Use of experimental design in the optimization of stir bar sorptive extraction for the determination of polybrominated diphenyl ethers in environmental matrices

Potentialities of two solventless extraction approaches—Stir bar sorptive extraction and headspace solid-phase microextraction for determination of higher alcohol acetates, isoamyl esters and ethyl esters in wines

“…Moreover, the TD mode does not offer the opportunity of multiple injections, which is an important issue in many studies during validation purposes. More recently, we proved that SBSE-LD is a remarkable alternative presenting interesting features to overcome these limitations [20,21,26]. In this approach, the analytes are trapped followed by removal through back-extraction with a small volume (typically microliters) of a convenient organic solvent prior to GC-MS analysis.…”

“…The latter methodology uses the Twister TM , a glass stir bar onto which is bonded a polydimethylsiloxane (PDMS) phase, in quantities far in excess of those found on SPME fibres [18]. The SBSE extraction takes place when the aqueous sample begins to be stirred by the bar during a period of time until the volatile or semivolatile compounds reach the equilibrium and after enrichment, are thermally desorbed (TD) followed by gas chromatography analysis usually coupled to mass spectrometry (GC-MS) [19][20][21]. These sorptive extraction approaches showed great advantages when compared with other conventional enrichment methodologies, since eliminate the use of toxic organic solvents, allow the determination of a large number of analytes with low limits of detection and good linear dynamic ranges, combine extraction, concentration and instrumental analysis into a single step, require no or little manipulation/sample preparation, reduce substantially the analysis time, are simple and faster methods, cover a wide range of sampling techniques, including field, in situ and air matrices and can be performed by immersing the polymeric coatings into sample medium or in the headspace (HS).…”

Optimisation of stir bar sorptive extraction and liquid desorption combined with large volume injection-gas chromatography–quadrupole mass spectrometry for the determination of volatile compounds in wines

“…In a preliminary study, different desorption solvents were tested for the back-extraction process, including MeOH and ACN, since they are the most used for LD of the semi-volatile compounds analysed by SBSE [6][7][8][9]. Nevertheless, this analytical approach needs a solvent switch step, i.e.…”

“…0.5-2 L, of this extract is injected in the gas chromatograph for analysis. Although this approach works quite successfully, the sensitivity can be highly enhanced through the combination of LD with large volume injection (LVI) [6][7][8][9].…”

“…In addition, TD does not offer the opportunity of reanalysis, which is an important issue in many studies for validation purposes. Alternatively, SBSE with liquid desorption (LD) has shown very interesting features to overcome these limitations and, besides being cost-effective, it has been successfully applied to the analysis of several classes of semi-volatile compounds in many types of matrices prior to GC-MS analysis [6][7][8][9]. Meanwhile, SBSE combined with LD as far as we know was never proposed for the enrichment of volatile compounds, which can be easily performed by trapping the analytes followed by removal through back-extraction with a small volume (typically microliters) of a convenient organic solvent.…”