Product recovery when using normal phase solvents is best carried out by bulking the fractions and removing the solvent in a rotary evaporator under reduced pressure. For reverse phase solvents that have a high water content, recovery can be best achieved by passing the fraction through a reverse phase, C18, column of high capacity. The solute and solvent is adsorbed, and the solute and solvent content of the fraction can be recovered by displacement with another solvent, and the solute, now concentrated is recovered by evaporation. Solvent Hazard Unless solvent recycling can be employed, which is not always

In the slurry method of coating, a weighed amount of the support is placed in the flask of a rotary evaporator and the required mass of stationary phase added. An appropriate volatile solvent is then added in sufficient quantity to produce a free flowing slurry. The flask is then rotated at room temperature for ten minutes to ensure complete mixing. The rotating flask is then heated and the solvent removed by evaporation. When the packing appears dry, the material is then heated to about 150˚C in and oven to remove the final traces of solvent. This method of coating gives an

, taken from the Raunds Area site in the Nene Valley Northhamptonshire UK.   Samples, about 2 g in weight, were scraped free from soil and ground to a fine powder in a carefully degreased pestle and mortar. A know mass of n-heptadecane was added as a standard, and the powder extracted twice with 10 ml of a mixture of chloroform and methanol (2+1) with supersonic agitation. After each extraction the mixture was centrifuged to remove the suspended solid. The extract was concentrated in a rotary evaporator and finally dried in a gentle stream of nitrogen. Trimethylester and ether derivatives were prepared by heating aliquots with excess N,O-bis(trimethylsilyl)trifluoroacetamide

  GC separations followed by negative ion chemical ionization mass spectrometry has been shown to be a very sensitive method for monitoring pesticide contamination of vegetable foodstuff (28). The procedure used was as follows. 15 g of the material was extracted with 60 ml of ethyl acetate and 13 g of anhydrous sodium sulfate and separated. The residue was then extracted with a further 30 ml of ethyl acetate and the two extracts combined. A 30 ml aliquot was evaporated to dryness in a rotary evaporator at 60 C. The residue was then dissolved in 5 ml of ethyl acetate and was used directly for analysis. The technique was tested using pepper extracts spiked with chlorothalonil and procymidone. 2 ml samples were injected onto a capillary column 30 m long, 0.25 mm I.D. carrying a film 0,25 mm thick of crosslinked 5% diphenyl-95% dimethylsiloxane Initially the column was held at 70 C for 1 minute and then programmed to 180 C at 35 C per minute, then to 240 C at 10 C per minute