Samples preparation strategies

There are numerous reports in the literature of SPE clean-up of a wide variety of analyses prior to chromatographic analysis. Thus, the application of SPE for the preconcentration of the metabolites of peptide-doxorubicin conjugate in human plasma [21], for the 

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Principles and Characteristics A sample can contain a great number of compounds, but analysts are usually interested only in the qualitative presence (and the quantitative amount) of a small number of the total compounds. Selectivity is an important parameter in analytical separations. The total analytical process clearly benefits from selectivity enhancement arising from appropriate sample preparation strategies. Selective separation of groups or compound classes can simplify a mixture of analytes before analysis, which in turn enhances analytical precision and sensitivity. Selective fractionation, in some cases, allows easier resolution of the compounds of interest, so analysts can avoid the extreme conditions of high-resolution columns. 

Wang, H., Hanash, S. (2005). Intact-protein based sample preparation strategies for proteome analysis in combination with mass spectrometry. Mass Spectrom. Rev. 24, 413 126. 

The recent trend of decreasing available sample volumes and requiring lower limits of quantitation (LLOQs) means better sample preparation procedures are under consideration. Further improvements MS sensitivity will eventually impact sample preparation strategies and sample throughput. 

Since one of the issues raised in this paper is whether the objects seen in the TEM images are a proper representation of the structures present in solution, we will describe briefly sample preparation strategies. For solutions of micelles in hexane, a very volatile solvent, samples for TEM studies could be obtained by aspirating a dilute solution directly onto a carbon-coated copper grid. Most of the solvent likely evaporated as the sample was deposited on the substrate. Alternatively, the TEM substrate could be dipped briefly into a dilute solution of the micelles and allowed to dry. This method also worked for less volatile solvents like decane. For decane, we could also place a small drop (a few pi) of solution on the grid and then touch the edge of the droplet with a Kimwipe to remove excess solvent. For several samples these methods were compared, and we observed the same morphology. 

Figure 8.4. Cation exchange HPLC-ICP-MS analysis of 77Se-enriched yeast using two enzymatic sample preparation strategies (a) sequential use of /3-glucosidase and a protease mixture (b) protease XIV and (c) mass balance of selenium and selenium species fractionated during the sample preparation and HPLC separation procedure. SeMet = selenomethionine SeOMet = selenomethionine Se-oxide. Reproduced from [133] by permission of The Royal Society of Chemistry.

A. P. Vonderheide, M. Montes-Bayon, J. A. Caruso, Solid-phase microextraction as a sample preparation strategy for the analysis of seleno amino acids by gas chromatography D inductively coupled plasma mass spectrometry,Analyst, 127 (2002), 49D53. 

Figures 6-17 and 6-18 illustrate a simplified sample preparation strategy using an SPE device. Only a fraction of the multicomponent sample shown in Figure 6-17 is of interest. The approach of using a solid-phase cartridge is...

FIGURE 6-18. Simplified sample preparation strategy using a solid-phase cartridge. 

Sample preparation strategies therefore tend to be very application orientated. When developing methods, it is advantageous to work in a logical and stepwise manner but recognising that potential problems are interlinked. As with other chromatographic methods, the use of internal standards closely related chemically to the analyte(s) of interest are extremely... 

Another development in CE is the coupling or integration of sample preparation strategies such as liquid and solid phase extractions into commercial CE equipmenC. ... 

It must be taken into account that usually several sample pretreatment steps are necessary between sampling and placing the prepared sample into the chromatograph. However, the fewer the sample preparation techniques before injection, the better. A clear and optimized sample preparation strategy is necessary to minimize the number of steps because each step represents additional time and is a potential source of errors (contamination, loss of analytes and changes in actual composition). 

Sample preparation strategy Components Applications and advantages... 

Although most HPLC applications utilize one or more sample preparation procedures, it is best to keep sample preparation as simple as possible [2]. Some simple procedures that have found success for protein and peptide samples are precipitation and chromatographic methods. This chapter reviews the commonly used methods and devices for sample preparation in chromatography of biomolecules, particularly proteins. The proper choice and execution of the methods can greatly affect the success of the analysis, especially in terms of recoveries [1,3,4]. Planning the sequence of procedures can minimize time and maximize efficiency a flowchart for sample preparation strategies was presented in LC-GC [5]. Table 1 summarizes some of the typical requirements for the preparation of a sample for injection onto an HPLC column. 

Gonzalez de la Huebra, M.J., Vincent, U. and von Holst, C. (2007) Sample preparation strategy for the simultaneous determination of macrolide antibiotics in animal feeding stuffs by liquid chromatography with electrochemical detection (HPLC-ECD). J. Pham. Biomed. Anal, 43, 1628-1637. 

Fig. 11.29. Sample preparation strategies for MALDI imaging of tissues. Reproduced from Ref.[218] with permission. John Wiley Sons, Ltd., 2001.

In view of the importance of API solubility in the HPLC analysis of pharmaceutical dosage forms, this chapter will examine some of the strategies that may be employed to assure optimum and quantitative recovery of the API during the sample preparation steps prior to HPLC analysis. In addition, emphasis on sample preparation strategies used for tablets and capsules will frequently be referred to and also serve as examples throughout the chapter because tablets and capsules are the most commonly used novel pharmaceutical dosage form delivery platforms. 

In the following sections, we will discuss and introduce a number of sampling and storing strategies applied prior to speciation analysis. For the interested reader, comprehensive information on sample preparation strategies in speciation analysis can also be found elsewhere. 

Sample preparation strategies such as sonication, microwave heating, SPE, SPME, etc., analytical techniques such as CE, GC-MS, sensors based on, etc. and automated flow methods should be taken into account in order to improve the official methods. Moreover, toxic organic solvents should be avoided or reduced. 

The analysis of AS C values of steroids found in doping control urine samples has been accomplished by various different sample preparation strategies. First approaches were published in 1994 and since, two principal routes (without and/or with analyte derivatization) were pursued providing the required symmetry and purity of GC peaks. As... 

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