid, adrenaline, creatine kinase (CK), thiobarbiturate reactive substances, adrenochrome; and in erythrocytes (RBC): reduced and oxidized glutathione (GSH and GSSG) and Mg. Venous blood samples were withdrawn before and 3 min after completion of a 40 min run. Only two significant changes were observed after effort: plasma Mg decreased (P < 0.009) and plasma adrenaline increased (P < 0.005). There was a non-significant tendency for indices of oxidative stress and antioxidant capacity to increase. The significant correlations between plasma Mg and CK (r = -0.88) and between RBC Mg and plasma ascorbate (r = -0.76) disappeared after the effort. Further research is necessary, with a larger number of subjects and variables, to obtain a better understanding of these interactions.