Solvent partition and column

A sensitive method was described for the detection and estimation of residues of niclosamide in bananas involving extraction of niclosamide, purification of the extract by solvent partition and column chromatography, formation of the hepta-fluorobutyryl derivative of 2-chloro-4-nitroaniline in 99% yield, and determination of the derivative by gas liquid chromatography with electron capture detection. 

Abscisic acid (ABA) levels in rice plants, 308,31Or levels in squash hypocotyls, 315/.316 Active component of brassins identification, 9,lQf pilot plant extraction, 6,7/,8 solvent partition and column chromatography, 8 Adventitious root(s) development, 233,234r,235 formation, 247 Agriculture, application of 24-epibrassinolide, 280-290 22-Aldehydes, synthesis of brassinosteroids, 47-50f a hormone function, description for brassins, 4... 

Tan [71] devised a rapid simple sample preparation technique for analysing polyaromatic hydrocarbons in sediments. Polyaromatic hydrocarbons are removed from the sediment by ultrasonic extraction and isolated by solvent partition and silica gel column chromatography. The sulphur removal step is combined into the ultrasonic extraction procedure. Identification of polyaromatic hydrocarbon is carried by gas chromatography alone and in conjunction with mass spectrometry. Quantitative determination is achieved by addition of known amounts of standard compounds using flame ionization and multiple ion detectors. 

Sample preparation Water was extracted with hexane for chlorpyrifos (a) and benzene for 3,5,6-trichloro-2-pyridinol (TCP) (b) banana samples were prepared using standard Food and Drug Administration procedures based on extraction, solvent partitioning, and silica gel or alumina column chromatography. 

Inevitably the study of steroid metabolism in infancy has had to be delayed until suitable techniques were available. Crystallographic techniques initially used for isolating steroids from adult and animal material were not applicable since considerable amounts of tissue or urine would be required. The early solvent partition and adsorption techniques involving countercurrent distribution and column chromatography could have been applied, but since considerable labor would have been involved and no gross difference from the adult pattern of steroid metabolism was suspected in infants, little work was done until the availability of paper and thin-layer chromatography greatly improved the feasibility of study. 

Chemical fractionation methods used in this study were gel cFromatography, acid-base neutral solvent partitioning and chromatography on silica gel columns. Identification of compounds was done by gas chromatography/mass spectrometry (GC/MS). Proton nuclear magnetic resonance (PMR) spectroscopy was used to characterize fractions and subfractions which were not amenable to GC/MS analysis. 

Prymnesin (toxic protein from phytoflagellate Pyrymnesium parvum) [11025-94-8]. Purified by column chromatography, differential soln and pptn in solvent mixtures and differential partition between diphasic mixtures. The product has at least 6 components as observed by TLC. [Ulitzur and Shilo Biochim Biophys Acta 301 350 1970.]... 

The analyst must remember that solubility of a polymer in the chosen eluant is a necessary, but not sufficient, requirement for ideal GPC separations. Once injected on the column, the polymer has a choice of partitioning onto the stationary phase or remaining in the solvent. It is imperative that the analyst choose solvent and column conditions such that the ideal, nonadsorptive, GPC mechanism can occur. 

AM columns are another means of measuring lipophilic characteristics of drug candidates and other chemicals [99-103]. 1AM columns may better mimic membrane interactions than the isotropic octanol-water or other solvent-solvent partitioning system. These chromatographic indices appear to be a significant predictor of passive absorption through the rat intestine [128]. 

In both cases, the entire method consists of four stages solvent extraction and partition, cleanup by gel permeation chromatography (GPC) and/or mini silica gel column chromatography and gas chromatography (GC) determination. Except for the central GPC, several variations occur at each stage depending on the kind of sample material and the residues to be analyzed. The variations can be combined with each other in a variety of ways according to the requirements. 

Residue analytical methods for neonicotinoids in crops, soil and water samples have been developed. The basic principle of these methods consists of the following steps extraction of the crop and/or soil samples with acetone or the other organic solvent, cleanup by liquid-liquid partition or column chromatography, and quantitative analysis by high-performance liquid chromatography with ultraviolet detection (HPLC/UV). Simple column cleanup procedures are used to improve the accuracy and sensitivity of these methods. 

Residues are extracted with acetone. The extract is rotary evaporated to remove acetone, the concentrated residue is diluted with 5% aqueous sodium chloride, and residues are partitioned into dichloromethane. The extract is then concentrated and purified on a silica gel column. Residues of pyriproxyfen are quantitated by gas chromatography with nitrogen-phosphorus detection (GC/NPD). For citrus, a hexane-acetonitrile solvent partition step is required for oil removal prior to the dichloromethane partition step. 

Food (fish) Grinding with petroleum ether solvent extraction clean-up by liquid-liquid partition, Florisil column chromatography GC/NPD 0.1 ppm Not specified Lombardo and Egry 1979... 

Solvent-partitioned mixtures are fractionated further by column chromatography involving Sephadex LH-20, silica gel, or a combination [19]. Quantitative recovery of constituents is often possible with Sephadex chromatography. With a MeOH/CHCl3 (1 1) eluent, pigmented and other polar material is removed in the early fractions, while the nonpolar isonitrile-related compounds elute later. 

PAHs were isolated from the crude extracts by a two-step procedure. The neutral fraction was separated by simple acid-base partitioning and then chromatographed on a silica gel column. The column was first eluted with TO ml of hexane. Subsequent elution with 200 ml of hexane containing 5 dichloromethane gave the PAH fraction. The solvent was carefully evaporated to produce the dry extract. The PAH fraction of SI and S2 were designated as S1-C2 and S2-C2, respectively. 

---