High-speed analysis

High speed analysis requirements which influence sample preparation demands (being the rate determining step of the analytical process). 

The corresponding high-speed analysis is also known as HTA. 

The elution strength should be adjusted so that the sample components of interest are eluted within a reasonable time. Generally > 0.3 are necessary to separate the sample components from unretained substances including the solvent. On the other hand, values of A < 10 are desired to reduce analysis time and minimize sample dilution which increases with increasing k value. In high-speed analysis optimum conditions are obtained if the k values of the sample components vary between 0.3 and 3. 

The viscosity dictates the driving pressure. For high-speed analysis, the ratio of viscosity to diffusion coefficient should be as small as possible. Hydrogen would be the best choice, followed by helium. 

George, C. and R.E. Majors. 2001. High-speed analysis of volatile organic compounds in environmental samples using small-diameter capillary columns and purge-and-trap GC-MS systems. LC-GC North America 19 578-588. 

Mitnik, L., Carey, L., Burger, R., Desmarais, S., Koutny, L., Wernet, O., Matsu-daira, R, Ehrlich, D., High-speed analysis of multiplexed short tandem repeats with an electrophoretic microdevice. Electrophoresis 2002, 23, 719-726. 

Another advantage of AES is the speed of the analysis. Cylindrical mirror analysers possess the ability to examine the complete Auger spectrum in less than a second and rapid data acquisition may be critically important in kinetic studies. This very high-speed analysis is most important in the presence of electron beam induced desorption and damages, which are one of the major drawbacks of AES. 

Due to its high sensitivity and specificity, mass spectrometry (MS) is a detector of choice in micro-separation techniques such as CE. This selective detector provides additional advantages by allowing high speed analysis, giving information about the mass, and potentially, fhe structure of fhe separated compounds. This... 

The need for both automation and high-speed analysis in the analytical laboratory has already been addressed. One technique that seems to combine the best of both is NIR analysis. Once an NIR assay is validated, an analyst can generate single-unit analyses usually in less than 1 minute per sample. In a single morning, dozens (possibly hundreds) of single-unit analyses can be performed and reported. 

G. R. Beecher, K. K. Stewart, and P. E. Hare, Automated High Speed Analysis of Discrete Samples. The Use of Nonsegmented, Continuous Flow. In Protein Nutritional Quality of Foods and Feeds (M. Friedman, Ed.). Marcel Dekker, New York, Part I (1975) 411. 

A 2008 paper has described for the first time a dilute and shoot strategy for the simultaneous extraction of wide variety of residues and contaminants (pesticides, myco-toxins, plant toxins, and veterinary drugs) from different foods (meat, milk, honey, and eggs) and feed matrices. Several antimicrobial classes were included (sulfonamides, quinolones, P-lactams, macrolides, ionophores, tetracyclines, and nitroimidazoles) in the analytical method. Sample extraction was performed with water/acetonitrile or acetone/1% formic acid, but instead of dilution of the extracts before analysis by UPLC-MS/MS, small extract volumes (typically 5 til) were injected to minimize matrix effects. Despite the absence of clean-up steps and the inherent complexity of the different sample matrices, adequate recoveries were obtained for the majority of the ana-lyte/matrix combinations (typical values for antimicrobials were in the range of 70-120%). In addition, the use of UPLC allows high-speed analysis, since all analytes eluted within 9 min. 

Time-of-flight mass spectrometry (TOFMS) is probably the simplest method of mass spectrometric measurement by the physical principle. The key features of TOFMS are extreme sensitivity (all ions are detected), practically unlimited mass range and as well as high-speed analysis (recent TOFMS instruments are able to measure hundreds full spectra per second). This all makes TOFMS one of the most desirable methods of mass analysis (Schlag, 1994 Guilhaus, 1995). The general scheme of TOFMS is shown in Scheme 1. 

Some Fundamental GC Theory and Routes toward High-Speed Analysis... 

Equation [4] is very useful for deducing the general operating requirements of high-speed analysis. The use of a short column, a higher than usual carrier gas velocity, and relatively small retention factors (which can be easily achieved by using high temperature and/or thin film columns), can reduce analysis times... 

Figure 1 The use of a selective stationary phase column for the high-speed analysis of ethanol in unleaded petrol.

Janca, J. Micro-thermal field-flow fractionation of colloidal particle Effect of temperature on retention and relaxation processes. CoU. Czech. Chem. Commun. 2003, 68, 672. Janca, J. Bemeron, J.-R Boutin, R. Micro-thermal field-flow fractionation New high-performance method for particle size distribution analysis. J. Coll. Interf. Sci. 2003,260, 317. Janca, J. Micro-channel thermal field-flow fractionation High-speed analysis of colloidal particles. J. Liq. Chromatogr. Relat. Technol. 2003, 26, 849. 

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