JP4784032B2 - Apparatus for quantitative analysis of moisture in sodium bicarbonate and method for quantitative analysis thereof - Google Patents

Description

【式３】

（２）全結晶水量：Ｃ（ｐｐｍ）の算出。
【００３０】
【式４】

（３）炭酸ソーダ一水和物の結晶水量Ｃ₁（ｐｐｍ）及びセスキ炭酸ソーダの結晶水量Ｃ₂（ｐｐｍ）の算出。
【００３１】
【式５】

【式６】

（４）炭酸ソーダ一水和物量Ａ（ｗｔ％）及びセスキ炭酸ソーダ量Ｂ（ｗｔ％）の算出。
【００３２】
【式７】

【式８】

上式（１）〜（７）において、Ｃは全結晶水量（ｐｐｍ）、Ｃ₁は炭酸ソーダ一水和物の結晶水量（ｐｐｍ）、Ｃ₂はセスキ炭酸ソーダの結晶水量（ｐｐｍ）、Ａは炭酸ソーダ一水和物量（ｗｔ％）、Ｂはセスキ炭酸ソーダ量（ｗｔ％）、Ｔは全水分量（ｐｐｍ）、Ｆは遊離水量（ｐｐｍ）、Ｄは遊離水が出終わるまでの全水分量（μｇ）、Ｍは炭酸ソーダ１水和物の結晶水が出終わるまでの全水分量（μｇ）、Ｈはセスキ炭酸ソーダの結晶水が出終わるまでの全水分量（μｇ）、ＢＬはガス中に含まれているバックグラウンド水分量（μｇ／ｍｉｎ）、Ｔ₁は遊離水が出終わるまでの時間（ｍｉｎ）、Ｔ₂は炭酸ソーダ一水和物の結晶水が出終わるまでの時間（ｍｉｎ）、Ｔ₃はセスキ炭酸ソーダの結晶水が出終わるまでの時間（ｍｉｎ）、Ｗｅは試料量（ｇ）を示す。
【００３３】
【実施例】
以下、本発明を実施例によりさらに説明するが、本発明はこれらに限定されるものではない。また、ｐｐｍ、％は重量に基づくものである
実施例１
東ソー株式会社製の重曹（平均粒径１２５μｍ）４ｇをガラス製５０ｍｌの試料部に入れ、これを６０℃±０．５℃に加熱した。この試料部にシリカゲル及びゼオライトにより脱水した乾燥窒素を２００Ｎ−ｃｃ／ｍｉｎで通じ、重曹から蒸発してくる水分を窒素ガスと共に電量滴定方式のカールフッシャ水分定量分析計に導き、経時的に、その水分量を測定した。そして重曹中の遊離水分量及び結晶水量を算出した。
【００３４】
遊離水分量および炭酸ソーダ１水和物の結晶水量、セスキ炭酸ソーダの結晶水量は、それぞれ３０ｐｐｍ、２９ｐｐｍ、２８８ｐｐｍであった。これから炭酸ソーダ一水和物量、セスキ炭酸ソーダ量はそれぞれ２００ｐｐｍ、１８１０ｐｐｍと定量分析できた。
【００３５】
比較例１
実施例１の重曹１００ｇを常温で焼成ゼオライトを入れたデシケータにセットし、２４時間後の重曹の減量から重曹中の水分量を求めた。その結果、水分量は０．１％以下となり定量分析できなかった。
【００３６】
比較例２
実施例１の重曹４ｇに水を０μｇ（無添加）、５０μｇ、１００μｇ、５００μｇ、１０００μｇ添加し、試料部での加熱温度を２０℃±０．５℃にした他は、実施例１の条件で重曹中の遊離水分量及び炭酸ソーダ一水和物の結晶水量、セスキ炭酸ソーダの結晶水量を定量分析した。測定した結果を表１に示す。結晶水は定量分析できなかった。添加した水は遊離水として定量できるもののその分析精度は悪かった。
【００３７】
【表１】

比較例３
実施例１の重曹４ｇに水を０μｇ（無添加）、５０μｇ、１００μｇ、５００μｇ、１０００μｇ添加し、試料部での加熱温度を１００±０．５℃にした他は、実施例１の条件で重曹中の遊離水分量及び炭酸ソーダ一水和物の結晶水量、セスキ炭酸ソーダの結晶水量を定量分析した。重曹の分解によりＢＬ値が増加しかつ安定せず、定量分析できなかった。
【００３８】
実施例２
実施例１の重曹４ｇに水を０μｇ（無添加）、５０μｇ、１００μｇ、５００μｇ、１０００μｇ添加し実施例１の条件で重曹中の遊離水分量及び炭酸ソーダ一水和物の結晶水量、セスキ炭酸ソーダの結晶水量を定量分析した。測定した結果を表２に示す。添加した水が遊離水として精度良く定量分析されていることが確認できた。
【００３９】
【表２】

