Multianalyte analysis of volatile compounds in virgin olive oils using SPME-GC with FID or MS detection: results of an international interlaboratory validation

The organoleptic assessment (Panel test) is the only procedure within the official methods for determining the quality of virgin olive oils that involves an expert panel. There is an urgent need for analytical methodology that can reliably measure volatile compounds in virgin olive oils that is capable of supporting and anticipating the official Panel test. For this reason, a new method based on solid-phase microextraction–gas chromatography with the choice of two possible detectors (FID or MS) was subjected to a large international interlaboratory validation study. The study involved a two-stage process: first, a pretrial phase in which 7 participants were exposed to the method for the first time to identify any initial problems with the methodology; then, a formal validation stage (trial proper), which involved 20 laboratories from Europe, USA, Japan and China. The performance of the different detectors was investigated. While both methods have advantages, the method using FID provided better results for 11 compounds, in terms of reproducibility, compared to MS. This information will allow to implement the method with accurate information of the method performance depending on the detector used. Practical applications: This study provides information from an interlaboratory validation of a method for measuring volatile compounds in virgin olive oils conducted with laboratories (from industry and academia) working in the olive oil sector. The information on the expected analytical errors in the determination of each volatile compound is necessary to apply this method for supporting the official Panel test (sensory analysis). The SPME-GC-MS/FID methods proposed in this work can be used for the internal quality control of a company/distributor/quality control laboratory and could also be used in cases of difficult/contradictory organoleptic assessment, or to confirm results from sensory panels in cases of disputes/disagreement (Reg. EU 2022/2105)

Shear Strengthening of R/C Beams with FRP Strips and Novel Anchoring

Abstract The shear strengthening behaviour of R/ C beams, when applying FRP strips externally with or without anchoring, is studied. This is done by subjecting six specimens of prototype dimensions with or without such strengthening to four-point bending. Specimens strengthened with either carbon or steel FRP strips without the use of anchors exhibited a modest increase in shear capacity, when co mpared to the non-strengthened control specimen, due to the debonding mode of failure of these FRP strips. The patented anchoring device was utilized together with either carbon or steel FRP strips for shear strengthening. In this case, the FRP strips debonding failure was prevented and the increase of the shear capacity was much larger than in identical specimens without anchors. An expert system developed for this purpose is quite efficient in producing successful shear capacity predictions based on the provisions of various codes. The Greek Code for ret rofitting existing R/ C structures yields shear capacity predictions in good agreement with measured values

Investigation of cell-level potential-induced degradation mechanisms on perovskite, dye-sensitized and organic photovoltaics

The study focuses on the effect of bias voltage degradation or Potential Induced Degradation (PID) on the efficiency of perovskite (PSCs), dye-sensitized (DSSCs) and organic (OPVs) solar cells. For the PID study, voltage-depended and time-depended degradation tests have been carried out at solar cell level; the cells were fabricated and tested in the same conditions. Furthermore, the solar cells were exposed to both, annealing and cooling tests in order tp highlight the various PID characteristics. Thus, the mechanisms induced during the PID degradation were thoroughly investigated. Results revealed that DSSCs are far more vulnerable to voltage degradation than other solar cell technologies. The current work illustrates that OPV solar cells can be considered as voltage durable compared to PSCs and DSSCs ones. OPV solar cells lost 23% of their initial efficiency whereas PSC and DSSC cells were entirely degraded after the application of 5.5 V and 2.5 V voltage respectively. Furthermore, in contrast to OPV, DSSCs and PSCs did not exhibit charging effect when a 5 V voltage was applied. © 2019 International Solar Energy Societ