Microextraction Tech

Our latest article, published as a paper in the forefront in Analytical and Bioanalytical Chemistry, presents a deep study of the reduction of the intrinsic components of wooden toothpicks (WTs) towards their use as a sorptive phase in the determination of six tricyclic antidepressants (amitriptyline, clomipramine, desipramine, imipramine, nortriptyline, and trimipramine) in saliva by direct infusion mass spectrometry (DI-MS) and LC-MS, and the in vivo qualitative analysis of acetaminophen in saliva samples. In the sample preparation context, WTs are used as sorbents according to their superficial -OH groups that provide electrostatic and hydrogen bond interactions with the target compounds. Moreover, they can be surface-modified to establish or improve the sorbent-analyte interaction. However, the presence of intrinsic components or impurities provided by the biosorbents can present a negative effect on the instrumental determination of the target compounds. To minimize this limit

  A decade ago, our research group introduced the concept of effervescence-assisted microextraction. The first approach of this alternative consisted of a micrometric sorbent (OASIS-HLB) compressed in a tablet along with a carbon dioxide source (sodium carbonate) and a proton donor (sodium dihydrogen phosphate) [1] . The tablet is then placed on a syringe, and an aqueous sample is drawn. Once the sample enters in contact with the tablet, an effervescent reaction occurs, and the sorbent is efficiently dispersed by the CO 2 bubbles formed. Later, the technique was challenged with a difficult-to-disperse nanometric sorbent, unmodified multi-walled carbon nanotubes (MWCNTs) [2] . In this second adaptation, the nanotubes are compressed along with the effervescence precursors in a tablet format, and as occurs with many pharmaceutical applications, dropped in a glass containing a large aqueous sample volume (100 mL) and effervescent reaction takes place. The in-situ generated gas can dispers

  In our latest research, wooden toothpicks (WTs) coated with a commercial polyamide such as nylon-6 (N6) were used in a solid phase microextraction (SPME) procedure for the determination of methadone, cocaine, and methamphetamine in saliva. Bare WTs present weak hydrophilic and hydrophobic forces provided by cellulose and lignocellulose, respectively. Consequently, the N6 polymeric coating was used to reinforce the hydrogen bonds and hydrophobic forces with the target analytes. The synthesis of N6-WTs is based on the dip coating technique, where the superficial -OH groups provided by the (ligno)cellulosic components of wood allow the coating of the WTs. This simple dipping-and-drying process consists of the immersion of the WTs in a N6 precursor solution (3 % (w/v) in formic acid), followed by the evaporation of the solvent to anchor the thin polymeric phase to the surface of the WTs. The synthesized sorbents were characterized by attenuated total reflection infrared spectroscopy (A

Recently a novel dual substrate for both SERS and PS-MS based on the deposition of silver nanoflowers (AgNFs) onto a paper-based analytical device (PAD) has been developed. Although the obtention of the substrate requires several steps, it is possible to synthesize a bunch of them at the same time. Figure 1 illustrates the different stages involved in the synthesis process of the so-called ny-AgNF PADs (further details are included in the full article). To obtain the silver nanoflowers, an already described protocol was followed, which is based on a simple reaction involving silver nitrate and ascorbic acid as the reducing agent (Figure 1, steps 4-7). Furthermore, previous modification of the paper was needed to anchor the nanoflowers to its surface (Figure 1, steps 1-3, and 8). First, a coating of nylon-6 was needed to assure the surface availability of the analytes in Surface-enhanced Raman spectroscopy ( SERS). Next, a surface of metallic silver was acquired by the deposition of

Electromembrane extraction (EME) is a liquid phase microextraction technique based on the voltage-assisted migration of the target analytes between two aqueous solutions (the sample and the acceptor phase) separated by a polymeric membrane where an organic solvent is immobilized in the form of a supported liquid membrane (SLM). The technique, which has been the subject of several posts in this blog, allows the rapid extraction of ionic species. The present post highlights a recent article, published in the Journal of Pharmaceutical and Biomedical Analysis, where polyacrylamide gels are proposed as a membrane in EME. Although polypropylene membranes are usually selected as a physical barrier between the two aqueous phases involved in EME, several research groups have proposed alternatives to this classical approach. In 2017, Tabani et al. proposed agarose gel as a greener alternative. Although good results were obtained, the large pore sizes of these gels (up to 300 nm)

Polymeric nanocomposites have demonstrated great potential as sorbents in analytical sample preparation. The polymeric domain usually provides the sorption ability while the nanometric element confers special properties (like magnetism) or improves the sorptive capacity introducing new interaction chemistries (different than those provided by the polymer) or increasing the superficial area of the nanocomposite. In a recent article published in Microchimica Acta by Prof. Bagheri and coworkers, a reference research group in this field, have outlined the use of dendrimeric nanocomposites as sorptive phases in solid-phase microextraction (SPME). Dendrimers are hyperbranched molecules with a multifunctional, homogeneous and spherical surface. They present multiple sites on the outer surface that may interact with the target analytes. PAMAM dendrimer ethylene diamine core, generation 0.  Source: chemspider.com Polyamidoamine (PAMAM) dendrimers can be obtained by a controlled and st

Microextraction is currently present in many analytical processes. Its advantages over conventional extraction approaches have been extensively pointed out and mainly refer to its simplicity and miniaturization while providing equal or even better analytical features. Also, the availability of the sorbents (carbon-based, silica, metallic, magnetic...), formats (fiber, capillary, powder, particles and membranes) and combinations among them make possible the processing of any sample-analyte binomial. A step forward in the development of novel sorbents phases is selectivity. Highly selective extractant allows to face the determination of the analytes in complex matrices such as biological fluids or food. Nickel foam The group of Prof. Zhang has proposed the synthesis and evaluation of molecularly imprinted polymers (MIPs) that allows the selective extraction of floxacin from water and biological samples. We are all aware about the ability of such polymeric phases to selective rec