JPS5940220A - Simultaneous fractional determining apparatus for multiple components - Google Patents

Abstract

PURPOSE:To perform highly accurate quantitative analysis, by differentiating the output of an absorption spectrum measuring part, and simulating the differentiated absorption spectrum by a method of least squares based on a standard absorption spectrum of each component. CONSTITUTION:The absorption spectrum, which is measured by an absorption spectrum measuring part 1, is differentiated by a differential operating part 2 and sent to an analytic operation part 3. The differentiated absorption spectrum is simulated by a method of least squares based on the differentiated absorption spectrum of each component. The concentration of each component is computed from each weight coefficient and outputted from a concentration output part 4. Thus, the highly accurate quantitative analysis is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for simultaneous fractionation and determination of multiple components, and more particularly to an apparatus for determining the concentration of each component in a multi-component sample using an absorption spectrum.

Conventionally, as a multi-component simultaneous fractionation quantification method, the absorption spectrum of a multi-component sample is measured, and the absorption spectrum data and the data of a standard absorption spectrum for which the concentration of each component is known are analyzed by applying the least squares method. A method for quantifying each component in a sample has been proposed (H, A, Barnet
t at, al; AnalChem B2 (1
960) 1158].

However, in the case of absorption spectra, there is a drawback that the baseline fluctuates from measurement to measurement due to dirt on the cell surface, mismatching of the cells, etc., resulting in poor quantitative accuracy.

As a result of intensive research under these circumstances, the inventor of this invention obtained a differential spectrum by differentiating the absorption spectrum of a multi-component sample and the standard absorption spectrum of each component, and calculated the minimum value for these differential spectra. It has been found that the above-mentioned drawbacks can be overcome and quantification can be performed with high accuracy by applying the square method for analysis.

On the other hand, conventional multi-component simultaneous fractionation devices such as liquid chromatographs and gas chromatographs,
Methods that spatially separate each component are mainly used, and there are almost no methods that perform quantitative determination using absorption spectra without spatial separation.

This invention was made under these circumstances and based on the above findings.

This will be explained below with reference to the drawings.

(5) shown in FIG. 1 is a simple embodiment of the multi-component simultaneous fractionation and quantification device of the present invention; an absorption spectrum measuring section (1);
It consists of a differential calculation section (2), an analysis calculation section (3), and a concentration output section (4).

The absorption spectrum measuring section (1) measures the absorption spectrum of a multi-component sample or a standard sample in which the concentration of each component is known.

It may be either one. It has a VC configuration similar to a normal spectrophotometer.

The differential calculation section (21 is for differentiating the absorption spectrum to obtain the differential spectrum, and is composed of a differential electric circuit or a calculation device for obtaining the differential spectrum by coefficient processing of the absorption spectrum. Also, using two spectrometers, It may also be configured using a device that obtains a differential spectrum.
In this case, the differential calculation section (2) is configured integrally with the absorption spectrum measurement section (1). Even the first derivative is 2
It may also be the second derivative.

The analysis calculation unit (3) is composed of a calculation device such as a microcomputer, and performs the following least squares analysis. That is, the differential absorption spectrum of the multi-component sample obtained by the differential calculation section (2) is 8 (λ), and the standard differential absorption spectrum of each component is Rj (λ) (j=l
-n), the data S(λ1) and Rj (λ1) for the wavelength λ1 [1=lm] are applied to the following equation (1), and the cjO value is determined by the least squares method.

If each component R1-Rn does not have an excessive concentration and the absorbance is linear, and each component is independent and there is no interference, the values obtained as 01 to On in equation (1) are This is the concentration of components R1 to Rn contained in .

In Fig. 2, the differential spectra S(λ), R1(λ)~R
An example of n(λ) is given below.

The density output unit (4) outputs the density obtained by the analysis calculation unit (3), and is constituted by a CRT display, a printer, or the like.

Next, an analysis example in which a multi-component sample was quantified using the apparatus of the present invention will be described.

First, the device uses a "Shimadzu self-recording spectrophotometer U'V-250 type" as an absorption spectrum measuring section, a differential calculation section,
[Horizontal Hewlett Pack Card UP-857J computer] was used as the analysis calculation unit and the concentration output unit, and the former and the latter were connected via a [Shimadzu optional unit OP knee 1 type] interface. computer, 5avi-”tgk7 method [mu, 5avitzky
et, al; Anal. Ohem.

