JPS59168355A - Analysis of ammonia and apparatus therefor - Google Patents

Abstract

PURPOSE:To perform high-precision ammonia analysis by means of neutralizing titration, by dosing a constant quantity of sample, dropping a titrating agent in a titrating vessel with aqitation to detect a PH value and measure a titrating quantity at a neutralizing point. CONSTITUTION:A sample is provided by a sampling pump 1, and the sample is allowed to flow into a sample dosing valve 3 through a sample dosing controller 4 with an electromagnet placed in ''ON'' position and later, an electromagnet 2' is placed in ''ON'' position and the magnet 2 switched to ''OFF''. Thus, a constant quantity of sample liquid is transported to a titrating vessel 8 under air pressure from an air pump 18. While a dH value of sample liquid is measured with a dH meter 11 through a pH electrode 12, HCl solution 10 of known concentration is dropped into a titrating vessel 8 by a pump 9 and at the same time, the liquid is stirred by blowing in air from the air supply pump 18. The dH value and titrating quantity of HCl solution 10 are delivered to a micro-computer 15 and after computation of ammonia concentration, the value is displayed on a display unit 16.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to ammonia analysis in which ammonium ions in a sample solution are measured by neutralization titration using a pH meter. The present invention relates to an analytical method and apparatus.

[Background of the Invention] In conventional ammonia analysis, the ion electrode method is widely used because it has few interfering components and has a quick response. However, in the ion electrode method, the intercept of the calibration curve differs due to changes in the electrode diaphragm, the electrode internal liquid, etc., and the apparent ammonia concentration changes, requiring calibration with a standard solution each time. Further, the ion electrode method can perform measurement using the Nernst relationship shown in the following equation (1).

T E"'Eo -2,303-1ogaN1(3----
-Curved surface, ,', , (11F As can be seen from the above relational expression, there is a logarithmic relationship between the ammonia concentration and the potential (mV) of the measurement system.

In other words, the measurement accuracy of the ion electrode method is determined by how precisely the potential of the measurement system is measured. However, the potential of the diaphragm-type ammonium ion electrode changes depending on the membrane condition of the diaphragm, deterioration of the electrode internal solution, etc., so it is theoretically difficult to measure the potential of the measurement system with high precision.

[Purpose of the invention]

An object of the present invention is to provide an ammonia analysis method and an apparatus for performing in-line highly accurate analysis of ammonium ions in an aqueous solution by neutralization titration.

[Summary of the invention]

In the ammonia analysis method of the present invention for the above-mentioned purpose, a fixed amount of sample liquid is taken out by a sample/separation unit controlled by switching between two electromagnets, and titration is carried out while stirring the sample liquid 1 in a titration container. The pH is detected while dropping the reagent, and the ammonia concentration is determined from the titration at the neutralization point. In this case, the sample is preferably stirred by air bubbling, and the titration reagent is preferably a hydrochloric acid solution of known concentration.

The ammonia analyzer for the method of the present invention is an ammonia analyzer for measuring ammonia nitrogen in an aqueous solution, and includes a sample collection pump, an electromagnet for dispensing a fixed amount of sample liquid, and a sample dispensing valve. Preparation section, air supply pump to feed the sample solution into the titration container and to constantly stir air by bubbling air during titration, to adjust the sample solution to pH
An ammonia concentration measuring section consisting of a reagent supply pump for dripping reagent acid while measuring with an electrode, a microcomputer that calculates the ammonia concentration from the measurement results of the above-mentioned one measuring section, and a display device that outputs the analysis results. It is something to be prepared for.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
This will be explained in more detail.

First, the principle of measuring ammonia concentration using the neutralization titration method according to the present invention will be described, and then explained with reference to a schematic diagram showing a specific example of the configuration of the ammonia analyzer according to the present invention.

The following description will be made with reference to the graph of FIG. 1 showing the change in pH with respect to the titration of hydrochloric acid in an aqueous ammonia solution in the present invention. In FIG. 1, titration curves a and b are obtained when aqueous solutions with ammonia contents of 30 and 32 μg were titrated with (1+2) HCt, respectively. In this titration curve a, p when titrating 365μ of hydrochloric acid
H is changing rapidly. In other words, it is shown that the correct neutralization point can be determined with high precision by measuring the change in pH. Note that this also applies to titration curves with increased ammonia content.

The relationship between ammonia concentration and hydrochloric acid titer in the present invention will be explained with reference to the graph in FIG. 2.

