Headspace gas chromatographic determination of methylene chloride in decaffeinated tea and coffee, with electrolytic conductivity detection. 1984

B D Page, and C F Charbonneau

A headspace gas chromatographic procedure is described for the determination of methylene chloride (MC) in decaffeinated tea and coffee. The tea or coffee sample, with added methylene bromide (MB) internal standard, is equilibrated for 1.5 h at 100 degrees C in aqueous sodium sulfate before manual headspace sampling. MC and MB are separated on a Porasil A column at 160 degrees C and detected by using a Coulson electrolytic conductivity detector. For coffee and tea samples spiked at 1.3 ppm MC, as well as commercially decaffeinated teas and coffees containing up to 8 ppm MC, coefficients of variation were 10% or less. For decaffeinated teas, problems involving sample homogeneity and loss of MC before sealing the headspace vial had to be overcome. Similar problems with decaffeinated instant and ground coffees were minimal. The headspace procedure was superior to a previously reported distillation technique. MC was readily detected at 0.05 ppm. Fourteen decaffeinated teas and 15 decaffeinated coffees were analyzed; MC was detected at levels that ranged up to 15.9 and 4.0 ppm, respectively.

UI MeSH Term Description Entries
D008752 Methylene Chloride A chlorinated hydrocarbon that has been used as an inhalation anesthetic and acts as a narcotic in high concentrations. Its primary use is as a solvent in manufacturing and food technology. Dichloromethane,Methylene Bichloride,Methylene Dichloride,Solaesthin,Bichloride, Methylene,Chloride, Methylene,Dichloride, Methylene
D002110 Caffeine A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling. 1,3,7-Trimethylxanthine,Caffedrine,Coffeinum N,Coffeinum Purrum,Dexitac,Durvitan,No Doz,Percoffedrinol N,Percutaféine,Quick-Pep,Vivarin,Quick Pep,QuickPep
D002621 Chemistry A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D002849 Chromatography, Gas Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix. Chromatography, Gas-Liquid,Gas Chromatography,Chromatographies, Gas,Chromatographies, Gas-Liquid,Chromatography, Gas Liquid,Gas Chromatographies,Gas-Liquid Chromatographies,Gas-Liquid Chromatography
D003069 Coffee A beverage made from ground COFFEA beans (SEEDS) infused in hot water. It generally contains CAFFEINE and THEOPHYLLINE unless it is decaffeinated.
D004553 Electric Conductivity The ability of a substrate to allow the passage of ELECTRONS. Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D005506 Food Contamination The presence in food of harmful, unpalatable, or otherwise objectionable foreign substances, e.g. chemicals, microorganisms or diluents, before, during, or after processing or storage. Food Adulteration,Adulteration, Food,Adulterations, Food,Contamination, Food,Contaminations, Food,Food Adulterations,Food Contaminations
D006843 Hydrocarbons, Chlorinated Hydrocarbon compounds with one or more of the hydrogens replaced by CHLORINE. Chlorinated Hydrocarbon,Chlorinated Hydrocarbons,Organochlorine Compound,Chlorine Compounds, Organic,Organochlorine Compounds,Compound, Organochlorine,Compounds, Organic Chlorine,Compounds, Organochlorine,Hydrocarbon, Chlorinated,Organic Chlorine Compounds
D013662 Tea The infusion of leaves of CAMELLIA SINENSIS (formerly Thea sinensis) as a beverage, the familiar Asian tea, which contains CATECHIN (especially epigallocatechin gallate) and CAFFEINE. Black Tea,Green Tea,Black Teas,Green Teas,Tea, Black,Tea, Green,Teas, Black,Teas, Green
D055598 Chemical Phenomena The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes. Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical

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