Rotary film evaporator

The submitters divided the mother liquor into 6 equal portions and concentrated each to a volume of 100 ml. at a pressure of 25 mm. in a 1-1. round-bottomed flask on a rotary film evaporator. The rotary film evaporator used was obtained from Cenco Scientific Co., Santa Clara, California. 

The submitters used a rotary film evaporator to evaporate the mother liquor at a pressure of 25 mm. in a water bath heated to 90°. 

A two-step evaporation process saves energy (Fig. 10). The feed is a concentrated alkanesulfonate solution with 35-47 wt % solid and 8-15 wt % neutral oil. In the first step the water and part of the neutral oil are vaporized at 0.4-0.5 MPa. In the second step the main part of the neutral oil is swept out by superheated steam at standard or reduced pressure. A spiral coil vaporizer or such a vaporizer in combination with a rotary film evaporator serves as a suitable apparatus. The pressurized vapor of the first step can be used for producing low-pressure steam. 

Filter the wet resin and rinse with distilled water. Repeat the washing procedure until the washing water is neutral to pH paper. Rinse with three 100-ml portions of methanol. Evaporate off the remaining methanol in a rotary film evaporator under vacuum, rotating slowly at 40°C, until visibly dry. 

Phenylazo)phenyl Dialkyldithiocarbamato Tellurium3 A solution of the sodium dialkyldithiocarbamate (1.03 mmol) in 15 ml dry methanol is added under an atmosphere of nitrogen to a stirred solution of 2-(phenylazo)phenyl tellurium chloride (0.35 g, 1.0 mmol) in dichloromethane (25 ml). The mixture is stirred for 20 min at 20°. The solvents are removed on a rotary film evaporator. Dichloromethane is added to the residue. The mixture is vigorously stirred and the solution is filtered to remove the sodium chloride. 

Benzeneazophenyl Tellurium Tris[dithiocarbamates]2 To a stirred solution of 1.25 g (3.0 mmol) of 2-benzeneazophenyl tellurium trichloride in 200 ml dichloromethane under an atmosphere of nitrogen is added a solution of 10 mmol the sodium dialkyldithiocarbamate in 100 ml of dry methanol. The mixture is stirred for 0.5 h at 20°. The solvents are removed on a rotary film evaporator. The residue is treated with 200 ml dichloromethane. Insoluble sodium chloride is removed by filtration. Removal of dichloromethane from the filtrate and recrystallization of the residue from methanol produces purple crystals. 

Identification Place about 150 mg of melted sample into a 16- x 125-mm tube equipped with a screw cap having a Teflon liner, and add 4 mL of absolute methanol, 4 drops of a 25% sodium methoxide solution in absolute methanol, and a boiling chip. Cap the tube, reflux for 15 min, and cool to room temperature. Extract as follows Add 8 drops of a 15% potassium acid sulfate solution, 4 mL of water, and 4 mL of n-hexane cap the tube shake for 1 min and centrifuge for 30 to 60 s. Decant and discard the M-hexane layer, and repeat the extraction with three additional 4-mL portions of M-hexane, discarding each extract. Transfer the aqueous alcoholic phase from the tube into a 50-mL round-bottom, glass-stoppered flask place the flask in a water bath at 50° to 55° and evaporate to near dryness (about 0.5 mL of residue) in a rotary film evaporator under full water aspirator vacuum. 

Adjust the urine sample to pH 5 by the addition of dilute hydrochloric acid. For each 9 volumes of urine add 1 volume of acetate buffer pH 5) containing 5000 Fishman units/ml of mixed glucuronidase/ sulphatase (from Helixpomatia), and incubate the mixture at 31 for 24 hours. Centrifuge, pour the supernatant liquid on to a column of Amberlite XAD-2 resin, wash the column with 50 ml of water, and then elute the steroids with 100 ml of ethanol. Evaporate the ethanol using a rotary film evaporator, dissolve the residue in 0.5 ml of ethanol, and add 2 ml of cyclohexane. 

Identification of Anabolic Steroids in Horse Urine Solvate a Sep-Pak C-18 cartridge (see Reagent Appendix) with 5 ml of methanol, followed by a wash with 5 ml of water. Pass 10 ml of the urine sample through the cartridge, wash with 10 ml of water, and elute with 10 ml of methanol. Evaporate the eluate at 50° in a rotary film evaporator and dissolve the residue in 1 to 2 ml of a mixture of chloroform and methanol (17 3). 

