Novel extraction approach for liquid samples: Stir cake sorptive extraction using monolith

Abstract

In this study, a new extraction approach for liquid samples--stir cake sorptive extraction using monoliths as extractive medium was developed. The preparation procedure of stir cake is very simple. First, monolithic cake is synthesized according to the in situ polymerization of monolith; then, the cake is inserted in an original unit (holder), which is constructed from a syringe cartridge and allows the magnetic stirring of the cake during the extraction process. The effects of dimension of monolithic cake and unit design on the extraction performance were optimized in detail. To demonstrate the usability of this new extraction approach, poly(vinylimidazole-divinylbenzene) was prepared and acted as the extractive cake. The analysis of steroid hormones in milk samples by the combination of stir cake with high-performance liquid chromatography with diode array detection, was selected as a paradigm for the practical evaluation of stir cake sorptive extraction. Under the optimized extraction conditions, low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target analytes were achieved within the range between 0.33-0.69 and 1.08-2.28 μg/L, respectively. The method also showed good linearity, repeatability, high feasibility and acceptable recoveries. Because the monolithic cake does not contact with the vessel wall during stirring, there is no friction loss of extractive medium and the stir cake can be used for more than 1000 h.

Spiral stir bar sorptive extraction with polyaniline‐polydimethylsiloxane sol‐gel packings for the analysis of trace estrogens in environmental water and animal‐derived food samples

“…The analytical performance of this method and other similar methods for estrogens analysis was compared (Table ). The LODs of this method were comparable with other SBSE‐based methods with home‐made stir bar coatings and UV/DAD detection , but it has a longer lifetime. Compared with monolith based stir bar coatings , the extraction kinetics of the PANi‐PDMS packed spiral stir bar is faster (extraction time of 40 min versus 60–170 min) and the extraction phase preparation is much simpler.…”

“…The LODs of this method were comparable with other SBSE‐based methods with home‐made stir bar coatings and UV/DAD detection , but it has a longer lifetime. Compared with monolith based stir bar coatings , the extraction kinetics of the PANi‐PDMS packed spiral stir bar is faster (extraction time of 40 min versus 60–170 min) and the extraction phase preparation is much simpler. Compared with the monolith based stir cake in which a 3 mL desorption solvent was needed and a vaporization step was used to remove the solvent before the subsequent HPLC analysis, the desorption process of PANi‐PDMS packed spiral stir bar is much simpler.…”

Extraction and stirring integrated techniques: examples and recent advances

“…In 2011 Huang et al proposed a new extraction approach, called stir-cake sorptive extraction (SCSE) [59], which shares some aspects of the RDSE, SME, and SRSE devices. In fact, SCSE use a monolithic material (as SRSE) in a disk format (similar to RDSE) as sorptive phase.…”

Recent Advances in Extraction and Stirring Integrated Techniques

“…Stir cake sorptive extraction (SCSE) was first proposed in 2011 by Huang et al [41]. It is very similar to stir bar sorptive extraction but, in this case, the sorbent is a monolithic cake placed in a homemade holder with a protected iron wire (Figure 9).…”

“…Their potential in separation techniques has been widely studied [42]. The preparation of the monolith-based SCSE unit is very simple [41]. The monolithic cake is synthesized and located in a cake-shaped plastic holder (see Figure 9).…”