JP3139628B2 - Spectrophotometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorptiometer capable of compensating for turbidity, and more particularly to an absorptiometer capable of simple calibration using a reference calibration plate.

[0002]

2. Description of the Related Art Conventionally, as this type of technology, a measuring cell and a comparison cell, which are configured to have the same conditions except that the cell length is different, are installed in parallel, and a common liquid is supplied to the two cells. The chromaticity and the turbidity are measured simultaneously by taking the ratio of the transmitted light (measurement light and reference light) to the light from the light source device, and the chromaticity signal is measured by the signal of the turbidity. There is an absorptiometer that obtains the correct chromaticity by performing the correction (for example, Japanese Patent Application No. Hei.
-85511).

[0003]

However, such a conventional technique has the following problems. In the case of a normal absorptiometer that does not need to compensate for turbid matter, zero water is simply flowed into both cells without performing calibration by flowing the chromaticity standard solution through the cell. In such a state, a reference calibration plate (usually made of slightly colored glass or the like) pre-valued is inserted into the optical path. However, in this case, the detection signal includes the turbidity component at the same time as the chromaticity component. Therefore, the output signal obtained by the computation is the one corrected by the turbidity signal. That is, such a simple calibration method cannot be used as a calibration replacing the chromaticity standard solution.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an absorptiometer that can be calibrated with a reference calibration plate. It is.

[0005]

In order to achieve the above object, the present invention provides a measuring cell and a comparative cell in which a liquid to be measured flows, and a measuring light passing through the measuring cell and a measuring light passing through the comparative cell. the reference beam is detected by a detector through the filter over and turbidity measurement filter for chromaticity measurement, the absorption photometer to measure the absorbance intensity of the test liquid was calculated using the calculating means the detector signals The calculating means has a function of calculating absorbance with chromaticity light, a function of calculating absorbance with turbidity light, a function of calculating chromaticity, a function of calculating turbidity,
The function of setting the value of the turbidity correction coefficient to "0", the function of setting the turbidity correction coefficient to a value corresponding to the liquid to be measured, and the value of the turbidity correction coefficient by switching and selecting. Having a function of leading the calculated value to a function of calculating the chromaticity,
By using these arithmetic functions , it also serves as a turbidity calibration plate
When calibrating using a standard calibration plate ,
Chromaticity can be calibrated by performing calculations with the value set to zero.

[0006]

An embodiment will be described with reference to the drawings. FIG. 1 is a view showing a specific embodiment of the absorptiometer of the present invention. FIG. 2 is a block diagram of an embodiment in which FIG. 1 is further developed.

In FIG. 1, 1 is a lamp, 2a and 2b are optical means composed of, for example, convex lenses, 3a and 3b are plane mirrors, 4 is a measurement cell, and 5 is a comparison cell (also referred to as a reference cell). Reference numeral 6 denotes a disk-shaped filter wheel, on which a filter 7 for chromaticity measurement and a filter 8 for turbidity measurement are mounted, for example, one by one. This filter wheel 6 has a notch on the outer circumference indicating the positions of the chromaticity measurement filter 7 and the turbidity measurement filter 8 and a notch for resetting the position (not shown).
Etc., and each notch is provided with a position detection sensor 9.
Will be detected.

[0008] 10a and 10b are concave mirrors, 11 is a detector.
Reference numeral 12 denotes a reference calibration plate (enter this position when performing normal calibration). Reference numeral 13 denotes a sample hold circuit (hereinafter referred to as "S / H") for separating the signal I from the detector 11 using the signal D from the position detection sensor 9 as a hold signal. 14
Is an I / O and storage means (R) provided for calculating the chromaticity and turbidity of the sample liquid based on the output from the S / H13.
AM, ROM), a CPU, an external setting device, and the like (details will be described later). Numeral 15 is an instruction means for instructing the values (turbidity, chromaticity) based on the result calculated by the operation means 14. 16 the introduction flow path of the sample water, 17 standard solution (chromaticity standard solution or turbidity standard solution) introducing passage, 18 turbidity for zero filter 18a clean water is supplied for zero calibration
And a zero liquid introduction flow path through which the zero liquid after passing through the chromaticity zero filter 18b flows.
4, leading to comparison cell 5.