Prepare a 10 mm internal diameter column of Sephadex LH-20 (see Reagent Appendix) using a slurry of 2 g of the resin in chloroform methanol (17 3). Apply to the column the dissolved residue obtained above and elute with 30 ml of chloroform methanol (17 3) to obtain the glucuronic acid conjugates. Carry out a second elution using 50 ml of chloroform methanol (1 1) to obtain the sulphate conjugates. Evaporate the two eluates separately in a rotary film evaporator. 

Hydrolyse the sulphate conjugates by dissolving the residue in 10 ml of ethyl acetate containing 0.1 ml of sulphuric acid and incubating at 37° for 18 hours. The ethyl acetate solutions from both hydrolysates are treated as follows. Wash the ethyl acetate solution with two 5-ml portions of 2M sodium hydroxide, followed by one wash with saturated sodium chloride solution, and evaporate the solutions to dryness in a rotary film evaporator. 

Gas Chromatography-Mass Spectrometry. Prepare methoxime derivatives by heating the extract from the thin-layer chromatographic plate with 100 xl of an 8% solution of methoxyamine hydrochloride in dry pyridine at 60° for 30 minutes, and evaporate in a rotary film evaporator. Silylate by dissolving the residue in 100 Lll of chloroform, adding 100 Lll of A,0-bis(trimethylsilyl)acetamide and 20 Lll of trimethylchlorosilane, then seal, and heat for 2 hours at 60°. When only 5a-estrane-3P,17a-diol is to be confirmed the methoxime formation can be omitted. Prepare a 2-cm column of Sephadex LH-20 in a Pasteur pipette with a cotton wool plug, using a... 

Gas Chromatography-Mass Spectrometry Negative-ion chemical ionisation mass spectrom-etry is the best method to identify a wide range of synthetic corticosteroids in horse urine (E. Houghton et at, Biomed. Mass Spectrom., 1982, 9, 459-465). Method. Extract 10 ml of urine with 25 ml of methylene chloride, separate the solvent layer, dry over anhydrous sodium sulphate, and evaporate to dryness in a rotary film evaporator at 30° to 40°. Heat the residue with 100 p.1 of an 8% solution of methoxyamine hychochloride in dry pyridine in a reaction tube at 80° for 30 minutes, add 50 pi of trimeOiylsilylimidazole, [Pg.98]

There are many variations in the details of the form of rotary film evaporators and a typical assembly is illustrated in Fig. 17.1. A general guide to the use of a rotary evaporator is given in Box 17.1. 

When using rotary film evaporators you should take note of the following safety advice ... 

Preparation of Oils for Analysis. The light oils were used as sampled. All were essentially free from water and particulates. The heavy oils contained some water and sand. Water was removed by using a Barrett receiver while azeotroping with toluene. The solutions of heavy oils in hot toluene subsequently were filtered through glass-fritted filter funnels with fine pore sizes (4-5.5 fi) to remove sand particles. Then the sand was washed several times with hot toluene. Toluene was removed in vacuo using a rotary film evaporator and a hot water bath. The final removal of solvent was accomplished at 4 mm of mercury pressure and at 90°C waterbath temperature. 

The homogenate was rotary film evaporated briefly to remove any residual dichloromethane. PectinolC (0.1 ) was added in pH5.0 buffer and the homogenate incubated at 30°C for 2h hours. After incubation, the terpene aglycons were extracted with 10 volumes of re-distilled dichloromethane as previously described. 

Filter off any undissolved material and remove the toluene by distillation under reduced pressure (rotary film evaporator). 

If the side-chain liquid crystalline cyclic siloxane tetramer is pure and free of starting monomer, redissolve the tetramer in the minimum amount of dry dichloromethane and filter using a disposable syringe filter (PTFE membrane 0.45 (Jim) to remove any small particulates. The solvent can then be carefully removed by distillation under reduced pressure (rotary film evaporator) and dried in vacuo overnight. 

Reduce volume by rotary film evaporation, add water to 40 ml and extract with ether. 

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