Solid phase aminopropyl column

Cleanup of macrolides and lincosamides from coextracted material can also be accomplished with solid-phase extraction columns. Nonpolar sorbents such as XAD-2 resin (148) or reversed-phase sorbents (133, 134, 137, 141, 142) are usually employed in solid-phase extraction. In the latter case, ion-pairing with pentanesulfonic acid can also be applied for enhancing retention onto the hydro-phobic Ci8 material (154). However, these sorbents are not always effective for efficient cleanup of liver and kidney extracts. The basic character of macrolides and lincosamides suggests that cation-exchange sorbents such as aromatic-sulfonic acid (145,147), or polar sorbents such as silica (144,152,153), aminopropyl (139), or diol (149-151), can be powerful alternative approaches for isolation and/or cleanup of these compounds. 

Cleanup of nitro furans from coextracted substances and concentration of the extracts can also be accomplished with solid-phase extraction columns. Nonpolar sorbents such as reversed-phase (Cis) (37, 159-161, 170, 173, 177) or XAD-2 (178) materials are usually employed, since they provide high recovery of the analytes. However, in many cases, cleanup on these nonpolar sorbents is not effective in removing interfering substances from the extracts. Therefore, polar sorbents such as silica (29, 162), alumina (160, 179, 180), or aminopropyl (175, 176) materials are also frequendy employed as a more powerful alternative for extract cleanup. 

Cleanup and concentration of quinolones from coextracted matrix constituents can also be accomplished with solid-phase extraction columns that contain either nonpolar reversed-phase (Cis) sorbents (177, 197, 198), or polar sorbents such as alumina (189-191, 194), aminopropyl (182, 187), and propylsulfonic acid (188). Reversed-phase Cis material has also been employed as the sorbent in matrix solid-phase dispersion cleanup for the determination of oxolinic acid in catfish muscle (206). 

Cleanup by solid-phase extraction has also been widely employed since it is a simple, fairly inexpensive, and easy-to-perform procedure for purification of the crude extract. The use of disposable solid-phase extraction columns is currently part of most, if not all, modern analytical methods for the determination of anthelminthics in biological matrices at residue levels. Both normal-phase columns based on silica (333-335, 340, 367, 372), alumina (346, 373-375), or aminopropyl (339, 365, 370) materials, and reversed-phase columns based on Ci8 (319, 323, 324, 328, 344, 346, 347, 349-351, 357-359, 364, 367) and cyclohexyl (329, 332, 360) sorbents have been described in analytical applications. 

Solid-phase extraction columns contain either nonpolar reversed-phase Cig sorbents, or polar sorbents such as alumina, aminopropyl, and propylsulfonic acidJ Matrix solid-phase dispersion cleanup, using reversed-phase Cig material, has also been employed for the determination of oxolinic acid in catfish muscleJ On-line dialysis and subsequent trace enrichment have been further described for the extraction/cleanup of flumequine residues from fish muscle,or oxolinic acid and flumequine from chicken liver and salmon muscleJ This process involves on-line use of a diphasic dialysis membrane, trapping of the analytes onto a preconcentration column filled with reversed-phase Cig or polymeric material, rinsing of the coextracted interfering compounds to waste, and, finally, flushing of the concentrated analytes onto the analytical column. 

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. 

Solid-phase extraction is also often used to remove interfering coextracted compounds. Solid-phase extraction columns contain either non-polar reversed-phase Cig sorbents or polar sorbents (such as alumina, aminopropyl acid, and propylsulfonic acid). Matrix solid-phase dispersion cleanup using reversed-phase Cig material has been also employed for the determination of oxohnic acid in catfish muscle.In-tube solid-phase microextraction (SPME) based on poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith coupled to high-preformance liquid chromatography (HPLC) with ultraviolet (UV) and fluorescence detection (FED) was... 

If the sample contains very polar constituents, it is advisaUe to remove them through sample preparation techniques like solid-phase extraction. Samples dissolved in water should not be injected directly onto a normal-phase column. When an aminopropyl column is used, additional precautions are necessary, which were outlined above when we discussed this stationary ffiase. 

Fatty acids can be extracted either as FFAs or as BFAs. FFAs are obtained by the hydrolysis of BFAs. Liquid-liquid extraction has been successfully applied in the isolation of several classes of lipids, or of single lipids from complex mixtures. Popular extraction methods for lipids are the Folch extraction technique, or the Bligh and Dyer method. Solid-phase extraction (SPE), and solid-phase microextraction (SPME), are also available as simple and economical time- and solvent-efficient sample preparation methods. Prefractionation can be performed using SPE silica or aminopropyl-silica columns. 

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. 

Spiramycin is used as a growth promoter and was extracted from chicken eggs and tissues and analyzed on an aminopropyl column (A = 231 nm). A mobile phase of 85/15 acetonitrile/water eluted the analyte prior to a large series of co-extracted material. Elution of the analyte occurred at <2 min, which for a 25 cm column operated at 1 mL/min seems to place the peak painfully close to the system void volume. This could lead to quantitation issues. Also, prior clean-up of the sample (e.g., with solid phase extraction) could remove the late-eluting peaks and markedly increase sample throughput and allow for a weaker mobile phase to be used (to move the analyte away from the system void area). Spike levels of 0.1-1.0 ppm were used and a detection limit of 0.1 ppm was reported [1352]. 

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