実施例３
実施例１の重曹４ｇにセスキ炭酸ソーダを０μｇ（無添加）、５μｇ、１０μｇ、５０μｇ、１００μｇ、５００μｇ、１０００μｇそれぞれ添加し実施例１の条件で重曹中の遊離水分量及びセ炭酸ソーダ一水和物の結晶水量、セスキ炭酸ソーダの結晶水量を定量分析した。結果を表３に示す。添加したセスキ炭酸ソーダの結晶水が精度良く定量分析されていることが確認できた。
【００４０】
【表３】

実施例４
実施例１の重曹に４ｇに炭酸ソーダ一水和物を０μｇ（無添加）、５μｇ、１０μｇ、５０μｇ、１００μｇ、５００μｇ、１０００μｇそれぞれ添加し実施例１の条件で重曹中の遊離水分量及びセスキ炭酸ソーダの結晶水量、炭酸ソーダ一水和物の結晶水量を定量分析した。結果を表４に示す。添加した炭酸ソーダ一水和物の結晶水が精度良く定量分析されていることが確認できた。
【００４１】
【表４】

【発明の効果】
以上の説明から明らかなように、本発明によれば加熱温度及びキャリヤーガス流量を制御する簡単な装置および方法により、重曹中の微量水分を正確に短時間で定量分析することができる。さらには、これまで不可能であった重曹中に微量存在する遊離水分、炭酸ソーダ１水和物、セスキ炭酸ソーダ（２水和物）等の結晶水、各々も正確に短時間で分別して定量分析することができる。そのため工程管理、品質管理上きわめて有用である。
【図面の簡単な説明】
【図１】本発明装置の実施態様を示す概略図である。
【図２】本発明による重曹中の水分定量分析の１例である。図２中、Ｘ軸（横軸）はガスを流通させた時間（ｍｉｎ）であり、Ｙ軸（縦軸）の左側は測定中の水分発生速度（単位は、μｇ／ｍｉｎ）であり、Ｙ軸（縦軸）の右側は測定中の積算水分発生量（単位は、μｇ）である。
【符号の説明】
１：ガス乾燥装置
２：試料部
３：水分定量分析手段
４：ガスをガス乾燥装置へ導く流通管
５：乾燥ガスを試料部へ導く流通管
６：水分同伴ガスを水分定量分析手段へ導く加熱流通管
７：水分定量分析手段より排出されるガスを導く流通管
８：ガス
９：乾燥ガス
１０：水分同伴ガス
１１：排ガス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a quantitative analysis apparatus for moisture in sodium bicarbonate and a quantitative analysis method thereof. More particularly, the present invention relates to a device for fractionating and quantitatively analyzing water in sodium bicarbonate into free water and crystal water such as sodium carbonate monohydrate and sesquicarbonate soda, and a quantitative analysis method thereof.
[0002]
[Prior art]
Baking soda is inexpensive and highly pure, and has an important function such as pH buffering action as a weak alkali, so it is widely used in pharmaceuticals, food additives, feeds and the like. This baking soda is generally handled as a powder, but the moisture in the baking soda is closely related not only to the stability of the product but also to the caking and fluidity of the product, which is a very important item in quality control. ing. .
[0003]
In addition, the water in the baking soda is not only free water, but also crystal water of compounds such as sodium carbonate monohydrate (Na ₂ CO ₃ ) and sodium sesquicarbonate (NaHCO ₃ · Na ₂ CO ₃ · 2H ₂ O). To do. These water species and water content are closely related to the stability, caking property, and fluidity of baking soda products, and the quantitative analysis of moisture has become a serious problem in process control and quality control. Yes.
[0004]
Heat loss method as a general method for measuring moisture (for example, Koichiro Shinra, Wataru Funasaka, Analytical Chemistry 6-C, Moisture Determination, page 5, published by Kyoritsu Shuppan (Showa 32), Kenji Hashimoto, Powder This method has a method of measuring the moisture content from the weight loss at that time by evaporating the sample by heating the sample above the boiling point of water. It is. However, in the case of baking soda, it is very difficult to measure moisture because it decomposes by this heating and releases water and carbon dioxide gas to form sodium carbonate.
[0005]
Therefore, as a method for quantitative analysis of the water content of sodium bicarbonate, a method in which sodium bicarbonate is dried with calcium chloride anhydride, calcined zeolite, sulfuric acid, etc. in a normal temperature desiccator, and the weight loss is used as the moisture content (for example, Koichiro Shinra, Wataru Funasaka, Analytical Chemistry Course 6-C, Moisture Determination, 8 pages, published by Kyoritsu Shuppan (Showa 32), Kenji Hashimoto, Moisture Measurement of Powders, 42 pages, published by Nippon Chemical Information Co., Ltd. ( 1990)). However, this method requires a long time for drying and has a large measurement error. Furthermore, it is extremely difficult to perform a quantitative analysis of moisture in sodium bicarbonate.
[0006]
Another measurement method is the Karl Fischer method (JIS K0068-1966). However, quantifying the water content in baking soda directly by the Karl Fischer method was extremely difficult because the Karl Fischer reagent and baking soda would react. Therefore, the solvent extraction Karl Fischer method is widely used (for example, Koichiro Shinra, Wataru Funasaka, Analytical Chemistry Course 6-C, Moisture Determination, page 39, published by Kyoritsu Shuppan (Showa 32)). This is a method in which baking soda is brought into contact with sodium bicarbonate in a dehydrated non-aqueous solvent and the water content in the baking soda is extracted into the non-aqueous solvent, and then the water content in the non-aqueous solvent is measured by a Karl Fischer moisture quantitative analyzer. It is. This method also requires a long time for extraction, has a large number of steps and is complicated in operation, and thus has a large measurement error. Further, the fractional quantitative analysis of water in sodium bicarbonate is extremely difficult.
[0007]
In addition, as another method of moisture measurement using the Karl Fischer method, there is a moisture vaporization type Karl Fischer method (JIS M-8211-1983). This method also heats a sample to 100 ° C. or more, evaporates the moisture, It is absorbed in a water solvent and the amount of water is determined by a Karl Fischer moisture quantitative analyzer. However, baking soda is decomposed by heating, and water and carbon dioxide gas as decomposition products are absorbed in a non-aqueous solvent, so that measurement of water and fractional quantitative analysis are extremely difficult.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned problems in the prior art. The purpose of the present invention is to quantitate the moisture in sodium bicarbonate with good operability and accurately in a short time. An object of the present invention is to provide an apparatus and a method capable of performing fractional quantitative analysis accurately in a short time with good operability in water of crystallization such as soda monohydrate and sodium sesquicarbonate.
