Optimization base extraction

The most active extracts were obtained8 from L. mesenteroides cultures containing sucrose extracts prepared from L. mesenteroides organisms repeatedly transferred through D-glucose broth were of low potency.48 Active extracts in dilutions of 1 2 or 1 4 produced dextran in 5% sucrose solutions after one to two hours at 23°, and at pH 5.6 with acetate buffer demonstrable amounts of dextran were produced after twenty days with 1/10,000 dilution of the extract. Optimal yields of dextran were less than 5% based on sucrose. Small concentrations of dextran were detected by means of precipitin titrations with pneumococcus antisera Types II or XX (see page 215). 

This chapter describes the simpler cleanup approach of base extraction for XAD resin extracts. Quality assurance procedures statistically define the benefits of this analytical approach for broad spectrum capillary GC. The extraction procedure was optimized by studying UV absorbance of the base extractant. 

Optimization of Base Extraction. The base extraction, sample cleanup procedure was optimized by taking into account the following facts ... 

The use of UV-absorbance measurements to optimize the base extraction was demonstrated. UV measurements over a wide wavelength range were demonstrated to be necessary because many humic materials being removed may not have the same maximum absorbance wavelength. 

Modolo, G., Asp, H., Schreinemachers, C., Vijgen, H. 2007. Development of a TODGA based process for partitioning of actinides from a PUREX raffinate Part I Batch extraction optimization studies and stability tests. Solvent Extr. Ion Exch. 25 (6) 703-721. 

Typical extraction programs developed for use with the Dionex 300 ASE system are noted in Tables IV and V, for the SWE of atrazine or avoparcin from bovine kidney tissue. Each extraction requires some fine tuning to optimize for the target analyte, particularly with respect to the choice and composition of aqueous-based extraction fluid, volume of solvent used, and the flush volume percent. Details of the analytical protocol can be found in the literature (48, 49). Because of the complexity of pressurized fluid extracts, SPME or SPE may be required for extract cleanup, and/or specific analyte monitoring techniques, such as single ion monitoring by mass spectrometry may also be necessitated. 

The continuous production of bacterial alginate from A. vinelandii coupled to membrane-based extraction appears to be possible but more detailed investigation must still being performed in order to optimize the process. However, it should be remarked the possibility of controlling the stmcture of resultant alginates obtained by using genetically modified bacteria. 

Holl MR et al (1996) Optimal design of a microfabricated diffusion-based extraction device. In Amtaican society of mechanical engineers meeting, New York, USA... 

In this work, a method based on the reduction potential of ascorbic acid was developed for the sensitive detennination of trace of this compound. In this method ascorbic acid was added on the Cr(VI) solution to reduced that to Cr(III). Cr(III) produced in solution was quantitatively separated from the remainder of Cr(VI). The conditions were optimized for efficient extraction of Cr(III). The extracted Cr(III) was finally mineralized with nitric acid and sensitively analyzed by electro-thermal atomic absorption spectrometry. The determinations were carried out on a Varian AA-220 atomic absolution equipped with a GTA-110 graphite atomizer. The results obtained by this method were compared with those obtained by the other reported methods and it was cleared that the proposed method is more precise and able to determine the trace of ascorbic acid. Table shows the results obtained from the determination of ascorbic acid in two real samples by the proposed method and the spectrometric method based on reduction of Fe(III). 

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

To extract and evalnate the color pigments from cochineals Dactylopius coccus Costa), a simple method was developed. The procednre is based on the solvent extraction of insect samples nsing methanol and water (65 35, v/v) and a two-level factorial design to optimize the solvent extraction parameters temperature, time, methanol concentration in mixtnre, and yield. For hydrophilic colorants that are more sensitive to temperatnre, water is the solvent of choice. For example, de-aerated water extraction at low temperatnre was applied to separate yellow saffrole and carthamine from saffron (Carthamus tinctorius) florets that contain about 1% yellow saffrole and 0.3% red carthamine. ... 

Experimental comparisons may suffer from a lack of optimal conditions for all methods considered or may be based on biased evaluation. It is frequently noticed that results quoted by the preferred extraction technique compare extremely favourably with existing extraction technology. Also, lack of prospects of using CRMs is not helpful for comparisons. However, it appears that for a given infrastructure (R D vs. plant laboratory) and need (routine vs. occasional operations), and depending on the mix of polymeric matrices to be handled, some preferences may clearly be expressed. 

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