CZ65697A3 - Steam sterilization indicator - Google Patents

Abstract

The solution relates to the composition of the indicator for control steam sterilization based on flexographic printing ink. The indicator is based on the fact that during . The process of steam sterilization will result in decomposition present of a carboxylic acid, thereby changing the pH and consequently coloring the pH indicator.

Description

Technical field

The subject of the invention is an indicator for steam sterilization control prepared in the form of a flake ink. Steam sterilization is a widely used type of sterilization of both medical and medical materials. aids for veterinary purposes and for laboratories where sterile instruments are used. Following the introduction of paper and combined steam sterilization bags, the need for clear visual control of this process has increased. The introduction of steam sterilization indicators addresses this need.

The general principle of all indicators of steam sterilization is that when the conditions necessary for the termination of steam sterilization (time, temperature, steam) are fulfilled, they will change irreversibly. In most cases, only so-called process indicators of steam sterilization are used, which change color a little before the time required for complete sterilization of the submitted material expires. These indicators are only intended to demonstrate that the labeled material has undergone a sterilization process at the desired temperature and humidity. The method of application of the indicator is a varied mixture of techniques depending on the possibilities of the manufacturer of bags for steam sterilization.

The indicator object of the invention changes the shade from light to dark shades during the steam sterilization process as a function of time. It is the above-mentioned process indicator of steam sterilization. Depending on the intensity of the color transition, it can be inferred from the time that the marked object was subjected to steam sterilization. However, the intensity of the color transition is completely reproducible and this change can reliably control the progress of the sterilization process, ΰ

BACKGROUND OF THE INVENTION

The indicators used so far, which utilized the reaction of lead carbonate with sulfur to form black lead sulphide, appear to be imperfect on several sides. This composition, which is applied in the form of flexographic ink, has many drawbacks. Due to their inhomogeneity, the active ingredients sediment unevenly over time and therefore the indicator does not show reproducible color changes. In addition, the use of lead salts is unsatisfactory in terms of hygiene.

The replacement of lead salts with copper salts (Japanese Patent No. 61,287,972, British Patent No. 145,855) only partially addresses the problem. Although the indicator is hygienically safe and sedimentes only slightly during application, the suspension is not completely stable and its properties change.

The solution can be found in the use of a mixture of organic acids and pH indicators, in which the organic acid decomposes during sterilization, thereby shifting pH values. No. 3,862,824 and EPA Patent No. 405,420. However, said patents have drawbacks both in the use of a type of pH indicator which does not exactly cover the pH change region and in the method of applying the indicator to the desired substrate.

The present invention proposes a comprehensive solution for both color transfer during the steam sterilization process and a method of applying the indicator to a paper substrate by means of a flexographic printing plate, which allows an automated method of producing both steam sterilization bags and self-adhesive labels used to seal bulkier sterilized material packages.

SUMMARY OF THE INVENTION

The steam sterilization control prepared by the proposed process is mixed from several components - an organic carboxylic acid that is subject to decomposition under the conditions of steam sterilization, a pH indicator, a filler, organic solvents and an alkali to adjust the color transition brilliance during steam sterilization. In addition, the indicator may contain other color components that adjust the saturation of the printed color.

The basic active ingredient of the indicator is carboxylic acid, which decomposes according to the following scheme during the steam sterilization process:

R-COOH -----------> RH + CO

Suitable carboxylic acids include 2,4-diliydroxybenzoic acid, 2,6-diliydroxybenzoic acid, phenylpropionic acid, trinitrobenzoic acid. The indicator may comprise one of the aforementioned acids or a mixture thereof. Under certain conditions, it is also possible to use salts of the above-mentioned carboxylic acids - calcium, sodium, potassium, zinc, copper, etc.

