Method and apparatus for measuring pH of medium solution

Patent metadata

Field	Value
Publication number	US-9291572-B2
Application number	US-201213441630-A
Country	US
Kind code	B2
Filing date	Apr 6, 2012
Priority date	Mar 31, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A pH measuring method includes: illuminating a medium solution, which includes: a first material; and a second material, with a plurality of light beams, which includes: a first light beam, a wavelength of which corresponds to a first absorption peak; a second light beam, a wavelength of which corresponds to a second absorption peak or a second convergence point; a third light beam, a wavelength of which corresponds to a third absorption peak or a third convergence point; and a fourth light beam, a wavelength of the fourth light beam at which an absorbance of at least one of the first and second materials is converged irrespective of a pH; receiving transmitted or reflected light beams of the first to fourth light beams; measuring absorbances at the wavelengths of the received light beams respectively; and calculating a pH of the medium solution based on the absorbances.

First claim

What is claimed is:

1. A pH measuring method comprising:
illuminating a medium solution with a plurality of light beams,
the medium solution including:
a first material which, in a wavelength region of 300 nm to 800 nm, has a first absorption peak; and
a second material which, in the wavelength region of 300 nm to 800 nm, has a second absorption peak or a second convergence point where an absorbance is converged irrespective of a pH, and a third absorption peak or a third convergence point where an absorbance is converged irrespective of a pH,

the plurality of light beams including:
a first light beam, a wavelength of which corresponds to the first absorption peak;
a second light beam, a wavelength of which corresponds to the second absorption peak or the second convergence point;
a third light beam, a wavelength of which corresponds to the third absorption peak or the third convergence point; and
a fourth light beam, a wavelength of the fourth light beam at which an absorbance of at least one of the first material and the second material is converged irrespective of a pH;

receiving transmitted or reflected light beams of the first to fourth light beams;
measuring absorbances at the wavelengths of the received transmitted or reflected light beams of the first to fourth light beams respectively; and
calculating a pH of the medium solution based on the measured absorbances,
wherein the pH of the medium solution is calculated with an expression including a sum of the absorbance of the first material with the absorbance of the second material.

2. The pH measuring method according to claim 1 , wherein the expression includes one of a first function in which the pH is a variable and a second function in which an absorption coefficient is a variable.

3. The pH measuring method according to claim 2 , wherein, in a case where the expression includes the first function, the pH is calculated by following expression:

(

A
λ1

A
λ2

A
λ3

A
λ4

)

=

(

α

FBS_
⁢
λ
⁢
1

B

0
⁢
_λ1

B

1
⁢
_λ1

S
λ1

α

FBS_
⁢
λ
⁢
2

B

0
⁢
_λ2

B

1
⁢
_λ2

S
λ2

α

FBS_
⁢
λ
⁢
3

B

0
⁢
_λ3

B

1
⁢
_λ3

S
λ3

α

FBS_
⁢
λ
⁢
4

B

0
⁢
_λ4

B

1
⁢
_λ4

S
λ4

)

·

(

C
FBS

·
D

Assignees

• Oura Mitsuhiro
• Kubo Hirotsugu
• Takeda Sunao
• Okano Teruo
• Shimizu Tatsuya
• Nihon Kohden Corp
• Univ Tokyo Womens Medical

Inventors

• Oura Mitsuhiro
• Kubo Hirotsugu
• Takeda Sunao
• Okano Teruo
• Shimizu Tatsuya

Classifications

• C12M41/26

  of pH · CPC title

• G01N2021/3181

  using LEDs · CPC title

• G01N31/221

  for investigating pH value · CPC title

• G01N21/80 Primary

  Indicating pH value · CPC title

• G01N2201/0627

  Use of several LED's for spectral resolution · CPC title