JPS60173466A - Quantitative determination method of sulfur - Google Patents

Abstract

PURPOSE:To analyze trace S with a small amt. of a sample and with good accuracy by burning the sample in gaseous oxygen flow, passing the combustion gas through an absorption part contg. a small amt. of absorbent liquid to have gaseous SO2 absorbed and adding a decolored Para Rosaniline soln. and H2CO soln. to the absorbent liquid so that said liquid forms a color. CONSTITUTION:The gaseous oxygen flow formed by passing oxygen of the first class level through a chromium-satd. sulfuric acid 7 and a silica gel column 8 to clean up said oxygen is fed to a quartz tube 6 heated by a combustion furnace 3 to burn S in the sample weighed in the boat 2 in the tube 6. An absorption part 4 contg. potash bulbs 4-1 in a support table 4-2 formed by opening a hole to foamed polystyrene is connected by a silicone tube, etc. to the tube 6 so that the generated SO2 is absorbed therein. The absorbent liquid is then delivered by gaseous O2, etc. to a beaker, etc. and a specified amt. thereof is exactly separated and respectively a specified volume of a soln. decolored by adding HCl to 0.2V/V% soln. of Para Rosaniline and 0.5%V/V soln. of H2CO are added to the separated liquid. Part of the liquid is taken after resting for about 20min and the absorbancy at 550nm wavelength is measured. The measured absorbancy is compared with a preliminarily obtd. calibration curve and the S in the sample is quantitatively determined with high accuracy.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for quantitative analysis of sulfur, specifically a small amount of sulfur.

Concerning a method for accurately analyzing trace amounts of sulfur in samples.

[Prior art and its problems]

Quantitative analysis methods for sulfur include burning the sample in an oxygen stream, oxidizing all the sulfur to sulfur dioxide gas, absorbing it in hydrogen peroxide and neutralization titration, and absorbing it in hydrochloric acid and titrating with iodine. Generally, sulfur is determined by the combustion volume method, or by burning in the same manner as described above, absorbing the combustion gas into a sodium mercury tetrachloride solution, and determining sulfur by the spectrophotometric method using Ballarot aniline (for example, by the JIat method). Specified method for determining sulfur in steel and copper products).

However, the combustion volume method described above has only a reliability of the order of 6 ppm (μ7/1) of sulfur content using sample 11, and cannot be applied to trace analysis for accurately analyzing sulfur. Further, although the combustion spectrophotometry method described above has relatively good sensitivity, it is suitable for sulfur contents of 10 to 40 ppm, and is insufficient for performing trace analysis on the order of μ7.

On the other hand, as devices used for this type of quantitative analysis of sulfur, a high-frequency induction heating device and a tubular electric furnace are generally used as a combustion furnace.

High-frequency induction heating devices have a narrow temperature range, and analysis near the effects of high-frequency oscillation poses problems. In addition, for tubular reactors, there are dimensions stipulated according to the JIS law.
Since the combustion section alone is large, 700 to 800 mm, it is inconvenient for small sample size and trace analysis.

[Purpose of the invention]

The purpose of the present invention is to solve the drawbacks of these conventional methods. Specifically, the present invention provides a quantitative analysis method that enables accurate analysis of trace amounts of sulfur contained in a sample using a small amount of sample. It is something.

[Key points of the invention]

In order to achieve the above object, the method of the present invention involves burning a sample in an oxygen stream, passing the combustion gas through an absorption section containing a small amount of absorption liquid to absorb sulfur dioxide gas in the combustion gas, The method is characterized by adding a decolorizing rose aniline solution and a formaldehyde solution to the absorption liquid to develop a color, and by measuring the amount of color development, the amount of sulfur in the sample is calculated and quantified.

[Embodiments of the invention]

Hereinafter, the quantitative analysis method for sulfur of the present invention will be explained with reference to Examples.

FIG. 1 is an explanatory diagram illustrating an apparatus used to carry out the method of the present invention. In the following, a method for quantitatively analyzing sulfur in a sample according to the present invention will be explained in conjunction with the apparatus shown in FIG.

First, in the method of the present invention, a sample is burned in an oxygen stream. Oxygen is used as the combustion supporting gas, and in the case of gold and copper products, the optimum oxygen flow rate is 0.15±Q, Q3L/min, and the optimum combustion temperature of the sample is 1150±20°C.

To purify the combustion-supporting gas, it is introduced into the system through a chromium-saturated sulfuric acid 7 and a silica gel column 8. In this case, generally the above 7
In addition to 8 and 8, it can be cleaned using soda lime, solid sodium hydroxide, activated alumina, sulfuric acid, etc.
In the case of the method of the present invention, as a result of conducting a blank test using ordinary grade 1 oxygen, it was found that cleaning using only two types 7 and 8 is sufficient for use. Therefore, from the point of view of simplicity, it is not necessary to use all of them, as is generally done.

The combustion furnace 3 was prepared for small-volume and trace analysis of samples.