[0009]
[Means for solving the problems]
In order to solve the above-mentioned problems, the present inventors diligently studied a method for quantitative analysis of moisture in sodium bicarbonate, and a method for fractional quantitative analysis of moisture in sodium bicarbonate. As a result, the baking soda is brought to a mild condition, that is, a temperature of 30 to 90 ° C., and by passing the drying gas therethrough, the decomposition of the baking soda hardly occurs, all the water in the baking soda can be evaporated and transferred to the drying gas, and The present inventors have found that the rate of transition to gas differs between free water, sodium carbonate monohydrate, and sesquicarbonate soda, and have completed the present invention.
[0010]
That is, the present invention has a sample part capable of controlling the temperature to 30 to 90 ° C. and capable of arranging baking soda powder, a moisture quantitative analysis means, and a mechanism for continuously circulating a water-entrained gas from the sample part to the moisture quantitative analysis means. Equipped with a quantitative analysis device for the moisture content in baking soda and 0.05 to 20 g of baking soda powder in the sample part, and continuously supplying a dry gas controlled at a predetermined temperature between 30 and 90 ° C. to the sample part. A method for quantitative analysis of moisture in sodium bicarbonate, characterized in that moisture entrained gas flowing out from a sample portion is guided to a moisture quantitative analysis means, and the moisture in the moisture accompanying gas is measured over time by the moisture quantitative analysis means. .
[0011]
Hereinafter, the present invention will be described in detail.
[0012]
The apparatus for quantitative analysis of moisture in baking soda of the present invention (hereinafter referred to as “the apparatus of the present invention”) includes a sample part for setting sodium bicarbonate powder having a function that can be controlled in a temperature range of 30 to 90 ° C., and quantitative analysis of moisture. And a mechanism for continuously flowing gas from the sample portion to the moisture quantitative analyzer.
[0013]
FIG. 1 shows an example of the apparatus of the present invention. A gas 8 to be sent to a sample to be measured, such as air or nitrogen, is sent to a gas drying apparatus 1 for drying a gas 6 through a flow pipe 4, and then. The dry gas 9 dried by the gas drying device 1 is sent to the sample unit 2 through the flow pipe 5. In the sample part 2, the baking soda that is the sample to be measured is heated, and the water in the baking soda evaporates and accompanies the dry gas 9. The moisture entrained gas 10 is sent to the moisture quantitative analysis means 3 such as a Karl Fischer moisture quantitative analyzer through the heating flow pipe 6. In this moisture quantitative analysis means 3, the moisture content is quantified over time, and the moisture content contained in the sample to be measured can be measured. The gas introduced into the moisture quantitative analysis means 3 is discharged as exhaust gas 11 through the flow pipe 7.
[0014]
The sample part that constitutes the apparatus of the present invention is not particularly limited in its heating method and temperature control method as long as it has a function capable of controlling the sample to be measured and controlling in the temperature range of 30 to 90 ° C. The heating method is preferably an electric heater, and the temperature control is preferably a PID control method using a computer. The temperature control function is preferably a heating mechanism capable of maintaining the temperature at a constant value between 30 and 90 ° C. or capable of continuously increasing the temperature between 30 and 90 ° C. over time. It is desirable to control the temperature to ± 1 ° C. or less with respect to the target temperature in order to avoid a measurement error due to large temperature fluctuations.
[0015]
The moisture quantitative analysis means preferably has a moisture detection sensitivity of 1 μg / min (min) or less, more preferably 0.1 μg / min or less, as a moisture supply rate supplied from the heating unit. In addition, there are no particular restrictions on the type of moisture quantitative analyzer as long as the moisture content can be continuously measured, but as a moisture quantitative analyzer having these capabilities, a gas chromatograph, an infrared moisture quantitative analyzer, a Karl Fischer moisture quantitative analyzer, etc. Can be illustrated. Among them, a Karl Fischer moisture quantitative analyzer is desirable, and a coulometric titration type is more preferable.
[0016]
A mechanism that allows the gas to flow continuously from the sample part to the moisture quantitative analyzer. Specifically, it is a distributor, but it is heated so that water vapor does not condense inside the tube, especially when a water-entrained gas is circulated. It is desirable. The heating method and temperature control method are not particularly limited, but a PID control method using an electric heater for heating and a computer for temperature control is preferable. Further, stainless steel, glass, Teflon or the like can be applied as the material of the flow pipe.
[0017]
