Browsing by Author "Machado, Ana"
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- Amostragem inteligente como abordagem expedita para monitorização de iões de metal em águas naturais: projeto Aqua_SmartPublication . Pereira, Mafalda G.; Melo, Maria M. P.; Mesquita, Raquel B. R.; Ribas, Tânia C. F.; Machado, Ana; Rangel, António O. S. S.
- Amostragem inteligente como abordagem expedita para monitorização de iões de metal em águas naturais: projeto Aqua_SmartPublication . Pereira, Mafalda G.; Melo, Maria M. P.; Mesquita, Raquel B. R.; Ribas, Tânia; Machado, Ana; Rangel, António O. S. S.O projeto Aqua_Smart (FCT ref. 2022.08713.PTDC) foi concebido com o objetivo de desenvolver um conceito de amostragem inteligente integrada numa monitorização automática do teor de iões potencialmente tóxicos em águas, permitindo monitorizar alterações ambientais que podem ter impacto na saúde pública, promovendo uma abordagem “One Health”. Neste trabalho reporta-se a utilização de uma PIM como suporte de troca aniónica, explorando a tendência para formar cloro complexos de cobalto, permitindo a determinação deste ião. Neste enquadramento, tornou-se relevante combinar com a determinação do teor em anião cloreto, usando um reagente colorimétrico de baixa toxicidade.
- António Carneiro's painting collection from the municipality of Oporto. Study and conservation in the 150th anniversary of the painter's birthPublication . Barata, Carolina; Cabral, Ana; Aguiar, Maria; Castro, Laura; Machado, Ana; Cardoso, Ana; Valadas, Sara; Piorro, LuisThis paper presents a summary of the results obtained in the first approach ever made to the characterization of the materials and techniques used in the oil painting production by António Carneiro (1872–1930), one of the best portuguese painters in the transition from the 19th to the 20th centuries. A selection of ten oils on canvas belonging to the Municipality of Oporto were analysed using a set of non-invasive techniques: Infrared Reflectography, Ultraviolet Fluorescence Photography, X-ray Fluorescence Spectrometry, Fiber Optics Reflectance Spectroscopy and Fourier Transform Infrared Spectroscopy. The results obtained suggest the use of materials and techniques established in Europe at the turn of the century. The palette is composed of Pb, Zn, Hg, Cr, Cd, Cu, and Co-based pigments, associated with both traditional and recently introduced materials. The great missing element is Ti, associated with Titanium White, available on the market since 1918.
- Assessment of the impact synthetic Fe(III)-chelates amendment in soil microbial community dynamicsPublication . Machado, Ana; Mesquita, Letícia S.; Rangel, Maria; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Bordalo, Adriano A.
- Assessment of the impact synthetic Fe(III)-chelates amendment in soil microbial community dynamicsPublication . Machado, Ana; Mesquita, Raquel B. R.; Mesquita, Letícia S.; Rangel, Maria; Rangel, António O. S. S.; Bordalo, Adriano A.Background Iron has a crucial role in plant nutrition, being an essential element for plant growth. However, one-third of the Earth soil is iron deficient, resulting in iron deficiency chlorosis (IDC) growth of several crops worldwide, including staple foods. The use of synthetic Fe(III)-chelates is one of the most effective measures to correct IDC in plants, but their environmental impact must be mastered. Therefore, the search for more effective Fe-chelates remains an important issue. Previously [1], a 3,4-HPO Fe-chelate was proposed as a novel-fertilizing agent. Since the increase of nutrients availability in soil is thought to have an impact on the microbial composition, this question needs to be addressed. Therefore, the aim of the study was to investigate the effect of iron complexes of the 3,4-HPO class of ligands on soil bacterial dynamics to better understand their pathways. Method Laboratory scale soil columns (LSSC) were set up, with different soils origin and characteristics (Agricultural, Forestry and Urban), and exposed to two iron-chelates using rain simulations. The structure and abundance of the bacterial community was evaluated by automated ribosomal intergenic spacer analysis (ARISA) and qPCR (rpoB) approaches. Results & Conclusions Cluster analysis of ARISA profiles revealed that the soil characteristics were the major driving selection for the microbial community composition, with the samples from the same soil type clustering together, disregarding the amendment performed. Also, it emerged that the microbial community of forestry and agricultural soils were more similar (46%) than the one present in urban soil, as expected due to the plant influence. Considering each soil type individually, it was possible to observe a clear response to Fe(III) amendment on the microbial assemblage. Additionally, it seems that one of the compounds, the Fe-chelate derived from the ligand Deferiprone, induced greater and/or faster changes, and that the forestry soil was more prone to the microbial shift. These changes can underline a selection for bacteria that can use Fe(III) in its metabolism, or more tolerant to its presence, that needs to be better understood.