Useful pH indicators are those that exhibit a color transition in the range of pi 15 to 10. These indicators include Bronicresol green, Bromocresol purple, Biomthymol blue, Phenophthalein, Methyl red, etc. Indicators can also be combined depending on the color shades for case desirable. However, the general principle is that it should be a transition from light to dark.

| The presence of a polymeric filler dissolved in a suitable organic solvent is necessary to fill the second component of the indicator functionality, i.e. good printing on paper. Ethylcellulose, nitrocellulose, vinyl acetate lacetate, polyvinyl chloride-polyvinyl acetate copolymer etc. are most commonly used as fillers. Acetone, ethanol can be used as the organic solvent. ethyl acetate, methyl ethyl ketone, tetrahydrofuranfuryl alcohol, toluene, etc. Organic solvents are mostly used in a mixture. Preference is given to those mixtures which contain ethanol.

The indicator paint also contains alkali in the form of sodium or potassium hydroxide. Their presence is necessary in terms of color transition speed. The molar ratio of alkali to carboxyl group ranges from 0.5: 1 to 1.8: 1. A ratio of 0.8: 1 to 1.7: 1 is preferred. The exact alkali content is determined only on the basis of the type of paper used, whether or not another color component is added which affects the pH of the mixture and depending on the type of carboxylic acid used. Generally, as the alkali content increases, the color change of the indicator is accelerated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Paper for steam sterilization pouches was used for testing.

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Example 1

0.2 wt. parts of 2,4-dihydroxy benzoic acid are dissolved in 1.5 wt. 0.75 vol. of methyl red solution (concentration - 0.2% in 60% ethanol) and 0.75 vol. of bromocresol green solution (concentration - 0.04% in water) were added. The mixture is mixed with 2 wt. parts by weight of ethylcellulose solution (concentration 5% in a mixture of ethanol and ethyl acetate) and 0.15 wt. parts by weight of NaOH solution (concentration - 5 wet). It receives a clear yellow solution which is printed on paper. After drying, the print has an ocher color which turns yellow-green after steam sterilization (temperature - 121 ° C, time - 20 minutes).

Example 2

0.2 wt. parts of 2,4-dihydroxybenzoic acid are dissolved in 1.5 wt. 1 part by volume of phenolphthalein solution (concentration - 0.1% in 70% ethanol) is added. The mixture is mixed with 2.5 wt. parts by volume of ethylcellulose solution (concentration - 5% in a mixture of ethanol and ethyl acetate) and 0.2 parts by volume of NaOH solution (concentration - 5 could). The slightly red solution is printed on paper. A virtually colorless print is obtained, which is placed in an autoclave with steam at a temperature of 121 ° C for various periods of time. The results of this experiment are summarized in the following table.

sterilization time (min) shade 0 colorless 1 slightly yellowish 3 orange 5 slightly reddish brown 10 russet 20 May deep reddish brown

Example 3

In mixture 20 lim. parts of ethyl acetate and 70 wt. 1.9 parts by weight of 2,4-dihydroxybenzoic acid, 0.1 parts by weight of ethanol are dissolved; parts of phenolphthalein and 5 wt. parts of ethylcellulose. To the mixtures were added 2 parts by volume of yellow alcohol for flexographic printing and 2.1 parts by volume of NaOH solution (concentration -10 mol Γ '). A brownish solution is obtained, which is printed on a paper in the form of a faint yellow but well noticeable print which, after passing through the steam sterilization process, is colored as follows: at 121 ° C after 20 minutes - reddish brown .

Research Institute of Organic Syntheses Joint Stock Company 53218 PARDUBICE - FISHING PATENTS AND NORMALIZATION

Claims (4)

PATENT CLAIMS 1. An indicator for the control of steam sterilization based on flexographic printing ink, which consists of one. or several carboxylic acids which decompose during the sterilization process in a pH indicator. fillers, alkali and mixtures of organic solvents. Steam sterilization control indicator according to claim 1, characterized in that the pH indicator has a color transition from light to dark shades between pH values of 5 to 10. Steam sterilization control indicator according to claim 1, characterized in that the filler consists of cellulose esters or ethers, vinyl alcohol pole esters or mixtures or copolymers thereof. The steam sterilization control indicator according to claim 1, wherein the molar ratio between the alkali and carboxylic acids present is in the range of 0.5 to 1.8: 1.