Evaporator centrifugal

Evaporation can be performed directly from reactors or kettles provided that substances are thermally stable. Such evaporation is time consuming because of the low heat-transfer surface area per unit volume. In the case of temperature sensitive materials, the residence time in the evaporator must be short and the temperature should be as low as possible. Consequently, continuous vacuum evaporators with a short residence time should be used to treat such materials. Falling-film (thin-film) evaporators are suitable to perform such operations. A typical falling-film evaporators is shown in Fig. 7.2-14. Centrifugal evaporators are also commonly used. 

Natural latex is concentrated by three main methods centrifuging, evaporation and creaming electrodecantation once showed promise, but the output of latex concentrated by this method is now negligible. 

Extraction with methano and centrifugation evaporation redisso ution in water and extraction wi th ethy acetate H2O removed (anhydrous Na2S04) and concentration separation by TLC... 

Speed Vac apparatus centrifugal evaporator (EYELA, http // www.eyelaworld.com/, CVE-1000) with a vacuum pump (Leybold Vakuum GmbH, http //www.oerlikon.com/ leyboldvacuum/, DIVAL 1.2 L). 

PrOH/hexane (3 2), centrifuge. Evaporate three times from 10 vol of CHCl3/MeOH, 2 1. Silica-column chromatography. Add menaquinone-7 as internal standard to purified fraction. 

Blend samples with appropriate solvent and added dihydrophylloquinone (internal standard). Centrifuge. Evaporate sample extracts to dryness (except edible oils) and dissolve residue in hexane. Add equal volume of MeOH/HjO (9 1), mix, and centrifuge. Remove upper hexane layer and evaporate to dryness. 

Current sample preparation procedures for water samples use low temperature vacuum evaporation of water with a centrifugal evaporator followed by derivatization. They are time consuming and... 

Centrifugal evaporator, with 4 to 8 sample rotor compatible with 25ml glass centrifuge tube glassware Rotorvane pump with water trap for centrifugal evaporator SPE 12 port vacuum manifold with vial holder compatible with the vials glassware... 

Extract with benzene centrifuge evaporate redissolve in benzene clean-up with TLC extract with benzene evaporate redissolve in benzene... 

Bromophenylisocyanate (0.2 mmol) was combined with the Step 3 product in 1 ml toluene and heated to 100°C for 3 hours, then concentrated by centrifugal evaporation. The residue was dissolved in 5 ml DMF and purified by HPLC on a Cl8 silica gel column using acetonitrile/water gradients containing 0.05% trifluoroacetic acid as eluent. 

Powder TLC Mix, shake and boil with EtOH-lead acetate sold., decant supernatant, extract with CHC1], centrifuge, evaporate, dissolve in MeOH-CHClj 0 1) Silica EtOAc-MeOH-H.O (30 4 3) Chloramine T USP 23, p. 512 TLC [440] HPLC (844 847)... 

Internal standard addition pH adjustment Centrifugation Evaporation... 

Centrifugal evaporators are used on an industrial scale for gentle distillation of temperature-sensitive materials (Fig. 2.49). Here, a thin film is evenly spread on a heated conical plate by centrifugal force. This technique reduces hold-up, contact time and foaming of the liquid on the heated surface considerably. Furthermore, the centrifugal force immediately throws the condensed steam away from the rotor s heating surface (dropwise condensation). This results in a uniformly heated rotor surface with a high overall heat transfer coefficient up to 30,000 kJ/(m h K). This heated evaporation surface is located opposite to a cooled box which results in the distillate removal. 

Treatment of resins 84 with SnCL H2O in DMF at room temperature for 24 h furnished the 3,4-dihydroquinoxalin-2-ones 85 in solution. The filtrates were collected in scintillation vials and concentrated in a centrifugal evaporator. The residues were partitioned between ethyl acetate and 5% aqueous NaOH and sonicated for 5-10 min. The organic layers were removed, dried over anhydrous Na2SO4, filtered into tared scintillation vials, and concentrated once more. 

In the Presence of Isooctane 0.05 M Zr(NO3)4 acidified with HNOjwas mixed ultrasonically with 0.15 M ammonia at nearly stoichiometric ratio (final pH7-10) in the presence of isooctane (1 1 to 1 5 organic/aqueous phase ratio) containing 0.01-0.5 M of carboxylic acid. The precipitate was centrifuged, evaporated at 150°C, and calcined at 1000°C. 

Sample preparation Prepare urine samples by adjusting pH to 5.0 with 2 M HCl then hydrol3 ing with 20 p,L 20 000 U/mL p-D-glucuronidase at 37° for 5 h. 500 pL Plasma or urine + 15 p,L 2.5 mg/L desmethylflunitrazepam in MeOH 50 pL 0.5 M NaOH + 5 mL diethyl ether, agitate, centrifuge, evaporate to dryness at 45° under vacuum, take up residue in 100 p,L MeOH, iiyect 25 pL aliquot. 

Sample preparation Add 2 volumes acetone to the hepatocyte suspension, centrifuge at 13000 g for 5 min. Remove the clear supernatant and evaporate it to dryness in a centrifugal evaporator, reconstitute the residue in 1 mL MeOH, sonicate, centrifuge at 13000 g for 5 min, inject an aliquot. 

Sample preparation 1 mL Plasma + 50 p.L MeCN water 60 40, shake at 150 cycles/min for 2 min, centrifuge at 1500 g for 3 min, remove the supernatant and extract the residue again with 400 pL MeCN, combine the supernatants, centrifuge, evaporate to dryness with a nitrogen stream under vacuum, reconstitute with 200 pL MeCN water 25 75, filter (0.45 pm), inject a 20 pL aliquot. 

Concentration of latex is necessary because of the preference by the latex products manufacturing industry for latex with high dry rubber content (DRC), and for transport economy and purification of the latex. The processes for concentration include evaporation, electrodecantation, creaming, and centrifuging. Evaporation removes only water and hence the ratio of non-rubber constituents to rubber, and the particle size distribution remain unchanged. However, the other three processes involve the partial removal of non-rubber materials and smaller rubber particles. Centrifuging and creaming are more popularly used for the production of concentrated latex. 

Hydrolyze sample with HPLC/UV NaOH and heat extract with hexane centrifuge evaporate reconstitute with ammonium acetate/ acetonitrile elute from reverse-phase column with ammonium acetate/ acetonitrile... 

---