Flow injection system with in-line Winkler's procedure using 16-way valve and spectrofluorimetric determination of dissolved oxygen in environmental waters

摘要

Flow injection spectrofluorimetry with in-line Winklers procedure was developed for the dissolved oxygen (DO) determination.2-Thiona-phthol reacted with iodine produced by Winkler's method to form fluorescence inactive disulfide compound.To automate the process completely,a 5-channel flow system with a newly designed 16-way valve was assembled.The system consisted of a dispersion coil (DC),a precipitate formation coil (PFC),a precipitate dissolving coil (PDC),and extraction coil (EC).A calibration can be constructed by using a standard iodine solution for dissolved oxygen.The calibration graph was linear over the range 1.2 x 10~(-4) approx 6.0 x 10~(-4) mol l~(-1) iodine (1.96 approx 9.80 mgO l~(-1))).The relative standard deviation (n = 6) was below 0.3% for the 4 x 10~(-4) mol l~(-1) iodine (6.27 mg O l~(-1)) determination.The sample throughput was 12/h.