title: A simple automated continuous-flow-equilibration method for measuring carbon monoxide in seawater.
abstract: A simple, robust, low-maintenance method using air-segmented continuous-flow equilibration was developed and automated to measure carbon monoxide (CO) in natural waters precisely and accurately. Finely regulated flows of CO-free air and of seawater or standard water were pumped into a glass coil, forming discrete gas/liquid segments. The partially CO-equilibrated gas effluent was injected into a Trace Analytical reduction analyzer for CO detection. A semiempirical mass-balance model was established for predicting and optimizing the performance of the CO extractor. The optimized gas and water flow rates were approximately 1.2 and approximately 14 mL min(-1), respectively, giving a response time of less than 15 min and a CO-extraction yield of approximately 80%. The analytical blank, precision, and accuracy were, respectively, 0.02 nM, +/-2.5% (at the approximately 1 nM level), and better than 5%. Two extractors can be interfaced to one detector at 4-6 samples per hour for each extractor. Coupled with a continuous surface-water sampler, the system was successfully applied to monitoring the diurnal variation of CO concentration in Sargasso Sea surface waters.
authors.affiliation: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Massachusetts 02543, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xie
authors.forename: O C
authors.initials: OC
authors.lastname: Zafiriou
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: C D
authors.initials: CD
authors.lastname: Taylor
mesh_terms: D001331:Automation; D002248:Carbon Monoxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D004867:Equipment Design; D005740:Gases; D012680:Sensitivity and Specificity; D014872:Water Movements; D014876:Water Pollution / Q000032:analysis*
chemical_list: D005740:Gases; D002248:Carbon Monoxide