Extraction, advantages differential

Since the analysis of terpenic compounds is often performed together with lipids, silylation has the advantage of being able to differentiate between carboxylic acids and naturally occurring methyl esters, which can be found for example in some terpenic resins and extracted together with lipids. 

Capillary electrophoresis (CE) coupled to MS has the advantage of high resolution and soft ionization for biomolecules, which may be used to differentiate post-translational modifications and variants of intact proteins and oligonucleotides. Different modes of CE (capillary zone electrophoresis, capillary isoelectric focusing, capillary electrochromatography, micellar electrokinetic chromatography, nonaqueous capillary electrophoresis) to MS as well as online preconcentration techniques (transient capillary isotachophoresis, solid-phase extraction, membrane preconcentration) are used to compensate for the restricted detection sensitivity of the CE methodology [77, 78]. 

If F(xa) is a scalar-valued function, the vector derivative VaF can be extracted from the variation of F along the path xr,(t) in Eq. (A115). This method has the advantage of reducing the calculation of the vector derivative of a scalar-valued function to ordinary scalar differentiation. As an example,... 

Atmospheric pressure ionization LC/MS has several distinct advantages over other more established quantitative approaches for these biochemical markers. The HPLC/fluorescence methods that have been reported require involved sample preparation, analyte extraction, and long chromatographic run times and are prone to interferences. The reported enzyme assays are less selective in that they cannot differentiate between the two compounds in a single run. Pyridinoline must therefore be quantified by difference. The API LC/MS/MS approach has allowed for a decrease in chromatographic run time, a streamlining of the sample preparation approach (dilute/inject as opposed to extraction), and a decrease in the analytical run time, while allowing simultaneous determination of both components. 

The major advantage of measurements on blood is that direct extraction without prior hydrolysis of conjugates is all that is usually needed, and that collection of the sample is rapid and volumetrically reliable. The latter is of importance, but not essential, in allowing the rapid performance of adrenocortical suppression and stimulation tests which are now needed in the differential diagnosis of virilism in women. 

Despite of clear advantages of a differentiated analysis over investigations of total sample - sequential chemical extraction is probably the most useful tool for predicting long-term adverse effects from con-tamined solid material - it has become obvious that there are many problems associated with these procedures (e.g., Kersten Fdrstner, 1986 Rapin et al. 1986) ... 

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