- Can non-fortified marine salt cover human needs for iodine?Publication . Lobato, Carolina B.; Machado, Ana; Mesquita, Raquel B. R.; Lima, Lurdes; Bordalo, Adriano A.Iodine deficiency remains a worldwide problem with two billion individuals having insufficient iodine intake. Universal salt iodisation was declared by UNICEF and WHO as a safe, cost-effective, and sustainable way to tackle iodine deficiency. In Portugal, the few studies available unravel an iodine status below the WHO guidelines for pregnant women and school-aged children. In the present study, the iodine levels of household salt consumed in Portugal was assessed, for thefirst time. Non-iodised (median 14ppm) and fortified (median 48 ppm) marine salt samples showed iodine levels lower than the minimum and above the maximum threshold recommended by non-mandatory Portuguese law and WHO recommendations, respectively. This study calls attention to the fact that marine salt per se, in spite of containing a natural high amount of iodine, requires further fortification in order to be used as an effective tool to deal with iodine insufficiency.
- Development of a noninvasive technique for the monitoring glucose levels in saliva by sequential injection determinationPublication . Machado, Ana; Maneiras, Rui; Bordalo, Adriano A.; Mesquita, Raquel B. R.
- Development of a robust, fast screening method for the potentiometric determination of iodide in urine and salt samplesPublication . Machado, Ana; Mesquita, Raquel B. R.; Oliveira, Sara; Bordalo, Adriano A.In this work, a potentiometric flow injection method is described for the fast bi-parametric determination of iodide and iodate in urine and salt samples. The developed methodology aimed for iodine speciation with a potentially portable system (running on batteries). The iodate reduction to iodide was effectively attained in line within the same manifold. The iodide determination was accomplished in the dynamic range of 2.50×10−6– 1.00×10−3 M and the total iodine dynamic range, resulted from iodide plus iodate, was 3.50×10−6– 2.00×10−3 M. The calculated limits of detection were 1.39×10−6 M and 1.77×10−6 M for iodide and iodate, respectively. A determination rate of 21 h−1 for the bi-parametric iodide and iodate determination was obtained for sample injection. The urine samples (RSD < 5.8% for iodide and RSD < 7.0% for iodate) results were in agreement with those obtained by the classic Sandell-Kolthoff reaction colorimetric reference procedure (RD < 7.0%) and standard samples from Centers for Disease Control and Prevention, Atlanta, USA (CDC) international inter-laboratory EQUIP program. The developed flow method was also successfully applied to the iodide and iodate determination in salt samples (RSD < 3.1% for iodate and iodide), with comparable results to conventional procedures. No significant interferences were observed interference percentage < 9% for both determinations.
- Disposable microfluidic paper-based device for on-site quantification of urinary creatininePublication . Melo, Maria M. P.; Machado, Ana; Rangel, António O. S. S.; Mesquita, Raquel B. R.In this work, a new microfluidic paper-based analytical device (µPAD) was developed for on-hand creatinine quantification in urine samples. When compared to conventional methods, this innovative paper device is more accessible and portable, it provides low-cost analysis (cost of consumables of 40 cents), and it is applicable to non-invasive biological fluids. Furthermore, the paper-based approach is used within an environmentally friendly assembly with no need for wax printing and small amounts of reagents resulting in low waste production and easy disposal by incineration. Its assembly method includes cutting paper discs arranged into several reading units within a plastic pouch, enabling effective creatinine quantification with accuracy based on a vertical flow approach. The method is based on the colourimetric reaction between creatinine and alkaline picric acid, where the solution colour changes from yellow to orange/red. Under optimal conditions, the developed method allowed creatinine quantification in the dynamic range of 2.20–35.0 mg/dL, with a limit of detection (LOD) of 0.66 mg/dL and a limit of quantification (LOQ) of 2.20 mg/dL. The colour intensity developed was processed in ImageJ software, based on digital image scanning, performed in 20 min (up to 4 h) after the sample insertion. The device is stable for up to one week when stored in a vacuum at 4 °C. The method was validated by comparing the results with a batch-wise procedure, where there were no statistically significant differences between both methods.
- A greener alternative for inline nitrate reduction in the sequential injection determination of NOx in natural waters: replacement of cadmium reduction by UV radiationPublication . Machado, Ana; Marshall, Graham; Bordalo, Adriano A.; Mesquita, Raquel B. R.The use of sequential injection analysis (SIA) for key nutrient determination in water has been previously described using a copperised cadmium column to attain nitrate reduction to nitrite prior to determination, yielding hazardous waste. Here, a greener alternative is proposed for nitrate reduction using a UV lamp, aiming to avoid the use of cadmium. This method was based on the colorimetric Griess reaction for nitrite determination, after the UV reduction of nitrate. The reduction was performed inline during the determination of nitrite, minimizing both effluent production and the overall determination rate. Its application to natural waters, namely river water, proved to be effective as the results were comparable to those obtained with the reference procedure. Furthermore, certified reference samples were analysed, and an average of 3% relative deviation was observed. A limit of detection of 5.30 mM was achieved, enabling the nitrate determination in the dynamic range of 25-500 mM with a determination rate of 24 h(-1), and with a recovery percentage rate around 100%.