In Figure 2, the horizontal axis represents the titration amount at the neutralization point (pH-7) when 1 mA of a sample containing ammonia is accurately taken out and titrated with (1+2)HCt, and the ammonia concentration The graph shows professional and sorted graphs on the vertical axis. As shown in the graph, the correlation was very good, and the experimentally determined correlation coefficient (γ) was 0998.

FIG. 3 is a schematic diagram showing the basic configuration of an apparatus according to an embodiment of the present invention having an ammonia concentration monitor based on the above concentration measurement principle.

The sample liquid is sampled by the sample pump 1, and the electromagnet 2 is turned ON (the electromagnet 2' is OFF) by the sample separation controller 4 in the sample separation section shown by the constant chain line
) in the sample separation valve 3, then the electromagnet 2'
Turn on the electromagnet 2 and turn off the electromagnet 2. By switching, a certain amount of the sample liquid in the sample separation valve 3 is swept away by the air sent by the air supply pump 18 and sent into the titration container 8. P
While measuring the electromotive force generated at the H electrode 12 with the pH meter 11 in the ammonia concentration measuring section 13 shown by the dashed line, a reagent, here a hydrochloric acid solution 10 of known concentration, is fed into the titration container 8 using a reagent supply pump. drip inside. At this time, the air supply pump 1
The sample liquid is constantly stirred by bubbling the air sent in by step 8 into the sample liquid. During the titration, the pH value output by the pH meter 11 and the amount of hydrochloric acid 10 dropped are sent to the microcomputer 15, and the ammonia concentration in the sample solution is determined from the relationship shown in FIG. 2 and output to the display device 16. . After the output, the sample liquid in the titration container is flowed out using the three-way solenoid valve 14, and then the three-way solenoid valve 7
is opened to the pure water supply pump 5 side, and the pure water supply pump 5 pours pure water 6 into the titration container 8 to wash the inside of the titration container. After washing, sample liquid is again collected using the sample collection pump 1.

By repeating this series, the ammonia concentration in the sample liquid can be analyzed with high precision.

〔Effect of the invention〕

As explained above, according to the present invention, unlike the conventional ion electrode method, there is no need to calibrate with a standard solution for each measurement, and slight deterioration of the pH electrode is almost no problem. It also enables maintenance-free analysis over long periods of time. Also,
Measurement accuracy is improved by more than an order of magnitude compared to the conventional ion electrode method.
It is capable of analyzing a large number of sample liquids in a short time with high accuracy of about 0.1%. When I experimented with ammonia-based hydrogen peroxide cleaning solution in semiconductor process, I found that 3.
It was 0 seconds.

[Brief explanation of drawings]

FIG. 1 is a graph showing an ammonia neutralization titration curve for explaining the principle of measuring ammonia concentration according to the present invention. FIG. 2 is a graph showing changes in the titer of hydrochloric acid with respect to ammonia concentration for explaining the principle of measuring ammonia concentration according to the present invention. FIG. 3 is a schematic diagram showing the basic configuration of an apparatus for explaining ammonia analysis in an embodiment of the present invention. Sample sampling pump 2, 2'... Electromagnet 3... Sample sampling valve 4. Sample separation controller 5/pure water supply pump
6... Pure water 7... Three-way solenoid valve 8... Titration container 9... Reagent supply pump 10... Reagent 11... pH meter 12. pH electrode 13... Ammonia concentration measuring section 14. ... Three-way solenoid valve 15 ... Microcomputer 16 ... Display device 17 ... Sample separation section 1
8... Air supply pump agent Junnosuke Nakamura 1Pl Figure (++2) Hc, + <μl)
Figure 2 Spear Figure 3

Claims (2)

[Claims] (1) A fixed amount of sample liquid is taken out by a sample separation unit controlled by switching between two electromagnets, and while stirring in a titration container,
An ammonia analysis method characterized by detecting pH changes while dropping a titration reagent and determining ammonia concentration from the titration amount at the neutralization point. (2) A sample collection unit consisting of a sample collection pump, an electromagnet for taking a fixed amount of sample liquid, and a sample separation valve.The sample liquid is fed into the titration container and constantly stirred by bubbling air during titration. Air supply pump to supply sample liquid to p
Equipped with an ammonia concentration measuring section consisting of a reagent supply pump for dripping a reagent while measuring with an H electrode, a microcomputer that calculates the ammonia concentration from the measurement results of the measuring section, and a display device that outputs the analysis results. An ammonia analyzer characterized by: