Development of a flow amperometric enzymatic method for the determination of total glucosinolates in real samples

An origami paper-based electrochemical biosensing platform for quality control of agri-food waste in the valorization strategy

The increasing demand for food and the need for a sustainability vision in the agri-food sector have boosted novel approaches for food management, enhancing the valorization of wastes and by-products belonging to the food industry. Herein, we present a novel paper-based origami device to assess the amount of both glucosinolate and glucose in a food waste product belonging to Brassicaceae plants, to evaluate the quality value and the correct management of waste samples. The device has been designed as an origami paper-based platform constituted of two paper-based biosensors to work synergistically in a multiplexed detection. In detail, a monoenzymatic biosensor and a bienzymatic biosensor were configured for the detection of glucose and glucosinolates, respectively, using filter paper pads preloaded with glucose oxidase and/or myrosinase. To complete the paper-based platform, the enzyme-preloaded pads were combined with office paper-based electrodes modified with Carbon black/Prussian Blue nanoparticles for the measurement of enzymatic by-product at a low applied potential (i.e., 0 V versus Ag/AgCl). Overall, this paper-based platform measured glucose and glucosinolate (i.e., sinigrin) with a linear range up to 2.5 and 1.5 mM, and detection limits of 0.05 and 0.07 mM, respectively. The repeatability corresponded to an RSD% equal to 5% by testing 10 mM of glucose, and 10% by testing 1 mM of sinigrin. The accuracy of the developed multiplex device was evaluated by recovery studies at two different levels of sinigrin, i.e., 0.25 and 0.5 mM, obtaining recoveries values equal to (111 ± 3) % and (86 ± 1) %, respectively. The multiplex detection of both glucose and glucosinolate in Brassicaceae samples evaluates the quality values of the waste sample, ensuring the quality of the re-used food product waste by using an eco-designed analytical tool. The combination of paper-based devices for quality control of food waste with the re-use of these food products represents a sustainable approach that perfectly matches sustainable agrifood practices as well as the overall approach of the circular economy.

Direct quantitation of glucoraphanin in dog and rat plasma by LC-MS/MS

A rapid method to quantify levels of the beta-thioglycoside N-hydroxyl sulfate, glucoraphanin, in dog and rat plasma to support pre-clinical toxicological and pharmacological studies has been developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glucoraphanin was extracted from plasma by protein precipitation with acetonitrile and separated via hydrophilic interaction liquid chromatography (HILIC) using a Luna 5microm Silica (2) 100A column (50mmx2.0mm) at a flow rate of 0.3mL/min. Solvent A consisted of 200mM ammonium acetate and formic acid (99:1, v/v) and Solvent B was acetonitrile. Initial conditions (90% Solvent B) were held for 0.01min after injection, decreased to 40% in 0.5min and held constant for 2.5min, returning to initial conditions for 3min (reequilibration time). Glucoraphanin was detected by MS/MS using a turbo ion spray interface as the ion source operating in negative ion mode. Acquisition was performed in multiple reaction monitoring mode at m/z 435.8-->96.7. The method was validated for the calibration range 10-2000ng/mL. Within- and between-run precision for the low, mid and high QC levels was 8% R.S.D. or less and accuracy ranged from 100 to 113%. The lower limit of quantification was 10ng/mL; calibration curves encompassed the range of plasma concentrations expected to be found in bioavailability and pharmacokinetics studies with glucoraphanin. The method has successfully been applied to the determination of glucoraphanin in dog and rat plasma and should be extendable to other species as well.

Microchip analysis of plant glucosinolates

We describe a new and selective analytical method for the separation and quantitation of plant glucosinolates. The new method, which utilizes microchip CE (micro-CE) with fluorescence detection, circumvents the multistep procedures characteristic of conventional methods. Glucosinolates form charge transfer complexes with the xanthene dyes phloxine-B and eosin-B. The glucosinolates-phloxine-B complex cannot be excited at 470 nm. Thus, the decrease in peak intensity of phloxine-B after complex formation is used to quantitatively measure total glucosinolates in Arabidopsis thaliana seeds. For qualitative analysis, complex formation with eosin-B is used. The sensitivity of eosin-B detection at excitation/emission 470 nm/540 nm was low. However, sensitivity increased following complex formation with sinigrin (> or =3 microg/mL). A batch-learning, self-organizing map was applied to visualize and organize analytical data into 2-D matrix with similar and related data clustered together or near each other. This organized matrix was used to optimize electrophoretic conditions for the analysis. This study suggests potential applications of micro-CE in plant metabolomics analyses without use of labeling fluorophores.

Determination of glucosinolates in traditional Chinese herbs by high-performance liquid chromatography and electrospray ionization mass spectrometry

A reversed-phase HPLC method has been developed for determination of twelve intact glucosinolates--glucoiberin, glucocheirolin, progoitrin, sinigrin, epiprogoitrin, glucoraphenin, sinalbin, gluconapin, glucosibarin, glucotropaeolin, glucoerucin, and gluconasturtiin--in ten traditional Chinese plants. The samples were extracted with methanol and the extracts were cleaned on an activated Florisil column. A mobile phase gradient prepared from methanol and 30 mmol L(-1) ammonium acetate at pH 5.0 enabled baseline separation of the glucosinolates. Glucosinolate detection was confirmed by quadrupole time-of-flight tandem mass spectrometric analysis in negative-ionization mode. Detection limits ranged from 0.06 to 0.36 microg g(-1) when 5 g of dried plant was analyzed. Recoveries of the glucosinolates were better than 85% and precision (relative standard derivation, n = 3) ranged from 5.3 to 14.6%. Analysis of the glucosinolates provided scientific evidence enabling differentiation of three pairs of easily confused plants.