JP3393701B2 - Spot test method for ionic samples - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot test method for an ionic sample, and more particularly to a novel spot test method for an ionic sample which is a highly sensitive and simple measurement method for a micro sample.

[0002]

2. Description of the Related Art Conventionally, as means for optically measuring a sample concentration of a metal (ion) in a solution, an atomic absorption method, an emission analysis method, and a ligand to a metal have been used. The absorptiometric method for measuring the absorbance by binding with a specific color and the fluorescence analysis method for measuring the fluorescence have been used. In addition, even for measurement objects other than metals (ions), the absorptiometry using the specific absorption wavelength of the sample and the fluorescence spectrophotometry using fluorescence have been widely used.

Although these methods are generally highly sensitive and have excellent specificity for elements and samples, they have problems in that they require expensive dedicated equipment and require skill in operation. On the other hand, as one of simple measuring means, a spot test method is known in which a colored solution is dropped on a filter paper and the color and size thereof are visually judged. However, in the conventional classical spot test method, there was a problem that the solution dropped on the filter paper spreads widely, the area per volume of the dropped sample becomes large, and the detection sensitivity is low.

As a method for controlling the size of the spot in the spot test method, there is a ring oven method. The ring-oven method evaporates the solvent and diffusion liquid by heating from the outer periphery of the filter paper when the sample solution dropped on the center of the filter paper permeates and diffuses. It is a method to control the size of the spot ring from the balance with. This is a method of concentrating the color of the sample in a ring shape and enabling highly sensitive detection by visual observation, but the device used for heating is complicated and the operability is difficult, and the size of the ring can be controlled. However, the diameter is still 20
There is a problem in that it is as large as about mm and sufficient sensitivity cannot be obtained.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on the spot test method in order to solve the above-mentioned problems, and as a result, the spread of the spot ring is suppressed by dropping the sample solution on the hydrophobic carrier. In addition, since the complex is concentrated in a ring shape around the spot ring, not only does it have sufficient detection sensitivity by visual observation,
The present invention has been completed by first discovering a new measuring method capable of improving quantitativeness and accuracy by using a reflection type absorptiometer, a fluorescence spectrophotometer and the like.

That is, the gist of the present invention is to add a coloring agent capable of forming a complex with an ionic analyte to a sample solution which is considered to contain the ionic analyte, and then drop the sample solution onto a hydrophobic carrier and evaporate it. The present invention resides in a spot test method for an ionic sample, which comprises measuring the color development of the complex at the sample dropping point after concentration. The ionic sample to be measured in the present invention is not particularly limited as long as it has the ability to form ions in the aqueous solution. Specifically, Fe, Cu, Pb, Ni, to which the colorimetric method can be applied,
Various metals (ions) such as Co, Ca, Al, Zn, V, ions such as F ⁻ , CN ⁻ , S ^{2 −} , ions of organic acids obtained by dissociation of trichloroacetic acid, salicylic acid, etc., ionized products of various alkaloids, etc. Etc., many samples currently measured by the absorptiometry, the fluorescence spectrophotometry, etc. are mentioned.

The color former capable of forming a complex with the ionic analyte is not particularly limited, but specifically, 2-nitroso-
5- [N-propyl-N- (3-sulfopropyl) amino] phenol, 2,2′-dihydroxyazobenzene, lumogallion, methylene blue and the like can be mentioned. The color former is added in an amount sufficient to form a complex with the analyte to be measured. It is usually added in an excessive amount as long as it does not interfere with the color reaction.

The hydrophobic carrier used in the present invention is not particularly limited as long as the surface of the carrier has at least a hydrophobic portion. FIG. 1 shows a schematic diagram of the spot test method of the present application. When the spot after the ring is formed is scanned in the diameter direction of the ring and the absorbance or fluorescence is measured, the following five patterns are observed. (1) p and r are large (2) p is large and r is small (3) p is small and r is large (4) p and r are both small (5) p is extremely small (however, p Is the peak height / half-width, r is the strength of the central part /
Represents the peak height)

Therefore, it is preferable that the hydrophobic carrier to be used be appropriately selected according to each case. For example, in the case of (1), hydrophobic filter paper or hydrophobic coated synthetic paper is used, in the case of (2) ceramic tiles or polyvinyl chloride, and in the case of (3) resin coated paper, etc. In the case of (4), a vinylidene chloride film, an acrylic acid ester film or the like is preferably used, and in the case of (5), a colorless and transparent resin sheet or the like is preferably used.

The amount of the sample solution dropped on such a carrier may be small because it has the effect of increasing the contrast with the background by concentrating it in the shape of a small ring and improving the sensitivity of visual detection. desirable. In practice, it is determined based on the relationship between the carrier, the composition of the sample solution, the viscosity, etc., and although it cannot be determined unconditionally, it is usually 5 to 500 μl, more preferably 20 to 200 μl. For example, when a sample of about 100 μl is dropped on a hydrophobic filter paper, a spot having a diameter of about 5 mm is formed on the filter paper.

Further, in the present invention, a buffer may be added as appropriate for the purpose of stabilizing the complex formed in the sample solution. Specifically, a so-called pH buffer solution such as Tris buffer solution, Good's buffer solution, MES buffer solution, borate buffer solution is preferably used. The sample solution dropped on the carrier is subsequently evaporated and concentrated. This may be naturally dried, or may be forcedly dried at about 60 to 100 ° C. for about 10 to 3 hours.

