References: ASTM D 1385-88 (Reapproved 1991), Hydrazine in Water.
L. C. Thomas and G. J. Chamberlin, Colorimetric Chemical Analytical Methods, 8th ed., p. 195, method I (1974).
Hydrazine, N2H4, is a powerful reducing agent which is used in various chemical processes as a raw material, and in boiler water as an oxygen scavenger.
To control corrosion, residual hydrazine typically is maintained in the range of 0.05 to 0.1 mg/L. Higher levels may be used. to guard against corrosion when the boiler is out of service for an extended period.
The Colorimetric Method. CHEMetrics' method is based on PDMAB, paradimethylaminobenzaldehyde. PDMAB in acid solution reacts with hydrazine to form a yellow product. Results are expressed as (mg/L) N2H4.
hope this is enough.Please suppress the hypochlorite by adding acid then proceed the above analysis