NON-INVASIVE NEAR-INFRA RED SPECTROSCOPIC TECHNOLOGY FOR EARLY PREDICTION AND OPTIMIZATION OF WINE QUALITY

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Review on recent applications of the liquid waveguide capillary cell in flow based analysis techniques to enhance the sensitivity of spectroscopic detection methods

Publication . Páscoa, Ricardo N.M.J.; Tóth, Ildikó V.; Rangel, António O.S.S.

Incorporation of long path length liquid waveguide capillary cell (LWCC or LCW) into spectrometric detection systems can increase the sensitivity of these by orders of magnitude (up to 500 times), and consequently can reduce the detection limits. The combination of the long path length spectrophotometry with flow methodologies can provide analytical solutions for various challenges in the field of environmental, biochemical and food chemistry. In this present work, the analytical applications of the long capillary cells are summarised and critically discussed. A historical overview of the cell development is given; applications in different areas are presented and grouped by analyte type. Major improvements achieved based on the use of the LWCC in the analytical characteristics (like sensitivity and detection limit) are emphasised while some of the limitations are also discussed.

2012Journal article

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In-line monitoring of the coffee roasting process with near infrared spectroscopy: Measurement of sucrose and colour

Publication . Santos, João Rodrigo; Viegas, Olga; Páscoa, Ricardo N. M. J.; Ferreira, Isabel M. P. L. V. O.; Rangel, António O. S. S.; Lopes, João Almeida

In this work, a real-time and in-situ analytical tool based on near infrared spectroscopy is proposed to predict two of the most relevant coffee parameters during the roasting process, sucrose and colour. The methodology was developed taking in consideration different coffee varieties (Arabica and Robusta), coffee origins (Brazil, East-Timor, India and Uganda) and roasting process procedures (slow and fast). All near infrared spectroscopy-based calibrations were developed resorting to partial least squares regression. The results proved the suitability of this methodology as demonstrated by rangeerror- ratio and coefficient of determination higher than 10 and 0.85 respectively, for all modelled parameters. The relationship between sucrose and colour development during the roasting process is further discussed, in light of designing in real-time coffee products with similar visual appearance and distinct organoleptic profile.

2016-03-30Journal article

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Flow-injection spectrophotometric determination of bromate in bottled drinking water samples using chlorpromazine reagent and a liquid waveguide capillary cell

Publication . Tóth, Ildikó V.; Santos, Inês C.; Azevedo, Cláudia F. M.; Fernandes, Jorge F. S.; Páscoa, Ricardo N. M. J.; Mesquita, Raquel B. R.; Rangel, António O. S. S.

In this work, aiming to develop a simple, inexpensive method for the determination of low bromate levels in water samples, a liquid waveguide capillary cell (LWCC) was coupled to a FIA system. The long optical path (100 cm) of the LWCC was used to improve the sensitivity and the limit of detection without resorting to any off-line or in-line preconcentration processes. The spectrophotometric determination was based on the oxidation of chlorpromazine by bromate in an acidic medium, resulting in the formation of a colored radical product. Sulfamic acid was added to the reagent for minimizing the interference of nitrite, and a chelating ion exchange resin was used to remove major cationic interferences. The developed system allowed the determination of bromate within the range between 1 - 20 mu g L-1 with a detection limit of 0.2 mu g L-1.

2013Journal article

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