After drying, a ring as shown in FIG. 1 is formed on the carrier. A halo-shaped complex of the sample to be measured and the coloring agent is formed around the ring.
Since such a complex is colored or fluorescing, the target sample can be qualitatively or quantitatively determined by visually observing the complex or measuring its absorbance or fluorescence intensity using a known analysis means. Can be measured.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 To a tetrahydrofuran solution of polyvinyl chloride (hereinafter, abbreviated as "PVC") was added dioctyl phthalate in which titanium dioxide was dispersed, stirred, and then spread on a petri dish to obtain a plasticized white PVC film. Was produced. A 2-nitroso-5- [N-propyl-N- (3-sulfopropyl) amino] phenol (hereinafter, abbreviated as "NPSAP") solution was added to a sample solution containing iron at 2 × 10 ⁻⁵ mol /
dm ³ and L-ascorbic acid at 5 × 10 ⁻⁴ mol / dm
³ , and borate buffer solution (pH 9.2) were added, and the volume was adjusted to constant with water.

100 μl of the mixed solution of the sample was dropped on the plasticized white PVC film and dried at 60 ° C. for 1 hour.
After that, the coloring ring of the Fe-NPSAP complex formed on the film was visually or reflected-type absorbance measuring device (flying spot scanning densitometer).
CS-9300PC, Shimadzu) 700nm
The absorbance of was measured. By visual measurement, the color tone changes from red to green with the iron concentration, and the detection limit is 1.0 ×
It was 10 ^-7 M. Figure 2 shows the calibration curve obtained by the absorbance measurement method.
Shown in. It can be seen that the peak area of absorbance increases as the concentration of iron in the sample solution increases.

Example 2 To a sample solution containing aluminum, 2,2'-dihydroxyazobenzene (hereinafter abbreviated as "DHAB") solution was added at 3 × 10 ^-6 mol / dm ³ , and Tris buffer (pH).
8.0) was added, and the volume was adjusted to constant with water.

100 μl of the sample mixture was added to a hydrophobic filter paper (A
DVANTEC 2S) and dried at 80 ° C. for 30 minutes. A red coloring ring of the Al-DHAB complex formed on the filter paper was used for 495n using a visual or reflection type absorbance measuring device (flying spot scanning densitometer CS-9300PC, Shimadzu Corporation).
The absorbance at m was measured. As a result, the visual detection limit was 2 × 10 ⁻⁷ mol / dm ³ , and the absorbance measurement was 1 × 1.
It was 0 ^-6 mol / dm ³ .

Example 3 Add 1 DHAB solution to the sample solution containing aluminum.
× 10^-Fivemol / dm ³ , And PIPES-KOH buffer
The liquid (pH 6.5) was added, and the volume was adjusted to constant with water. Sample mixture
100 μl on hydrophobic paper (ADVANTEC 2S)
And was dried at 70 ° C. for 30 minutes. Formed on paper
The formed Al-DHAB complex is visually or fluorescently attached.
Illuminate the color ring with an ultraviolet lamp (TOPCON FI-5S)
Reflection type fluorimeter (flying spot scan)
Ningden Citometer CS-9300PC, Shimadzu
Place).

A calibration curve obtained by a fluorometer is shown in FIG.
It can be seen that the fluorescence intensity showing good linearity is obtained with the aluminum concentration in the sample solution. The visual detection limit was 2 × 10 ⁻⁸ mol / dm ³ .

Example 4 To 20 ml of a sample solution containing aluminum ions, 25 μl of 1 × 10 ⁻³ mol / dm ³ of lumogallion solution,
And 0.1 mol / dm ³ MES-KOH buffer (pH
1 ml of 6.9) was added, and water was added to make the volume constant 25 ml.

100 μl of the mixed solution of the sample was added to the hydrophobic paper (A
DVANTEC 2S) and dried in a forced convection dryer at 80 ° C. for 30 minutes. Visual observation of the Al-lumogallion complex formed on the filter paper, or irradiation of a fluorescent coloring ring with an ultraviolet lamp (TOPCON FI-5S), and a reflection type fluorometer (flying spot scanning densitometer CS-9300PC, Shimadzu). (Manufacturing). The detection limit was 5 × 10 ⁻⁸ mol / dm ³ both visually and with a fluorometer.

[0021]

INDUSTRIAL APPLICABILITY The spot test method for an ionic sample of the present invention is simple in addition to the conventional method, and the spot size is controlled to be small. Therefore, the sample in the sample is concentrated at a high magnification and at the ppb level. It becomes possible to measure by the sensitivity of
It can be used as a highly sensitive simple measurement method for micro samples.

[Brief description of drawings]

FIG. 1 schematically shows the outline of the steps of the spot test method of the present invention.

FIG. 2 shows the result of measuring the concentration of the Fe—NPSAP complex in Example 1 by a reflection absorption method.

FIG. 3 shows the result of measuring the concentration of an Al-DHAB complex in Example 3 by a reflection fluorescence method.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-48643 (JP, A) JP-A-62-161053 (JP, A) JP-A-3-111761 (JP, A) JP-A-6- 148076 (JP, A) JP-A-6-321908 (JP, A) JP-A-5-196616 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/75-21 / 83 G01N 31/22 121 JISST file (JOIS)

Claims (4)

(57) [Claims] 1. A color-forming agent capable of forming a complex with an ionic analyte is added to a sample solution suspected of containing the ionic analyte,
Next, a spot test method for an ionic sample, which comprises dropping the sample solution on a hydrophobic carrier, evaporating and concentrating the sample solution, and then measuring the color development of the complex at the sample dropping point. 2. The method according to claim 1, wherein the hydrophobic carrier is a hydrophobic filter paper. 3. The method according to claim 1, wherein the color development of the complex is measured by absorbance. 4. The method according to claim 1, wherein the color development of the complex is measured by fluorescence intensity.