Estimation of Dissolved Oxygen with a Luminescence-based Oxygen Quenching Sensor

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Estimation of Dissolved Oxygen with a Luminescence-based Oxygen Quenching Sensor By Cary B. Jackson, Ph.D. Hach Company

Measurement of Dissolved Oxygen Introduction The estimation of DO is fundamental in surveying it's impacts on regular waters, handle streams, and control of sewage treatment When used to report DO in releases and to infer the biochemical oxygen request from wastewater, it turn into an administrative device Therefore, exactness and precision is a basic issue of enthusiasm for assessing the level of water quality or refinement, and ascertaining the mechanical release stacking costs

Dissolved Oxygen Determinants Winkler Titration Procedure EPA Method 360.2 ASTM Standard D888-92 (Method A) Membrane Probe (Clark-sort Electrodes) EPA Method 360.1 ASTM Standard D888-92 (Method B)

Principle of Operation Winkler Titration Destructive synthetic oxidation-diminishment response Limitations Subject to various obstructions Oxidizing and lessening specialists Nitrate and nitrite particle Ferris and ferric particle Suspended solids and natural matter Field utilize unrealistic Labor Intensive

Luminescence-Based Oxygen Sensors Membrane Electrode Oxygen immoderate decrease from an electrolyte and two metallic anodes Oxygen must diffuse through a layer to be diminished at a cathode Limitations Requires high stream crosswise over film Narrow linearity go Electrolyte and terminal debasement Membrane fouling

Luminescence-Based Oxygen Sensors Luminescence-Based Oxygen Sensors Measures the light emanation attributes of a reversible luminescent response within the sight of oxygen the radiance is quantitatively diminished or extinguished Dissolved oxygen focus is conversely corresponding to the glow lifetime of the light discharged by the photograph iridescence prepare The lower the DO fixation, the more noteworthy the flag to clamor proportion Limitations None known

Luminophore Structure

Comparative Accuracy of DO Determinants

Comparative Precision and Accuracy of DO Determinants

EPA Quality Assurance Acceptance Criteria for Precision and Recovery Theoretical [DO] – 1.71 ppm Mean 99.3% 95% Confidence Interval 0.024 % Lower Limit 96.9% % Upper Limit 101.8%

EPA Quality Assurance Acceptance Criteria for Precision and Recovery Theoretical [DO] – 7.31 ppm Mean 100.7% 95% Confidence Interval 0.003 % Lower Limit 101.1% % Upper Limit 101.4%

EPA Quality Assurance Acceptance Criteria for Method Detection and Method Limit Method Statistics Single research center 9 distinct instruments 7 imitates Theoretical [DO] = 0.07 ppm Mean Recovery 98% Method Detection Limit 0.02 mg/L Method Limit 0.06 mg/L

Standard Methods Quality Control Results for Biochemical Oxygen Demand

Standard Methods Quality Control Results for Biochemical Oxygen Demand