In the figure, 3-1 is a magnesia brick with excellent workability.
It is a heat insulating material made by cutting a sheet into a semi-cylindrical shape. Place the porcelain protection tube 3-3 into this. The combustion furnace 3 is constructed by inserting a silicone silicone tube 3-2 as a heating element inside the combustion chamber. In addition, the outer diameter of the quartz tube 6 is 18 mm and the inner diameter is 15 mm, and when using the known sample boat 2, the dimensions are small for the purpose of reducing the amount of sample, such as 12 + nm in height and 8 nm in width.
However, it is preferable to use one with a length of 80 mm or smaller. The combustion furnace 3 has the feature that it can be manufactured easily at a low cost, and is important in illegal cases as an accessory device that has a one- to two-digit amount difference compared to general analysis methods such as the JIS method. Also, because of its small size, it is convenient to transport by using a foldable wagon.

The combustion gas generated in -1- is then passed through the absorption liquid and sulfur dioxide gas is absorbed therein. The absorption part (potash bulb) numbered 4 in the figure absorbs combustion gas, and has a volume of approximately ]0rn.
The aim is to absorb efficiently with a small amount of 1. This makes it possible to reduce the amount and trace amount of the sample. The volume of the absorbent section commonly used is 50 me or 10
(h++/!), so it is possible to reduce the amount by 115 to 1/1o.

It is sufficient that the temperature control device 5 has a temperature error of about 20°C.

Since the potash bulb 4 is unstable, it is convenient to use a light and easy-to-operate styrene foam support base 4-2 for the absorption part when connecting it to the quartz tube 6 using a silicon tube or the like.

The combustion time required to burn the sample with the above analyzer and efficiently absorb the combustion gas is 0.05 for the gold and copper samples.
When carried out at about 0.5 to 12 minutes, combustion will be slightly incomplete if it is less than 14 minutes, but combustion will be complete if it is more than 15 minutes.3, Preferably, 20 minutes is sufficient for combustion.

Approximately 20ml of the solution that has absorbed sulfur through the above operations
Pour a certain amount of this solution into a 50 ml beaker using oxygen gas, for example, 8nr into a 10 ml volumetric flask.
Separate the liquid accurately.

Next, this was added with a decolorized rose rose aniline solution (rose rose aniline 0.2% (VA: + solution 20 me to hydrochloric acid 8.
10++! ! ) Add 0.5me number. Next, after adding 0.5 me of formaldehyde solution (0.5% (VA) solution),
Add water to 10me. After standing for 20 minutes, a portion of the sample was placed in a 10 mm cell, and the absorbance at a wavelength of 550 nm was measured using a spectrophotometer. The concentration of sulfur is determined by comparing the obtained water measurement value with a calibration curve prepared in advance, and the sulfur in the sample is calculated and quantified.

The coloring volume of the cell is 50 to 100m+e in the general method.
However, in the method of the present invention, 10 m
Since the concentration of hydrochloric acid used to decolorize roserose aniline, which is an added reagent during color development, affects the measurement, it is therefore important to set it to 8% (V/v).

Next, in order to confirm the accuracy of the quantitative analysis method for sulfur, a simple method for preparing a standard sample and a method for confirming accuracy using the standard sample will be explained.

First, a first-class or special-grade reagent of sulfide, such as lead chloride, is prepared 1. The sulfur content in this sample is analyzed by a suitable method such as a gravimetric method or a volumetric method. Next, in the case of a metal sample, prepare a similar pure metal foil. Cut this into an appropriate size using scissors, etc., and fold it into a box shape using a pinot set, etc. Place this on a chemical balance, weigh out the heavy F soil, add a small amount of the reagent with a known sulfur content, weigh it, fold it, and use this as a standard sample.

This standard sample is burned according to the method of the present invention, the combustion gas is absorbed, and the amount of sulfur is measured to check the accuracy. This confirmation analysis method is particularly useful for standard samples of metals that are difficult to obtain.

Figure 2 shows an example of the analysis results for confirming the accuracy of the method of the present invention.As mentioned above, gold foil and copper foil are folded into a box shape, a sulfide reagent is added thereto, and the sulfur This shows a relationship line between amount and absorbance. The accuracy of this relationship line was confirmed by the method described above using gold foil and copper foil. In addition to agreement for both metals, good linearity was observed in sulfur content and absorbance in accordance with Beer. moreover,
In order to confirm the accuracy of this, the results matched those measured by directly developing color with a pure sulfide salt without burning it. Therefore, it can be seen that the quantitative analysis method of the present invention has sufficient accuracy.

〔Effect of the invention〕

According to the present invention, it is possible to analyze accurately even if a small number of samples are delivered. Moreover, unlike conventional methods, it is possible to perform trace analysis.Furthermore, the analyzer is small and takes up a lot of space, and can be easily manufactured at low cost. It is particularly useful for analyzing unstandardized structural materials.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a specific example of an apparatus for carrying out the method of the present invention. FIG. 2 is a graph showing an example of the accuracy of the sulfur quantitative analysis method of the present invention. 2 is a sample boat, 3 is a combustion furnace, 4 is an absorption part (potash sphere),
5 is a temperature control device, 6 is a quartz combustion tube, and 7 and 8 are combustion supporting gas purifiers.

Claims (1)

[Claims] 1) Burn the sample in an oxygen stream, pass this combustion gas through an absorption section containing a small amount of absorption liquid to absorb sulfur dioxide gas in the combustion gas, and decolorize the absorption liquid. A sulfur quantitative analysis method comprising adding a pararose aniline solution and a formaldehyde solution to develop a color, and calculating the amount of sulfur in a sample by measuring the colored needle.2. A quantitative analysis method for sulfur, characterized in that the absorption part for combustion gas is composed of potash spheres.