Kudema-Danish apparatus

The sample is extracted with dichloromethane by using one of three techniques Soxhlet extraction (10 g of sample with 300 mL of solvent for 16 h), blender extraction (25 g of sample with sodium sulfate and 3 X 150 mL of solvent), or sonication (25 g of sample with sodium sulfate and 3 X 150 mL of solvent) (21). Once the sample has been extracted, the solvent volume is reduced by using either rotary evaporation or a Kudema-Danish apparatus. 

Analytical Procedures. Hydrophobic Neutral Fraction. The hydro-phobic neutral fraction, which was desorbed in methylene chloride, was concentrated to an appropriate volume (1 mL) in a Kudema-Danish apparatus. Then, under a stream of N2 and after addition of the internal standard (i.e., hexa-methylbenzene), this fraction was analyzed by GC-FID and GC-MS. 

Hydrophobic Base Fraction. The hydrophobic base fraction was adjusted to pH 10. A 50-/uL aliquot of the aqueous solution was subjected to HPLC analysis to test for the presence of 5-chlorouracil. The remaining aqueous solution was solvent extracted with methylene chloride. The extract was first concentrated in a Kudema-Danish apparatus, then under a stream of N2, and analyzed by GC-FID and GC-MS. 

Each extract was concentrated to 50 mL in a Kudema-Danish apparatus and then diluted to 500 mL with toluene. This solution was then separated on a 75- X 1-cm i.d. glass column of basic aluminum oxide (150 g, Brockman activity grade 1, 60-100 mesh). This solution and another solution eluted from another 500 mL of toluene were combined as the first fraction. Three other fractions were collected by sequential elution with 1 L each of ethyl acetate, dichloromethane, and a 1 1 mixture of dichloromethane and methanol. The first three fractions were usually intensely fluorescent the first fraction was blue or violet, and the other fractions were various shades of green (from aquamarine to greenish yellow, depending on the reactants). The fluorescence was used to monitor the elution of each fraction from the column. Each fraction was dried under nitrogen on a steam table and redissolved in 50 mL of dichloromethane. HPLC analyses of the fractions were then performed. 

Isolation of the Volatile Compounds. The total reaction mass was simultaneously distilled and extracted into diethyl ether using a Likens-Nickerson (L-N) apparatus. After distillation, 5 ml of heptadecane stock solution (0.0770 g in 200 ml diethyl ether) was added to the isolate as the internal standard. After drying over anhydrous sodium sulfate and filtering, the distillate was concentrated to about 5 ml using a Kudema-Danish apparatus fitted with a Vigreaux distillation column. It was further concentrated under a stream of nitrogen in a small sample vial to a final volume of 0.2 ml. 

Method 3500 is a procedure for extracting nonvolatile or semivolatile compounds fi-om a liquid or solid sample. The sample is extracted with an appropriate solvent, dried, and concentrated in a Kudema-Danish apparatus prior to further processing for analysis. 

What is the distinction between a Kudema-Danish apparatus and a Soxhlet apparatus ... 

Concentration can be performed under a gentle stream of inert gas or with a micro-concentration apparatus (e.g., Kudema-Danish sample concentrator, Supelco, or microconcentrator). This step generates volatile losses (mainly very volatile compounds that have a boiling point lower than the solvent) and will modify the quantitative ratio. 

After drying (removal of water), the extract is quantitatively transferred into a Kudema-Danish flask equipped with a concentrator tube and a Snyder column for sample concentration. The apparatus is placed in a water bath and ether is evaporated out. Use boiling chips in all heating operations. The volume of the extract is concentrated down to 1 to 2 mL. 

Figure 2.13. Liquid-liquid extraction apparatus (a) separatory funnel and (b) evaporative Kudema-Danish sample concentrator. (Reprinted with permission from Ref. 46. Copyright 2002 Kimble/Kontes.)...

Kudema-Danish (KD) Apparatus. 500 mL evaporating flask, 10 mL graduated concentrator tubes with ground glass stoppers, three ball macro-Synder column. 

Concentrating Apparatus. Kudema-Danish concentrator, 250-ml. capacity. 

The combined extracts, contained over the sodium sulfate in the 125-ml. Erlenmeyer flask, are decanted quantitatively into a Kudema-Danish concentrating apparatus. Remove most of the hexane by heating on a fluidized sand bath at 100°C. Since all the hexane is not evaporated, the temperature of the extract will not exceed the boiling point of hexane. 

Apparatus. Separatory funnels, with Teflon stopcocks—125-ml. and 4-liter capacities Kudema-Danish evaporators with Snyder three-ball columns Immerex extractor, A. H. Thomas Cat. No. 1228-E chromatographic tubes—25 mm. o.d. x 300 mm. glass tube with sintered glass in bottom and Teflon stopcock. 

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