A method of manufacturing indicator paper for detection and determination of active chlorine

 

(57) Abstract:

The inventive method comprises applying to the paper a 2.5 5% aqueous solution of ethylenediaminetetraacetate sodium, followed by drying at room temperature, application of a 0.05 to 0.1% solution of diacetone Michler in acetone and drying the surface at room temperature. table 4.

The invention relates to the field of analyzing materials by determining their chemical properties, in particular for the qualitative and semiquantitative determination of the content of active chlorine in the water.

The closest in technical essence is a method of manufacturing indicator paper for detection and determination of active chlorine, including the application not paper solution thioketone Michler in an organic solvent and subsequent drying.

However, the sensitivity and expressnet determine if the use of such paper is not high enough.

The purpose of the invention to provide indicator paper and with high sensitivity and expressnet definition.

This objective is achieved in that in the method of manufacturing indicator paper for the detection and semiquantitative determination is to Umag and subsequent drying, according to the invention, the paper is treated with 2.5 to 5% aqueous solution of sodium ethylenediaminetetraacetate (Na-EDTA), dried at room temperature, and then impregnated with 0.05 to 0.1% solution of 4,4-bis-(dimethylamino)thiobenzophenone (thioketone Michler) in acetone and again dried.

Use in the manufacture of the indicator layer thioketone Michler has the potential to significantly increase the sensitivity of the indicator paper to determine in tap water up to 0.1 mg/l of active chlorine. Na-EDTA is used as a pH regulator and a masking agent to eliminate the interfering influence of iron (III), copper (II), manganese (II) and other heavy metals normally present in tap water.

Best results are obtained when the content in solutions of thioketone Michler of 0.05-0.1% Na-EDTA, a 2.5-5.0% As can be seen from the table. 1, upon receipt of the concentration of thioketone Michler up to 0.2 wt. reduced contrast color reaction due to the color changes of indicator paper from yellow to orange-red, which is accompanied by a decrease in detection sensitivity chlorine 0.5 mg/l When the concentration of thioketone Michler less than 0.04% also decreases the sensitivity of the indicator paper to chlorine due to the lack of registrator and its sensitivity to chlorine. However, in the presence of up to 5 mg/l iron (III), 10 mg/l copper (II) and manganese (II) at low concentrations of Na-EDTA ions of these metals react with thioketones Michler, and the color of the indicator paper varies from yellow to orange-red and red-violet, which leads to a reduction of sensitivity in the determination of chlorine. Preliminary impregnation of the paper with a solution of Na-EDTA with a concentration in the range of 2.5-7% excludes the impact of these metals on the determination of free chlorine.

However, when increasing the concentration of Na-EDTA to 6-7% significantly deteriorates the mechanical properties of the indicator paper, because of the formation of crystals of Na-EDTA on paper it becomes brittle. Therefore, to handle the paper with a solution of Na-EDTA selected concentration in the range of 2.5-5% This concentration of EDTA allows you to completely eliminate the influence of heavy metals and to achieve high sensitivity in the determination of chlorine.

To date, according to the case-finding is not known indicator of similar composition with high sensitivity relative to the active chlorine level MPC (0.3 mg/l). Based on this we can assume that the proposed solution has a significant difference from sweets is they are preparing 2,5-5% solution of Na-EDTA, which impregnate sheets of filter paper and dried them at room temperature. Then these sheets impregnated with 0.05 to 0.1% solution thioketone Michler in acetone and dried at room temperature.

Below are examples of the method of manufacture of the indicator.

Dissolved in 50 ml of distilled water to 1.25 g Na-EDTA, and the resulting solution is impregnated with a strip of filter paper with a length of 10-15 and 3 cm wide Paper strip is dried in air at room temperature and treated them 0,05% solution of diacetone Michler in acetone and again dried at room temperature. Resulting bands stored in a dry and dark place.

Other examples of the method of manufacture of the indicator are given in table. 1.

Determination of active chlorine. For the detection of active chlorine on indicator paper size 1,5x3,0 cm put a drop of water. When a drop of the solution with a volume of 0.03 ml of 0.003 g or more of active chlorine for 2-5s on a yellow background appears depending on the chlorine content of the blue ring or spot that the colour intensity of which depends on the amount of chlorine in the straw.

When polukolichestvennogo, prepared by depositing on the indicator paper freshly prepared solutions of chloramine-T with concentrations of 0.1-5 mg/l chlorine or 0.003-0,150 mcg per drop volume of 0.03 ml

Data metrological evaluation of the results of the semiquantitative determination of chlorine in solutions of chloramine T are given in table. 2. To obtain these results on the test paper was applied 1 drop of a solution of chloramine T and to estimate the concentration of chlorine using the scale proposed observers.

As can be seen from this table, the proposed indicator paper enables reliability sufficient to polaco - quantitative method to determine the 0.1-3.0 mg of chlorine in 1 l of water.

The correctness of the results of the semiquantitative determination of residual chlorine in tap water using the proposed indicator carried out using iodometric titration in accordance with GOST 18180-72 "drinking Water. Methods for determination of residual chlorine". The corresponding results are given in table. 3. As can be seen from the table, the results of determination of chlorine in water using the proposed indicator and using the standard iodometric method satisfactorily match and indicate the reliability of the PE the time. The relevant data are given in table. 4.

As can be seen from the table, indicator paper does not lose sensitivity to active chlorine, at least for 3 months. from the date of manufacture.

Data tables of the performed tests show that the proposed solution improves the overall sensitivity of active chlorine and provides for the determination of trace amounts of active chlorine in water to 0.1 mg/l, significantly increased the speed of the determination of chlorine to 2-5 C. Indicator is characterized by high selectivity, as resolved preventing influence of iron, copper, manganese and other heavy metals present in tap water. The resulting indicator is stable when stored in a dark place.

Thus, the method provides a limit of detection of residual chlorine in tap water, regulated by the sanitary norms (0.3 mg/l) at higher speed.

A METHOD of MANUFACTURING INDICATOR PAPER FOR detection AND DETERMINATION of ACTIVE CHLORINE, including drawing on paper solution thioketone Michler in an organic solvent and subsequent drying, characterized in that the organic solvent Espana Michler on paper cause 2,5 5% aqueous solution of sodium ethylenediaminetetraacetate and dried, both drying is carried out at room temperature.

 

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6 cl, 15 dwg, 1 tbl, 5 ex

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