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2065811 
Journal Article 
Effect Of Ligand Doping On The Gas Chromatography Of The Trifluoroacetylacetonates Of Chromium(III), Aluminium(III), And Iron(III) 
Siu, KWM; Fraser, ME; Berman, SS 
1983 
1 
Journal of Chromatography
ISSN: 0021-9673 
NIOSH/00141605 
256 
3 
455-459 
The effect of doping a relatively small amount of trifluoroacetylacetone (367577) (TAA) into the carrier gas of a gas chromatographic system using a flame ionization detector for analyzing the trifluoroacetylacetonates of chromium(III) (16065831) (Cr), aluminum(III) (22537231) (Al/TAA), and iron(III) (20074526) (iron/TAA) was investigated. Memory effects with and without TAA doping were also examined by injecting a concentrated TAA solution immediately after elution of the trifluoroacetylacetonate and examining the amount of metal ion retained in the system. The gas chromatograph column was a stainless steel tube packed on Chromosorb-W. It was kept at 125 degrees-C for Cr/TAA and iron/TAA and at 115 degrees-C for Al/TAA. The carrier gas was helium at a flow rate of 25 milliliters per minute. The trifluoroacetylacetonates were injected as solutions in hexane. TAA was introduced into the system by routing a variable fraction of the carrier gas steam over a small pool of the dopant. Amounts of TAA could not be quantitated but were determined by number of turns of the valve routing the helium over the TAA. With two turns of the valve, relative increases in response of 50 percent for Al/TAA, 60 percent for iron/TAA, and 270 percent for Cr/TAA were recorded. Without TAA doping 1.9 percent of the previous peak of the chromium(III), 9.0 percent of the aluminum(III), and 33 percent of the iron(III) were measured. Following TAA doping, however, retained metal ions were reduced to 1.0 percent for chromium(III), 3.2 percent for aluminum(III), and 3.6 percent for iron(III). The authors conclude that TAA doping of the carrier gas improves the gas chromatographic response of Cr/TAA, Al/TAA, and iron/TAA. This effect does not appear to be due to reduction of the dissociation of these rather labile chelates, however, since Cr/TAA and Al/TAA form two of the most stable trifluoroacetylacetonates.