Determination of synthetic cannabinoids in oral fluids by liquid chromatography with fluorescence detection after solid-phase extraction.

Synthetic cannabinoids are one of the most consumed new psychoactive substances, being absolutely necessary the development of analytical methodologies for the determination of these substances in biological fluids. In this study, a liquid chromatography with fluorescence detection (LC-FD) method has been developed for the analysis of 8 synthetic cannabinoids in oral fluids. The method has been validated in terms of linearity, precision and extraction recoveries, giving limits of detection as low as 0.7 µg L-1, and limits of quantification of 2.6 µg L-1. Different silica and polymeric commercial solid sorbents such as C18, Supel-Select HLB, EB2 ExtrabondⓇ and SampliQ-OPT were tested, concluding that Supel-Select HLB provided quantitative recoveries for the extraction of synthetic cannabinoids in oral fluids.•Analysis of synthetic cannabinoids in oral fluids.•Analytical procedure based on liquid chromatography with fluorescence detection.•Sample treatment based on solid phase extraction with HLB cartridges.

Combining microfluidic paper-based platform and metal-organic frameworks in a single device for phenolic content assessment in fruits.

A microfluidic paper-based device (µPAD) has been combined with metal-organic frameworks (MOFs) for total phenolic compounds (TPC) quantification in fruit samples for the first time. The performance of the µPAD, based upon the vertical flow approach, was enhanced in order to determine the TPC content with high accuracy in fruit samples. The method was based on the traditional Folin-Ciocalteu Index using gallic acid or oenotannin as reference phenolic compounds. This novel design and construction of the device are in agreement with the principles of Green Chemistry avoiding wax technology (lower toxicity). The analytical parameters that affect the colorimetric method (using digital imaging of the colored zone) performance were optimized including design, sample volume, and MOF amount. Then, the analytical features of the developed method were investigated such as dynamic range (1.6-30 mg L-1), limit of detection (0.5 mg L-1), and precision (RSD < 9%). Besides, the in-field analysis is achievable with a color stability up to 6 h after the loading process of the sample and storage stability for at least 15 days without performance losses (under vacuum at - 20 °C). Furthermore, the MOF ZIF-8@paper was characterized to study its composition and the successful combination. The feasibility of the proposed method was demonstrated by determining the TPC in 5 fruit samples using oenotannin as reference solute. The accuracy was validated by comparison of the data with the results obtained with the recommended protocol proposed by the International Organisation of Vine and Wine (OIV).

Design of a microfluidic paper-based device for the quantification of phenolic compounds in wine samples.

In this work, the design and development of a microfluidic paper-based device (µPAD) for the quantification of total phenolic compounds (TPC) in wines is described. The developed µPAD was based upon the vertical flow concept and the colour reaction used was the known Folin-Ciocalteu reaction using gallic acid as reference phenolic compound. After studying operational parameters, namely type of paper, reagents and sample volume, a dynamic range of 5-50 mg L-1 was obtained with a limit of detection of 1.2 mg L-1. The described device proved to have good precision (relative standard deviation < 5%) and no significant interferences were observed from known compounds present in wines. Furthermore, the stability of the colour product and of the device itself were assessed; the µPAD was stable for 30 days (in the dark at room temperature) and it could be scanned up to 8 h after sample introduction. The developed µPAD pose as a simple method for TPC quantification and was successfully applied to several wine samples including sparkling and table wines with two different approaches: i) using gallic acid as reference compound with standard addition; and ii) using taniraisin with external calibration. The accuracy of the proposed µPAD method was assessed by comparison with the reference spectrophotometric method according to the International Organisation of Vine and Wine (OIV) recommendations.

Development of hybrid monoliths incorporating metal-organic frameworks for stir bar sorptive extraction coupled with liquid chromatography for determination of estrogen endocrine disruptors in water and human urine samples.

A novel coating based on hybrid monolith with metal-organic framework (MOF) onto conventional Teflon-coated magnetic stir bars was developed. For this purpose, the external surface of the Teflon stir bar was firstly vinylized in order to immobilize a glycidyl methacrylate (GMA)-based polymer onto the magnet. Then, an amino-modified MOF of type MIL-101 (NH2-MIL-101(Al)) was covalently attached to the GMA-based monolith. After the synthesis process, several parameters affecting extraction of target estrogens by stir bar sorptive extraction (SBSE) including pH, ionic strength, extraction time, stirring rate, desorption solvent, and desorption time were also investigated. The resulting hybrid monolith was evaluated as SBSE sorbent for extraction of three estrogens (estrone, 17ß-estradiol, estriol) and synthetic 17ß-ethinylestradiol from water and human urine samples followed by HPLC with fluorescence detection (excitation and emission wavelengths, 280 and 310 nm, respectively). Under the optimal experimental conditions, the analytical figures of the method were established, achieving satisfactory limits of detection in the range of 0.015-0.58 µg L-1, recovery results ranging from 70 to 95% with RSD less than 6%, and precision values (intra- and inter-extraction units) below 6%.

Polymer-based materials modified with magnetite nanoparticles for enrichment of phospholipids.

A polymeric material modified with magnetic nanoparticles (MNPs) has been synthesized and evaluated as sorbent both for solid-phase extraction (SPE) and dispersive magnetic solid-phase extraction (MSPE) of phospholipids (PLs) in human milk samples. The synthesized sorbent was characterized by scanning electron microscopy and its iron content was also determined. Several experimental variables that affect the extraction performance (e.g. loading solvent, breakthrough volume and loading capacity) were investigated and a comparison between conventional SPE and MSPE modalities was done. The proposed method was satisfactorily applied to the analysis of PLs in human milk fat extracts in different lactation stages and the extracted PLs were determined by means of hydrophilic interaction liquid chromatography using evaporative light scattering detection.