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A modification of magnetic-based solvent-assisted dispersive solid-phase extraction (M-SA-DSPE) has been employed for the determination of the biomarkers cortisol and cortisone in saliva samples. M-SA-DSPE is based on the dispersion of the sorbent material by using a disperser solvent like in dispersive solid phase extraction (SA-DSPE) but a magnetic sorbent is used like in magnetic dispersive solid-phase extraction (M-DSPE). Thus, the magnetic sorbent containing the target analytes is retrieved using an external magnet like in M-DSPE. Finally, the analytes are desorbed into a small volume of organic solvent for the subsequent chromatographic analysis. To this regard, a M-SA-DSPE-based method was developed using a magnetic composite as sorbent, made of CoFe 2 O 4 magnetic nanoparticles embedded into a reversed phase polymer (Strata-X TM -RP), which exhibits affinity to the target analytes. Then, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to measure both analytes in the M-SA-DSPE extract. Under the optimized conditions, good analytical features were obtained: limits of detection of 0.029 ng mL -1 for cortisol and 0.018 ng mL -1 for cortisone, repeatability (as RSD) ≤ 10 %, and relative recoveries between 86 and 111 %, showing no significant matrix effects. Finally, the proposed method was applied to the analysis of saliva from different volunteers. This new methodology allows a fast and non-invasive determination of cortisol and cortisone, and it employs small amounts of sample, organic solvent and sorbent. Likewise, the sample treatment is minimum, since any supporting equipment (vortex, centrifuge, ultrasounds, etc.) is required., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

2-Hydroxy-4-methoxybenzophenone (HMB), which is one of the most commonly used UV filters in sunscreen cosmetics to protect skin from the deleterious effects of the sun, can be percutaneously absorbed, further metabolized, and finally excreted or bioaccumulated. An analytical method for the sensitive determination of HMB and its three metabolites in both human urine and semen is developed. The presented analytical method is based on a solid-phase extraction (SPE) procedure to clean-up and preconcentrate the target analytes from the urine and semen samples followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. The methodology was fully validated and the standard addition calibration method was used to quantify the target analytes in order to correct the matrix effects observed. Considering this approach, the accuracy of the method was evaluated and the recoveries ranged from 98% to 115% and from 86% to 111% in urine and semen samples, respectively, depending on the analyte. For urine samples, the limits of detection ranged between 0.027 and 0.103 ng mL(-1) and the repeatability of the method, expressed as relative standard deviation, was in the range of 7.2-9.2%, depending on the analyte. In the case of semen samples, the limits of detection ranged between 1 and 3 ng mL(-1) whereas the repeatability was in the range of 2.2-6.4%, depending on the analyte. The described SPE-LC-MS/MS method was satisfactorily applied to both urine and semen samples from a male volunteer who applied a sunscreen cosmetic product containing HMB. HMB and its metabolites were found and quantified in the low ng mL(-1) range in both urine and semen samples, although at a different extent.

An analytical method for the determination of tetrahydrocannabinol (THC) at trace level in cosmetics is presented. As psychoactive compound, the presence of THC in consumer products should be avoided. However, it might be unintentionally present in cannabidiol-rich or hemp-based products by contamination or isomerization of cannabidiol. Due to the low concentrations expected, a sensitive and selective method is necessary for the analytical control of these products. In this sense, the presented method is based on stir bar sorptive dispersive microextraction (SBSDME) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this work, a magnetic composite made of CoFe 2 O 4 magnetic nanoparticles embedded in a commercial reverse-phase polymer (Strata™-X-RP) was employed as magnetic sorbent material taking advantage of its affinity to the target analyte. Under the optimized conditions, the method was validated and showed good analytical features in terms of linearity (at least up to 10 ng mL−1), limits of detection and quantification (2.2 and 7.2 ng g−1, respectively) and repeatability (RSD <10%). Moreover, relative recoveries between 99 and 109% were obtained, showing matrix effects were negligible using deuterated THC (THC-D 3) as surrogate. This new approach was successfully applied to ten commercially-available cosmetic samples of different matrices, thus showing it is suitable for the analytical control of THC in cosmetic products. The proposed methodology overcomes some of the drawbacks of the previous works with the same purpose, such as the higher limits of detection, time-consuming procedures, and consumption of large volumes of organic solvents. [Display omitted] • A sensitive analytical method for determining THC in cosmetics is presented. • The method makes use of stir bar sorptive dispersive microextraction (SBSDME). • CoFe 2 O 4 -Strata-X™-RP composite is used as magnetic sorbent material. • Trace levels of THC in the low ng g−1 range can be determined by this method. • The method uses less solvents and require shorter analysis time compared to others. [ABSTRACT FROM AUTHOR]

