Correlation extraction procedure

Using a simple solvent extraction procedure to minimize matrix effects, a diclofop-methyl immunoassay was developed for milk, a number of edible plant products, and other matrices. Gas chromatography (GC) and liquid scintillation counting (LSC) of a C-labeled analyte were used as reference methods to compare with enzyme immunoassay (EIA) results. The methods were well correlated, with comparison of EIA... 

Virgin olive oil contains considerable amounts of simple phenols that have a great effect on the stability/sensory and nutritional characteristics of the product. Some of the most representative are hydroxytyrosol (3,4-dihydroxyphenylethanol) and tyrosol (4-hydroxyphenylethanol) however, phenolic compounds are removed when the oil is refined (Tovar and others 2001). The phenolic content of virgin olive oil is influenced by the variety, location, degree of ripeness, and type of oil extraction procedure used, and that is why hydroxytyrosol can be considered as an indicator of maturation for olives (Esti and others 1998). Hydroxytyrosol concentrations are correlated with the stability of the oil, whereas those of tyrosol are not (Visioli and Galli 1998). 

Calibration curves for DEC in human plasma were linear using unweighted linear regression in the concentration range of 100-2000 ng/mL, with correlation coefficients greater than or equal to 0.9934 for all curves. The limit of quantification (LOQ) in human plasma was accepted as 70 ng/mL. Plasma samples were spiked to a nominal concentration of 70 ng/mL with DEC working solution and internal standard and carried through the extraction procedure. At the LOQ, the C.V. (n = 6) of the measured concentration was 4.5 %, and the deviation of the mean of the measured concentrations from the nominal value was -6.1 %. 

In other words, extraction procedures used in control extraction studies and for routine extraction tests of container closure system components must produce extractables profiles that can be qualitatively and quantitatively correlated with drug product leachables profiles to the proposed end of a drug product s shelf life. As stated in the regulatory guidance ... 

In relation to the choice of EDTA or DTPA as extraction procedure for CRM 600, there was a general consensus to prefer EDTA because this procedure is easier to apply (better soil to solution ratio for EDTA). In addition, it was stressed that EDTA and DTPA extractions are closely correlated which renders questionable the use of both extraction procedures at the same time. It was assumed that EDTA extraction enables a complete extraction to be achieved and mimics the mobility of trace metals from soils DTPA is widely used in the USA and is rather applied to predict plant uptake. The choice of the extractant is, therefore, closely related to the objective of the study. 

For species characterization, whole-cell and extracellular proteins (CUnk and Pennington 1987 Berber et al. 2(X)3) or cellular fatty acid analysis and/or combined with gas chromatography may be applied. In general, fatty acid profiles correlate with the data on DNA homology and phenotype features (Behme et al. 1996). Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDl-TOF MS) was experimentally applied to intact bacterial cells or specimens prepared nsing extraction procedures. This chemotaxonomic method was used for identification of the staphylococcal species and MRSA strains (Du et al. 2(X)2 Carbonnelle et al. 2007). 

For the bioassay or cytotoxicity tests the extract (from both the supercritical extraction and 95% ethanol extraction procedures) is dissolved to various concentration levels in 95% ethanol, and the bioactivity is tested in vitro with the 9KB leukemia cell. Samples of cells are treated with various concentration levels of the extract and are then incubated. Cell growth inhibition is determined from protein measurements, which can be correlated to the number of cells. The ED50 value, expressed in mg/1, is defined as the extract concentration at which 50% of the cell growth is inhibited. Obviously, the lower the value, the more cytotoxic the extract. 

Satisfactory correlations between extractable heavy metals and pH for a variety of soils are notoriously poor. Thome et al, (233) found no consistent correlations for Utah soils between pH 3.2 acetic acid plus 0.05N potassium chloride extractable or total zinc with pH (or organic matter content). They concluded that total zinc differentiated zinc-deficient soils as well as the extraction procedure used. Brown et al, (38) observed no correlation between soil pH and either response to zinc application or ammonium acetate-dithizone extractable zinc. Kanehiro (129) did not find a satisfactory relation between soil pH and acid-extractable zinc however, if his samples which were more acid than pH 5.5 are ignored then there is a tendency for acid-extractable zinc to decrease with soil pH. Furthermore, if surface and subsurface samples are segregated the relationship is improved. This may be because of the presence of greater amounts of organic matter in the surface horizon samples hence, the hydrous oxides and their occluded metals were more soluble. 

The procedure of resin extraction of Mo proposed by Bhella and Dawson (1972) has not been well tested for evaluating Mo availability in alkaline soils. A comparison between that method and the AAO extraction (Karimian and Cox, 1979) did not show any positive correlation between the Mo extracted by either of the methods and plant Mo uptake. Lombin (1985) tried the resin extraction procedure for assessing the availability of Mo in semiarid savannah soils of Nigeria, but did not find it suitable. Compared with resin extraction, AAO extraction showed good correlation with Mo uptake by peanuts, provided that soil organic-matter content was used as an independent variable. 

Huang et al. described a simple, rapid method for the quantitative monitoring of five sulfonamide antibacterial residues in milk. The analytes were concentrated by SBSE based on poly(vinylimidazole-divinylbenzene) monolithic material as coating, and analyzed by HPLC with diode-array detection. The extraction procedure was very simple. Milk was first diluted with water and then directly subjected to sorptive extraction without a requirement for additional steps to eliminate fats and protein in the samples. Under the optimized experimental conditions, low detection limits (S/N = 3) (where S/N = signal-to-noise ratio) and quantification limits (S/N = 10) were achieved for the target compounds within the range of 1.30-7.90 and 4.29-26.3 p.g/1 from spiked milk, respectively. Good linearities were obtained for the sulfonamides with correlation coefficients (R ) above 0.996. Finally, the proposed method was successfully applied to the determination of sulfonamides in different milk samples. 

The phase behaviour a such mixtures is nowadays well-understood and several extraction procedures based on supercritical dissolution processes are on stream. Laboratory equipment, as well as bench-scale units for such high-pressure research, are commercially available and thermodynamic models have been developed that can direct and correlate the experimental research. 

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