Solid-phase extraction batch

In the case of batch processing the scavenger is added to the reaction mixture after completion. For flow-through processing the scavenger is packed into a column (solid-phase extraction, HPLC, etc.) and the reaction mixture is passed through the column until scavenging is complete. 

The synthesis of 6-hydroxy fluvastatin with M. rammaniana DSM 62752 gave high conversion (>95 %) in shake flask culture on 400 mL scale with 0.1 g L of fluvastatin as well as on 22 L scale in a Wave bioreactor-fed batch process at a final substrate concentration of 0.4 g L Instead of the partial purification by a second solid-phase extraction described above, 6-hydroxy fluvastatin can be obtained in high purity ( 95 %) by, for example, preparative medium-pressure liquid chromatography (MPLC) on RP18 silica gel. ... 

The synthesis of PET radiopharmaceuticals is always carried out at very small scale (only a few dozen micrograms of the radiopharmaceutical are obtained) and each batch can sometimes only be used for a single patient or a few patients at most. Consequently, there is always a big excess of the precursor in the reaction medium, and proper purification systems must be used to get rid of all the possible contaminants. Such systems must also be very efficient and fast, and the most usual is to apply either semipreparative high-performance liquid chromatography (HPLC) or solid-phase extraction-based procedures. 

Molecular recognition elements are useful in a broad range of applications where selective binding is advantageous, for example, chromatographic and batch-wise separation and purification, trace enrichment by solid-phase extraction,... 

This chapter has four sections that focus on laboratory-scale capture steps solids removal, solvent extraction, solid phase adsorption, and expanded bed adsorption. Although these techniques are widely applicable, most of this chapter is aimed at extraction of microbial fermentation broth. Techniques specific to initial extraction of plants and marine organisms can be found in Chapters 12 and 13, respectively. The first section describes laboratory-scale procedures for batch filtration and centrifugation. The second section describes solvent-extraction procedures with either water-miscible or -immiscible solvents. The third section describes using adsorbents for solid-phase extraction. The fourth section describes a technique known as expanded bed adsorption, which is unique in that it enables resin-column recovery of product directly from unclarified fermentation broth. 

Solid phase extraction is carried out by gently mixing the polymer particles (50 mg mL ) in the resulting solution for 1 h. After centrifugation, the supernatant is collected and treated with another batch of polymer, and this batch-mode extraction is repeated for several times. At each step the composition of the supernatant is analyzed by RP HPLC. A plot of byproduct content after each extraction vs. the number of extraction cycles is established. 

In solid-phase extraction (SPE), solutes are extracted from a liquid phase into a solid phase. Most commonly, the liquid phase is a predominately aqueous sample solution and the extractive solid phase consists of small porous particles of silica with a bonded organic outer layer or else it is an organic polymer, such as cross-linked polystyrene. The extraction can take place in a batch mode in which the solid extractant particles are intimately mixed with the sample and then filtered off. However, in chemical analysis it is more common to use a flow-through mode in which the liquid sample is passed through a bed of the solid extractant packed in a small tube. This technique gives more complete extraction of the desired analytes than the batch mode, in which there is only a single equilibration of analytes between the liquid and solid phases. 

Dedicated automation is usually limited to a specific task, which may be varied by programming or parameterization of the basic commands of the program controlling the instrument. This can take the form of autosamplers, autoanalyzers, or batch processors, and these can offer a cost-effective means of automating an instrument assay. These autosamplers can automate techniques such as solid-phase extraction or dialysis. 

For the determination of the Hg species methylmercury, phenylmercury and Hg(ll), ozone was used successfully in a batch cold-vapor system [126]. The preconcentration and speciation of Cr(lll) and Cr(VI) in water sample can be performed using solid-phase extraction (SPE) [105]. An SPME (solid-phase microextraction) technique has been used as the sample preparation system for the innovative simultaneous multielement/multi-species determination of six different mercury, tin. and lead species in waters and urine with GC/MS-MS [141], [142], The determination of arsenic species [As(III), As(V), MMA. DMA, arsenocholine, arsenobetaine)] has also been shown to work with an on-line digestion step prior to hydride generation AAS [125] (see Fig. 7). 

Isolation can be performed by liquid-liquid extraction (LLE) at a pH at which the analyte is nonionized or by solid-phase extraction (SPE) preceded or followed by cleanup steps. Sample pretreatment for SPE depends on the sample type whole blood and tissue (homogenates) need deproteinization and filtration/ centrifugation steps before application to the SPE columns, whereas for urine usually a simple dilution step and/or centrifugation is satisfactory. Whatever SPE column is used, the analyst should keep in mind that there are large differences from batch to batch, and that the same sorbents from different manufacturers also... 

In simple experiments, particulate silica-supported CSPs having various cin-chonan carbamate selectors immobilized to the surface were employed in an enantioselective liquid-solid batch extraction process for the enantioselective enrichment of the weak binding enantiomer of amino acid derivatives in the liquid phase (methanol-0.1M ammonium acetate buffer pH 6) and the stronger binding enantiomer in the solid phase [64]. For example, when a CSP with the 6>-9-(tcrt-butylcarbamoyl)-6 -neopentoxy-cinchonidine selector was employed at an about 10-fold molar excess as related to the DNB-Leu selectand which was dissolved as a racemate in the liquid phase specified earlier, an enantiomeric excess of 89% could be measured in the supernatant after a single extraction step (i.e., a single equilibration step). This corresponds to an enantioselectivity factor of 17.7 (a-value in HPLC amounted to 31.7). Such a batch extraction method could serve as enrichment technique in hybrid processes such as in combination with, for example, crystallization. In the presented study, it was however used for screening of the enantiomer separation power of a series of CSPs. 

---