JPS58172554A - Reagent composition for measuring creatinine - Google Patents

Abstract

PURPOSE:To achieve an extremely safe, handy and accurate measurement of creatinine by preventing the precipitation and setting of a reagent at a low temperature employing a decile sulphate as surface active agent. CONSTITUTION:A reagent comprises an alkali test liquid system, a picric acid test liquid system, an acid solution system and a standard test liquid system. The alkali test liquid system uses, for example, borax and sodium hydroxide or a potassium salt thereof. The picric acid test liquid system uses a sodium salt, a potassium salt, a lithium salt or the like of picric acid and decile sulphate as main component and sodium hydroxide or a potassium salt thereof. The acid solution is preferably an acid material which can make pH acid. For example, acetic acid, chloric acid, sulfuric acid, nitric acid or the like is applicable. The standard test liquid system uses creatinine, chloric acid or the like. In the precipitation of a crystal as preserved by an ice cooling or a refrigerator (for 16 days at 1-3 deg.C below zero), there is no precipitation takes place up to 0-6% in the concentration of a decile sulphate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reagent composition for quantitatively measuring creatinine in body fluids.

Creatinine is produced by non-enzymatic dehydration of creatine phosphate, which is one of the energy sources for muscle contraction, and is not utilized at all in the body and is released into the urine as a final metabolite. Excreted. Therefore, measurement of creatinine provides meaningful information for diagnosing renal disorders such as nephritis and renal failure, muscular dystrophy, and observing the progress of treatment.

A widely used method for measuring creatinine in body fluids is the Yanofue method, which involves a condensation reaction between hylylic acid, an alkaline source, and the active methylene group of creatinine, and the resulting coloration is measured colorimetrically.

However, this measurement method is not specific for creatinine because it is a reaction between picric acid and active methine/creatinine, and other active methylene group-containing substances in serum, such as acetoacetic acid and ochinobutyric acid, exhibit a similar color. It causes a reaction and produces a positive error. Therefore, in order to remove interfering substances such as proteins present in serum, a protein removal operation was required. However, the protein removal procedure is complicated and is not suitable for clinical testing methods that require rapidity.

Therefore, surfactants have come to be used as a method for suppressing interference with proteins and the like without requiring a protein removal operation. Conventionally, as this surfactant, an ionic higher alcohol sulfate ester or a nonionic polyoxyethylene oxide condensation type is used. In particular, lauryl sulfate is widely appreciated, but it has a major disadvantage in that it tends to precipitate and precipitate during low-temperature storage in winter or during measurement, resulting in cloudy reagents.

In view of the above points, the present inventors have investigated various surfactants and have found a stable reagent for measuring reatinine that can solve the conventional drawbacks by using decyl sulfate.
The invention has been completed.

The present invention consists of an alkaline reagent system, a picric acid reagent system, an acidic solution, and a standard reagent system.

As the alkaline reagent system, for example, borax and sodium hydroxide or its potassium salt are used.

The picric acid test solution system uses picric acid, decyl sulfate as main components such as sodium, potassium, or lithium, and sodium hydroxide or its potassium. The acidic solution is preferably an acidic substance that can change the pH to the acidic side. for example,
Use acetic acid, hydrochloric acid, sulfuric acid, nitric acid, etc. The standard test solution system used is Fre1□1 atinine and hydrochloric acid.

According to the present invention, no crystal precipitation is observed at decyl sulfate concentrations of 0 to 6% 1 during water cooling and refrigerator storage (16 days at minus 1°C to 3°C). No crystal precipitation was observed even in a mixed solution of a picric acid test solution and an alkaline test solution at a ratio of 1:1 under similar concentrations and storage conditions.

Under these storage conditions, precipitation is observed in the conventional picric acid test solution system containing lauryl sulfate. Table 1 is a mixture of picric acid test solution and alkaline test solution (measurement solution)
This figure shows a comparison of the presence or absence of precipitation between the concentration of sodium decyl sulfate and the concentration of conventional sodium lauryl sulfate.

The reagent for measuring creatinine of the present invention prevents precipitation and precipitation of the reagent in low temperature conditions in winter compared to conventional reagent systems using lauryl sulfate, and enables extremely safe, simple, and accurate measurement of creatinine. This is what we provide.

The present invention will be explained below with reference to Examples.

Example 1 (1) Preparation of reagent ■ Creatinine alkaline test solution (hydroxide at 8.35 F in about 800rnt water) IJ
Add and dissolve 22.06F borax and adjust the total volume to 1,000ml with water.

■ Creatinine picric acid test solution: 1.06 f sodium hydroxide and 7
．． Add and dissolve 10 f picric acid, then 25,0
Decyl sulfate of f) Add IJium and bring the total amount up to 1. Adjust to OOO-.

■ Creatinine acidic solution Dissolve 8001 nl of glacial acetic acid in 1.000ml of water.

■, creatinine standard solution 0.05 f creatinine concentration in water of about 800 - acid 9
．． Dissolve 0- and adjust the total amount to 1.000- with water.

(2) Measurement procedure ■ When using as a measurement reagent, mix creatinine alkaline test solution and creatinine picric acid test solution at a ratio of 1.1.

■ Put serum or 10-fold diluted urine (24
(use hourly urine), 0.2-liter of diluted water, and a standard solution as a reagent blank. Next, add measurement reagent solution 3.0-
Add, mix and leave at room temperature for 30-35 minutes. After standing, read the absorbance of the sample (1) and the standard solution at 510-m using the reagent blank as a control, and return the sample and reagent blank to the test tube. Within 30 minutes after reading the absorbance, add 3 drops of creatinine acetic acid test solution, mix and leave at room temperature for 10 minutes. After standing, 510-L was added using the reagent blank as a control.
The absorbance of the specimen (II) is measured within 50 minutes at m. Then, calculate the creatinine concentration using the following formula.

formula〉

[Brief explanation of the drawing]

FIG. 1 is a graph showing the correlation between the reagent of the present invention and the reagent of the conventional method. Patent applicant: Gino Test Institute Co., Ltd. Kaihe - Test 4

Claims (1)

[Claims] A reagent composition for measuring creatinine in body fluids, characterized in that a decyl sulfate is used as a surfactant in a reagent system consisting of an alkaline reagent system, a picric acid reagent system, and an acidic solution.