Extracting parameters

Comprehensive comparative investigation of the main extraction parameters shows that 2-octanol is more selective than 1-octanol, with PTa/m equal to... 

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. ... 

TABLE 3 Extraction Parameters in the Ion-Association Extraction of Fe(II) with Phen and Its Derivatives... 

Need for definition of extraction parameters (optimisation required for every polymer/additive combination)... 

One of the attractive features of SFE with CO2 as the extracting fluid is the ability to directly couple the extraction method with subsequent analytical methods (both chromatographic and spectroscopic). Various modes of on-line analyses have been reported, and include continuous monitoring of the total SFE effluent by MS [6,7], SFE-GC [8-11], SFE-HPLC [12,13], SFE-SFC [14,15] and SFE-TLC [16]. However, interfacing of SFE with other techniques is not without problems. The required purity of the CO2 for extraction depends entirely on the analytical technique used. In the off-line mode SFE takes place as a separate and isolated process to chromatography extracted solutes are trapped or collected, often in a suitable solvent for later injection on to chromatographic instrumentation. Off-line SFE is inherently simpler to perform, since only the extraction parameters need to be understood, and several analyses can be performed on a single extract. Off-line SFE still dominates over on-line determinations of additives-an... 

Gur ev, I. A. Gushchina, E. A., Use of extraction parameters to predict the results of the dual-phase titration of phenolate ions with a liquid ion-slective electrode, J. Anal. Chem. USSR 37, 1297-1301 (Engl.) (1982). 

A. Keszler, K. Heberger, Influence of extraction parameters and medium on efficiency of SPME sampling in analysis of aliphatic aldehydes, J. Chromatogr. A, 845, 337 347 (1999). 

In conclusion, it should be mentioned that extraction parameters (the equilibrium constants of exchange reactions and ion-pair stabilities) were introduced into the theory of ion-selective electrodes in [2, 31,33, 34, 35,69]. The theory of ISEs with a liquid membrane and a diffusion potential in the membrane was extended by Buck etal. [11, 13, 14, 73, 74] and Morf [54]. 

The automated extraction procedure was optimized for maximum extraction efficiency. The extraction parameters investigated were shaking time, shaking speed and solvent/ sample ratio. Three different shaking times (30 min, 60 min, and f20 min), two different shaking speeds (iOO and 190) and two different solvent/sample ratios (0.25 and 0.1667) were examined. These parameters resulted in 12 possible sets of experimental conditions. Twelve spiked water samples were analysed in dupficate, in random order (selected using software), under these experimental conditions. The total volumes and the analyte concentrations were kept constant. 

When there is a nonlinear function involving more than one predictor, in general there is no simple method for extracting parameter values from a given set of data. In some functions, such as... 

One has to design the experiment to take a set of data designed to facilitate the task of parameter extraction. If a set of data is taken under constant volume conditions, and the pressure is plotted against the temperature, then there will be an intercept of —alV and a slope of R/ V — b). The van der Waals equation of state is the simplest of the equations of state beyond the perfect gas law, and the task of extracting parameter values from experimental data for the more complicated equations of state would require more ingenuity. The Redlich-Kwong equation has two parameters, A and B ... 

Pressurized hot water can be used to extract two fungicides, thiabendazole (TBZ), and carbendazim (MBC), from agricultural commodities including banana pulp, whole lemons, orange pulp, mushrooms, and rice at extraction temperatures below 100°C and an extraction pressure of 50 atm. The extraction parameters that were studied include temperature, equilibration time, flow rate, pH, and collection volume. Liquid-... 

P. Vanloot, J. L. Boudenne, C. Brach-Papa, M. Sergent and B. Coulomb, An experimental design to optimise the flow extraction parameters for the selective removal of Fe(III) and Al(III) in aqueous samples using salicylic acid grafted on Amberlite XAD- and final determination by GF-AAS, J. Hazard. Mater., 147(1-2), 2007, 463-470. 

As a case-study, the decaffeination process for tea will be considered, where in every case the extraction parameters (pressure, temperature and extraction cycle) are maintained. In the... 

Chlorophylls are also present in many oleoresins. By fractionation of fennel oil in two separators in series, the pigments precipitate in the first separator [80]. The effects of the extraction parameters on chlorophyll concentration are shown in Table 9.6-4. Increasing extraction pressure and/or temperature favour the dissolution of the pigments. 

Comparison of chlorophyll-contents in fennel extracts obtained with different extraction parameters ... 

Figure 9.6-9. Effects of extraction parameters on the total pigment-content of the paprika oil ( Kalocsai Csemege , Hungary).

Soxhlet Extraction Parameters. The parameters used for Soxhlet extraction are summarized in Table I. 

Unlike the real samples, a high level spike pipetted onto the same identical sample just prior to SFE was much easier to extract using mild conditions. The same extraction parameters of C02 only at 40°C/4000psi, when used for a spiked sample, gave a recovery of 88%. 

Supercritical fluid extraction (SFE) is a new and promising technique for sample preparation. Because SFE is so new, and there are so many control parameters available to the scientist, it can be difficult to know how to proceed when developing an SFE method. This paper discusses two samples and describes a systematic approach for evaluating SFE extraction parameters for methods development. The effects of modifiers are investigated. 

Although supercritical extraction (SFE) has been known for some time, it is still a relatively new technique to the analytical chemist. Before developing an SFE method, the chemist must understand the composition of the matrix and the analyte properties. The key instrumental parameters affecting the extraction of analytes from the matrix include fluid density, temperature, and fluid composition. Both the make-up of the matrix and the analytes must be considered when selecting the extraction conditions. Consideration of the extraction parameters must be given with respect to their affect on the analytes of interest and on the compounds present in the matrix that may either coextract with the analytes or inhibit their extraction by physical or chemical means. 

In addition to these extraction parameters the matrix itself will have a large impact upon the choice of the extraction conditions. The matrix, besides containing coextractable materials will impact the solute-solid interaction kinetics and thermodynamics. The coextractants themselves can also act as modifiers and, as their concentrations change over the course of an extraction, the make-up of the extraction fluid will dynamically change. 

Extraction Parameters. The challenge in SFE is to determine the best extraction parameters for the analytes of interest in a particular matrix. These parameters are listed in Table I. The solvent power of the extraction fluid as controlled by the density, temperature, and composition is the primary parameter which must be controlled to obtain optimal recoveries. The definition of solvent power used here is that of Snyder and Kirkland (1). As previously mentioned low densities will extract non-polar volatile compounds and high densities will extract relatively more polar, less volatile compounds. 

Two examples were chosen to show the effect of these SFE parameters and the process of developing a method. The first example is the extraction of paprika and an examination of some of these extraction parameters in a qualitative way. The second example, developing a method for the extraction of several herbicides from soil, shows a more quantitative approach. The herbicide... 

It is merely an extension of these ideas to demonstrate the conditions that the same membrane, containing MY, should also be responsive, in a Nernstian fashion, to Y activities+in solution. These conditions are again a three-ion situation M, Y and N. The salt NY is the aqueous sample whose Y activity is to be measured. N is typically a hydrophilic ion such as Na. When aqueous NY activity is varied, the interfacial pd is again S-shaped (mV vs log[NY]). These responses are illustrated from a theoretical calculation in Figure 1. The assumed extraction parameters are given in the legend. The similarity with silver halide membrane electrodes are summarized below. 

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