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 Title: |
EP0486156B1:
Flow injection analysis of total inorganic phosphate[German][French]
[ Derwent Title ]
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Country:
Kind: |
EP European Patent Office (EPO)
B1 PATENT SPECIFICATION i
(See also:
EP0486156A2,
EP0486156A3 )
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| Inventor: |
O'Lear, Christina;
Salamony, Keith J.;
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| Assignee: |
CALGON CORPORATION
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| Published / Filed: |
1997-03-26
/ 1991-10-14
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| Application Number: |
EP1991000309429
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| IPC Code: |
Advanced:
G01N 21/78;
G01N 33/00;
G01N 35/08;
Core:
G01N 21/77;
more...
IPC-7:
G01N 21/00;
G01N 21/78;
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| ECLA Code: |
G01N21/78; G01N33/00D2D4; G01N35/08F;
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| Priority Number: |
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| Abstract: |
[From equivalent
EP0486156A2]
A method for flow injection analysis of total inorganic phosphate contained in an aqueous system such a cooling tower or boiler is described which uses a reducing agent and preservative composition therefore as the carrier for the sample to be analyzed, thereby creating a facile process which permits conversion of the various polyphosphates to orthophosphate and development of the molybdenum blue complex color reaction at 60ø-95øC and under 2-10 psi. This method has less stringent pressure and temperature requirements than those employed heretofore, thus permitting the use of more reliable and economic devices for measuring total inorganic phosphate in the field.
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| Attorney, Agent or Firm: |
McCormack, Derek James ;
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| INPADOC Legal Status: |
Show legal status actions
Family Legal Status Report
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| Designated Country: |
AT BE CH DE DK ES FR GB GR IT LI LU NL SE
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| Family: |
Show 14 known family members
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First Claim:
Show all claims |
1. A flow injection analysis method for determination by the molybdenum blue complex colorimetric reaction of total inorganic phosphate concentration in an aqueous system containing dissolved inorganic polyphosphate as well as orthophosphate, comprising the steps of (1) establishing a filtered sample stream from said aqueous system from which sample units may be selected at designated intervals; (2) bringing together and admixing on a continuous basis the following two reagent composition streams which then form the basic flow injection analysis stream: (a) a color-forming reagent comprising an inorganic acid and molybdenum (V and VI), and (b) a reducing agent and preservative composition therefor; (3) interrupting the flow of reagent composition stream (b): a reducing agent and preservative composition therefor, and substituting therefor the filtered sample stream of step (1) for sufficient time to select a sample unit, which then becomes admixed with reagent composition stream (a): a color-forming reagent comprising an inorganic acid and molybdenum (V and VI); (4) restoring the flow of reagent composition stream (b); (5) heating the reaction mixture to 60°-95°C for between 10 and 25 minutes in order to effect conversion of substantially all of the polyphosphate contained in the sample unit to orthophosphate, said time also being sufficient to effect the reaction of said orthophosphate with the molybdenum (V and VI) to form a color complex; and thereafter allowing said reducing agent to partially reduce the molybdenum (V and VI) so that it has an average oxidation state between 5 and 6; (6) passing the reaction mixture containing the color complex through a colorimeter having a 600-850 nm filter and reading the signal produced thereby; and (7) from the signal information and previously available standardization data, calculating the concentration of dissolved inorganic phosphates in the aqueous stream; wherein all of the above steps are carried out under a pressure of from 13.8 · 103 Pa - 68.9 · 103 Pa.
[German]
[French]
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Description
Expand description |
[From equivalent
EP0486156A2]
+ BACKGROUND OF THE INVENTION
+ 1. Field of the Invention
The present invention is in the field of methods and apparatus for flow injection analysis of total inorganic phosphate in aqueous systems. Inorganic phosphates such as orthophosphate and polyphosphate are products which are used in aqueous systems such as cooling towers and boilers to prevent calcium scales and corrosion. There is a threshold concentration at which phosphates work by causing crystal distortion that prevents calcium scale and/or steel corrosion. Thus, it is important to determine on a regular basis the concentration of dissolved inorganic phosphates so that the threshold levels necessary to prevent deposition of calcium scales is maintained. A secondary goal is to prevent high phosphate concentrations which may result in subsequent phosphate scale.
+ 2. Brief Description of the prior Art
+ SUMMARY OF THE INVENTION
+ DETAILED DESCRIPTION OF THE INVENTION
+ Description of the Drawings
+ DESCRIPTION OF THE PREFERRED EMBODIMENTS
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