[0009] calculation of the arithmetic unit 14 of FIG. 2, each function of the storage, 14a is a function of calculating the absorbance (chromaticity absorbance) A _c in chromaticity light (hereinafter referred to as "chromaticity absorbance calculation function"),
14b the absorbance at turbidity light function for calculating the (turbidity absorbance) A _t (hereinafter referred to as "turbidity absorbance calculation function"), 14c functions to obtain the calculated chromaticity (C) outputs a chroma C (hereinafter 14d is a function for calculating the turbidity T to obtain a turbidity (T) output (hereinafter referred to as a "turbidity calculating function"), and 14e is a function for calculating the turbidity correction coefficient α to "0". A value of the turbidity correction coefficient α (a value other than “0”, that is, an arbitrary value corresponding to the liquid to be measured) is set in 14f (for example, the turbidity correction coefficient is externally measured). The function 14g is a function of switching and selecting the value of the turbidity correction coefficient α and guiding the selected value to the chromaticity calculation function 14c. Shown respectively.

In such a configuration, the white light emitted from the lamp 1 is divided into two parts, becomes parallel rays at the respective lenses 2a and 2b and is reflected by the plane mirrors 3a and 3b, and one is measured as measurement light (M light). The cell 4 is used as a reference light (R light) and the other is used as a reference cell 5
Pass through. Each passing light is a filter for chromaticity measurement provided on a filter wheel 6 rotating at a constant speed.
7 and a concave mirror after passing through the turbidity measurement filter 8
The light is reflected by 10a and 10b and focused on the light receiving surface of the detector 11. The light detected by the detector 11 passes through a rotating filter wheel, and is divided into two types relating to the chromaticity C and the turbidity T of the M light and the R light, namely, C _M (chromaticity C , C _R (comparison cell signal of chromaticity C), T _M (turbidity T
, And T _R (comparison cell signal of turbidity T). Therefore, considering the signal obtained when the zero standard solution is put in the cell and the signal obtained when the measuring solution is put in the cell, there are eight types of signals. Here, with respect to these eight kinds of signals, each signal when the zero liquid is put is represented by a suffix "0" added after each of the above-mentioned signals, and C _MO , C _RO , T _MO , T _RO And Also, each signal when the measuring solution is filled is represented by adding a suffix “M” after each of the above-mentioned signals, and C _MM , C _RM ,
_TMM and _TRM . The signals classified in this way are detected by the detector 11 and guided to the arithmetic function 14 via the S / H 13 to perform a predetermined operation, and the operation result is indicated by the instruction means 15.

Next, the operation of the calculating means 14 will be described. Chromatic absorbance Ac calculated by the chromatic absorbance calculating function 14a
Is: Ac = −log ｛(C _MM / C _MO ) / ( C _RM /
_{C RO)} = k1 · C} (L M -L R) ... a (1). However k1 is a proportional constant, L _M is the measurement cell length, L _R
Represents the comparison cell length. The turbidity absorbance calculation function 14b
Turbidity absorbance At of the operation, the _{At = -log {(T MM /} T MO) / T RM / T RO)} = k2 · T (L M -L R) ... (2) In. Here, k2 represents a proportionality constant.

[0012] Chromaticity absorbance A _c is guided to the chromaticity calculation function 14c, obtaining chromaticity C of the test solution based on the following arithmetic expression. C = β (A _C −αA _t ) (3) where β represents a chromaticity sensitivity calibration coefficient. On the other hand, turbidity absorbance A _t is guided in turbidity calculation function 14d, to obtain the turbidity T of the test solution based on the following arithmetic expression. T = γ · A _t (4) where γ represents a turbidity sensitivity calibration coefficient.

By the way, as is apparent from the relationship between the above equations, in equation (3), the absorbance due to chromatic light is affected not only by the chromaticity component of the measurement liquid but also by the turbidity component (turbidity component). And the turbidity light is included in the chromaticity component. Indicates that it is not affected.