In the present invention, the baking soda used as the measurement target sample has a purity of 90% or more, and the amount of water contained in the baking soda is preferably about 5 ppm to 10%. The average particle size is not particularly limited, but is 500 μm or less. Is preferably about 45 to 250 μm.
[0018]
The amount of baking soda placed in the sample part is preferably 0.05 to 20 g, more preferably 0.1 to 5 g. The amount of water contained in the sample baking soda is preferably about 30 μg to 10 mg as an absolute amount, and more preferably about 3 to 10 mg. At this time, sensitivity and accuracy are maximized. If the absolute amount of water in baking soda is too small, it may be less than the measurement sensitivity of the moisture quantitative analyzer, which may make it difficult to measure the water content of crystal water and free water. It may be difficult to measure the water content of crystal water and free water beyond the measurement limit of the quantitative analysis means.
[0019]
The heating temperature of baking soda is preferably 30 to 90 ° C, more preferably 40 to 70 ° C. When the temperature is higher than 90 ° C., the baking soda is decomposed and the measurement becomes difficult. If the temperature is lower than 30 ° C, the water evaporation rate becomes extremely slow. The amount of water evaporation may be below the measurement sensitivity of the moisture quantitative analyzer, making it difficult to measure the water content. Takes a long time.
[0020]
The baking temperature of the baking soda is preferably ± 1 ° C. or less with respect to the target temperature when controlled at a constant temperature. If the temperature changes, it causes a measurement error and makes it difficult to separate and quantitatively analyze the moisture described later. On the other hand, if the temperature is continuously raised over time, the measurement time can be shortened. In this case, the control temperature is desirably ± 1 ° C. or less with respect to the target temperature. When the temperature changes, a measurement error occurs, and the moisture quantitative analysis described later becomes difficult.
[0021]
Keeping the baking soda in a dry atmosphere, and the drying gas as a carrier gas for guiding moisture evaporated from the baking soda to the moisture quantitative analysis means should be substantially free of moisture and inert to the baking soda. Although it is not limited, it is desirable that moisture is 0.1 mg / liter or less with nitrogen gas or air. This can be dried by introducing a carrier gas into a gas drying device, as seen in FIG. For example, silica gel and zeolite are placed or filled in the gas drying device, and the gas drying device can be easily obtained by performing a treatment such as contacting nitrogen gas or air used in the gas drying device. If the moisture content in the dry gas is too high, evaporation of moisture in the baking soda is hindered, and the background becomes large, which may cause measurement errors.
[0022]
The flow rate of the drying gas is preferably 100 to 300 N-cc / min. If the gas flow rate is too high, water vapor from the baking soda may be diluted, which may cause errors in measurement with the moisture quantitative analysis means. If the gas flow rate is too low, evaporation of water in the baking soda will be hindered. May cause measurement errors. Note that the flow rate of the drying gas is desirably ± 5 N-cc / min or less. If the flow rate fluctuates, it will cause an error in moisture measurement.
[0023]
Moisture (water vapor) evaporating from the baking soda is introduced into the moisture quantitative analysis means using nitrogen gas, air or the like as a carrier gas, and the moisture evaporation rate and evaporation amount are obtained over time from the measured moisture values.
[0024]
The detection sensitivity of the moisture quantitative analysis means is desirably 1 μg / min or less, more preferably 0.1 μg / min or less, as the moisture supply rate supplied from the heating unit.
[0025]
In addition, the moisture can be separated and quantitatively analyzed from the moisture evaporation rate and the amount of evaporation from the baking soda in the sample part to the free water, and the crystal water such as sodium carbonate monohydrate and sesquicarbonate. This is also a major feature of the present invention.
[0026]
The present inventors have found that water from sodium bicarbonate evaporates in the order of free water, crystal water of sodium carbonate monohydrate, and crystal water of sodium sesquicarbonate. This moisture was measured over time with a moisture quantitative analyzer, and for the first time, fractional quantitative analysis of crystal water and free water was successful from the peak position and peak area.
[0027]
As a method for obtaining the peak position and the peak area, an appropriate method may be used each time. For example, the method of directly reading from the graph illustrated in FIG. 2, the method of calculating the inflection point from the measurement data indicating the moisture generation rate, calculating the peak position and peak area, the waveform of the graph as a normal distribution function, etc. And a method of obtaining by approximating with one or more functions. The data may be processed by an appropriate method such as using a computer each time.
[0028]
The amount of trace water in sodium bicarbonate and the amount of sodium carbonate monohydrate and sodium sesquicarbonate in sodium bicarbonate can be calculated from the water content of crystal water and free water by the following formula (see FIG. 2).
(1) Calculation of total water content: T (ppm), free water content: F (ppm).
[0029]
[Formula 2]