In this work, a lab-made and affordable high-throughput pipette tip microextraction strategy is presented. In this approach, a magnetic sorbent is quickly dispersed in the sample by means of a disperser solvent and the resulting dispersion is immediately aspirated into a pipette tip containing a small neodymium magnet inside, which entraps the magnetic sorbent containing the analytes. The sample is then discarded, and the subsequent cleaning and desorption steps are conducted by aspirating/dispensing the suitable solvents. This methodology provides satisfactory results when compared with previous pipette tip extraction strategies (i.e., pipette-tip solid-phase extraction and dispersive pipette extraction). Furthermore, it requires a minimum number of aspirating/dispensing cycles, thus benefiting the ergonomics for the operator, and it is not commercially dependent. This new approach has been tested by measuring testosterone levels in saliva of volunteers as a proof-of-concept. In this regard, a magnetic composite made of CoFe 2 O 4 magnetic nanoparticles embedded in octadecyl bonded silica microparticles was employed as sorbent material. Testosterone was quantified by liquid chromatography coupled to tandem mass spectrometry. Under the optimized conditions, low limits of detection and quantification (7.5 ng L−1 and 24.8 ng L−1, respectively), good repeatability (RSD <9%) and relative recoveries between 82 and 106% were obtained with just one adsorption and two desorption cycles, which requires few seconds per sample. In order to increase even more the sample throughput, a multichannel pipette was also evaluated. [Display omitted] • A high-throughput dispersive pipette tip microextraction approach is presented. • The use of a magnetic sorbent reduces significantly manipulation and analysis time. • Good results are obtained when compared with other pipette tip-based strategies. • The sample throughput is further increased with a multichannel pipette. • Salivary testosterone is selected as proof-of-concept to test the proposed approach. [ABSTRACT FROM AUTHOR]

A novel microextraction technique combining the principles of stir bar sorptive extraction (SBSE) and dispersive micro-solid phase extraction (DμSPE) is presented. The main feature of the method is the use of a neodymium-core stirring bar physically coated with a hydrophobic magnetic nanosorbent. Depending on stirring speed, the magnetic sorbent either acts as a coating material to the stir bar, thus affording extraction alike SBSE, or as a dispersed nanosorbent medium for the collection and extraction of the target analytes, in close analogy to DμSPE. Once the stirring process is finished, the strong magnetic field of the stir bar prevails again and rapidly retrieves the dispersed MNPs. Alike SBSE, the stir bar is collected and the analytes are back-extracted by liquid desorption into an appropriate organic solvent, which is used for analysis. This enrichment technique is easy to prepare since it does not require special surface modification procedures, uses low volumes of non-toxic organic solvents and most importantly imbues SBSE with additional functionalities against a wide range of analytes (since nanosorbents with various coatings can be employed) while it affords additional merits to DμSPE in terms of extraction and post-extraction treatment. As proof-of-concept this new approach was applied to the determination of organic UV filters in seawater samples using oleic acid-coated cobalt ferrite (CoFe 2 O 4 @oleic acid) magnetic nanoparticles as sorbent material. The method showed good analytical features in terms of linearity, enrichment factors (11–148), limits of detection (low ng mL −1 ), intra- and inter-day repeatability (RSD < 11%) and relative recoveries (87–120%). [ABSTRACT FROM AUTHOR]

