Supercritical fluid extraction as an on‐line clean‐up technique for determination of riboflavin vitamins in food samples by capillary electrophoresis with fluorimetric detection

Abstract

An automatic method for the separation and determination of riboflavin (RF) vitamins (RF, flavin mononucleotide and flavin adenine dinucleotide) in food samples (chicken liver, tablet and powder milk) is proposed. The method is based on the on-line coupling of a supercritical fluid extractor (SFE) with a continuous flow-CE system with guided optical fiber fluorimetric detection (CF-CE-FD). The whole SFE-CF-CE-FD arrangement allowed the automatic treatment of food samples (clean-up of the sample followed by the extraction of the analytes), and the direct introduction of a small volume of the extracted plug to the CE-FD system for the determination of RF vitamins. Fluorescence detection introduced an appropriated sensitivity and contributed to avoid interferences of nonfluorescent polar compounds coming from the matrix samples in the extracted plug. Electrophoretic responses were linear within the 0.05-1 microg/g range, whereas the detection limits of RF vitamins were in the 0.036-0.042 microg/g range. The proposed arrangement opens up interesting prospects for the direct determination of polar analytes in complex samples with a good throughput and high level of automation.

Bioanalytical Applications Using Supercritical Fluid Techniques

“…However, when the analytes are soluble in water, low recovery was obtained due to the losses produced when water was passed through the solidphase trap. The direct coupling of SFE with CE was described on two occasions [52,71]. In the first, Mardones et al developed a new interface to automate analyses by coupling a SF extractor online to a commercial capillary electrophoretic system, to integrate extraction with separation and detection [52].…”

“…In the first, Mardones et al developed a new interface to automate analyses by coupling a SF extractor online to a commercial capillary electrophoretic system, to integrate extraction with separation and detection [52]. In the second, Zougagh et al used a flow injection interface for coupling a SF extractor to a homemade CE for determination of vitamins in meat samples [71].…”

A review on analytical methods for the determination of natural colorants (green) in food commodities and beverages

“…The alternative analytical approach like biochemical fluorimetric technique with front-face light emission and biosensors based on surface plasma on resonance with on-chip measurement for the determination of riboflavin in milk is available also. Moreover, high-throughput planar chromatography with confirmatory electrospray LC-MS and supercritical fluid extraction, followed by capillary electrophoresis with fluorimetric detection were reported for energy drinks and milk [94].…”

Supercritical fluid extraction: Recent advances and applications

“…Some of these couplings have involved the use of SFE. For instance, SFE has been directly coupled to a CE instrument with fluorimetric detection to effectively carry out the clean-up of the sample and the direct CE analysis of riboflavin from chiken liver and powdered milk [45]. A scheme of the instrumentation employed can be seen in Figure 1.…”

“…Later on, the valve was again actuated releasing the extract to the capillary inlet. There, a certain amount was injected in the CE system and analyzed [45]. Nevertheless, this is not the only direct coupling developed in the last years.…”