Fast and Sensitive New High Performance Liquid Chromatography Laser Induced Fluorescence (HPLC-LIF) Method for Quinine. Comparative Study in Soft Drinks

Multifunctional Portable System Based on Digital Images for In-Situ Detecting of Environmental and Food Samples

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.

Comparison of column-coupled electrophoresis with liquid chromatography methods in food analysis of quinine

Comparison of column-coupled electrophoresis with liquid chromatography methods in food analysis of quinine (QUI) is presented in this work. The capillary isotachophoresis (CITP) on-line coupled with capillary zone electrophoresis (CZE) and hyphenated with fibre-based spectrophotometric diode array detection (DAD) was compared with, (i) high performance liquid chromatography (HPLC) method with DAD detection, and (ii) HPLC method with fluorescence detection (FD). These methods were compared through their performance parameters and determined concentrations of QUI in beverages. The concentrations of QUI in two selected bitter drinks determined by the CITP-CZE-DAD method were in a good accordance with the HPLC-DAD and HPLC-FD methods. In addition, the electrophoretic method, as well as the chromatographic methods, was able to separate potential QUI related impurities from the QUI peak. The CITP-CZE-DAD method provided excellent performance parameters that were comparable (precision, accuracy, LOD, robustness) or even better (separation efficiency) than those ones provided by the chromatographic methods. Moreover, the effectivity of the electrophoresis method was higher when considering cost of analysis (equipment, consumption of separation systems), environmental aspects (organicvs. aqueous solvents), on-line sample pretreatment (CITP preconcentration and sample clean-up suitable also for the more complex matrices). Considering these findings, CITP-CZE-DAD was approved as a routine automatized method for the highly reliable quality food control.