## 3 Results and Discussion
Most of the relative standard deviations (RSD) were less than 15%, with the exception of SLB resin for the removal of the more volatile aldehydes (isobutyraldehyde, 2-methylbutanal and 3-methylbutanal) at both levels of SO\({}_{2}\). The removal percentages obtained were relevant. For isobutyraldehyde, they reached 22%, except for SXAW resin where a significant increase (\(p\) = 0.03) was observed at higher levels of SO\({}_{2}\). For 2-methylbutanal, the decrease ranged from 0.2 to 47%. Nearly all the resins showed significant reductions in their amounts of 3-methylbutanal and methional compared to the control for both SO\({}_{2}\) levels (Table 5) achieving elimination percentages up to 46% and 43%, respectively. Phenylacetaldehyde increased its concentration after 24 h in contact with the scavengers. This type of resin cannot remove phenylacetaldehyde at all, and at the end of the process the concentration of aldehyde has increased. Two possible options are considered to explain this fact:  
(a) Some nucleophile that is present in the resin reaches to break stable adducts (adducts that the method of determination of total aldehydes using glyoxal is not able to break). (b) Another possibility will be that some trace contaminant, such as the amino acid phenylalanine, has been transferred from the resin and if there are \(\alpha\)-dicarbonyls present in the medium, the Strecker reaction has occurred. Notwithstanding, phenylacetaldehyde showed good elimination results using mixed mode resins such as MAX, SXA and SXAW (Table 5). These resins achieved removal percentages higher than 68% for the two sulphur dioxide levels. These types of resins have aromatic rings in their structures that would stabilize with the phenylacetaldehyde reaction. In addition, they have a large pore size (73-98 A) and specific surface area (727-889 m\({}^{2}\)/g), making the reaction with phenylacetaldehyde, which is a voluminous molecule, more favourable. However, pure anion exchange resins exhibit less removal for this compound. Acetaldehyde exhibited removals up to 20% with DOW pure anion exchange resin. These removal percentages are very high if we compare with previous works where the concentration of total acetaldehyde did not change significantly, when an ionic exchange in column was applied to a wine of the Auren variety in order to improve its colour [36]. Briefly, the resins that are repeated more times with significant differences, with respect to the control for all aldehydes (Table 5), are principally DOW and SXA for both SO\({}_{2}\) levels. Furthermore, by increasing the SO\({}_{2}\) level, the formation of hydroxyalkylsulfonates would be favoured and, in principle, a greater reducing effect of the pure and mixed mode ion exchange resins would be expected. Nevertheless, data show that only the removal of acetaldehyde has been significantly favoured with the pure ion exchange resins DOW (\(p\) = 0.017) and IRA (\(p\) = 0.018). In the case of phenylacetaldehyde, a greater reduction was also found due to the effect of sulphur dioxide in the DOW resin (\(p\) = 0.05). The existence of significant effects only for these two aldehydes may be due to the fact that acetaldehyde is the most reactive compound with SO\({}_{2}\)[9], and although the formation constant of the adduct with methional is greater than that of phenylacetaldehyde (50 \(\times\) 10\({}^{3}\) versus 17 \(\times\) 10\({}^{3}\)[10]), the phenylacetaldehyde adduct could be stabilized on the aromatic ring structures of mixed resins.