CROMATOGRAFIA DE GASES FUNDAMENTO PDF DOWNLOAD!
De ionización en cromatografía de gases-espectrometría de masas en el campo En la Tabla I.7 se resumen los fundamentos, así como algunas ventajas y. Principios Básicos de la Cromatografía de Gases. Principales bloques de un cromatógrafo y sus funciones. Cromatografía de gases convencional y de alta re. 1 What Gas Chromatography Is This chapter describes gas chromatography—its effects and its uses—and the chromatographic hardware. 2 Injecting Samples.
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Figure 15 A few seconds later The yellow-dot component is not attracted to the coating. It moves through the column at the speed of the carrier gas and will cromatografia de gases fundamento first. The blue-dot component divides its time between the stationary coating and the carrier gas.
It travels through the column at a slower speed and will emerge later. The sample has begun to separate into two peaks. How much less depends on the strength of the attraction.
Fundamentals of GC 29 3 Separating Components Column Types Capillary columns A capillary column is an open tube with the stationary phase coated on its inside surface.
There is no packing.
These columns range from about 0. A typical column length is 30 m. Coating on inside surface Figure 16 Cromatografia de gases fundamento capillary column Capillary columns produce very narrow peaks. This allows the separation of very complex mixtures.
For example, a typical automobile fuel yields between and peaks. These columns, when made with fused silica tubing, are very inert. Difficult samples such as mercaptans, which tail severely on metal or glass columns, separate to the baseline on such columns.
Capillary columns require smaller samples than packed columns. Packed columns In a packed column, the stationary phase is coated on a finely-divided cromatografia de gases fundamento material to maximize its area and minimize its thickness.
Chromatography & Spectrometry Innovation.
The coated material is then packed into a metal, glass, or plastic tube. Coating on packing Figure 17 A packed column Packed columns have high sample capacity, a necessity with older, less sensitive detectors. However, with modern high-sensitivity detectors, this cromatografia de gases fundamento has vanished.
Packed columns are still useful for gas samples, but capillary columns offer better resolution for most liquid samples. Column tubing Possible tubing materials include: Fundamentals of GC 31 3 Separating Components Column Characteristics Cromatografia de gases fundamento purpose of a column is to produce narrow, well-separated peaks from a multi-component sample.
These two purposes are not entirely separate.
Column efficiency A high-efficiency column produces narrow peaks. See Table 2 for recommended flow rates. The higher value speeds the analysis without sacrificing very much efficiency.
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Even higher flows, above the range given, can be used when separation is great or a shorter column is used. Flows below the range given increase analysis time and may cause an abrupt loss of efficiency.
Gas control Flow in packed columns is usually controlled using cromatografia de gases fundamento flow controllers.
Capillary columns, because of the very low flow rates, are usually pressure-controlled. Such instruments allow setting flows from a keyboard and reading them on a display.
Fundamentals of GC 33 3 Separating Components Column resolution A high-resolution column separates peaks down to the baseline. This cromatografia de gases fundamento much easier if the peaks are narrow the column is efficient. A small change in flow rate can have an appreciable effect on resolution.