The Analytical Development group is composed by researchers with established background in addressing real-life problems concerning quantification of small molecules in a plethora of matrixes. They combine expertise in Instrumental Methods of Analysis, Organic Chemistry, Chemometrics, and Chemical Engineering to develop new analytical solutions using preferably sustainable methods.
The Group focuses on modernization of analytical methods, developing innovative approaches towards reduction of reagents consumption, protection of work/lab environment, deployment of point-of-care/in situ analysis, and exploitation of technological developments from other areas, namely from mechanical and electronic engineering. To achieve these goals, research efforts will aim the miniaturization of devices and methods, the advanced data analysis through chemometrics, and the development of highthroughput methods mainly through intervention on sample preparation.
Innovative sample treatment
Multidimensional methods for total analysis
Greener analytical methods
- Automation for monitoring dynamic systems
Assessment of dynamic properties requires suitable, real-time methods because the target concentration will change along time. Automatic strategies were developed to evaluate the permeation of compounds through synthetic membranes or cell layers. In this scope, a low-pressure liquid chromatography system for the on-line quantification of caffeine loaded into lipid nanoparticles that permeates pig skin was proposed. The apparatus includes a Franz diffusion cell with computer-controlled sampling that allows collection of acceptor solution with automatic compensation for sample withdrawing, and a C-18 reversed-phase monolithic column where separation of caffeine from other matrix elements is performed before spectrophotometric quantification. Due to the real time automated sampling and high throughput, transdermal permeation profiles of nanoformulations can be established within a time frame seldom observed by conventional techniques.
- Targeting volatiles by gas-diffusion microextraction
Gas-diffusion microextraction (GDME) targets volatile and semi-volatile analytes present in liquid and solid samples. Its implementation is based on a dedicated device developed by LAQV researchers, where sample and acceptor fluids are separated by gas-permeable membranes. In fact, GDME is one of the few membrane-based techniques where solids are directly analyzed, without previous treatment or manipulation. The main advantage of this analytical proposal is the built-in capabilities for determination of labile fractions, surpassing reference methods. GDME is also amenable to direct coupling to different detectors (spectrophotometric, fluorimetric or electrochemical) as removal of most matrix interferences is performed in the extraction step and derivatization reagents can be added to the acceptor fluid.
- Sensors for real-life applications
Sensors based on electrochemical features are particularly tailored for real-life applications. They are adaptable to both field and lab conditions, providing almost immediate results and making them suitable for both point-of-care and screening analysis. T4, a thyroid hormone with many relevant roles in human metabolism, was determined with an antibody-based biosensor, consisting on a multi thiol self-assembled monolayer whereas anti-serpina7 polyclonal antibody was attached. Electroanalytical measurements were performed by impedance on a ferricyanide redox probe, achieving detection of target hormone above 4 ppb.
- Fast, non-invasive screening methods for industrial applications
Industry requires suitable tools for monitoring and quality control. Ideally, these tools should be noninvasive (to prevent contamination of production line, for instance) and non-destructive (to avoid economic losses from sampling for control purposes). Real-time capabilities and multi-parametric features are also sought. Infra-red spectroscopy methods offer suitable solutions for this field, as shown by several successful applications developed for pharmaceutical and food industries. A rapid and non-destructive methodology for assessing the potential of spent coffee grounds as a source of bioactive compounds was developed using near-infrared spectroscopy. High-throughput evaluation of three main phenolics (caffeic acid, (+)-catechin and chlorogenic acid) and three methylxanthines (caffeine, theobromine and theophylline) was implemented in spent coffee grounds samples obtained from different coffee brands and diverse coffee machines.
- Molecular imprinting for selective analysis
Molecular imprinting consists of preparing solid material where cavities are created by template molecules. After removal of the template, these cavities will have affinity to the template molecules or their analogues, rendering highly selective material. Their application to analytical development can follow two paths: (i) selective adsorbents for sample treatment prior to chromatographic analysis or (ii) selective recognition elements in sensors. The first approach was implemented for trace analysis of pesticide residues in olive oil, using a dual-layer cartridge packed with molecularly imprinted polymers targeting dimethoate and terbuthylazine.
- Innovative sample treatment coupled to chromatography for societal challenges
Current societal challenges demand access to more information regarding environmental conditions,health status, and commodities’ quality. This means a growing pressure on analysts, who have to deal with multicomponent analysis in complex samples, targeting low concentrations. In this context, sample is undeniably the bottleneck concerning analytical throughput and automation circumvents this problem. At-line automatic micro-solid phase extraction method for the determination of salivary cotinine followed by its analysis via hydrophilic interaction liquid chromatography was developed. Based on the bead injection concept incorporated in the mesofluidic lab-on-valve platform, all steps of solid-phase extraction procedure were performed without human intervention, providing a high-throughput method for evaluation of environmental tobacco exposure.