RESUMEN

An on-site extraction device is presented consisting of scotch tape modified with concentric domains of micrometric hydrophilic-lipophilic balance (HLB) particles surrounded by a ring of nanometric magnetic ones. On the one hand, HLB microparticles are readily available at the surface of the tape, exposed to interact with the target analytes, being responsible for the extraction capacity of the sorptive phase. On the other hand, the presence of magnetic nanoparticles enables the attachment of the modified tape onto a metallic screw via a magnet, which is then coupled to a wireless drill, enabling the stirring of the microextraction device. Both are simply fixed to the cost-effective, flexible, and versatile support, i.e., scotch tape, owing to their adhesive properties. The microextraction device has been applied to the determination of six benzophenones in swimming pool water samples. The variables that may affect the extraction process have been evaluated. Under the optimum conditions and using liquid chromatography-tandem mass spectrometry as the instrumental technique, the method provided a limit of detection of 0.03 µg L-1. The intra-day precision, evaluated at three different concentration levels and expressed as relative standard deviation, was lower than 10%, which also comprises the variability within single-use sorptive tapes. The accuracy, calculated with spiked samples and expressed as relative recovery, ranged from 71 to 138%. The method was applied to the analysis of swimming pool water, revealing the presence of such compounds.

RESUMEN

Direct mass spectrometry (MS) is an exciting strategy in bioanalysis, enabling rapid decision-making in different scenarios. Its application is usually hindered by matrix effects and the typically low concentration of the target compounds in the biofluids. In this sense, combining a previous sample preparation step minimizes or removes these shortcomings. This article describes sorptive tape-spray tandem mass spectrometry (STS-MS/MS) based on mixed-mode particles as a strategy to combine sample preparation and MS analysis in a single device. The technique uses a sorptive tape (ST) consisting of mixed-mode polymeric microparticles (combining ionic exchange and hydrophobic interactions) coated over aluminum foil in a spatial controlled way. The tapes act as the sorptive phases to isolate the analytes from the sample matrix and substrates for STS-MS/MS. The performance of the technique has been evaluated by developing a method to determine codeine in saliva as proof of concept. The affordability of the STs elements allows the preparation of many individual phases at low cost so that several samples can be extracted simultaneously, thus increasing the sample throughput. The extraction variables were optimized following a multivariate approach. Working under the optimum conditions, the limit of detection was 0.3 µg L-1, while the intraday precision, calculated as relative standard deviation (RSD) at three concentration levels, was better than 9.4 %. The accuracy, expressed as relative recovery, was in the range of 78-98 %. The method was also applied to the analysis of real samples. Despite being a powerful strategy, the direct combination of microextraction to MS is not always affordable in all laboratories. For this reason, the STs were also combined with commercial liquid chromatography-MS working under the direct infusion mode to demonstrate the usefulness of the ST in classical extraction workflows.

Asunto(s)

RESUMEN

This article describes the synthesis of mixed-mode cationic exchange (MCX) tapes as sorptive phases in bioanalysis, and it faces the determination of methadone and tramadol in saliva as the model analytical problem. The tapes are synthesized using aluminum foil as substrate, which is subsequently covered with double-sided adhesive tape where the MCX particles (ca. 1.4 ± 0.2 mg) finally adhere. MCX particles allow the extraction of the analytes at the physiological pH, where both drugs are positively charged, minimizing the potential co-extraction of endogenous matrix compounds. The extraction conditions were studied considering the main variables (e.g. ionic strength, extraction time, sample dilution). Under the optimum conditions and using direct infusion mass spectrometry as the instrumental technique, detection limits as low as 3.3 µg·L-1 were obtained. The precision calculated at three different levels, and expressed as relative standard deviation, was better than 3.8%. The accuracy, expressed as relative recoveries, ranged from 83 to 113%. The method was finally applied to determine tramadol in saliva samples from patients under medical treatment. This approach opens the door to easily preparing sorptive tapes based on commercial (or ad-hoc synthesized) sorbent particles.

