Nitrogen evaporation

Sample extracts may be concentrated by nitrogen evaporation. Turbovap concentrators direct a steam of nitrogen over the extract surface. Vessels are housed in a temperature-controlled water bath. Although some losses of volatiles occur, this technique is suited to semi-volatile analysis such as DRO. 

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Vacuum evaporator, Btichi Model RE121, Brinkmann Instruments, Inc. (Burlingame, CA, USA), with temperature-controlled water-bath Nitrogen evaporator, Meyer Model 111, Organomation Associates, Inc. (South Berlin, MA, USA), with temperature-controlled water-bath... 

Laboratory homogenizer and mechanical shaker Nitrogen evaporator pH meter... 

Snyder column Kudema Danish concentrator Nitrogen evaporation Vacuum... 

Figure 3 (A) Robot system for lipofection screening (A) Worktable with racks for microplates, buffer reservoirs, plastic, and glass vials. (B) Four tip liquid handling arm. (C) Gripper for transport of microplates and glass test tubes. (D) High power water bath sonicator. ( ) Nitrogen evaporator. (F) Microplate washer. (G) Absorbance reader. (H) Luminescence reader. (/) Transparent hood. (/) CO2 incubator with pneumatic door (from the rear, front view in B). (B) Self-constructed robotic conveyor for the transport of cell culture plates from the incubator to the worktable.

N-EVAP model 112 nitrogen evaporator (Organomation) with moisture trap in line from N2 source (Fig. Dl.2.1)... 

Using a nitrogen evaporator, dry the sample down completely under a stream of nitrogen at 40°C in a 15-ml glass tube with a Teflon-lined screw-cap. 

Figure D1.2.1 An example of a multiport (24-position) nitrogen evaporator (N-EVAP, Organomation Associates, reprinted with permission).

Nitrogen evaporation apparatus (N-Evap Analytical Evaporator Model 111. Organomation Association Inc., Northborough, MA, or equivalent). 

Prior to column chromatographic cleanup procedures die extracts from all matrices must be concentrated to approximately 1.0 mL. This concentration may be accomplished using either K-D or rotary evaporator, followed by nitrogen evaporation. 

Transfer the centrifuge tube containing the sample extract to a nitrogen evaporation device. Adjust the flow of nitrogen so that the surface of the solvent is just visibly disturbed. 

The sample was denatured with formic acid and extracted with cyclohexane. The organic extracts were purified 130 on a Power Prep automated sample cleanup system with acidic silica gel, acid/base/neutral silica, and a carbon column. PCBs were eluted using dichloromethane and cyclohexane. The eluates were concentrated using a nitrogen evaporator for analysis by GC-HRMS... 

The rates of decomposition for the nitrogen-evaporated films, when corrected for the difference in surface area, are very close to those for the most active high-vacuum films. 

The gas used for the curtains is the only gas that is discharged to the atmosphere and, provided that the curtains work effectively, very little of the solvent-rich gas in the evaporation zone mixes with them. Therefore, the amount of liquid nitrogen evaporated in the third stage is determined primarily by the requirements of the gas curtains. If the solvent is not very volatile there is little solvent stiU in the circulating gas at this point and to return it to the evaporation zone rather than condensing it does little harm to the efficiency of the system. 

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