JPH0961416A - Quantification of lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantify lead while removing a destructing component by utilizing the complex forming capacity of a metal component and a complex forming agent and the difference between the complex forming capacity and the distribution with an ion exchange range in pretreatment. SOLUTION: A complex forming agent is added to a sample soln. and the pH of the sample soln. is adjusted to 5-9 by alkali or aid and this sample soln. is passed through an ion exchange resin to hold lead on the ion exchange resin. A washing soln. prepared by adding the complex forming agent to purified water and adjusted to pH5-9 is passed through an ion exchange resin to remove an obstructing component. Next, dilute sulfuric acid or nitric acid is passed through the ion exchange resin to elute lead. Lead in the obtained eluted soln. is measured. As the complex forming agent, citric acid or malonic acid is pref. and the concn. of citric acid or malonic acid in the soln. passed through the ion exchange resin depends on the amt. or flow velocity of the sample soln. through the ion exchange resin or ion exchange capacity of the resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a simple lead quantification method for quantifying lead in a sample solution using an absorptiometer.

[0002]

2. Description of the Related Art Lead, which is a harmful substance, has a drainage standard regulated to 0.1 mg / l. Therefore, for factories or business establishments that have facilities that may emit lead, it is obligatory to manage the drainage so as not to exceed the above lead discharge standards. Therefore, it is necessary to quantify lead in wastewater at these factories or business establishments.

When it is necessary to report the analysis value to a public institution, the lead quantification method is a method of verification concerning the effluent standards established by the Director General of the Environment Agency based on the provisions of the Prime Minister's Ordinance which establishes the effluent standards, that is, the official approval. Must be done according to law. Specifically, flame atomic absorption spectrometry, electric heating atomic absorption spectrometry, ICP
It is necessary to quantify lead by either an emission spectrometry method or an ICP mass spectrometry method.

These official methods require that the analyzer used is expensive, it is necessary to secure an installation place having a local exhaust facility in the analyzer, and human resources having some experience in analysis operation are required. Due to the above reasons, there is a problem that its use is limited.

On the other hand, the lead determination for internal control does not necessarily have to be performed by the official method, and may be a simple analysis method. In that case, if there is no difference between the quantitative value obtained by the adopted method and the quantitative value obtained by the official method, or if the extent of the difference between them can be grasped, the simple analytical method is rather quick and simple. It can be said that this is a preferable method because it is prioritized and the analysis device and the like are inexpensive.

[0006] In order to meet the requirements of such a simple analysis method, it is necessary that the handling be simple and that the analyzer be inexpensive. As a simple analytical method satisfying these requirements, an absorptiometric method, specifically JIS K 0102 54.1 citizone absorptiometry, porphyrin absorptiometry, and 4-
There is a (2-pyridylazo) -resorcinol (PAR) absorptiometry (hereinafter referred to as PAR absorptiometry).

[0007] In these absorptiometric methods, a water quality measuring kit for simple analysis, in which a coloring reagent and a pH buffer are combined together with the absorptiometer, is commercially available. In the case of PAR absorptiometry, the analysis method is that the color-developing reagent for one measurement and the pH buffer are enclosed in a poly container, so that they are dissolved in a sample solution to cause a color reaction, and an absorptiometer is used. It is used to measure the absorbance.

[0008] However, these absorptiometric methods have no selective coloring reagent for lead, and therefore are affected by components (interfering components) other than lead that react with the coloring reagent, so that wastewater containing a large amount of interfering components is affected. It cannot be applied directly. In order to apply to wastewater containing such interfering components, in its pretreatment,
It is necessary to separate the lead from the interfering components or mask the interfering components.

