Patent ID: 8352207

Claim:
A method for calibrating a fluorometer comprising the steps of: a) providing a fluorometer configured to measure a fluorescent signal from a fluorescent marker in a sample of water from an industrial water system and determine from the fluorescent signal a concentration of a water treatment product in the sample of water, wherein a nominal concentration C 0 of the water treatment product corresponds to a nominal concentration C f of the fluorescent marker; b) withdrawing a water sample from the industrial water system; c) measuring a first fluorescent signal, S 1 , from the water sample with the fluorometer; d) preparing a first calibration solution, comprising the steps of i) preparing a spike solution containing the water treatment product at a concentration of about P×C 0 and the fluorescent marker at a concentration of about P×C f , and ii) adding about 1 part of the spike solution to about N parts of the water sample; e) measuring a second fluorescent signal, S 2 , from the first calibration solution with the fluorometer; f) calculating a slope coefficient, K m , approximately equal to C f / ( S 2 ⁡ ( N + 1 P ) - S 1 ⁡ ( N N + 1 ) ) ; g) measuring a third fluorescent signal, S 3 , from a sample of a zero water sample; h) setting a zero shift, Z 0 , equal to S 3 ; and i) calibrating the fluorometer with the slope coefficient and the zero shift.