Generation of improved gas linear velocities in a comprehensive two-dimensional gas chromatography system.
A comprehensive two-dimensional gas chromatography (GC x GC) system (for convenience defined as "split flow" GC x GC), which may be operated at improved gas linear velocities in both dimensions, has been developed. The setup is formed of an apolar 30 m x 0.25 mm i.d. column connected, by means of a Y press fit, to a detector-linked 1 m x 0.1 mm i.d. polar analytical column, which passes through the (cryogenic) modulator, and to a 0.3 m x 0.1 mm i.d. retention gap, which is connected to a manually operated split valve. The latter enables the regulation of gas flows through the second analytical column [e.g., 60:40 (FID) ratio, 50:50 ratio, 40:60 (FID) ratio, etc.], in order to generate the most appropriate gas linear velocity, which is related to each specific analysis. In the pre-sent investigation, two sets of traditional and split flow GC x GC analyses were carried out on a cod liver oil fatty acid methyl ester sample by using the same temperature programs [180-250 degrees C at (a) 3 degrees C/min and at (b) 1.3 degrees C/min] and at an average first-dimension linear velocity of approximately 35.0 cm/s; thus, primary column retention times (and therefore elution temperatures) were essentially maintained. The second-dimension linear velocity was calculated to be approximately 333 cm/s in the traditional applications, while it was split valve-regulated until the most appropriate values [(a) approximately 213 cm/s; (b) approximately 264 cm/s] were attained in the alternative applications. Substantial improvements were observed and measured in the chromatography along the y-axis, while the contour plot chemical class structure was maintained.
Tranchida
Peter Quinto
PQ
Dipartimento Farmaco-Chimico, Facoltà di Farmacia, Università di Messina, viale Annunziata, 98168-Messina, Italy.
Casilli
Alessandro
A
Dugo
Paola
P
Dugo
Giovanni
G
Mondello
Luigi
L
D000818:Animals; D002849:Chromatography, Gas / Q000295:instrumentation* / Q000379:methods*; D003060:Cod Liver Oil / Q000737:chemistry; D005740:Gases; D013696:Temperature
D005740:Gases; D003060:Cod Liver Oil