Solid-phase extraction media

Solid-phase extraction media Time (min) HOBt removed1 (%)... 

A simple first strategy to recover residues for ELA is to try existing multiresidue methods, or to use solvents and solid-phase extraction media that have proven satisfactory in the first steps of more involved instrumental analyses. This approach makes the transition from instrumental methods to ELA easier for technical personnel, and it facilitates confirmatory instrumental analysis during method validation. The uncommon structure of avermectin antibiotics makes it very unlikely that the ELA would detect compounds other than an avermectin in multi-residue extracts, though this remains to be tested. The greater concerns are completeness of the extractions, efficiency and reproducibility of recoveries, and freedom from non-specific matrix effects and interference by solvents. 

Senseman, S. A., Lavy, T. L., Mattice, J. D., Myers, B. M. and Skulman, B. W. 1993. Stability of various pesticides on membranous solid-phase extraction media. Environ. Sci. Tech., 27 516-519. 

Supercritical fluid extraction Polychlorinated biphenyls and organochlorine pesticides from soils, sediments, fly ash, solid-phase extraction media, and other solid materials which are amenable to extraction with conventional solvents As method 3560... 

A growing area for MIP materials has been in the area of pesticide detection and remediation. MIP based solid-phase extraction media lave been made to remove triazine herbicides like terbumeton (9) and combined with LC-MS liquid chronatography/ diode array detection LC AD and LC-MS to detect triazines... 

Analytical methods used for determining DNOC in environmental samples are given in Table 6-2. Most of the methods for products, waters, soils, and sludges rely on extraction of DNOC from an acidified matrix acidification minimizes dissociation of the phenolic hydrogen and thus facilitates extraction into an organic solvent or adsorption onto a solid phase extraction medium. The influence of pH on the adsorption of DNOC to humic materials in coal waste waters has been studied (Porschmann and Stottmeister 1993) and significant adsorption was found to occur at pH 7 but not... 

Concentration" Compounds at low concentrations in relatively large volumes can be concentrated by extraction onto a solid phase extraction medium and then eluted m a small volume of a strong eluent. This is typically used for concentrating analytes that are present in only trace amounts, such as drug metabolites in serum samples, or environmental contaminants in seawater. 

The fact that the neutral saccharide residue is trapped on the column and subsequently can be eluted as though it contains carboxylate functionality frirther supports the thesis that the saccharide monomer is incorporated into the poly(acrylic acid). In a control experiment, glucose was not retained on the ion exchange column in the presence of the copolymer while the copolymer was. These observations were used to advantage in the determination of saccharide monomer incorporation into the acrylic acid copolymer. A solution of polymer made from a feed containing 2 mole% monomer 5f that was not otherwise purified was subjected to the solid phase extraction technique. Forty-six percent of the saccharide present in the copolymer solution prior to solid phase extraction was not retained on the solid phase extraction medium 54% of the saccharide was retained and therefore bound to the copolymer. This indicates that a feed of 2 mole% of this saccharide monomer leads to the incorporation of 1.1 mole% monomer in the copolymer. Similar levels of monomer incorporation were observed in other copolymerizations of monomer 5f and with monomer 5e (75). 

Although most of the reactions are performed in liquid state - which is the simplest reaction medium - a combination of solid-phase extraction (SPE) and reaction... 

Application of SPE to sample clean-up started in 1977 with the introduction of disposable cartridges packed with silica-based bonded phase sorbents. The solid phase extraction term was devised in 1982. The most commonly cited advantages of SPE over liquid-liquid extraction (LLE) as practiced on a macroscale include the reduced time and labor requirements, use of much lower volumes of solvents, minimal risk of emulsion formation, selectivity achievable when desired, wide choices of sorbents, and amenability to automation. The principle of operation consists of four steps (1) conditioning of the sorbent with a solvent and water or buffer, (2) loading of the sample in an aqueous or aqueous low organic medium, (3) washing away unwanted components with a suitable combination of solvents, and (4) elution of the desired compound with an appropriate organic solvent. 

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. ... 

