20 February / March 2016
which can clog fuel systems. Watercol 1460 was evaluated for the suitability to perform the analysis of water in gasoline. In addition to producing a sharp water peak, its selectivity results in elution of the water peak free from most other constituents present in gasoline. Plus, its maximum temperature of 260°C allows for timely elution of the heaviest gasoline components.
Figure 4: Water Calibration Curve (0.05-1%) on WatercolTM Conditions
column: WatercolTM 1460 1460, 30 m x 0.25 mm I.D., 0.20 µm (29695-U);
two identical columns installed in the same inlet using a 2 hole ferrule, each going to a separate detector.
oven temp: 45°C (4 min), 5°C/min to 75°C, 10°C/min to 220°C (10 min) inj. temp.: 250°C detector: FID, 250°C detector: TCD, 200°C carrier gas: helium, 20 cm/sec (measured in each column at an oven temperature of 135°C) injection: 1 µL, 50:1 split
liner: 4 mm I.D., split/splitless type, wool packed single taper FocusLiner™ design sample: 5 standards, water at 0.05, 0.1, 0.25, 0.5, and 1% (v/v), each in ethanol
Two identical columns were installed in a single inlet using a 2-hole ferrule. Each column was connected to a separate detector to permit the simultaneous detection of gasoline components as well as water. Triplicate samples of unleaded gasoline were analysed, both “as is” and spiked with water at 0.25% (v/v). Figure 5 shows representative chromatograms. Reproducibility was very good (RSD <5%) for the spiked gasoline replicates. The calibration curve shown in Figure 4 was used for quantitation. The average response factor calculated from each point of the curve had an RSD value of <20%, thus it was used to calculate the amount of water in the gasoline samples. The average concentration found in the unspiked gasoline replicates was subsequently subtracted from the average concentration measured in the spiked replicates. The blank corrected method accuracy was determined to be 79% at the spike level used.
Aroma Fusel Alcohols in Tequila
Figure 5: Spiked Gasoline Conditions
sample: unleaded gasoline, spiked with water at 0.25% (v/v) All other condition the same as Figure 4
Fusel alcohols are by-products of the fermentation process. Four of these (n-propanol, isobutanol, active amyl alcohol, and isoamyl alcohol) are important to alcoholic beverage manufacturers due to their contributions to the aroma characteristics. A tequila sample was analysed for the presence of aroma fusel alcohols using an FID and TCD detectors. The FID yielded greater responses for the alcohols, whereas the TCD produced a response for water. As shown in Figure 6, all four aroma fusel alcohols were detected in the tequila sample. Good peak shapes and resolution were obtained, allowing for distinct detection of these compounds. In addition, the selectivity of the phase resulted in elution of both ethanol and water free from all other analytes.
Conclusions
Ionic liquid GC phases based on new selective combinations of cations and
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