When calibrating the chromaticity span (sensitivity), the chromaticity standard solution is measured from the standard solution inflow channel 17.
The output of the detector 11 is introduced into the fixed cell 4 and the comparison cell 5
Is calculated by the calculator 14 and is calibrated. However, since the turbidity component is not included, the turbidity absorbance At is zero. Chromaticity C _L chromaticity standard solution from _{(3), C L = β (A C} -αAt) = β · A C ... (5) becomes the demanded and it can be seen that the correct chromaticity calibration . On the other hand, the reference calibration plate 12 is used for chromaticity calibration.
In the case of using , zero solution is supplied to the measurement cell 4 and the comparison cell 5.
With the calibration plate 12 inserted into the optical path on the side of the comparison cell
Calculates the output of the detector 11 by calculating with the calculator 14
However, since this calibration plate also serves as a turbidity calibration plate, it absorbs the chromaticity measurement light and also absorbs the turbidity measurement light, so that the turbidity compensation term in equation (3) does not become zero and At ≠ 0 because made, chromaticity C _E from _{(3), C E = β (a C} -αAt) ... (6) becomes, as it will be affected by the absorbance by turbidity light correctly chromaticity calibration You can not do that.

Here, α in the equation (6) takes various values depending on the condition of the measuring solution, and the chromaticity by the calibration plate cannot be unambiguously determined as it is. Therefore, during such chromaticity calibration, the switching function 14g is switched to output a calibration value that sets the value of the turbidity correction coefficient α to “0” 14e.
By selecting, the chromaticity of the calibration plate can be set to a constant value by performing an operation to make α of the turbidity compensation term zero by always setting α to “0”, and calibration using the calibration plate is possible Becomes
In other words, equation _{(6), C E = β (A C} -αA t) = β · A C "... (7) can be obtained. Incidentally, At = 0 as originally the case with standard solutions Therefore, at this calibration, α = 0
There is no hindrance. Therefore, the calibration by switching the arithmetic expression may be used at the time of calibration with the standard solution.

As described above, even when the calibration is performed using the reference calibration plate, the calibration value obtained from the calculating means is a calibration according to the "calibration with the standard solution". After such a calibration, the switching function 14g is changed to the turbidity correction coefficient α.
The normal measurement can be performed thereafter by switching to the function 14f side where the value is set and excluding the calibration plate 12.

[0017]

As described above, the present invention is configured so that the turbidity compensation term is set to zero by switching the arithmetic expression, so that the calibration using the reference calibration plate can be performed correctly and easily. This has a practically remarkable effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a specific example of an absorptiometer of the present invention.

FIG. 2 is a block diagram of an embodiment in which FIG. 1 is further developed.

[Explanation of symbols]

 1 Lamp 4 Measurement cell 5 Comparison cell 6 Filter wheel 11 Detector 12 Reference calibration plate 14 Calculation means 15 Indicator means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01J 3/51 G01N 21/27 G01N 21/31 G01N 21/59

Claims (1)

(57) [Claims] 1. A measurement cell (4) through which a liquid to be measured flows and a comparison cell (5) are installed, and a measurement light passing through the measurement cell and a reference light passing through the comparison cell are used as a chromaticity measurement filter. br /> detected by the detector (11) through te (7) and the turbidity measurement filter (8), computing means the detector signal (1
In absorptiometer to measure absorbance intensity of the test liquid was calculated using the 4), the operation manual stage function of calculating the absorbance at chromaticity light (14
a), a function of calculating absorbance with turbidity light (14b), a function of calculating chromaticity (14c), and a function of calculating turbidity (14)
d), a function of setting the value of the turbidity correction coefficient to “0” (14e),
A function (14f) in which the turbidity correction coefficient is set to a value corresponding to the liquid to be measured, and a function of switching and selecting the value of the turbidity correction coefficient and calculating the selected value to calculate the chromaticity ( It becomes a function of (14 g) leading to 14c), these operations
When using a function to calibrate using a reference calibration plate (12) that also serves as a turbidity calibration plate, the value of the turbidity correction coefficient
An absorptiometer characterized in that the chromaticity can be calibrated by performing an arithmetic operation with zero as the value .