Solid phase extraction cartridge procedure

This sample preparation involved, firstly, an extraction and the elimination of the solid matrix by filtration and, secondly, a concentration procedure employing a solid phase extraction cartridge. The compounds of interest were separated solely by dispersive interactions with the reversed phase. In the example given, the corn meal was spiked with the aflatoxins. 

When samples contain high quantities of interfering material (e.g., sugars, colloids), a sample-cleanup procedure is recommended. A sample preparation with solid-phase extraction cartridges (C18) was found to be quite useful and effective (180,193). Prior to HPLC analysis, all samples should be filtered through a 0.45-/zm or smaller membrane filter. 

For certain procedures, a picture or illustration may be helpful. Accessories and Supplies A listing of all nonroutine items, such as the special filters, low-actinic autosampler vials, or solid-phase extraction cartridges required. 

It is too often assumed that because precolumn sample preparation devices, such as solid-phase extraction cartridges, are simple tools, they require relatively little skill or attention to detail for successful use. Cartridges do, however, require attention to detail for successful operation in sample enrichment procedures. Two of the most important parameters to control and understand are flow-rate effects and recovery (or loadability) effects. 

The relative PLMA MW was determined by using nonaqueous SEC with THF as solvent and an HP1037A refractive index detector from Hewlett-Packard. A solid-phase extraction cartridge (Waters Sep-Pak) was used to take the PLMA and surfactants from the water phase to THF and to adjust the concentration for SEC. Sodium sulfate was used to dry the THF extract before injection into the SEC columns. For some samples there was too much surfactant present, and it overloaded the cartridge in such cases ion-exchange beads were used to reduce the concentration of the ionic surfactants in the aqueous phase before extraction. The advantage of this extraction procedure is its simplicity. The overall separation scheme is shown in Scheme I. 

Figure 4.3 Matrix solid phase dispersion (MSPD) procedure. Main steps of MSPD (I) the sample is blended with the dispersant material in a mortar with a pestle (II) the homogenized powder is transferred in a solid phase extraction cartridge, and compressed (III) elution with a suitable solvent or solvent mixture is performed by the aid of a vacuum pump. (Adapted from Capriotti et al. and with permission from Elsevier copyright 2010.)...

When an extract is prepared with a solid-phase extraction cartridge alone, the microcystins in lake water cannot be precisely detected because of the unstable baseline and many peaks on the chromatograms from coexisting substances (Fig. 2a). When this extract is further purified with the immunoaffinity column, the microcystin peaks are clearly detected (Fig. 2b) and effectively quantified because the coexisting substances are virtually eliminated. The recoveries from lake water (1 L) spiked with 100 ng each of microcystins-LR, -YR, and -RR are 92.2%, 89.2%, and 85.5%, respectively, with coefficients of variation of 3.3-7.6%. One of the advantages of this method is its speed it took only 3 hr to complete the entire procedure, starting from the microcystin extraction, the immunoaffinity purification, and the quantification, whereas the previous procedures (tandem use of ODS sihca gel and silica gel cartridges) took a day to complete. The detection limit for all of the three microcystins in lake water is 0.005 xg/L. 

Solid phase extraction (SPE) procedures require only a few milliliters of solvent. Graphitized carbon black (GCB) cartridge was applied for the extraction of 27 polar pesticides (28a) (Table 1). Phthalate herbicides, OC insecticides, and PAHs were examined in water samples (28b) (Table 1). The GCB cartridge was applied in a multiresidue method also (28c) (Table I). 

A Modified Bligh and Dyer Procedure for Lipidomics To succeed in lipidomic analysis with ESI-MS using direct infusion or with MALDI-MS, a key point is to have a lipid extract carrying only a minimal amount of inorganic salts. Although solid-phase extraction cartridges can be used to eliminate the salt contaminants, a careful solvent wash is recommended as routinely used in the author s laboratory [36, 38]. 

A number of methods have been described for determination of tetracycline (chlortetracycline, tetracycline, and oxytetracycline) residues in tissues of food-producing animals (53-62), fish (63), eggs (64), and honey (65,66). Most of these methods use reversed-phase HPLC for determination. However, one uses TLC with UV densitometry ( ) and one uses GLC ( ), and one uses a direct mass spectrometric method CAD MIKE spectrometry (collisionally activated decomposition mass-analyzed ion kinetic spectrometry) for oxytetracycline in milk and meat (62). Several use solid-phase extraction in the cleanup procedure using XAD-2 resin (56,58) or Cj g cartridges... 

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