Automated sample introduction

An exeuaple of a nodular apparatus for capillary electrophoretic separation methods, is shown in Figure 4.43 [637-639,681-684]. It Offers a choice of automated sample introduction methods with on-column detection and has a... 

The UV- and carbohydrate analyzers use a sample injection valve that contains six ports, each pair of which is interconnected. In one orientation of the valve, a sample can be loaded into the sample loop, which becomes a part of the eluent line when the ports are reoriented (by turning the valve handle) (Fig. 5). Valves that allow automated sample introduction at pressures up to 5000 psi without interrupting the eluent flow have been developed and are now available commercially (S2). 

Open-access LC/MS formats have spawned new dimensions in access and data management. The use of a direct exposure probe (DEP) for automated sample introduction has been developed for quick (ca. 3 min) molecular weight determination of new lead compounds and quantitative analysis. Fig. 7 illustrates an automated direct probe system for molecular weight determination. Versatile software packages for data manipulation and processing has been a popular... 

In the field of sample introduction, hyphenated systems and devices allowing online preconcentration, automated sample introduction or speciation will become more and more important. 

The sample introduction system must be capable of introducing a known and variable volume of sample solution reproducibly into the pressurized mobile phase as a sharp plug without adversely affecting the efficiency of the column. The superiority of valve injection has been adequately demonstrated for this purpose and is now universally used in virtually all modern instruments for both manual and automated sample introduction systems [1,2,7,31,32]. Earlier approaches using septum-equipped injectors have passed into disuse for a several reasons, such as limited pressure capability, poor resealability, contamination of the mobile phase, disruption of the column packing, etc., but mainly because they were awkward and inconvenient to use compared with valves. For dilute sample solutions volume overload restricts the maximum sample volume that can be introduced onto the column without a dramatic loss of performance. On-column or precolumn sample focusing mechanisms can be exploited as a trace enrichment technique to enhance sample detectability. Solid-phase extraction and in-column solid-phase microextraction provide a convenient mechanism for isolation, concentration and matrix simplification that are easily interfaced to a liquid chromatograph for fully or semi-automated analysis of complex samples (section 5.3.2). 

Figure 3 Chip layout comprising a larger channel for automated sample introduction via pressure-driven flow (connecting reservoirs 1 and 2), the width and depth of the sample channel are less than 10% of the sample introduction channel, reservoir 3 is the sample waste, resen/oirs 4 and 5 are connected by the separation channel (resen/oir 5 buffer waste).

FIG. 1. Large-size furnace for solid sampling, manufactured by Grim Analytische Mess-Systeme G.m.b.H., Ehringshausen, Germany, model SM 20. The test substance is introduced either manually with a pincn- and the L vov platform, or by an automated sample introduction system. Dimensions of the furnace OD S3 mm and ID 10.5 mm. 

A tandem mass spectrometer must be equipped with an electrospray source and is plumbed as in Fig. 4. LC-pump and an appropriate LC autosampler are used for solvent delivery and automated sample introduction. The mobile phase is acetoni-trile water mixture (80 20, v/v) with 0.05% formic acid at a flow rate of 60 (xL/min. The autosampler is programmed to inject a volume of 40 p,L of the sample. 

Elemental Scientific, Inc., Automated Sample Introduction with the SC Fast, ESI Application Note, 2007, http //www.icpms.com/pdf/SC-FAST.pdf. 

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