Low force stereolithography is exploited for the first time for one-step facile fabrication of chemiluminescence (CL) flow-through cells that bear unrivalled features as compared to those available through milling or blowing procedures or alternative 3D printing technologies. A variety of bespoke cross-section geometries with polyhedral features (namely, triangular, square, and five-side polygon) as well as semicircular cross-section are herein critically evaluated in terms of analytical performance against the standardcircular cross-section in a flat spirally-shape format. The idea behind is to maximize capture of elicited light by the new designs while leveraging 3D printing further for fabrication of (i) customized gaskets that enable reliable attaching of the active mixing zone of the CL cell to the detection window, (ii) in-line 3D-printed serpentine reactors, and (iii) flow confluences with tailorable shapes for enhancing mixing of samples with CL reagents. Up to twenty transparent functional cells were simultaneously fabricated without inner supports following post-curing and surface treatment protocols lasting less than 5 h. In fact, previous attempts to print spirally-shaped cells in one-step by resorting to less cost effective photopolymer inkjet printing technologies were unsuccessful because of the requirement of lengthy procedures (>15 days) for quantitative removal of the support material. By exploiting the phthalazinedione-hydrogen peroxide chemistry as a model reaction, the five-side irregular pentagon cell exhibited superior analytical figures of merit in terms of LOD, dynamic range and intermediate precision as compared to alternative designs. Computational fluid dynamic simulations for mapping velocities at the entry region of the spiral cell corroborated the fact that the 5-side polygon cross-section flow-cell with Y-type confluence permitted the most efficient mixing of reagents and sample while enabling larger flow velocities near the inlet that contribute to a more efficient capture of the photons from the flash-type reaction. The applicability of the 3D-printed 5-side polygon CL cell for automatic determination of hydrogen peroxide using a computerized hybrid flow system was demonstrated for the analysis of high matrix samples, viz., seawater and saliva, with relative recoveries ranging from 83 to 103%.

Vegetables are a rich source of macro and micronutrients. Particularly, potatoes and sweet potatoes are widely consumed and are two of the most important food crops in the world. Therefore, contamination of these products due to their content of inorganic contaminants is of great concern. Considering the healthy trend of consuming these tubers and roots with their skins, which are rich in fiber and other nutrients, analysis of the whole product could provide valuable information in relation to their food safety. Therefore, the presence of arsenic (As), cadmium (Cd) and lead (Pb) in peeled and whole potatoes and sweet potatoes was studied. To do so, analytical methods were optimized and validated according to the Association of Official Analytical Collaboration International (AOAC) requirements for food analysis. Although the content of As, Cd and Pb was in most cases more than three times below the maximum allowed levels for these contaminants, the presence of Cd was detected in the samples of whole sweet potato but not in the peeled ones. The same behavior was observed for Pb in most of the sweet potato samples analyzed. This information points to the need to generate information on the whole root and tuber contaminants content, and to have analytical methods available to gather data on the occurrence of these contaminants in the whole vegetable in order to perform their risk assessment according to the consumption habits.

A hydride generation nitrogen microwave induced plasma optical emission spectrometry (HG-MIP OES) system was developed for lead determination. Plumbane chemical generation was performed using 0.045 mol L⁻¹ K₃Fe(CN)₆ as the additive in acidic medium and 2.0% w/v NaBH₄ in 1% w/v NaOH as the reductant. The additivated sample and the reductant were pumped towards a cyclonic chamber where hydride generation and separation from the solution occurred. Operating conditions such as the additive and reductant concentration, sample, reductant and nitrogen flow-rate, the cyclonic chamber stabilization time and the viewing position in the torch were optimized. A meticulous study of the variation of the nitrogen plasma response as a function of the hydrochloric acid concentration was carried out. The analytical performance of the method was studied and its applicability evaluated in a Trace Element in Water Certified Reference Material and a Soil Reference Material. The method performance in terms of limits of detection and quantification (0.54 μg L⁻¹ and 1.8 μg L⁻¹ Pb, respectively) was found comparable to other atomic spectrometry techniques. This is to our knowledge the first research on the analytical performance of lead determination by PbH₄ generation and determination by MIP OES.

This work proposes the revaluation of honeys from the native flora of Uruguay. The results obtained in the pollen and physicochemical analysis allow us to conclude that it is possible to characterize and distinguish monofloral honeys produced from Uruguayan native flora, and that they also present interesting properties that make them stand out from the rest of the honeys. This could be a starting point for the exploitation of this market of little-known honeys with great nutritional potential.