We successfully transferred and applied -omics concepts to the study of material degradation, in particular historic paper. The main volatile degradation products of paper, constituting the particular “smell of old books”, were determined using headspace analysis after a 24 h predegradation procedure. Using methods of multivariate data analysis, we were able to quantitatively correlate volatile degradation products with properties important for the preservation of historic paper.
COBISS.SI-ID: 33296901
Five different isolation techniques were combined with gas chromatographic–mass spectrometric determination of aroma compounds from buckwheat: dynamic headspace (DHS) with cryotrapping or sorbent trapping, solid-phase microextraction (SPME), headspace sorptive extraction (HSSE), solvent extraction (SE) and simultaneous distillation–extraction (SDE). Only SPME with DVB/CAR/PDMS fibre was suitable for the isolation of highly volatile compounds in a wider polarity range. The applied isolation techniques are complementary in their ability to extract a representative aroma profile of buckwheat.
COBISS.SI-ID: 33728005
Volatile organic compounds (VOCs) play an important role in the chemistry of the atmosphere and in biogeochemistry. They contribute to the oxidative capacity of the atmosphere, particle and air pollutants, as well as to the production of greenhouse gasses (for instance ozone). Among analytical techniques for their determination in the atmosphere gas chromatography coupled with mass spectrometry (GC–MS) offers several advantages. However, for an accurate quantification calibration with standard substances is necessary. A quantitative structure– property relationship (QSPR) model for the prediction of MS response factors was developed on basis of our experimental measurements for the quantification of ozone precursors present in the atmosphere. A linear correlation between chemical structures and response factors was established by using a 7 parameter MLR model. The average error in the prediction of response factors was calculated by crossvalidation procedure and was below 20%, which is sufficient for the determination of VOCs in the air. The proposed procedure is time consuming so it is more suited for the quantification of tentatively identified organic compounds during the reprocessing of MS chromatograms in cases when the original sample is no longer available.
COBISS.SI-ID: 1448796
Single or multiple system peaks can be observed in ionexclusion chromatography (IEC) based on whether the eluent is composed of single or multiple active eluent constituents. It was confirmed experimentally that the number of system peaks is always equal to or lower than (when coelution occurs) the number of active eluent components. Positive and negative system peaks can be recorded in the IEC systems. Negative system peaks can be expected for each eluent component that is also present in the injected sample plug at a lower concentration than in the eluent. In the opposite case, where the eluent components in the injected sample plug are present at a higher concentration than in the eluent, positive system peaks will be recorded. The appearance of the system peaks in IEC is based on the column capacity which is analyte–depending. Variable column capacity was used to determine the absolute time window in which an individual system peak can be expected.
COBISS.SI-ID: 1609007
The mechanism of corrosion of copper was investigated in a wide potential window and in a broad range of concentrations of various species (0.2–3.5 mol/L NH3, 0–0.1 mol/L Cu2+, pH 10–12.5). Using conventional electrochemical methods in combination with an optical SEM method, we show that a two-step EC reaction yielding Cu2O proceeds. Finally, we confirm proposed mechanism by performing impedance analysis at various experimental conditions.
COBISS.SI-ID: 4152858