Comprehensive study of retention influencing gas chromatographic parameters affecting linear retention indices.

Retention in gas chromatographic systems has a central role in the identification of compounds even if detectors providing spectral information are used. But linear retention indices (LRI) of a single compound originating from multiple sources tend to vary greatly, probably due to differences in the experimental settings of the determinations. The effect of gas chromatographic parameters on LRI has been investigated using 41 compounds - previously identified from food contact plastics - and n-alkanes (n-C7-n-C40) used as reference series. As the reproducibility of LRIs under the same conditions is generally very good, the smallest changes in the settings often caused statistically significant, though irrelevant changes in the LRI values. Therefore, a multicriterial scoring-ranking system has been worked out to highlight the LRI value differences. Our results highlight that column length, heating rate, and film thickness can all be the reasons of the varying published LRI values. We also demonstrated that for the reproduction of LRI data, the chemistry (and not simply the polarity) of the stationary phase is crucial.

Long-term effects of grain husk and paper fibre sludge biochar on acidic and calcareous sandy soils - A scale-up field experiment applying a complex monitoring toolkit.

Biochar is produced from a wide range of organic materials by pyrolysis, specifically for improvement of poor quality soils. One of the main issues nowadays in studying biochar as soil amendment is to upscale experiments and move from short-term, laboratory conditions to long-term field trials. This paper presents a long-term field study, being the final step of a scale-up technology development, on grain husk and paper fibre sludge biochar application for soil improvement with focus on two degraded soil types of a temperate region. The effects of biochar on an acidic and a calcareous sandy agricultural soil were studied applying a complex approach including physico-chemical, biological and ecotoxicological methods. Our study demonstrated that the applied biochar had positive direct and indirect influences on the acidic sandy soil, but these effects were different in terms of extent and time. 30 t/ha biochar addition improved the pH of the acidic sandy soil by 24% and also increased significantly the nutrient concentrations (P2O5 by 68%, K2O by 11% and organic matter by 33%), and the water-holding capacity after 30 months. Furthermore, biochar addition improved also the microbiological activity and diversity in the acidic sandy soil. Biochar application did not induce any negative effects. Biochar had no toxic effect on the plants and the biochar-treated soil provided a more liveable habitat for soil living animals than the untreated acidic sandy soil. The favourable biochar-mediated influences on soil properties were manifested mainly in the acidic sandy soil, proving that the biochar-related advantages have to be verified for different soil types. The benefits of grain husk and paper fibre sludge biochar application in an acidic sandy soil were confirmed on the long term by the applied tiered approach.

Acidic sandy soil improvement with biochar - A microcosm study.

Biochar produced from a wide range of organic materials by pyrolysis has been reported as a means to improve soil physical properties, fertility and crop productivity. However, there is a lack of studies on the complex effects of biochar both on the degraded sandy soil physico-chemical properties and the soil biota as well as on toxicity, particularly in combined application with fertilizer and compost. A 7-week microcosm experiment was conducted to improve the quality of an acidic sandy soil combining variations in biochar types and amounts, compost and fertilizer application rates. The applied biochars were produced from different feedstocks such as grain husks, paper fibre sludge and wood screenings. The main purpose of the microcosm experiment was to assess the efficiency and applicability of different biochars as soil amendment prior to field trials and to choose the most efficient biochar to improve the fertility, biological activity and physical properties of acidic sandy soils. We complemented the methodology with ecotoxicity assessment to evaluate the possible risks to the soil as habitat for microbes, plants and animals. There was clear evidence of biochar-soil interactions positively affecting both the physico-chemical properties of the tested acidic sandy soil and the soil biota. Our results suggest that the grain husk and the paper fibre sludge biochars applied to the tested soil at 1% and 0.5 w/w% rate mixed with compost, respectively can supply a more liveable habitat for plants and soil living animals than the acidic sandy soil without treatment.

Migration of Tinuvin P and Irganox 3114 into milk and the corresponding authorised food simulant.

Migration of Tinuvin P (UV stabiliser) and Irganox 3114 (antioxidant) from high-density polyethylene (HDPE) was studied. HDPE pieces were soaked in either milk (1.5% or 3.5% fat content) or 50% (v/v) ethanol-water mixture - the food simulant for milk as specified in Regulation No. 10/2011/EC. The obtained extracts were analysed by LC-MS/MS. For statistical assessment variography was used. It proved to be a useful tool for making a distinction between the early migration range and the equilibrium, despite the variance of the data. Regulation No. 10/2011/EC specifies 10 days of contact time for milk at 5°C. Our experiments with the food simulant with 24 dm(2) kg(-1) surface/mass ratio showed that both Tinuvin P and Irganox 3114 need less than 1 h to reach equilibrium. Furthermore, 10-day experiments with daily sampling showed that these additives are stable in milk, as well as in the food simulant. The effect of the concentration of the additives in HDPE was studied in the 0.01-5% (m/m) range. For both Tinuvin P and Irganox 3114 and all three extractants the migrated amount became independent of the concentration of the additive in the HDPE approximately at 1% (m/m). For Tinuvin P the food simulant gave a close estimate for the milk samples. However, using the food simulant for modelling the migration of Irganox 3114 into milk gave an overestimation with a factor of minimum 3.5. In the case of Tinuvin P special care must be taken, since the recommended amount in the HDPE can result in additive concentrations near or even over the specific migration limit (SML). However, Irganox 3114 cannot reach the SML either in milk or in the food simulant.