JPH01320461A - Reagent for analyzing ammonia - Google Patents

Abstract

PURPOSE:To determine NH3 in sea water with high accuracy by incorporating trans-1, 2-cyclohexadiamine-N, N, N', N'-tetraacetic acid-hydrate (CyDTA) into the reagent. CONSTITUTION:This reagent is formed of the combination of an aq. alkaline soln. contg. CyDTA (the soln. prepd. by dissolving 15g CyDTA, 5g NaOH and 5g Na2CO3 into 10<3>ml pure water), aq. nitroprusside soln. (the soln. prepd. by dissolving 0.6g Na2[Fe(CN)5NO]2H2O into 10<3>ml pure water), an aq. alkaline phenol soln. (the soln. prepd. by dissolving 95g phenol and 38g NaOH into 10<3>ml pure water), and aq. NaCHlO soln. (the soln. prepd. by dissolving about 150ml NaCHlO into 10<3>ml rate water and usually used by being maintained at about 1.5% effective chlorine content). The measured value having good reliability is thus obtd. without indicating the negative measured value and without being affected by the chemicals to be used (particularly alkaline concn.) and Mg ions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an analytical reagent useful for colorimetric analysis of ammonia in water, particularly ammonia in seawater.

[Conventional technology]

Conventionally, the indophenol method has been used to quantify ammonia in seawater. This quantitative method is based on the colorimetric determination of the color reaction between indophenol (N-Cp-oxyphenyl)-p-quinoneimine) and nitroprusid produced by the reaction of the following formula.

The complex reagent used at this time is an aqueous solution in which about 20 g each of sodium potassium tartrate and sodium citrate and about 0.2 g of nitroprusid are dissolved in 10100 O water, and about 130 g of alkaline phenol.
It consists of an aqueous solution containing 10,100 O dissolved in water and an aqueous hypochlorous acid solution containing about 1.5% available chlorine.

For measurement, add and mix the mixed reagent to the sample, then add and mix alkali phenol, then add and mix sodium hypochlorite, heat to about 45°C, and measure the color of the formed indophenol using 630 nm colorimetry. It is something to do.

According to the findings of the present inventors, ammonia can be quantified using the method described above with good reproducibility in samples with a relatively high ammonia content, but in cases where the concentration is extremely low, such as in open ocean water. The reliability decreased, and when using an automatic analyzer or the like, the measured values often showed lower values than the target values for paper water. This finding is a phenomenon that has been recognized due to improved accuracy due to improvements in automated analyzers and technology.

[Problem to be solved by the invention]

The present invention aims to solve the above-mentioned problems of the prior art, particularly to search for the causes of negative values in measurement results and to solve them.

[Means for Solving the Problems] The above-mentioned problems of the present invention are to provide an alkaline aqueous solution containing trans-1,2-cyclohexanediamine-N, N, N', N'-tetraacetic acid monohydrate, nitroprusside. This is achieved by employing a reagent for the colorimetric analysis of ammonia in water consisting of a combination of an aqueous sodium solution, an aqueous alkaline phenol solution and an aqueous sodium hypochlorite solution.

The preparation of the reagent for colorimetric analysis of the present invention used to solve the above-mentioned problems will be described below, but the concentration of the reagent in each prepared aqueous solution may be varied depending on, for example, the automatic analyzer used, the liquid to be measured, etc. Furthermore, the chemicals to be added are not limited to those described below; for example, it is possible to add chemicals such as fungicides or other color development aids for the purpose of preserving the prepared aqueous solution. There are no restrictions whatsoever.

In the present invention, the alkaline aqueous solution containing trans-1,2-cyclohexanediamine-N, N, N', N'-tetraacetic acid monohydrate (hereinafter abbreviated as CyDTA) is
For example, it can be obtained by dissolving 15 g of CyDTA, 5 g of sodium hydroxide, and 5 g of sodium carbonate in 10100 O pure water.

As the CyDTA used in this case, those that are normally available as commercial products can be used.

Nitroprusid aqueous solution is Na2 [Fe (CN
)s No] 0.6g of 2Hz O in pure water 10100O
Obtained by dissolving in.

The CyDTA aqueous solution and the nitroprusid aqueous solution are usually stored, and prior to use, for example, the former one is
60 mj of the latter and 40 ml of the latter.

The alkaline phenol aqueous solution is obtained by dissolving 95 g of phenol and 38 g of sodium hydroxide in 100ml of pure water.

A sodium hypochlorite aqueous solution is obtained by dissolving about 150a+j of sodium hypochlorite in 10100O pure water, and is usually used with the amount of available chlorine maintained at about 1.5%.

When quantifying ammonia in seawater by the indophenol method using the colorimetric reagent of the present invention, the addition order of each reagent can be carried out in the same manner as in the conventional case described above, and the CyDTA reagent can be added to the sample. After mixing, add and mix an aqueous alkali phenol solution, further add and mix an aqueous sodium hypochlorite solution, heat to 40°C to 55°C to complete the color reaction, and then perform colorimetric measurement at a measurement wavelength of 630 nm. .

Although it is preferable to use an automatic analyzer as the means for colorimetric measurement, there will be no problem even if the measurement is carried out non-automatically.

The amount of complex reagents and other reagent aqueous solutions to be used is as follows:
Although it differs depending on the target sample and reagent concentration, for example, Plan Loupe Co., Ltd.'s TRAA is an automatic analyzer.
Flow diagram 1 when using C3-800
An example is shown in FIG. In the figure, 5T
indicates a 5-turn coil, and HT indicates heating bath 2.
3ml capacity is shown. FC indicates a 30 mm long flow cell with a 0.5 mm inner diameter.