For this reason, in the dithizone absorptiometry, potassium cyanide is used to mask the interfering components and the lead-dithizone complex is extracted into carbon tetrachloride. Similarly, porphyrin absorptiometry and PAR absorptiometry also use potassium cyanide. That is, when these methods are carried out, there is a problem that carbon tetrachloride or potassium cyanide which is a harmful substance is used in the pretreatment. There is also a method of using an ion chromatograph to separate lead from interfering components without using harmful substances, but there is a problem that this analyzer is expensive.

Furthermore, the PAR absorptiometry method has a lower limit of quantification of 0.2 mg / l, and therefore the lead drainage standard is 0.1 m.
It cannot be directly applied as a method for quantifying lead below g / l. Therefore, in the case of wastewater with low lead concentration, P
In the AR absorptiometry, it is necessary to concentrate lead in the waste water in its pretreatment. The lead can be concentrated by a relatively simple method such as a heating concentration method or a concentration method by precipitation separation, but there is a problem that the interfering components are simultaneously concentrated with the concentration of lead.

[0011]

As described above, there is an absorptiometric method as a simple quantitative analysis method for lead in wastewater, but a harmful substance is used for separation of lead from interfering components, and further lead concentration. In some cases, the method for easily quantifying lead in wastewater using an absorptiometer has not been put into practical use.

In view of the above conventional circumstances, an object of the present invention is to prevent harmfulness in pretreatment when quantifying lead in a sample solution below a lead discharge standard of 0.1 mg / l using an inexpensive absorptiometer. It is an object of the present invention to provide a method for quantifying lead by an absorptiometric method, which can remove interfering components without using a substance or the like and can perform necessary lead concentration.

[0013]

In order to achieve the above object, a method of providing lead provided by the present invention is a method for determining lead by absorptiometry, in which a complexing agent is added to a sample solution and an alkali or an acid is added. PH is adjusted to 5 to 9 by using, and the sample solution is passed through an ion exchange resin to hold lead in the ion exchange resin, and then a complexing agent is added to purified water and an alkali or an acid is used. The washing solution whose pH is adjusted to 5 to 9 is passed through the ion exchange resin to remove interfering components, and then dilute hydrochloric acid or dilute nitric acid is passed through the ion exchange resin to elute lead. It is characterized by measuring lead in the eluate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in a pretreatment for quantifying lead in a sample solution using an absorptiometer, the complex forming ability between a metal component and a complex forming agent and its complex forming ability are described. It utilizes the difference in distribution from ion-exchange resins to separate lead from interfering components.

By adding a complexing agent to the sample solution,
Many of the interfering components in the sample solution form a complex, and lead is adsorbed and held on the ion-exchange resin by utilizing the complex formation ability and the difference in partitioning reaction with the ion-exchange resin. Can be drained as. The complexing agent is a substance having a complexing ability with a metal component, and citric acid or malonic acid is suitable. Citric acid and malonic acid may be salts thereof or alkali salts thereof, and they are used as an aqueous solution.

The concentration of citric acid or malonic acid in the solution passed through the ion exchange resin depends on the amount of the sample solution passed through the resin or the flow rate thereof, or the ion exchange capacity of the resin. However, for example, the ion exchange capacity is 350 μe
As in the case of passing 100 ml of the sample solution at 10 ml per minute through a column packed with 720 mg of ion exchange resin of q / g, its concentration under general processing conditions is preferably 0.1 to 1 g / l. , 0.4 to 0.6 g / l is more preferable. Concentration of citric acid or malonic acid is 0.1g /
If it is less than 1, since the complexing ability is insufficient, the amount of interfering components retained in the ion exchange resin is large, and if it exceeds 1 g / l, the lead is insufficiently retained in the ion exchange resin and lead leaks out. Because.

The pH of the sample solution containing the complexing agent is adjusted to 5-9.
The reason for adjusting to the range of is that when the pH is less than 5, the retention of lead in the ion exchange resin becomes insufficient and a part of it leaks out.
This is because if the pH exceeds 9, the metal components in the sample solution will precipitate as hydroxides, making it difficult to pass through the ion exchange resin. Therefore, adjusting the pH of the sample solution to the range of 5 to 9 is an essential condition for holding lead in the ion exchange resin.

An alkali or an acid is used to adjust the pH.
As the alkali, a water-soluble alkali salt can be used, and for example, sodium hydroxide or potassium hydroxide is suitable. Furthermore, it is desirable to use a solution prepared by dissolving sodium hydroxide or potassium hydroxide in water. As the acid, hydrochloric acid or nitric acid is suitable.

By adding a complexing agent and adjusting the pH of the sample solution to 5 to 9 and passing it through an ion exchange resin, lead is retained in the resin as described above. The flow rate at which the sample solution is passed through the ion-exchange resin is, for example, 0.5 g / l of the concentration of citric acid or malonic acid as a general processing condition.
When passing 100 ml of sample solution, which is 1 to 2 per minute
A range of 0 ml is suitable, more preferably 8-12 ml per minute. This is because if the flow rate of the liquid passing through the ion-exchange resin exceeds 20 ml / min, the lead is insufficiently retained in the resin and lead leaks out. On the contrary, if the flow rate is slow, the treatment takes a long time. .

By this treatment, lead is retained in the ion exchange resin, but some of the interfering components are also retained in the resin at the same time. Therefore, in the method of the present invention, the interfering component retained in the resin is eluted by passing the pH-adjusted cleaning solution by adding a complexing agent to purified water. By performing this washing operation, the only component retained in the ion exchange resin is lead, and it becomes possible to separate lead from interfering components. The adjustment of the washing solution, that is, the type and concentration of the complex-forming agent, the potash and acid used for pH adjustment, the adjustment range of pH, and the like are the same as in the case of the sample solution described above.

The amount of the washing solution necessary for eluting the interfering component from the ion exchange resin depends on the kind of the metal component contained in the sample solution or the concentration thereof. For example, in the case of a column in which a relatively clean sample solution has been passed, a washing solution with a concentration of citric acid or malonic acid of 0.5 g / l is used at 10 m / min.
A small amount of the washing solution may be used when the washing is performed by passing the solution at a flow rate of l. However, in the case of a sample solution containing 1 ml / l of an interfering component such as copper or manganese, it is 150 to 2 under the same flow conditions.
00 ml of wash solution is required.

As a method of passing the sample solution and the washing solution through the ion-exchange resin, for example, a pump for feeding a fixed amount of the sample solution or the washing solution and a column filled with the ion-exchange resin are provided with a corrosion-resistant tube. Use the connected one. In addition, if there are floating substances in the sample solution, it is desirable to remove them in advance.

The lead retained on the ion exchange resin is easily eluted with diluted hydrochloric acid or diluted nitric acid. That is, the retained lead is eluted by passing dilute hydrochloric acid or dilute nitric acid through the ion exchange resin. In particular, by eluting lead with a dilute hydrochloric acid or dilute nitric acid in an amount smaller than the volume of the sample solution containing lead passed through the ion exchange resin, the lead concentration in the eluate is the same as that of the original sample solution. Higher than the concentration, for example 4 ~
It is possible to concentrate lead about 10 times.

Since the lead-containing eluate eluted from the ion-exchange resin in this manner contains almost no interfering components, the porphyrin absorptiometry or PA is used as usual.
Quantitative analysis of lead can be performed using each luminescent reagent by an absorptiometric method such as R absorptiometry.

[0025]

Example 1 Using a standard solution having a lead concentration of 1 g / l, Solution A and Solution B having the compositions shown in Table 1 below were prepared. In these solutions A and B, in addition to the components shown in Table 1, hydrochloric acid, nitric acid, in which lead and other metal components were dissolved when a standard solution was prepared,
And sulfuric acid, etc. are included.

