Method of component concentration detection based on reference wavelength
View Patent ↗A method of detecting a concentration of a target component by using a reference wavelength includes: defining a wavelength at which a light intensity is insensitive to the variation of the target component concentration as a reference wavelength for the target component; detecting spectra at both the reference wavelength and a further measuring wavelength; processing the spectrum detected at the further measuring wavelength, with the spectrum detected at the reference wavelength as an inner reference, to obtain a characteristic spectrum including specific information of the target component; building a calibration model between the characteristic spectrum and the concentration of the target component; and determining the concentration of the target component based on the calibration model.
1. A method of detecting a concentration of a target component in a sample, including steps of:
1) defining a wavelength at which a light intensity is insensitive to variation of the target component concentration as a reference wavelength for the target component;
2) detecting spectra at the reference wavelength and a further measuring wavelength;
3) processing the spectrum detected at the further measuring wavelength, with the spectrum detected at the reference wavelength as an inner reference, to obtain a characteristic spectrum including specific information of the target component;
4) building a calibration model between the characteristic spectrum and the concentration of the target component; and
5) determining the concentration of the target component based on the calibration model,
wherein the reference wavelength λ r is defined as follows:
for a pure absorption sample, α g (λ r )+α w (λ r )·k=0; and
for a scattering sample,
6.44
*
10
-
5
*
r
2.37
*
ρ
s
*
n
s
*
(
n
s
-
n
w
)
1.09
λ
r
0.37
*
n
w
3.09
*
1
1
-
g
(
λ
r
)
=
α
g
(
λ
r
)
+
α
w
(
λ
r
)
·
k
,
wherein α w and α g are absorption coefficients of the water molecule and the target component molecule respectively, k is a replacement coefficient between the water and the target component, g is an anisotropic factor of the scattering sample, n s is a refractive index of scattering particles of the scattering sample, n w is the refractive index of the water, r is a radius of the scattering particles, ρ s is the number of scattering particles per unit volume of the sample (nm −3 ).
2. The method according to claim 1 , wherein the reference wavelength for the glucose in the aqueous glucose solution is 1525 nm.
3. The method according to claim 1 , wherein a wavelength at which light intensity is most sensitive to the variation of the target component concentration is selected as the measuring wavelength.
4. The method according to claim 1 , wherein in step 3), the specific information of the target component is obtained as follows:
for a pure absorption sample, the specific information including the variation of the target component concentration is:
A
G
(
λ
)
=
-
Ln
(
I
s
(
λ
)
I
b
(
λ
)
·
I
b
(
λ
r
)
I
s
(
λ
r
)
)
;
for a scattering sample, the specific information including the variation of the target component concentration is:
A
G
(
λ
)
=
Ln
I
b
(
λ
)
·
I
s
(
λ
r
)
I
s
(
λ
)
·
I
b
(
λ
r
)
+
K
Δ
c
·
Ln
(
I
b
(
λ
)
I
b
(
λ
r
)
·
I
0
(
t
b
,
λ
r
)
I
0
(
t
b
,
λ
)
)
,
where I s (λ r ) and I b (λ r ) are intensities of the transmitted light from the sample and a background sample at the reference wavelength respectively, I s (λ) and I b (λ) are intensities of the transmitted light from the sample and the background sample at the measuring wavelength respectively, I 0 (t b , λ r ) and I 0 (t b , λ) are intensities of the light incident to the background sample at the reference wavelength and the measuring wavelength respectively, and K Δc is a percentage coefficient of the light path length variation caused by the concentration change of the target component of Δc.
5. The method according to claim 1 , wherein the calibration model is built by the Partial Least Squares (PLS) method or the net analyte signal method.