Patent ID: 11860075
Assignee: ORGANO CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  B  C | IPC B  C  G

Claim 0:
1. An analyzing method of quantifying urea in a sample solution with a urea concentration up to 50 ppb, the method comprising:
pretreating a sample solution with a membrane device including a reverse osmosis membrane; and
analyzing by quantifying urea in the pretreated sample solution directly after the pretreating,
wherein a rate of urea in the sample solution removed in the membrane device is obtained by an analyzer and a quantitative value of urea concentration detected during the analyzing is corrected based on the rate of urea removal,
wherein during the analyzing quantification of urea by flow injection analysis based on a colorimetric method, the analyzing comprises:
injecting a certain amount of the sample solution subjected to the pretreating into a carrier solution being fed to a reaction coil;
adding reagents to the carrier solution into which the sample solution has been injected to react with urea in the reaction coil; and
performing quantification of urea by measuring absorbance of liquid discharged from the reaction coil,
wherein the reagents comprise a diacetyl monoxime-containing reagent solution and an antipyrine-containing reagent solution, and
wherein a temperature of the antipyrine-containing reagent solution is maintained at 5° C. or higher and 15° C. or lower after preparation of the antipyrine-containing reagent.