Conference Agenda

Alkyl substances, including normal alkanes and perfluorinated alkyl substances (PFAS), represent a challenging class of compounds to detect and identify due to their lack of polar functional groups, low reactivity, and presence in complex mixtures with numerous structural isomers. Mass spectrometry (MS) is a powerful tool for analyzing such compounds because it offers excellent selectivity andcan provide both elemental composition and structural information through fragmentation. However, the ionization of alkanes remains difficult, hindering the development of rapid and selective MS methods capable of fully exploiting MS’s potential.

Environmental analysis of polar alkyl substances is typically performed using electrospray ionization (ESI) MS and tandem MS (MSⁿ). Yet, the detectability and sensitivity for these compounds vary significantly, depending on their functional groups. Recent studies comparing total organofluorine content with compound-specific measurements reveal that most PFAS present in environmental samples are not detectable by conventional ESI-MS/MS. These undetected compounds are believed to be primarily non-polar, linear, or branched alkanes.

This study explores the application of atmospheric-pressure glow discharges, specifically the flowing atmospheric-pressure afterglow (FAPA), to chemically modify and thereby enable detection of non-polar compounds. The fundamental plasma chemistry of these ion sources was characterized using optical spectroscopy and MS to identify conditions favoring molecular transformation. For instance, the helium-based FAPA was used to convert normal alkanes into oxidized and unsaturated products via hydrogen loss. Offline analysis suggested that unsaturation and oxidation proceed via separate pathways with competing reaction rates.

In a separate experiment, FAPA was employed to functionalize and detect perfluorooctane (PFO), generating [M+O–F]⁻ ions for rapid MS detection. Accurate mass measurements and ion-optic parameter optimization enabled identification of reaction intermediates such as carboxylic acids. These insights allowed for the proposal of candidate reagent ions and reaction mechanisms based on MS² spectra. This plasma-based chemical modification approach offers a promising path toward expanding the detectability of PFAS and other non-polar compounds, enabling more comprehensive compositional analyses of environmental samples.

This presentation will focus on two different applications of an off-line and on-line separation method, coupled to either HPLC or LC-ICP-MS, for the study of aqueous suspensions of sediment or soil in contact with a target analyte. The method allows for a whole sediment or soil aqueous suspension (slurry) to be directly injected in a liquid chromatograph. A micro-extraction cell (developed in-house), positioned after the injection loop, is used to intercept the sediment/soil particles prior to the analytical column. This system can be used in a traditional HPLC setup or with hyphenated LC-ICP-MS. The off-line and on-line separation method allows the partitioning of the analyte into three compartments: dissolved phase, labile sorbed phase, and non-labile sorbed phase. Injection of the sample into the LC using a membrane filter (the off-line separation) allows for the separation and detection of dissolved phase species only. When the sample is injected without the membrane filter, the whole aqueous slurry goes into the micro-extraction cell in which the soil/sediment particles are intercepted (the on-line separation). During the on-line separation, the mobile phase acts as an extraction solvent which will carry the dissolved and extractable (labile sorbed) analytes onto the column for separation followed by detection of the combined dissolved and labile sorbed analyte phases. The non-labile fraction is determined by difference of total analyte amount minus the combined dissolved and labile sorbed analyte phases. Results from two separate studies will show how the target analytes are being distributed in the three above-mentioned compartments: dissolved phase, labile sorbed phase, and non-labile sorbed phase. The first study looks at the interaction between atrazine (a well-known pesticides) and an aqueous suspension of soil. The second study will show results from metal ions (Cu, Pb, Ni, Cd, Zn)-EDTA complexes in contact with an aqueous suspension of sediment.

Plastic waste pollution along coastal environments is a critical contributor to marine litter and a precursor to microplastic formation. Accumulated plastic debris in these zones not only threatens biodiversity but also acts as a primary source of long-term environmental contamination. This study explores the application of a ground-based hyperspectral imaging (HSI) system (DV Optics, Italy) for the detection and classification of plastic waste in sandy beach environments. The field trials were carried out at Torre Guaceto beach (Brindisi, ), located in a natural protected area along the Adriatic coast of the Apulia region (southern Italy). Hyperspectral images were acquired using a system working in the visible - near infrared spectral range (VIS–NIR: 400–1700 nm), enabling accurate differentiation of polymer types under natural lighting conditions. The proposed methodological framework includes in-field data acquisition, radiometric and spectral correction procedures and data-driven analysis for material discrimination in complex sandy environments. The results demonstrated the system’s effectiveness in identifying and classifying plastic debris, including items partially buried in sediment or obscured by vegetation. By capturing detailed spectral fingerprints of macroplastics, this approach provides a robust basis for tracing potential sources of microplastic formation, enabling early intervention and pollution mitigation. The integration of VIS–NIR information enhances detection reliability and supports the development of scalable, non-invasive tools for continuous environmental monitoring, particularly in ecologically sensitive coastal regions.

Growing environmental concerns have incited the search for environmentally and economically sustainable solutions to solid waste management challenges. The use of organic waste for compost production appears to be a viable management strategy, both at the industrial and community levels. This strategy reduces the weight and volume of waste while generating a valuable product. Compost is used as a fertilizer, and its application has demonstrated numerous benefits. These include enhanced water infiltration and retention, decreased temperature fluctuations, reduced erosion, increased biological activity, promotion of natural pest control, and increased availability of micronutrients (e.g. Cr, Cu, K, Mn) for crop sustenance and growth.

Energy dispersive X-ray fluorescence spectroscopy (EDXRF) is an analytical technique that offers several advantages, including the absence of sample preparation treatment, non-destructive analysis, and no requirement for calibration standards. However, due to its relatively high limits of detection and quantification compared to other techniques, the determination of micronutrients could be challenging.

In this work, the concentrations of Mn, Cr, Cu and K were evaluated to characterize compost from a micronutrient perspective. Compost samples were dried at 105ºC and then milled in a ball mill to achieve a 0.38 mm diameter. Analyses were performed using a Shimadzu EDX-7200 spectrometer equipped with a rhodium X-ray source. For quantification the fundamental parameters method was used. The analytical conditions were optimized using a representative compost sample. The best conditions found were: using an air atmosphere, with a 5 mm collimator diameter and a measure time of 100 s for all the analytes.

Limits of detection ranged from 1.0 to 2.6 mg kg^-1 and limits of quantification from 3.2 to 8.7 mg kg^-1. For this task, low concentrations of the analytes were added to carboxymethylcellulose. Precision (repeatability) as %RSD of 6 replicates of compost samples was less than 10% for all analytes. Trueness was evaluated using two different reference materials: soil and marandú (plant material) (Embrapa, Brasil), and spiked samples, with recoveries ranging from 77% to 117%.

Eight commercial compost samples were analysed. The elemental concentrations obtained were 8.27-13.73 mg kg^-1 for Cr, 21.24-27.69 mg kg^-1 for Cu, 5.65-8.63 mg kg^-1 for K and 388.63-632.50 mg kg^-1 for Mn.

The performance of the developed method was assessed by comparing results with those obtained by MIP OES (Cr, Mn), FAAS (Cu) and FAES (K) after microwave-assisted acid digestion. A Student’s t-test was applied, and all calculated t values were below the critical value (α = 0.05, n = 8), indicating no statistically significant differences between the proposed method and microwave acid digestion methods at the 95% confidence level.

The proposed method is simple, fast, and multielemental, without sample preparation treatment. Therefore, it aligns well with the principles of green analytical chemistry and provides reliable results for micronutrient determination in compost.