Florisil, Chromatography

Alford Stevens et al. [49] carried out a multi-laboratory study of automated gas chromatography-mass spectrometric determinations of polychlorinated biphenyls in soil. The influence of various factors on the accuracy of analytical results were studied. Shaker extraction for 12.5h followed by Florisil chromatography were demonstrated to be the most reliable methods for extraction and clean-up. 

The reddish organge methoxycarbonyl mer-(CO)3(dppe)W[C=CH-(C02Me)], can be made in a similar fashion using methyl 2-propynoate and purification by florisil chromatography using toluene, CH2CI2, and diethyl ether. 

New acid chloride-based preparation of picolinyl esters. A solution of HMP in CH2CI2 (20 mg/mL) is prepared and stored over anhydrous sodium sulfate. The solution is stable in a refrigerator for 1 mo. The stoek solution of HMP in CH2CI2 (0.5 mL) is added to the freshly prepared acid chloride (synthesis of the fatty aeid ehloride, see procedure for DMOX derivatives), eooled in an iee bath, and the mixture is then left to warm up to room temperature for 1 h (a white preeipitate may form). The solvent is added in a stream of nitrogen isohexane (5 mL) is added, followed by 0.5% aqueous sodium bicarbonate. The mixture is shaken thoroughly and then the solvent layer is removed by Pasteur pipette. It is dried via a small sodium sulfate column and concentrated under nitrogen. If necessary, the product can be purified by Florisil chromatography as described above. 

Florisil Trade name of a magnesium silicate used for chromatography, especially of fluorine-containing compounds. 

Adsorption column chromatography has been employed to separate the constituents of pyrethrum. Florisil and aluminum oxide have been used as adsorption columns to retain much of the pigmented materials. The pyrethroids may be caused to elute with several solvents. In our experience mixtures of hexane with ethyl acetate, methanol, ethyl ether, dichloromethane, or acetone have provided different elution patterns. 

The primary method for detecting methyl parathion and metabolites in biological tissues is gas chromatography (GC) coupled with electron capture (BCD), flame photometric (FPD), or flame ionization detection (FID). Sample preparation for methyl parathion analysis routinely involves extraction with an organic solvent (e g., acetone or benzene), centrifugation, concentration, and re suspension in a suitable solvent prior to GC analysis. For low concentrations of methyl parathion, further cleanup procedures, such as column chromatography on silica gel or Florisil are required. 

For multi-analyte and/or multi-matrix methods, it is not possible to validate a method for all combinations of analyte, concentration and type of sample matrix that may be encountered in subsequent use of the method. On the other hand, the standards EN1528 andEN 12393 consist of a range of old multi-residue methods. The working principles of these methods are accepted not only in Europe, but all over the world. Most often these methods are based on extractions with acetone, acetonitrile, ethyl acetate or n-hexane. Subsequent cleanup steps are based on solvent partition steps and size exclusion or adsorption chromatography on Florisil, silica gel or alumina. Each solvent and each cleanup step has been successfully applied to hundreds of pesticides and tested in countless method validation studies. The selectivity and sensitivity of GC combined with electron capture, nitrogen-phosphorus, flame photometric or mass spectrometric detectors for a large number of pesticides are acceptable. 

In place of silica gel, Florisil is also used as the adsorbent in column chromatography. Purification of chlornitrofen using a Florisil column is as follows after installing a column packed with 10 g of Florisil suspended in n-hexane, the sample solution is added continuously to the column and the initial eluate is discarded. A 100-mL volume of diethyl ether-n-hexane (1 19, v/v) is charged to the Horisil column and the eluate is discarded. Chlornitrofen is eluted with 30 mL of this mixture and the eluate is concentrated to dryness before the addition of acetone for GC analysis. ... 

Florisil column chromatography is effective in eliminating interfering substances in soil. The organic solvent extracts from soil samples are charged to a column plugged with Florisil which has been activated at 130 °C overnight before use. The effluents from the column with a mixed solvent such as n-hexane-acetone are concentrated to... 

Residues of flumioxazin are extracted from plant matrices with aqueous acetone. The extracted residues are partitioned into dichloromethane. The dichloromethane is removed through rotary evaporation. Partitioning between hexane-acetonitrile followed by Florisil column chromatography purifles the plant extract. Residues of flumioxazin are quantitated by gas chromatography GC. 

Residues of flumioxazin in/on soil are extracted with acetone-0.1 N HCl (5 1, v/v), partitioned into dichloromethane, cleaned up with Florisil column chromatography and quantitated by GC. 

Flumioxazin is extracted from water with dichloromethane. If needed, the sample is cleaned with Florisil column chromatography prior to quantitation by GC. 

The eluate from the Cig cartridge is concentrated by rotary evaporation and the residue is dissolved in n-hexane and then subjected to a cleanup procedure using a Florisil cartridge. The eluate is dried and analyzed by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). 

This technique is based on the same separation mechanisms as found in liquid chromatography (LC). In LC, the solubility and the functional group interaction of sample, sorbent, and solvent are optimized to effect separation. In SPE, these interactions are optimized to effect retention or elution. Polar stationary phases, such as silica gel, Florisil and alumina, retain compounds with polar functional group (e.g., phenols, humic acids, and amines). A nonpolar organic solvent (e.g. hexane, dichloromethane) is used to remove nonpolar inferences where the target analyte is a polar compound. Conversely, the same nonpolar solvent may be used to elute a nonpolar analyte, leaving polar inferences adsorbed on the column. 

The sample is homogenized with acetonitrile. An aliquot of the extract is evaporated to dryness and the residual material is dissolved in ethyl acetate-toluene (3 1, v/v), and subjected to cleanup by gel permeation chromatography (GPC). After GPC, the sample is subjected to an alumina and Florisil SPE cleanup procedure. The concentrated eluate is analysed by gas chromatography/thermionic nitrogen-specific detection (GC/TSD). 

Transfer the concentrate into a 200-mL separatory funnel using two portions of 20 mL of n-hexane. Add 100 mL of saturated sodium chloride aqueous solution and extract twice with 100 mL of n-hexane by shaking for 5 min and allow the phases to separate. After dehydration of the n-hexane extract with 10 g of anhydrous sodium sulfate, concentrate the extract to dryness below 40 °C with a rotary evaporator. Transfer the residue with three portions of 5 mL of n-hexane into a glass column containing 10 g of Florisil (deactivated by water at a rate of 1%). Elute with 100 mL of n-hexane-ethyl acetate (9 1, v/v) and then with 100 mL of n-hexane-ethyl acetate (7 3, v/v). Concentrate the second eluate to dryness and dissolve the residue in 10 mL of n-hexane and analysis by gas chromatography/flame thermionic detection (GC/FTD). 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

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