Postigo C, de Alda MIL, Barcelo D et al (2010) Analysis and occurrence of selected medium to highly polar pesticides in groundwater of Catalonia (NE Spain) an approach based on on-line solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry detection. J Hydrol 383 83-92... 

Pushing detection limits of nitroaromatic explosives into the parts per trillion (ppt) level requires sample preconcentration. Collins and coworkers used solid-phase extraction (SPE) of explosives from sea water which was followed by rapid on-chip separation and detection [18]. Explosives were eluted from SPE column by acetonitrile and were injected in the microchip separation channel. Lab-on-a-chip analysis was carried out in nonaqueous medium. The mixed acetonitrile/methanol separation buffer was used to produce the ionized red-colored products of TNT, TNB and tetryl [27,28]. The chemical reaction of the bases (hydroxide and methoxide anions) with trinitroaromatic explosives resulted in negatively charged products, which were readily separated by microchip... 

Jedlicka A, Grafnetterova T, Miller V. 2003. HPLC method with UV detection for evaluation of digoxin tablet dissolution in acidic medium after solid-phase extraction. J. Pharm. Biomed. Anal. 33 109 115. 

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. 

Extraction and stripping of copper(I) as a neocuproine complex in a surfactant medium was used to determine Cu in steel [4], Solid-phase extraction based on the preconcentration of the complex with neocuproine on a preconditioned membrane disc containing octadecyl-bonded silica followed by extraction of Cu and elution with isopentyl alcohol was applied to the determination of copper in distilled, tap and spring waters [5]. 

Eiquid- or solid-phase extraction methods have been adopted for the isolation of catecholamines and their metabolites from urine samples. The liquid extraction system is ordinarily based on the formation of a complex, in alkaline medium, between diphenylborate and the diol group in the catecholamines. However, the liquid extraction methods reported in the literature are relatively tedious and often involved multiple extraction steps.For the more widely used solid-phase extraction methods, catecholamines may be selectively isolated from the urine sample by adsorption with activated alumina," " phenylboronic acid or cation-exchange resins. All the specimen preparative procedures are specific for the free catecholamines, i.e. the extracted catecholamines do not include the conjugated fraction. 

HPLC also seems to be a good method for separating cucurbitacin mixtures [3]. Since these compounds tend to exhibit at least medium polarity, an RP system is the most appropriate stationary phase (Cjg column), with a linear gradient from 20% to 50% of acetonitrile [3] or methanol [42,44] in water being the best mobile phases for separation of both free-aglycones and glycosides. In this case, previous purification of samples by means of a solid-phase extraction (SPE) is advisable. The addition of 0.01% of trifluoroacetic acid (TFA) improves the separation and reduces complications from interfering substances [3]. 

Most cyanotoxins are secondary metabolites that stay inside the cells during the growth phase and are released in the extracellular medium following cell lysis. In the environment, the concentration of toxins in the water is generally very low and the determination of the toxic potency is often facilitated by the analysis of the cells themselves or by preconcentrating the dissolved toxins by solid-phase extraction (SPE). 

Solid-phase extraction (SPE) offers an alternative way for enrichment of chlorinated fatty acids. Akesson-Nilsson presented an aminopropyl-based SPE technique for enrichment of chlorinated FAMEs in a cell-culture medium and for previously silver nitrate and urea treated eel lipids. In this application, a 500-mg aminopropyl column was connected to a vacuum manifold and conditioned with 2 ml of hexane. After transesterified lipid samples in 0.2 ml of hexane were loaded, the column was first eluted with 6 ml of hexane and then with 4 ml of a solvent mixmre made of hexane-diethyl ether-dichloromethane (89 1 10). In this way, the majority of non-chlorinated FAMEs were removed in the first elution and chlorinated FAMEs enriched in the later elution. 

Akesson-Nilsson, G. Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column. J. Chromatogr. A, 2003, 996 (1-2), 173-180. 

The use of an appropriate chelating solid-phase extraction (SPE) medium permits the selective retention of actinides, elimination of alkali and alkaline earth metal ions and halogens, and removal of organic material, thus enhancing sensitivity and minimizing interferences. In addition, SPE can improve sensitivity by concentrating analytes from low concentrations in urine to higher concentrations in smaller SPE eluent volumes. 

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