Asunto(s)

RESUMEN

The spatial heterogeneity of environmental systems makes sampling at multiple locations crucial to provide complete and representative information. The on-site application of an extraction technique simplifies the sampling logistics, increasing sample integrity during transportation and storage. This article presents a portable, simple, and low-cost device capable of performing the simultaneous on-site extraction of several environmental water samples. The device consists of a small electric motor integrated into the plastic cap of a conventional glass bottle and operated with a portable battery. The electric motor provides stirring to a novel magnetic sorptive phase based on the deposition of hydrophilic-lipophilic balance (HLB) particles over a magnetic tape. The use of open technology makes the device globally affordable. In this first approach, the isolation and preconcentration of atrazine and simazine have been selected as proof of concept. Using an internal standard made unnecessary the adjustment of the ionic strength before the extraction, thus simplifying the analytical procedure. Under the optimum conditions and using direct infusion mass spectrometry as the instrumental technique, detection limits as low as 15 ng/L were obtained. The precision calculated at three different levels was better than 8.3%. The accuracy, calculated with spiked samples, indicates the applicability of the approach for environmental water analysis.

Asunto(s)

RESUMEN

In this article, a magnetic paper-based sorptive phase is synthesized, which synergically combines the sorption capacity of a polyamide with the magnetic behavior of silica shielded Fe3O4 nanoparticles. The resulting material can be easily integrated into a drill-based environmental sampler, minimizing the diffusion boundary layer for enhanced mass transference. The new material has been evaluated for the extraction of four parabens and triclosan from swimming pool water samples. The main variables affecting the extraction have been studied in detail. The sampler is easy to transport allowing the on-site extraction of the analytes. This aspect can simplify the overall analytical procedure as only the sorptive phases, and not the samples, must be transported to the lab for the final analysis. The combination of the sampler with liquid chromatography-mass spectrometry allows determining the target analytes with limits of detection between 0.07 µg/L (butylparaben) and 0.1 µg/L (methylparaben and propylparaben). The precision, calculated at 5 µg/L, provides relative standard deviations better than 8%. The accuracy, which was evaluated spiking a blank swimming pool water sample with the target analytes at a concentration of 0.75 µg/L, provided relative recoveries in the range from 88 to 98%.

RESUMEN

Magnetite nanoparticles (Fe3O4) functionalized with graphene oxide (GO) have been synthesized through a silanization process of the magnetic nanoparticles with tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane and further coupling of GO. The synthesized nanomaterials have been characterized by several techniques, such as transmission electron microscopy (TEM), and infrared and Raman spectroscopy, which enabled the evaluation of the different steps of the functionalization process. The hybrid nanomaterial has been employed for the extraction of five benzophenones (benzophenone-1, benzophenone-3, 4-hydroxybenzophenone, benzophenone-6 and benzophenone-8) in aqueous samples by dispersive micro-solid phase extraction, combining the magnetic properties of magnetite nanoparticles with the excellent sorption capacity of graphene oxide via hydrophobic interactions with the analytes. The subsequent separation and quantification of the analytes was performed by liquid chromatography with tandem mass spectrometric detection, achieving limits of detection (LODs) in the range 2.5 to 8.2 µg·L-1, with relative standard deviations ranging from 1.3-9.8% and relative recovering in the range 86 to 105%. Positive swimming pool water samples analysed following the developed method revealed the presence of benzophenones in from 14.3 to 39 µg·L-1.

RESUMEN

A portable device that integrates sampling and extraction is proposed in this work. The unit is fabricated using commercial and standardized elements which guarantees the construction reproducibility. Also, it is simple to be mounted and on-site deployed making possible the multi-site sampling. The device uses a commercial nylon membrane as extraction phase for the isolation of the target compounds, but it can be adapted to other flat sorptive phases thus expanding the applicability. Once mounted, the unit is stirred into the sample by means of a portable drill enhancing in that way the diffusion of the target analyte towards the extraction phase. The hydrodynamic behavior and the design have been optimized and the device has been finally used for the extraction benzophenones from swimming pool samples. These endocrine disruptive compounds are determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) at concentrations as low as 0.1 µg/L with precision, expressed as relative standard deviation, better than 9.9%. The accuracy, calculated as relative recovery, was in the range from 74 to 111 % thus being considered appropriate.

Asunto(s)