Coulometric determination of trace water in active carbonyl compounds using modified Karl Fischer reagents

Journal Article · Sun Mar 01 00:00:00 EST 1987 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac00132a015· OSTI ID:6881667

Nordin-Andersson, I; Cedergren, A

Improved conditions for the coulometric determination of trace water in samples containing potentially interfering substances like aldehydes and ketones were obtained by using a formamide-based, rapidly reacting Karl Fischer reagent in which methanol was replaced by 2-methoxyethanol. The shape of the potentiometric titration curves obtained by titrating spent Karl Fischer reagents with iodine indicates a less degree of triiodide formation in the presence of formamide. The corresponding increase in iodine results in a more rapid overall reaction rate since the reaction involving iodine is much more rapid than that with triiodide. For water amounts corresponding to less than 0.1% the stoichiometry of the Karl Fischer reaction was found to be 1:1, relatively independent of the concentration of 2-methoxyethanol. For larger amounts of water this stoichiometric ratio was attained by using a reagent containing 2-methoxyethanol/formamide 80/20 (v/v), 0.6 M imidazole, and 0.4 M sulfur dioxide.

• Research Organization: Univ. of Umea, Sweden
• OSTI ID: 6881667
• Journal Information: Anal. Chem.; (United States), Vol. 59:5, Issue 5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHANOL
CHEMICAL REACTIONS
FORMAMIDE
IMIDAZOLES
IODINE
ORGANIC OXYGEN COMPOUNDS
SULFUR DIOXIDE
WATER
POTENTIOMETRY
ALDEHYDES
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
INTERFERING ELEMENTS
KETONES
PH VALUE
QUANTITATIVE CHEMICAL ANALYSIS
STOICHIOMETRY
TRACE AMOUNTS
ALCOHOLS
AMIDES
AZOLES
CHALCOGENIDES
CHEMICAL ANALYSIS
DATA
ELEMENTS
HALOGENS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
KINETICS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SULFUR COMPOUNDS
SULFUR OXIDES
TITRATION
400102* - Chemical & Spectral Procedures
400201 - Chemical & Physicochemical Properties