Trifluoroacetic acid, soils

Various other workers have reported on the determination of volatile organic compounds in soils [186,187] and landfill soils [188]. Soil fumigants such as methyl bromide have also been determined by this technique [189]. Trifluoroacetic acid is a breakdown product of hydrofluorocarbons and hydrochlorofluorocarbon refrigerant products in the atmosphere and, as such, due to the known toxicity of trifluoroacetic acid, it is important to be able to determine it in the atmosphere, water and in soil from an environmental point of view [190]. In this method the trifluoroacetic acid is extracted from the soil sample by sulfuric acid and methanol, which is then followed by the derivatisation of it to the methyl ester. The highly volatile methyl ester is then analysed with a recovery of 87% using headspace gas chromatography. Levels of trifluoroacetic acid in soil down to 0.2 ng/g can be determined by the procedure. 

Cahill et al. [241] have developed a simple and sensitive analytical procedure for determining the concentration of trifluoroacetic acid in plant, soil, and water samples. The analysis involves extraction of trifluoroacetic acid by sulfuric acid and methanol followed by derivatisation to the methyl ester of trifluoroacetic acid. This is accomplished within a single vial without complex extraction procedures. The highly volatile methyl ester is then analysed using headspace gas chromatography. The spike recovery trials from all media ranged from a low of 86.7% to a high of 121.4%. The relative standard deviations were typically below 10%. The minimum detectable limit for the method was 34 ng/g for dry plant material, 0.20 ng/g for soil and 6.5 ng/1 for water. 

Lincomycin in plasma (human or povine) and urine determined by HPLC at 214 nm using ion - pair HPLC column with an acetonitrile - trifluoroacetic acid ( 0.1 - 0.2 % v/v in the mixture) as an eluent (33). More than 1800 samples were assayed by this method. Soil - phase extraction (SPE) procedure was used in this analysis followed by an evaporation step. 

Two chlorophenoxyacetic acids, 2,4-D and dicamba, were extracted from soil and water and analyzed on a C g column (A = 236nm) using a 50/50 methanol/water (1% acetic acid) mobile phase [201,202], Detection limits of 0.1 pg/g in soil or l.Opg/mL in water were reported. In a similar fashion, eight chlorophenoxyacid residues (e.g., mecoprop, 2,4-D, dichlorprop, fenoprop) were extracted from water samples and analyzed on a C g column (A = 228nm) using a 60/40 methanol/water (30 mM phosphate buffer at pH 3.0) mobile phase [203]. The authors noted that 0.05% trifluoroacetic acid (TFA) used in place of the phosphate buffer as the mobile phase modifier was just as effective and produced significantly different retention times for the analytes. Molar absorptivities were tabulated for the analytes at 205 nm, 228 nm, and 280 nm. Detection limits of 0.5-2 pg/L were reported. 

The elucidation of a levan polysaccharide produced by a novel halophilic isolate from soil samples taken from Camalti Saltern area in Turkey, Halomonas smyrniensis was achieved thanks to the glycosyl analysis. In particular, the microbial EPS was hydrolyzed with trifluoroacetic acid (0.5M TFA at temperature of 120°C for 1.5h) and subsequently analyzed by HPAE-PAD (High-Performance Anion-Exchange Chromatography Pulsed Amperometric Detection), a high-performance anion-exchange... 

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