Solvent Clean-up

After recovering fluthiacet-methyl from the crop extract with n-hexane, acidify the residual aqueous layer and extract the free form of fluthiacet-methyl with n-hexane-ethyl acetate (2 1, v/v). After evaporating the solvent, clean up the residue with an Ci8 Empore Disk Cartridge. After methylation of the free form with trimethylsilyl-diazomethane, clean up the ester with a Bond Elut LRC SI and a Sep-Pak Plus NH2 cartridge, and quantify as fluthiacet-methyl by GC/FTD. 

To provide a more generalized picture for achieving separations by solvent extraction one can consider a number of possibilities, according to direction of transfer. Such possibilities are (i) pre-extraction (aqueous — solvent) (ii) extraction (aqueous — solvent), scrubbing (solvent —> aqueous) (iii) stripping/back extraction (solvent — aqueous) and (iv) solvent clean up (solvent —> aqueous — solvent). The direction of transfer has been shown in the parentheses of the four possibilities that have been listed. A reference to Figure 5.14 is relevant in this premise. 

Second, as a solvent recycle process, which ran for 54 hours without solvent clean-up to treat 3.85 L of a DIAMEX An(III) + Ln(III) product. This second hot test, which generated 6.5 L of Am(III) + Cm(III) product, revealed partial degradation of t Pr-BTP, probably because of alpha/gamma radiolysis reflected by a 40% decrease in the solvent-extraction performance observed after two cycles (207). 

Cames, B., Saucerotte, B., Faucon, M., Rudloff, D., Gastaldi, M., Bisel, I. 2004. Long term evolution of recycled DIAMEX solvent properties under hydrolysis and radiolysis with or without solvent clean-up. ATALANTE 2004 Advances for Future Nuclear Cycles, June, Nimes, France. 

Tse, P.K., Reichley-Yinger, L., Vandegrift, G.F. 1990. Truex process solvent clean-up with solid sorbents. Sep. Sci. Technol. 25(13-15) 1763-1775. 

Lawrence, J.F., C. Menard, M.C. Hennion, V. Pichon, F. LeGoffic, and N. Durand (1996). Evaluation of immunoaffinity chromatography as a replacement for organic solvent clean-up of plant extracts for the determination of triazine herbicides by hquid chromatography. J. Chromatogr. A, 752 147-154. 

Wipe and liquid samples from pyrolized transformer oil (CDDs) Extraction with organic solvent clean-up on neutral silica/basic silica/acidic silica column clean-up and fractionation by sequential chromatography on basic alumina, carbon/silica gel, and Sepralyte columns HRGC/HRMS No data 58-151 (wipe) 51-136 (liquid) Hardin et al. 1989 (ASME method)... 

These studies resulted in the proposed solvent extraction recovery process for Am as given in the flowsheet of Figure 14. Solvent clean-up and recycle are included. The Am product stream is to enter the present Am02 production line either before or behind the ion exchange step (Figure 3) depending upon the concentration of Pu in the extracted americium. 

The extraction cycles lead to the production of various aqueous and organic waste solutions, mainly from solvent clean-up and washing. Some of the aqueous LLW solutions may be released directly into the environment if their activity is low enough. Others are decontaminated by precipitation, coprecipitation, ion exchange or sorption procedures. The general tendency in handling liquid wastes is to reduce the volume as far as possible and to transform LLW into MLW, as already mentioned. Liquid organic wastes are either incinerated or the radionuclides contained therein are separated by precipitation or other procedures. 

Random-contamination buildup —> Flush column with strong solvent clean up sample use HPLC grade solvent. 

Meat, vegetable Vacuun distill ground sample, extract distillate with solvent, clean up by column chromatography, derivatize with peroxytrifluoroacetic acid and column chromatographic clean up and concentrate. GC-ECD 0.2 ppb (for 250 g sample) <78% Telling 1972... 

The different sample pretreatment (dissolution into various solvents), clean-up (using a variety of techniques to remove lipids and other interfering compounds), and GC-ECD or GC-MS conditions are described in detail in the certification report [16]. 

First, the solvents should be relatively free of trace impurities while dissolving the compounds of interest effectively. The solvent trace impurities, while not detectable in the bulk, can produce spurious peaks after the concentration of the volume of extracted sample. Whenever an extensive solvent clean-up is either impossible or impractical, appropriate sample blanks should frequently be run. With today s capabilities of high-resolution GC and spectral identification, occasional solvent impurities are tolerated as convenient markers . A good sample solubility is required to minimize possible losses due to sample adsorption on the glassware or, simply, its unnoticed precipitation. 

Carbon dioxide analysers, based on heat capacity, electrical conductivity or partial pressure measurements, but especially on IR light absorption, are therefore used at various points in industrial processes. Carbon monoxide and dioxide are the species most commonly analysed for by the last of the above-mentioned detection techniques, which is also employed in a variety of processes [6], namely (a) control of the hydrogenation of plant oils in order to avoid production of unwanted trans isomers (b) measurement of sugars and CO2 In soft drinks (c) measurement of moisture (d) determination of CO2 In Industrial environments (e) determination of isocyanates In the production of polyurethane (f) determination of methane In argon from nuclear plants (g) control of the efficiency of solvent clean-up and recovery systems. 

The medium level liquid waste (MLLW) results essratially from evaporating various streams from the chemical process, such as solvent clean-up, off-gas scrubbers, product concentration, etc Table 21.8. It may contain up to 0.5 % of the uranium and up to 0.2%... 

The liquid organic waste consists of spent TBP diluent mixtures originating from the organic solvent clean-up circuits and from the diluent (keros e) washings of the aqueous streams (to remove entrained solvent) in addition to degradation products of TBP and die diluent it contains small amounts of actinides (mainly U and Pu) and FP (mainly Ru, Zr, and Nb). 

Fat from tissue extracted with solvent cleaned up by column chromtography and concentrated... 

Extract sample with solvent clean up with Florisil and/or activated copper and concentrate extract... 

The separation section, which must include means for solvent clean-up and recycling... 

Wood (1985) suggested that chloroform might be a more effective extractant. However, chloroform has the disadvantage of forming hydrochloric acid upon storage, and hence its use will lead to the production of phaeophytins and phaeophorbides during the extraction procedure. While this may not seriously affect total analyses, it will surely be noted in HPLC analysis. Thus, if chloroform is to be employed as the extractant, frequent solvent clean-up becomes necessary. 

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