Mini-columns

After extraction, an extract purification stage is generally reconunended. This is most often done by liquid-solid exchange using resins such as Sephadex, Amber-lite XAD-7, or Cjg mini-columns. ° All the polar compounds are first trapped on the resin, and then in succession the sugars, acids, and other polar compounds (excluding polyphenolic compounds), polyphenolic compounds (excluding anthocyanidins), and anthocyanidins are respectively eluted with acidified water (HCl 0.01% v/v), ethyl acetate, and acidified methanol (HCl 0.01% v/v). 

Silica gel mini column, Sep-Pak Plus Silica To set up, attach a Sep-Pak Plus Silica column to a vacuum manifold and rinse with 10 mL of ethyl acetate Empore Cig extraction disks (3M) To set up, attach Cig extraction disks to a two-piece Alter funnel and load 30 g of Filter Aid 400 on its surface. Wash the Alter with 20 mL of acetoniAile and 20 mL of 0.01 M acetate buffer (pH 4) in that order Filter Aid 400 (3M)... 

The extracts of plant, soil and water samples, if necessary, should be purified with the following method prior to methylation Dissolve the residue prepared as in Section 6.1.2 or 6.2.1 in 5 mL of ethyl acetate and transfer the solution into a silica gel mini column. Rinse the column with 15 mL of ethyl acetate. Allow the solution to percolate through the column and discard the eluate. Collect the bispyribac in a 50-mL round-bottom flask with 20 mL of methanol-ethyl acetate (3 7, v/v). Evaporate the eluate to dryness under pressure. 

Two steps have been added to the original Pesticide Analytical Manual method to increase the stability of the trimethylsilyl derivatives and to clean up the final extract prior to GC analysis, namely the use of a sodium sulfate mini-column to dry the extract after derivatization and the use of a Florisil Sep-Pak cartridge to remove matrix interferences. The advantages of the current method are the simultaneous evaluation of the four analytes, reproducibility and low matrix interference. 

A French Standard, which corresponds to ISO 10095 issued in 1992, specifies a method for determination of caffeine in green or roasted coffee or in coffee extracts (decaffeinated or not).33 Caffeine is extracted with water at 90°C in the presence of MgO. The extract is filtered, then cleaned-up on a mini-column packed with a silica phenyl group derivative, and analyzed by HPLC on a C18 column with a methanol/water (30 70) mobile phase and a UV detector operating at 254 to 280 nm. 

Bonded-phase silica and ion-exchange resins in plastic cartridges and mini-columns are very useful for off-line prepurification of samples, especially those for preparative chromatography, when appropriate pre- or guard columns may not be available for on-line clean-up of a sample. 

These have been effectively used to remove lignin and hydrophobic metabolites from plant-derived samples. Bonded-phase mini-columns are also ideal for the prechromatographic purification of a perbenzoylated sugars, glycopeptides (and derived oligosaccharides), and peralkylated oligosaccharides. ... 

The first toxic peak(s) from the Bio-gel P-2 run (volume reduced to 1 ml) is passed through a preparative mini column (Sep-pak 18 to separate the toxin(s) from yellowish pigments. The eluant is then subjected to HPLC using a semipreparative column (CN bonded phase 9.4 mm x 25 cm). Fig. 3 illustrates the presence of neosaxitoxin (second last peak) and saxitoxin (last peak). A total of 150 mu (mouse units) was loaded. The profile in Fig. 4 shows only neosaxitoxin (500 mu) is present because only a portion of the first toxic peak(s) from the P-2 run was injected. The bottom profile is that of a standard neosaxitoxin (200 mu). 

Extract clean up with GPC and mini-column chromatography concentratbn... 

SAMPLE PREPARATION USING ANION-EXCHANGE MINI-COLUMNS... 

Sample matrices with high levels of citric or other organic acids (e.g., cranberry juice) can result in poor resolution. This method of sample preparation isolates sugars (i.e., neutral compounds) from acids using anion-exchange mini-columns. Development of this protocol is based on research conducted by Hong and Wrolstad (1986). Although the procedure does require additional time (i.e., twelve samples per hour), it does result in improved resolution and a more stable baseline. 

Anion-exchange columns, sugar sample, preparation using mini-columns, 665-666... 

Pour juice onto the polyamide-6 mini column, wash with water, elute flavonol glycosides with methanol, elute flavonol glucuronide, acylated flavonols, and elute ellagic acid with 0.5% NH, in MeOH. Evaporate MeOH to dry sample, redissolve in 4% H3P04, filter (0.45 /nm). 

Purification of the proteins from the cultures grown in 24-well blocks can be performed in 96-well filter plates using a vacuum manifold for column forming, washing, and elution steps, as outlined below. The hexahistidine-tagged proteins in cleared cell lysates are batch loaded onto Ni-NTA agarose in a 96-well filter plate. Columns are formed by applying low (200 mbar) vacuum pressure. These mini-columns are extensively washed, and subsequently the proteins are eluted into a microtiter plate. 

The performance of ARC AII was studied with tracers of Zr, Nb, Hf, Ta, Pa, and some lanthanides produced on line and transported to ARCA n with a He(KCl) jet. To this end, the effluents from the TiOA mini columns were collected in fractions of three drops in small test tubes and were assayed for y-ray activities using two Ge detectors. In agreement with earlier tracer studies, chemical yields for Nb, Ta, and Pa were consistently found to be 85 5%. 

Anion exchange chromatography was used to separate iron from other cations. The remainder of the acid solutions were added to mini-columns (4 ml Pasteur pipettes, Fisher Scientific Co.) containing anion-exchange resin (Bio-Rad AG 1-X8). In 6 N HCl, iron is anionic (FeCl/ ) and binds to the resin. After washing with 25 ml of 6 N HCl to remove cations, iron was eluted as a cation with 0.5 N HCl. 

Transfer each sample to a mini-column using a Pasteur pipette. When this solution has washed onto the column, wash each tube with 1 ml water and transfer this to the column also. As these two solutions leave the column collect them in a scintillation vial. Add 10 to 15 ml aqueous scintillation fluid to the vial and set it aside. 

Fig. 5.8. (A) General scheme of a dynamic focused microwave-assisted extractor. (B) Experimental set-up used to integrate microwave-assisted extraction with the subsequent steps of the analytical process. (1) Leaching step CT controller, MO microwave oven, S sample, R condenser, WR water reservoir, TCPP two-channel piston pump, ER extract reservoir, SV switching valve. (2) Clean-up/preconcentration step M methanol, A air, B buffer, PP peristaltic pump, F filter, EL elution loop, MC mini-column, R retention direction, E elution direction, 1V1-1V3 injection valves, W waste. (3) Individual separation-detection step HPIV high-pressure injection valve, AC analytical column, DAD diode array detector, SR solvent reservoirs.

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