1. Introduction of a spectrophotometric method for salivary iodine determination on microplate based on Sandell-Kolthoff reactionAdrijana Oblak, Jernej Imperl, Mitja Kolar, Gregor Marolt, Blaž Krhin, Katja Zaletel, Simona Gaberšček, 2024, original scientific article Abstract: Background. Iodine is an essential element for the synthesis of thyroid hormones. Therefore, a reliable marker of iodine supply is important. Iodine is predominantly excreted via kidneys, but also via salivary glands. Our aim was to introduce a new and simple method for determination of salivary iodine concentration (SLIC). Materials and methods. Self-prepared chemicals and standards for Sandell-Kolthoff reaction on microplate with ammonium peroxydisulfate (AP) in the range 0−400 µg/L were used. Suitability of water-based standards (WBS) and artificial saliva-based standards (ASS) for standard curve were tested. We followed standards for method validation, defined concentration of used AP and compared our results with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results. WBS gave more reliable results than ASS as an underestimation of iodine concentration was found for ASS. LoB was 6.5 µg/L, LoD 12.0 µg/L, therefore analytical range was 12−400 µg/L. Intra- and inter-assay imprecisions at iodine concentrations, namely 20, 100, 165, and 350 µg/L were 18.4, 5.1, 5.7, and 2.8%, respectively, and 20.7, 6.7, 5.1, and 4.3%, respectively. Suitable molarity of AP was 1.0 mol/L and showed no difference to 1.5 mol/L (P values for samples with concentration 40, 100, and 150 µg/L, were 0.761, 0.085, and 0.275, respectively), whereas there was a significant change using 0.5 mol/L (P<0.001). Saliva samples could be diluted up to 1:8. There was no interference of thiocyanate and caffeine up to 193.5 mg/L. Our original method was comparable to ICP-MS. Spaerman coefficient was 0.989 (95% CI: 0.984−0.993). Conclusions. The new method for SLIC determination is in excellent agreement with ICP-MS and easy-to-use.
Keywords: iodine, salivary iodine concentration, Sandell-Kolthoff reaction
Published in DiRROS: 26.06.2026; Views: 259; Downloads: 178
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2. An advanced miniature fluidic system in multilayer ceramic technology with precise temperature and flow control for in situ pollution monitoringDanjela Kuščer, Barbara Repič, Kostja Makarovič, Maksimiljan Dekleva, Gregor Marolt, Helena Prosen, Darko Belavič, 2024, original scientific article Abstract: Rapid, on-site, water-quality monitoring is necessary to prevent and remediate environmental pollution. This study aims to develop a miniature, portable, fluidic system (MFS) designed for the easy insertion of disposable, screen-printed electrodes (SPEs) and the measurement of an electrochemical response (EC) under controlled temperature and flow conditions. The three-dimensional MFS, realised in low-temperature, cofired ceramic and multilayer ceramic technology, consist of three distinct cavities, each with separate inlet and outlet channels. These channels are designed to maintain an equivalent flow rate across all three cavities. The MFS allows simultaneous measurements at three measuring sites, temperature control of the fluid from room temperature to 125 °C via integrated heaters and temperature sensors, and flow regulation up to 20 mL/min via an external fluid pump. The EC values obtained from the SPEs in a standard solution of potassium ferrocyanide/potassium ferricyanide at room temperature and under stagnant conditions were consistent with measurements conducted in the MFS, droplet and conventional electrochemical cells, confirming the accuracy and reliability of the MFS. The EC response was confirmed in the MFS under flow conditions of 4 mL/min and temperatures of 25 °C, 35 °C, and 45 °C. This shows that multilayer ceramic technology enables the fabrication of a miniature, three-dimensional MFS with integrated fluidic and electronic components that provide reliable and accurate electrochemical measurements using a commercial SPE under controlled flow and temperature conditions.
Published in DiRROS: 23.10.2025; Views: 657; Downloads: 378
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4. Carbon-based thick films for electrochemical detection of neonicotinoid insecticidesBarbara Repič, Gregor Marolt, Danjela Kuščer, 2025, original scientific article Abstract: Neonicotinoids (NNIs) are water-soluble, toxic, widespread-used systemic insecticides commonly found in the environment. Integrated electrochemical sensors enable the rapid on-site detection of NNIs in aqueous samples by analysing the reduction of the NNI's nitro functional group on the working electrode. We have investigated graphite (G), glassy carbon (GC) and carbon black (CB) thick films as working electrodes for the electrochemical detection of the NNI imidacloprid (IMD). Up to 35-μm-thick films of G, GC and CB on alumina were prepared by screen printing and subsequent firing at 850 °C in argon. G had the largest grain size, the roughest surface, and the lowest sheet resistance of 6.9 Ω/sq. GC and CB had a smoother surface, while their sheet resistances were up to 27 Ω/sq. All three films showed a reversible response to the Fe(CN)63−/4− redox probe with G having the highest electrochemically active surface area and the highest heterogeneous electron transfer rate constant. In the IMD solution with neutral pH, G, GC and CB exhibited characteristic reduction peak at −1.1 V and a re-oxidation peak at +0.2 V. An additional adsorption cathodic peak was observed with CB, indicating a significantly higher affinity of CB for IMD adsorption. With LODs under 1 μM, the G, GC and CB pristine thick films exhibiting great potential for the sensitive detection of IMD
Published in DiRROS: 23.10.2025; Views: 673; Downloads: 251
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5. Microplastics from cigarette filters : comparative effects on selected terrestrial and aquatic invertebratesAndraž Dolar, Branka Mušič, Tina Skalar, Gregor Marolt, Damjana Drobne, Andrijana Sever Škapin, Anita Jemec Kokalj, 2025, original scientific article Abstract: Cigarette filters comprise plasticised cellulose acetate, a synthetic polymer categorized as bioplastic. They represent a significant source of microplastics (MPs), in particular microfibers, and associated chemicals, yet their impact on organisms, especially soil invertebrates, is not well-studied. This research examines the effects of MPs milled from smoked (SCF-MPs) and unsmoked cigarette filters (UCF-MPs) on terrestrial invertebrates (Porcellio scaber, Tenebrio molitor) and aquatic invertebrates (Daphnia magna, Brachionus calyciflorus). SCF-MPs and UCF-MPs were found to be 9.06 ± 4.1 μm and 12.71 ± 6.82 μm in size, respectively. Both samples contained triacetin and potentially toxic metals, while SCF-MPs also contained nicotine and a larger number of trace organic compounds. While exposure to SCF-MPs or UCF-MPs (up to 1.5 % MPs, w/w in soil) did not affect the survival of either terrestrial invertebrate, several physiological responses were observed. These included changes in immune parameters, energy-related biomarker levels, and altered glutathione S-transferase and acetylcholinesterase activities. Both types of MPs were acutely toxic to aquatic invertebrates, reducing the survival rates of B. calyciflorus (10 mg L−1 of either particle after 48h exposure) and D. magna (100 mg L−1 of SCF-MPs after 48h exposure). SCF-MPs generally caused more pronounced effects than UCF-MPs. This study highlights the need for effective environmental management to address both smoked and unsmoked cigarette filters.
Keywords: cigarette buts, cigarette filters, microfibers, crustaceans, insects, rotifers
Published in DiRROS: 09.05.2025; Views: 1053; Downloads: 932
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