As detailed above, the reagent for colorimetric analysis of ammonia in water, especially seawater, which is made of the combination of the specified aqueous drug solution of the present invention, is a reagent for colorimetric analysis of ammonia in water, especially seawater. It can be put to practical use by a method similar to the method.

[Function] The reagent for colorimetric analysis of ammonia in water of the present invention is trans-1,2-cyclohexanediamine-N, N, N
By including ', N'-tetraacetic acid monohydrate, conventionally,
There is no negative measurement value observed in the measurement of samples containing low concentrations of ammonia such as open ocean water, the measurement value is not affected by the chemicals used, especially the alkaline concentration, and the magnesium ion contained in seawater is not affected. Reliable measurement values can be obtained without being affected by

[Example] The effectiveness of the colorimetric reagent of the present invention will be explained in more detail below using Examples and Reference Examples.

Reference Example 1 A colorimetric analysis of ammonia in seawater was performed using reagents used in the conventional indophenol method.

The analytical reagent is a complex reagent in which 24g of sodium potassium tartrate, 18g of sodium citrate, and 0.2g of sodium nitroprusside are dissolved in 10100O pure water: 95g of phenol, 38g of sodium hydroxide.
An aqueous alkali phenol solution prepared by dissolving 100 On+1 in pure water: An aqueous sodium hypochlorite solution in which the effective chlorine concentration was maintained at 1.5% was used.

The above-mentioned TRA ACS-800 automatic analyzer was used for the measurement, and the addition order and amount of reagents were performed according to the flow diagram shown in FIG.

Seawater samples in this experiment were collected from three locations. Also,
The standard solution was (NHa)2 with a concentration of 10 μmol N/β.
Colorimetry was performed using an SO4 aqueous solution at a measurement wavelength of 630 nm. The experimental results under these conditions are shown in Table 1.

Table 1 Reference Example 2 In the experiment of Reference Example 1, the amount of alkali added to the alkaline phenol aqueous solution was changed as shown in Table 2, and magnesium chloride was added to investigate the influence of magnesium ions contained in seawater. The concentrations were adjusted to the concentrations shown in Table 2, and seawater containing low concentrations of ammonia was also tested as one sample. The results are shown in Table 2.

As is clear from the results in the table above, when using conventional reagents, it was observed that the measured values varied significantly depending on the amount of alkali in the alkali phenol and the presence of magnesium ions.

Example 1 The reagent for analysis was tested using the reagent of the present invention instead of the conventional reagent of Reference Example 1. The analytical reagent was CyDTA alkaline aqueous solution: Nitro Sodium nitroprusside aqueous solution prepared by dissolving 0.6g of sodium prusside in 10100O pure water: Phenol 9
An alkaline phenol aqueous solution in which 5 g and sodium hydroxide 38 g were dissolved in 10100 O pure water: and a sodium hypochlorite aqueous solution with an available chlorine content of 1.5% were prepared.

The CyDTA aqueous solution was adjusted to pH 10 with concentrated hydrochloric acid,
Prior to use, 160 ml of C3/DTA aqueous solution and 40 ml of sodium nitroprusside aqueous solution were mixed and used as a CyDTA reagent.

The measurement was carried out in the same manner as in Reference Example 1. Table 3 shows the test results conducted on the same seawater sample used in Reference Example 1.

Table 3 Example 2 Tests were conducted in the same manner as in Reference Example 2 except that the reagent of the present invention used in Example 1 was used in place of the conventional reagent in the experiment of Reference Example 2. The test results are shown in Table 4.

As is clear from the results in the above table, when using the reagent of the present invention, the influence of the amount of alkali in the alkaline phenol and the presence of maglucium ions is almost negligible, especially when seawater is used as the target. It was confirmed that reliable results were obtained.

Reference Example 3 A test was conducted using an aqueous solution of ethylenediaminetetraacetic acid in place of the reagent of the present invention. The analytical reagent was 20 g of disodium ethylenediaminetetraacetate (EDTA>2Na).
and 0.2 g of sodium nitroprusside to 1010
Complex reagent dissolved in 0O pure water: 95g of phenol and 38g of sodium hydroxide at 1000a+1
Aqueous solution of alkaline phenol dissolved in pure water: An aqueous solution of sodium hypochlorite kept at an effective chlorine concentration of 1.5% was prepared. The measurements were carried out in the same manner as in Reference Example 2, and the results are shown in Table 5.

[Effects of the Invention] As is clear from the comparison between Tables 1 and 2 and Tables 3 and 4, fluctuations in measured values when using conventional reagents have been eliminated by employing the analytical reagent of the present invention. Results with good reproducibility were obtained, and as shown in the results of Reference Example 3, it is shown that the purpose of the present invention cannot be achieved by using a general chelate compound.

[Brief explanation of the drawing]

FIG. 1 is an example of a flow diagram when measuring with an automatic analyzer using the analytical reagent of the present invention. Procedural amendment (voluntary) July 22, 1988

Claims (1)

[Claims] (1) trans-1,2-cyclohexanediamine-N
, N,N',N'-tetraacetic acid-hydrate, a sodium nitroprusside aqueous solution, an alkaline phenol aqueous solution and a sodium hypochlorite aqueous solution.