Chem Elut

The liquid-liquid partition procedure described above can be substituted by using a Chem Elut column. After concentrating the extract derived from Section 2.2 to 20 mL, the concentrate is applied to a Chem Elut column and charged at room temperature for 5-10 min. Naproanilide, propanil and mefenacet are eluted with 80 mL of n-hexane when using the Chem Elut column. The recoveries are in the range 96-110% (personal data). 

The other column chromatography cleanup procedure uses a macroporous diatoma-ceous column (e.g., Chem Elut column) and an SPE column Cig cartridges are effective columns for sample cleanup. 

The MDC is an effective procedure for the cleanup of the sample. The sample residue obtained in Section 2.2.1 is transferred to the MDC (Chem Elut, etc.) and the column is left at room temperature for 10 min. Bifenox is eluted with 80 mL of n-hexane, and the eluate from the MDC is concentrated to near dryness below 40 °C. ... 

Macroporous diatomaceous column (e.g.. Chem Elut column). The combined soil extract is concentrated to dryness under vacuum, the residue is dissolved in 15 mL of water and the solution is applied to a Chem Elut column. After charging for 20 min, acetamiprid is eluted with 100 mL of dichloromethane. The eluate is evaporated to... 

SPE column Cis cartridge. The concentrated eluate from the Chem Elut column as described above is dissolved in 5 mL of distilled water and charged on a Cig cartridge pretreated with 20 mL each of methanol and distilled water. Acetamiprid is eluted with the 30 mL of 15% acetonitrile solution and the eluate is collected and concentrated to dryness at 40-50 °C under vacuum. The residue is dissolved in a suitable volume of acetone and analyzed by GC. ... 

Chem Elut cartridges are packed with specially cleaned and sized diatomaceous earth. 

One advance in the area of LLE is the use of solid supports that facilitate the partitioning of the analyte(s) of interest. LLE extraction methods involving nonpolar matrices often suffer from the formation of emulsions, and using the solid support is a possible solution. In one study, polychlorinated biphenyls, dioxins, and furans were extracted from the lipid fraction of human blood plasma [32], using diatomaceous earth as the solid support. Long glass columns (30 cm) were packed with several layers of Chem-Elut (a Varian product) and sodium chloride. The plasma samples were diluted with water and ethanol and passed over the columns. A mixture of isopropanol and hexane (2 3) was passed over the column and the LLE was performed. It can be concluded that the LLE with the solid support is easier to perform and can be applied to other lipid heavy matrices such as milk [32]. 

Saponification extraction using a Chem Elut column, semi-preparative HPLC (Lichrosorb Si 60, 250mmx4.0mm, 5pm)... 

Liquid-liquid partitioning cleanup on a hydrophilic matrix has also been employed for purification of the primary sample extract. This procedure was only applied in the determination of fenbendazole and four metabolites in plasma and liver using a Chem Elut disposable column to partition an alkalinized aqueous sample extract into dichloromethane (371). In a few instances, further cleanup can also be achieved by submitting an organic extract to freezing at 20 C, a procedure that can precipitate dissolved matrix components (359, 366, 367). 

Repaglinide stock solution in MeOH then diluted with water Sample SPE continued with LLE Sample added with 250 ml water and 500 ml 0.1 ammonium acetate, then loaded on 1 ml Chem Elut extraction cartridge. LLE performed with 4 ml dicholorometane, dried, and reconstituted with 200 [A of mobile phase... 

The SPE method used by the Miami-Dade County Medical Examiner s Office, Toxicology Laboratory, in Miami, Florida (Andollo and Hearn, 1998) uses Chem-Elute - SPE columns, p-hydroxybutyric acid internal standard, pretreatment of urine with sulfuric acid and pretreatment of blood with sodium tungstate and sulfuric acid. The Dade County method gave an absolute recovery of 30% with a limit of detection of 2 pg mL and a limit of quantitation of 10 pgmL ... 

Sample preparation Dilute, if necessary, 100 p.L-1 mL urine to 1 mL with water, add to a Chem Elut high surface-area diatomaceous earth extraction column, after 5 min elute with two 6 mL portions of ethyl acetate, combine the eluates and wash them twice with 1 mL 200 mM NaOH. Dry the organic layer over 1 g anhydrous sodium sulfate, evaporate to dryness at 30° under a stream of nitrogen, reconstitute the residue in 250 p-L mobile phase, inject a 50 p,L aliquot. 

Sample preparation Place 100 p-L 100 p,M diclofenac in dichloromethane in the bottom of a tube and evaporate it to dryness under a stream of nitrogen, add 100 p-L plasma, add 25 pL 1 M HCl, mix, add to a dry Chem Elut diatomaceous earth SPE cartridge (Varian), let stand for 5 min, elute with 6 mL n-hexane diethyl ether isopropanol 50 ... 

Sample preparation For total melatonin, mix 300 [xL 60 mM trichloroacetic acid with 1 mL plasma or CSF, let stand at 0° for 10 min, centrifuge at 5000 g for 10 min, adjust the pH of the supernatant to 7.4 with 20 xL 1 M NaOH, add to a 1 mL Chem-Elut 1001 SPE cartridge (without preconditioning), let stand for 3-5 min, elute with two 4 mL portions of dichloromethane. Evaporate the eluate to dryness at 37°, reconstitute the residue with 60 LL mobile phase, inject a 40 [xL aliquot. For free melatonin add 1 mL plasma or CSF directly to the SPE cartridge. 

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