0000000000329007

AUTHOR

Amparo Pérez-ponce

Fourier-transform infrared determination of nicotine in tobacco samples by transmittance measurements after leaching with CHCl3

Abstract A new procedure is proposed for the FT-IR spectrometric determination of nicotine in tobacco. The method is based on the extraction of nicotine in CHCl 3 from tobacco samples, wetted with an aqueous solution of NH 3 (0.1 M), and the measurement of absorbance in the stopped-flow mode at 1316 cm −1 , using a spectral baseline correction established from 1334 to 1300 cm −1 . The procedure developed does not requires a complex sample preparation, and provides a limit of detection of 0.045 mg ml −1 nicotine, a sampling frequency of 3.3 h −1 and a coefficient of variation of 0.3% for five independent measurements of a tobacco sample with a nicotine content of 1.5% w/w. The accuracy of th…

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Determination of carbonates in waters by on-line vapor generation FTIR

Abstract An electrically heated gas-permeation unit (GPU) has been employed for the vapor-generation Fourier transform infrared (FTIR) determination of total carbonate in waters. The developed method is based on the simultaneous injection of 100 μ l sample and 100 μ l nitric acid in a two-channel manifold with a merging zone, which provides the generation of CO 2 through the GPU, heated at 90°C, from which CO 2 is swept by a stream of N 2 to a long-path infrared gas cell. Absorbance measurements were made in the range from 2500 to 2150 cm −1 and the corresponding flow injection recordings were obtained as a function of time. The areas of these peaks are interpolated in a calibration equatio…

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Direct vapor generation Fourier transform infrared spectrometric determination of ethanol in blood

Abstract A new procedure is proposed for a direct determination of ethanol in plasma and whole blood. The method is based on the injection of a discrete sample volume of 10 μl into an electrically heated Pyrex glass reactor in which, at a temperature of 90 °C, the ethanol is volatilized and introduced by means of a N 2 carrier flow inside a long-path infrared gas cell and the corresponding flow analysis recording registered as a function of time. The measurement of the area of the flow injection recording, obtained from the absorbance of the transient signal in the range 1150−950 cm −1 , allows the direct quantification of ethanol upto 2 g l −1 , with a limit of detection of 0.020 g l −1 an…

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Flow injection Fourier transform infrared determination of nicotine in tobacco

A fully automated procedure is proposed for the Fourier transform infrared (FTIR) determination of nicotine in tobacco. The method is based on the on-line extraction of nicotine with CHCl3. Samples, weighed inside empty extraction cartridges, were humidified with NH3 and the cartridges were installed in a flow manifold in which they were extracted with 2 ml CHCl3 for 2 min, then 400 microliters of the extract were introduced into a micro-flow cell using a carrier of CHCl3 and the IR spectrum was registered continuously. The absorbance, in the wavenumber range 1334-1300 cm-1, was measured, obtaining a peak as a function of time. The area of this peak was interpolated on a calibration line es…

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Direct determination of ethanol and methanol in liquid samples by means of vapor phase-Fourier transform infrared spectroscopy

Abstract A FTIR procedure is proposed for the direct determination of methanol and ethanol in liquid samples, such as alcoholic beverages and eau-de-cologne, based on vapor generation from small injected volumes of untreated samples into a heated Pyrex glass reactor in which, at a temperature of 80°C, ethanol and methanol are volatilized and introduced into a long-path IR gas cell by means of a N2 carrier flow. The IR spectra obtained present two characteristic ethanol bands (1050 and 880 cm−1) and a single characteristic methanol band (1030 cm−1). The measurement of the area of the transient recording obtained for the wavenumber range between 1025–950 and 950–820 cm−1 allows us the determi…

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Microwave-assisted vapour-generation Fourier transform infrared spectrometric determination of carbonate in waters

Abstract A microwave-assisted vapour-generation Fourier transform infrared spectrometric procedure is proposed for the determination of total carbonate in waters. The method is based on the simultaneous injection of 100 μl of sample and 300 μl of 0.1 M nitric acid in a two-channel manifold with a merging zone; a coil located inside a microwave oven encourages the removal of CO 2 . The carbon dioxide is separated from the distilled water employed as carrier by means of gas–liquid separator and is introduced by a nitrogen carrier flow inside a long-path infrared absorption gas cell, from which the corresponding flow analysis recording is registered as a function of time in the wavenumber rang…

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