[0026]

[Table 1] Component solution A (mg / l) Solution B (mg / l) Pb 0.1 0.07 Zn 1 1 Ni 1 1 Co 1 1 Mn 1 1 Fe 1 1 Cu 1 1 Mg 5 5 Na 400 400 400 K 50 50 Ca 200 200

To 100 ml of the solution A shown in Table 1 above, 5
1 ml of 5 g / l citric acid solution was added, and the pH was adjusted to 2, 4, 5, 6, using sodium hydroxide solution.
Adjusted to 7, 9 and 10. The concentration of citric acid in each of these sample solutions becomes 0.5 g / l by being diluted.

Two of these sample solutions were directly connected to each other by a liquid-sending pump at a flow rate of 10 ml / min and a weak acid cation exchange resin (trade name: Accell CM) manufactured by Waters Co. The solution was passed through each.

Then, add hydrochloric acid (1
+120) 3 ml and 6 ml of water were passed through, and water was added to the obtained eluate to give 10 ml of a measurement liquid, which was used for quantification of lead. The standard solution for the calibration curve was prepared by adding the same hydrochloric acid. An ICP emission spectroscopic analyzer (SPS120OVR) manufactured by Seiko Instruments Inc. was used for the measurement of lead.

Since the obtained measured value is a value obtained by concentrating 100 ml of the sample solution into 10 ml of the measuring solution 10 times, the value obtained by dividing this measured value by 10 was taken as a quantitative value. The quantitative results obtained are shown in Table 2. From these results, when the pH of the sample solution was in the range of 5 to 9, the lead quantitative value was
It was in good agreement with the lead concentration of.

[0031]

Table 2 pH quantitative value (mg / l) 2 <0.05 4 0.07 5 0.1 6 0.1 0.1 7 0.1 0.1 9 0.1 10 0.08

Example 2 1 ml of a 55 g / l citric acid solution was added to 100 ml of the solution A shown in Table 1 above, and the pH was adjusted to 5.5 using a sodium hydroxide solution. This sample solution was passed through Seppack Plus under the same conditions as in Example 1.

Subsequently, 20 ml of a 55 g / l citric acid solution was added to the purified water, the pH was adjusted to 5.5 using a sodium hydroxide solution, and further purified water was added to bring the total amount to 2
l of washing solution. The wash solution was passed through the sample solution as described above, and then the solution was passed through the Seppak-plus 50, 50, 100, 150, 200, 250 and 30 respectively.
The solution was passed through 0 ml to wash the ion exchange resin.

Hydrochloric acid (1%) was added to each Sepp Plus that was washed as described above and Sepp Plus that was not washed.
+120) 3 ml and 6 ml of water were passed through, and water was added to each of the obtained eluates to make 10 ml to be a measurement liquid. The standard solution for the calibration curve was prepared by adding the same hydrochloric acid. Pb in each measurement solution and Zn, Ni, C which are interfering components
O, Mn, Fe, Cu and Mg were measured using an ICP emission spectrophotometer. For the same reason as in Example 1, the obtained measured value was divided by 10 to give a quantitative value.

The quantitative results are shown in Table 3. Most of the interfering components were eluted in the range of the washing solution flow rate of 150 to 200 ml, and the quantitative value of lead was in good agreement with the concentration of lead in solution A, and lead was almost completely separated from the interfering components. I understand.

[0036]

[Table 3] Cleaning solution Pb interference component (μg / l) Flow rate (ml) (mg / l) Zn Ni Co Mn Fe Cu Cu Mg 0 0.1 82 16 31 31 180 4 370 550 50 0.13 2 <1 65 <1 140 69 100 0.1 1 <1 <1 4 <1 5 4 150 0.1 <1 <1 <1 <1 <1 <1 <1 200 0.1 <1 <1 <1 <1 <1 <1 <1 250 0.09 <1 <1 <1 <1 <1 <1 <1 <1 300 0.08 <1 <1 <1 <1 <1 <1 <1

Example 3 It was confirmed by the above Examples 1 and 2 that only lead can be separated from the interfering components shown in Table 1. Therefore,
Each solution A and B shown in Table 1 was PAR-treated by the method of the present invention.
It was applied to an absorptiometry to quantify lead.

