Potentiometric detection of organic acids in liquid chromatography using polymeric liquid membrane electrodes incorporating macrocyclic hexaamines.
Potentiometric detection employing coated-wire electrodes was applied to the determination of organic acids in liquid chromatography (LC). Poly(vinyl chloride)-based liquid membranes, incorporating lipophilic macrocyclic hexaamines as neutral ionophores were used as electrode coatings. The selectivity and sensitivity of the macrocycle-based electrodes were found to be superior to an electrode based on a lipophilic anion exchanger (a quaternary ammonium salt). Sensitive detection was obtained for the di- and tricarboxylic acids tartaric, malonic, malic, citric, fumaric, succinic, pyruvic, 2-oxoglutaric and maleic acids after separation in reversed-phase LC. Detection limits (signal/4sigmanoise=3) of 6 pmol for malonic acid and 2 pmol for maleic acid were attained. The detection was explained using a molecular recognition model. The hexaamine-based potentiometric electrodes had a 1-s response time at 1 ml min(-1) flow-rates. They were stable for at least 4 months, with an intra-electrode variation of 3.2% (n=5).
Zielinska
D
D
Warmia and Masuria University in Olsztyn, Department of Chemistry, Poland.
Poels
I
I
Pietraszkiewicz
M
M
Radecki
J
J
Geise
H J
HJ
Nagels
L J
LJ
D000143:Acids / Q000032:analysis*; D000588:Amines / Q000737:chemistry*; D002138:Calibration; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods*; D004563:Electrochemistry; D004566:Electrodes; D009930:Organic Chemicals / Q000032:analysis*; D011108:Polymers; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000143:Acids; D000588:Amines; D009930:Organic Chemicals; D011108:Polymers