Separation of oxypurines by ligand-exchange chromatography and determination of caffeine in beverages and pharmaceuticals

Rapid determination of twenty amino acids by gas chromatography

“…An excellent review on the analysis of these compounds by classical methods and conventional chromatographic techniques has been edited by Higuchi (10). The determination of caffeine in beverages and pharmaceuticals by anion-exchange and ligand-exchange chromatography has also been reported (11,12). However, no study has been done using high-speed partition liquid chromatography for the separation of three major purine alkaloids which commonly occur together.…”

Comparison of gas chromatographic and spectrophotometric methods of determination for caffeine in coffees and teas

“…A recognized method of determining drug absorption profiles in animals entails perfusing the drug solution (here, brews of coffees and teas) through the intestine of anesthetized rats and determining (via sampling 100 µ of solution) the amount of drug remaining to be absorbed (Doluisio, 1969). Reported methods of determination of CAF include a variety of spectrophotometric assay procedures (Ishler, 1948; Cornish and Christman, 1957; Newton, 1969;Somorin, 1973; Association of Official Analytical Chemists, 1970), gravimetric methods (Martinek and Wolman, 1955; Marine Font and Sancho Riera, 1973), Kjeldahl procedures (Wolman, 1955;Moores and Campbell, 1948; Association of Official Agricultural Chemists, 1965), and liquid chromatographic procedures (Wolford, 1971;Nelson, 1973;Murgia, 1973). Although many of these methods have been available for some time, the applicability of these procedures for the determination of small quantities of CAF dissolved in small sample volumes is limited.…”

Response of cyanide ion selective membrane electrodes in the presence of metal ions

“…Recently (3) it was shown how the response of the cyanide electrode is affected by pH and it was concluded that the following reaction:…”