That is, 1 ml of a citric acid solution of 55 g / l was added to 100 ml of each of the solutions A and B shown in Table 1 and the waste water of a factory, and sodium hydroxide solution was used to add p.
Each H was adjusted to 5.5, and used as sample solutions A and B and sample factory wastewater. These sample solutions A and B and the sample factory wastewater were passed through Seppak Plus under the same conditions as in Example 1.

Subsequently, 2 of the cleaning solution prepared in Example 2 was used.
00 ml was passed through each Seppakplus to wash the ion exchange resin. After that, 3 ml of hydrochloric acid (1 + 120) and 6 ml of water were passed through each of these Seppakplus, and water was added to each of the obtained eluates to make 25 ml.
It was used for the determination of lead by an absorptiometer.

That is, PAR (a luminescent reagent or the like) of a water quality test reagent set manufactured by Kyoritsu Institute of Science was dissolved in each of the above-described measurement solutions, and the absorbance of this solution was measured by an absorptiometer (U-2000 manufactured by Hitachi Ltd.). ) Was used for the measurement. The concentration of the obtained absorbance was calculated from the lead calibration curve. The lead concentration is 25 ml of the measurement solution for 100 ml of each sample solution.
The value obtained by dividing this by 4 was used as the quantitative value. The absorbance is measured at a wavelength of 515.6n.
m with a measuring cell of 10 mm.

The quantitative results obtained are shown in Table 4. As can be seen from the results in Table 4, in the quantification of lead in the sample solutions A and B, values in good agreement with those concentrations shown in Table 1 were obtained. The quantitative value of lead in the sample factory wastewater was 0.05 mg / l or less, which is the lower limit of quantitative determination by the absorptiometry (I
Quantitative value by CP mass spectrometry is 0.01 mg / l).

[0042]

[Table 4]

Even when each sample solution was prepared in the same manner as in Example 3 using a malonic acid solution having the same concentration instead of the citric acid solution, the lead content measured by the absorptiometric method according to the method of the present invention was measured. The quantitative values were in good agreement with the concentrations shown in Table 1.

[0044]

According to the present invention, the lead drainage standard is 0.1 m.
Quantitation of lead in the sample solution below g / l can be easily performed using an inexpensive absorptiometer. That is, since lead can be separated from interfering components without using harmful substances in the pretreatment and lead can be concentrated, a simple method using a normal absorptiometric method using a luminescent reagent can be used. Can be used to quantify lead.

Claims (6)

[Claims] 1. In a method for quantifying lead by absorptiometry, a complexing agent is added to a sample solution and the pH is adjusted to 5 to 9 with an alkali or an acid, and the sample solution is passed through an ion exchange resin. After the lead is held on the ion exchange resin, a complexing agent is added to the purified water, and a cleaning solution whose pH is adjusted to 5 to 9 with an alkali or an acid is passed through the ion exchange resin to disturb the components. And then dilute hydrochloric acid or nitric acid is passed through the ion exchange resin to elute lead,
The lead quantification method characterized by measuring lead in the obtained eluate. 2. The method for quantifying lead according to claim 1, wherein the complexing agent is citric acid or malonic acid. 3. The method for quantifying lead according to claim 2, wherein the concentration of citric acid or malonic acid in the sample solution or the washing solution is 0.1 to 1 g / l. 4. The lead quantification method according to claim 1, wherein the flow rate of the sample solution passed through the ion exchange resin is 1 to 20 ml / min. 5. The lead quantification method according to claim 1, wherein the amount of the washing solution passed through the ion exchange resin is 150 to 200 ml. 6. The lead quantification method according to claim 1, wherein the ion exchange resin is a weakly acidic cation exchange resin.