Kieselguhr chromatography

Graded Adsorbents and Solvents. Materials used in columns for adsorption chromatography are grouped in Table 12 in an approximate order of effectiveness. Other adsorbents sometimes used include barium carbonate, calcium sulfate, calcium phosphate, charcoal (usually mixed with Kieselguhr or other form of diatomaceous earth, for example, the filter aid Celite) and cellulose. The alumina can be prepared in several grades of activity (see below). 

Purity can be checked by chromatography (on thin-layer plates, Kieselguhr, paper or columns), by UV or NMR procedures. 

Geraniol [106-24-1] M 154.3, b 230 , d 0.879, n 1.4766. Purified by ascending chromatography or by thin layer chromatography on plates of kieselguhr G with acetone/water/liquid paraffin (130 70 1) as solvent system. Hexane/ethyl acetate (1 4) is also suitable. Also purified by GLC on a silicone-treated column of Carbowax 20M (10%) on Chromosorb W (60-80 mesh). [Porter Pure Appl Chem 20 499 7969.] Stored in full, tightly sealed containers in the cool, protected from light. 

The reagent, which can also be employed to impregnate the layer before chromatography, is best suited for silica gel layers [4] it can, however, also be employed on aluminium oxide, kieselguhr. Si 50000, cellulose and polyamide layers [4]. 

In liqnid partition chromatography a solute distributes itself between a mobile liqnid phase and an immobile solvent attached to a solid matrix (in the earliest experiments a claylike kieselguhr). It is ontside the scope of this chapter to discuss this technique, which, however, is briefly described in Chapter 15. 

Nerolidol [142-50-7] M 222.4, m of semicarbazide 134-135 . Purified by thin layer chromatography on plates of kieselguhr G [MeSweeney JC 17 183 7965] or silica gel plates impregnated with AgNO3, using 1,2-dichloromethane/CHCl3/ethyl acetate/propanol (10 10 1 1) as solvent system. Also by gas/liquid chromatography on butanediol succinate (20%) on Chromosorb W. Stored in a cool place, in an inert atmosphere, in the dark. 

Phosphonium salts, which are generally stable in the form of iodide and tetraphenyl-borate crystalline solids, are frequently purified by recrystallization. Where this is not possible, thick-layer chromatography (0.2-1 mm Kieselguhr, silica) may afford a satisfactory method of purification12,13. In this manner, analysis using secondary ion mass spectrometry (SIMS) has a detection limit 10-50 ng per spot14. 

Karl Fischer titration A sensitive technique for determining water, based on the reaction of HzO with an amine, I2, S02, and an alcohol, kelvin, K Absolute unit of temperature defined such that the temperature of water at its triple point (where water, ice, and water vapor are at equilibrium) is 273.16 K and the absolute zero of temperature is 0 K. Kieselguhr German term for diatomaceous earth, which was formerly used as a solid support in gas chromatography. 

LCAA LC-MS LDA Leu Lys Macrosorb long chain alkylamine spacer liquid chromatography coupled with mass spectrometry lithium diisopropylamide S-leucine S-lysine cross-linked polyacrylamide adsorbed onto kieselguhr... 

Reversed-phase chromatography is the term commonly applied to a system where a nonpolar liquid phase is coated on the solid support and elution carried out with an immiscible polar phase. Such systems are often necessary for separations which cannot be carried out by normal partition or adsorption chromatography. For TLC, the stationary phase is normally a liquid of high boiling point which does not readily evaporate from the adsorbent. Paraffin oil, silicone oil or n-tetradecane coated on silica gel or Kieselguhr are frequently used with water-based mobile phases such as acetone—water (3 2) or acetic acid-water (3 1). Reversed-phase chromatography is very useful for the TLC analysis of lipids and related compounds. 

A solution of S-iodomethyl-6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (310 mg) in acetonitrile (10 ml) was stirred with silver fluoride (947 mg) for 3 days at room temperature in the dark. Ethyl acetate (100 ml) was added and the mixture was filtered through kieselguhr. The filtrate was washed successively with 2 N hydrochloric acid, water, saturated brine, then dried. The solvent was removed and the residue was subjected to column chromatography in chloroform then chloroform-acetone (19 1). The product was eluted with ethyl acetate and crystallised on concentration of the solution to give S-fluoromethyl 6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (0.075 g) melting point 272-273°C (dec.), [a]D= +30° (c 0.35). 

These workers [20] also examined thin layer chromatography of 2,4-DP (Dichloroprop) and MCPP (mixture of Mecoprop and 2-(2-chloro 4-methylphenoxy)propionic acid). In this method the ethyl ether extract of the sample is purified on a column of silicic acid and the herbicides are separated by thin layer chromatography on silica gel-kieselguhr (2 3) with light petroleum-acetic acid-kerosene (10 1 2) as solvent. The sensitivity is 3pg of either compound per litre, the average recoveries of Dichlorprop and MCPP are 85.7% and 87.4%, respectively, and the corresponding standard deviations were 13.9% and 15.5%. 

Separation of TPE and REE by Extraction Chromatography - Extraction chromatography was used for the separation of trivalent TPE and REE. HDEHP was used as the stationary phase on red-kieselguhr as the inert support. Trivalent TPE and REE were loaded on the column filled with this stationary phase from dilute nitric acid. Then, the column was eluted with a solution of 0.05M DTPA-1M lactic acid at pH=3.0. Trivalent TPE were eluted from the column. The influence of aluminum ion was studied, and the pH and flow rate of elution solution and column temperature were also studied as a function of separation. 

Separation of TPE and REE - Fig. 2 presents the flow-diagram of extraction chromatography. The column was filled by stationary phase which was made up of HDEHP and red-kieselguhr with a mesh size of 120-140 mesh. The column was 50 cm high and the diameter was 2.5 cm. All operations were carried out at 28°C and the flow rates were controlled at below 2 mL/min/cm2. 

Catalytic tests in sc CO2 were run continuously in an oil heated flow reactor (200°C, 20 MPa) with supported precious metal fixed bed catalysts on activated carbon and polysiloxane (DELOXAN ). We also investigated immobilized metal complex fixed bed catalysts supported on DELOXAN . DELOXAN is used because of its unique chemical and physical properties (e. g. high pore volume and specific surface area in combination with a meso- and macro-pore-size distribution, which is especially attractive for catalytic reactions). The effects of reaction conditions (temperature, pressure, H2 flow, CO2 flow, LHSV) and catalyst design on reaction rates and selectivites were determined. Comparative studies were performed either continuously with precious metal fixed bed catalysts in a trickle bed reactor, or discontinuously in stirred tank reactors with powdered nickel on kieselguhr or precious metal on activated carbon catalysts. Reaction products were analyzed off-line with capillary gas chromatography. 

The oil was dissolved in 45 ml THF and added to a mixture of 10% palladium on carbon (0.50 g) and 5.82 ml 2,6-lutidine in 30 ml THF, then hydrogenated 4 days at 2 atm hydrogen. The mixture was then filtered through a kieselguhr pad, the filtrate concentrated, and a solid isolated. The solid was then dissolved in 20 ml DMF and treated with 4.53 ml ethyl cyanoacetate and sulfur (1.36 g), then stirred 2 hours at 50°C. The mixture was then treated with 300 ml water and 50 ml brine and extracted three times with 300 ml diethyl ether. The extracts were dried with MgS04 and concentrated. The residue was purified by chromatography with silica using diethyl ether/hexane, 2 3, and ll.OOg product isolated. 

---