86 (1964) 1627) to obtain the second-order differential spectrum through coefficient processing, and also functions as a differential calculation section by calculating the second-order differential spectrum through coefficient processing according to It functions as an analytical calculation unit by performing a least squares method analysis using p, 19).

Multi-component samples include commercially available phenacetin and aspirin.

Caffeine was mixed in the following ratio using a 9:1 methanol-chloroform mixed solution as a solvent.

6- Note 1: Aspirin was dried in a desiccator (silica gel) for 5 hours, zenacetin was dried at 105°C for 2 hours, and caffeine was dried at 80°C for 4 hours before use.

Note 2: Tzenacetin aspirin is soluble in methanol, but
Since caffeine is insoluble, chloroform, which is soluble, was added to form a mixed solvent. Chloroform has strong absorption from below 250 nm, so we reduced its proportion in the mixed solvent, but at 228 nm, which is the absorption peak of aspirin, the absorbance of the mixed solvent itself is 2> f 2.80. When we calculated a calibration curve using the absorption peak at 228 nm, we found that there was a shift in the linearity between the absorbance and the concentration at around 1.8. It was adjusted so that it was .8 or less.

Standard samples were zenacetin, aspirin, and caffeine at 10μ, 40μf/ml, and 20μr/sl, respectively.
Eight solutions with a concentration of fc were used.

Tzenacetin, aspirin, and caffeine only absorb in the ultraviolet region, so the absorption spectrum measurement unit detects wavelength 8.
Absorbance and wavelength were measured from Q Q nm to 285 nm at 0.5 nm intervals to obtain an ultraviolet absorption spectrum.

Figure 8 shows the obtained ultraviolet absorption spectra (Shu is sample 2, (a) is the standard of zenacetin, (
b) is the aspirin standard; (c) is the caffeine standard. (Sample 1.8 is omitted) Second-order differential spectra were obtained from the obtained ultraviolet absorption spectra, and these were subjected to analytical calculation processing at intervals of 0.5 nm. Table 2 shows the results.

Table 2 Tzenacetin Aspirin Caffeine Sample 1 4.0
100.5 80.0 101.8 10.0 10
0.1 sample 2 6.0 99.7 20.0 1G2
．． 8 2Q, 0 102.8 Sample 8 8.0 97.
9 10.0 1085 Bo, 0 99. ? The average recoveries for zenacetin, aspirin, and caffeine were 99°±0.6°, 104.8°±1.9°, and 100°.
It is 9±0.8 inches, which agrees well with the amount added.

In the case of a differential spectrum, since the flat absorption portion of the absorption spectrum is zero, it has the advantage of eliminating fluctuations above and below the baseline due to contamination on the cell surface, and therefore, data variation is small.

Note that aspirin has a larger error than zenacetin and caffeine, but this is probably because the absorption of the mixed solvent itself is large near the absorption peak of aspirin, affecting the absorption spectrum of aspirin. Therefore, it is more preferable to improve the solvent.

As can be understood from the above explanation, the multi-component simultaneous fractionation and quantification device of the present invention can easily and simultaneously measure the concentration of each component in a multi-component sample with high precision, without the influence of baseline fluctuations. Become able to quantify. Therefore, the device of the present invention is extremely useful for applications such as a quality inspection machine for pharmaceuticals and the like.

−〇　− It is.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the configuration of an embodiment of the multi-component simultaneous separation and quantification device of the present invention, Figure 2 is a spectrum diagram illustrating a differential spectrum, and Figure 8 is an example of an absorption spectrum when an actual sample is analyzed. FIG. (1)...Absorption spectrum measurement section, (2)...Differential calculation section, (3)...Analysis calculation section, (4)...Concentration output section, (5)...Multi-component simultaneous Differential quantitative device. 10- Figure 1 Figure 2 Wave length Figure 3 Week length

Claims (1)

[Scope of Claims] 1. An absorption spectrum measurement section, a differential calculation section for differentiating the output of the absorption spectrum measurement section to obtain a differential spectrum, and a multi-component sample obtained by the absorption spectrum measurement section and the differential calculation section. Differential spectrum data 8 (λ1) and standard differential spectrum data Rj (λ1) of each component
), and an analytical calculation unit that calculates Cj that satisfies the following formula % formula % (1) by least squares analysis, and the concentration of each component Xj of the multi-component sample as the concentration of the O
A multi-component simultaneous separation and quantification device comprising a concentration output section that outputs j. 1-