0000000000441227
AUTHOR
Máximo Gallignani
Comparative study of different approaches for the flow injection-fourier transform infrared determination of toluene in gasolines.
Abstract A single channel flow injection manifold has been employed to carry out the direct determination of toluene in gasolines by FT—IR without any sample pretreatment and by using different strategies. Toluene can be directly determined by measuring the absorbance at 728 cm −1 , using a base line established between 835 and 575 cm −1 ; and in this case a limit of detection of 0.01% (v/v) can be obtained with a dynamic range up to 2% (v/v). In some cases it could be convenient to determine toluene by derivative flow-injection FT—IR in order to avoid matrix interferences in the analysis of some types of gasolines. Carrying out the first order derivative FI—FT—IR measurements on the 728 cm…
Derivative Fourier transform infrared spectrometric determination of ethanol in alcoholic beverages
Abstract A derivative Fourier transform infrared (FT-TR) spectrometric procedure was developed for the direct determination of ethanol in alcoholic beverages, from beers to spirit samples. The method is based on first-order derivative FT-IR measurements between the peak at 1052 cm −1 and the valley at 1040 cm −1 , which are present in aqueous solutions and alcoholic beverages, by using a micro flow transmittance cell with ZnSe windows and a spacer of 0.029 mm. The method involves the accumulation of ten scans and provides accurate results in the determination of ethanol in alcoholic beverages without requiring any previous chemical treatment of the sample or a previous separation or extract…
Direct determination of benzene in gasoline by flow-injection Fourier transform infrared spectrometry
Abstract A Fourier transform infrared spectrometric procedure for the automated determination of benzene in gasoline was developed, based on the use of flow-injection analysis. The method permits the direct determination of benzene without any pretreatment of samples, with a limit of detection of 0.02% (v/v) and a relative standard deviation of ca. 1% [for five independent analyses of a diluted sample containing a 0.4% (v/v) of benzene]. Results found by direct analysis agreed with those obtained by off-line and on-line standard addition methods. A rapid quality control procedure was developed, based on the on-line injection of gasoline samples (diluted 1 + 9 in hexane) into a carrier strea…
Simultaneous determination of acetylsalicylic acid and caffeine in pharmaceuticals by flow injection with fourier transform infrared detection.
Abstract A fast quality control methodology has been developed for the simultaneous determination of acetylsalicylic acid (ASA) and caffeine in pharmaceuticals by flow injection—Fourier Transform Infrared Spectrometry. The method is based on the solubilization of ASA and caffeine in CH2Cl2 and the use of a flow system to introduce samples and standards in the spectrometer. Two solutions, containing 90 and 110% of the reported concentration of the two active principles in the sample, were employed in order to control the extreme tolerance levels accepted by the International Pharmacopeia for the composition of formulations. A 300 μl volume of each solution was injected in turn, into a carrie…
FIA—FT—IR determination of ibuprofen in pharmaceuticals
A method has been developed for the determination of Ibuprofen (2-[4-isobutylphenyl]-propionic acid) in pharmaceuticals by FT-IR, using the carbonyl band which this compound presents at 1710 cm(-1) in carbon tetrachloride solutions. Samples are dissolved in carbon tetrachloride. In this solvent the excipients are not soluble and so the drug can be directly determined without any additional treatment. The use of a simple FIA manifold permits one to carry out this analysis with a low consumption of reagent and the FT-IR provides a continuous monitoring of the spectral base-line which permits an accurate determination of the maximum in the absorbance band. Also, the FIA system permits easy and…
Flow-injection determination of water in organic solvents by near-infrared spectrometry
Abstract A flow-injection (FI) procedure was developed for the direct determination of water in organic solvents by using the O-H stretch absorbance band of water in the near-infrared (NIR) region. Dichloromethane was employed as a test solvent to study the influence of the flow parameters (carrier flow and sample injection volume) and time interval on the sensitivity and repeatability of the FI-NIR measurements. The developed procedure permits the determination of water in dichloromethane and isobutyl methyl ketone samples with limits of detection of 0.01 and 0.005% (v/v), respectively. Real and spiked samples of solvents were analysed by FI-NIR and accurate results were found. The method …