Abstract: A powerful analytical method for the determination of the family of the nitro musk compounds at trace level in environmental waters—river, sea, and water from a treatment plant—is presented. The method is based on the use of molecularly imprinted silica (MIS) as sorbent for solid phase extraction (SPE) used for the clean-up and the concentration step of the target analytes previous to their determination by gas chromatography–mass spectrometry. The optimized extraction procedure allowed extraction recoveries between 61% and 87% using the MIS. The comparison with a non-imprinted silica (NIS) sorbent, for which extraction recoveries between 8% and 26% were obtained, showed the high selectivity of the MIS for the nitro musks. Moreover, high enrichment factors, ranging between 580 and 827, were achieved. The imprinted sorbent was compared to a conventional polymeric SPE sorbent for the extraction of the target compounds from environmental waters, showing high selectivity of the MIS and its clean-up potential. For the first time, the five nitro musk compounds were selectively extracted with an imprinted material. [Copyright &y& Elsevier]

Abstract: 2-Hydroxy-4-methoxybenzophenone and 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid, commonly known as benzophenone-3 (BZ3) and benzophenone-4 (BZ4), respectively, are substances widely used as UV filters in cosmetic products in order to absorb UV radiation and protect human skin from direct exposure to the deleterious wavelengths of sunlight. As with other UV filters, there is evidence of their percutaneous absorption. This work describes an analytical method developed to determine trace levels of free BZ3 and BZ4 in human urine. The methodology is based on a solid-phase extraction (SPE) procedure for clean-up and pre-concentration, followed by the monitoring of the UV filters by liquid chromatography–ultraviolet spectrophotometry detection (LC–UV). In order to improve not only the sensitivity and selectivity, but also the precision of the method, the principle of sequential injection analysis was used to automate the SPE process and to transfer the eluates from the SPE to the LC system. The application of a six-channel valve as an interface for the switching arrangements successfully allowed the on-line connection of SPE sample processing with LC analysis. The SPE process for BZ3 and BZ4 was performed using octadecyl (C18) and diethylaminopropyl (DEA) modified silica microcolumns, respectively, in which the analytes were retained and eluted selectively. Due to the matrix effects, the determination was based on standard addition quantification and was fully validated. The relative standard deviations of the results were 13% and 6% for BZ3 and BZ4, respectively, whereas the limits of detection were 60 and 30ngmL−1, respectively. The method was satisfactorily applied to determine BZ3 and BZ4 in urine from volunteers that had applied a sunscreen cosmetic containing both UV filters. [Copyright &y& Elsevier]

Current trends in sample preparation focus on the miniaturization of the process resulting in what is known as microextraction techniques. Among them stir bar sorptive dispersive microextraction (SBSDME) is one of the most recent techniques. It was presented a few years ago as a hybrid microextraction technique that combines the principles of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE). This novel technique introduces, into the sample solution, a bar-shaped magnet coated with a magnetic (nano)material, which is maintained on the surface by magnetism. Once stirring starts, the competitive action between magnetism and rotational force is exploited. At low rotational speed the (nano)material is retained on the magnet reminding SBSE, whereas at high sufficiently rotational speed the rotational force surpasses magnetism so that the magnetic (nano)material is dispersed into the sample solution as in DSPE. Upon halting rotation, the magnetic field prevails again and attracts the magnetic (nano)material containing the analytes back on the surface of the stirring bar. Finally, the extracted analytes are chemically or thermally desorbed before their measurement with the appropriate analytical instrument. When compared separately to SBSE and DSPE procedures, SBSDME affords, in a single approach, advantages such as lower extraction times than SBSE and easier extraction and post-extraction treatment than DSPE. The main purpose of this tutorial review is to describe the fundamentals and the experimental variables involved in this technique, as well as to compile and critically discuss the published papers concerning analytical methods based on the use of the SBSDME approach, analyzing its evolution and future prospects. [Display omitted] • Fundamentals of stir bar sorptive dispersive microextraction (SBSDME) are described. • Advantages and benefits compared to other microextraction approaches are discussed. • Special emphasis on the experimental variables involved in the technique is done. • An overview of the published SBSDME-based methods is presented. • This tutorial may be used as guide for the development of SBSDME-based methods. [ABSTRACT FROM AUTHOR]