[Formula 3]

(2) Calculation of total crystal water amount: C (ppm).
[0030]
[Formula 4]

(3) Calculation of the amount of crystal water C ₁ (ppm) of sodium carbonate monohydrate and the amount of crystal water C ₂ (ppm) of sodium sesquicarbonate.
[0031]
[Formula 5]

[Formula 6]

(4) Calculation of sodium carbonate monohydrate amount A (wt%) and sodium sesquicarbonate amount B (wt%).
[0032]
[Formula 7]

[Formula 8]

In the above formulas (1) to (7), C is the total crystal water amount (ppm), C ₁ is the crystal water amount (ppm) of sodium carbonate monohydrate, C ₂ is the crystal water amount (ppm) of sodium sesquicarbonate, A Is the amount of sodium carbonate monohydrate (wt%), B is the amount of sodium sesquicarbonate (wt%), T is the total amount of water (ppm), F is the amount of free water (ppm), and D is the total amount of free water Moisture content (μg), M is the total water content (μg) until the crystallization water of sodium carbonate monohydrate ends, H is the total water content (μg) until the crystallization water of sodium sesquicarbonate ends, BL Is the amount of background water contained in the gas (μg / min), T ₁ is the time until free water finishes out (min), T ₂ is the time until the crystal water of sodium carbonate monohydrate ends time (min), T ₃ is the time until after out crystal water of sodium sesquicarbonate (min), We Weight sample (g) shows.
[0033]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these. Further, ppm and% are based on weight. Example 1
4 g of baking soda (average particle size 125 μm) manufactured by Tosoh Corporation was placed in a 50 ml glass sample and heated to 60 ° C. ± 0.5 ° C. Dry nitrogen dehydrated with silica gel and zeolite was passed through this sample part at 200 N-cc / min, and the water evaporated from the baking soda was introduced into a coulometric titration type Karl Fuchter moisture quantitative analyzer together with nitrogen gas. The amount was measured. And the amount of free water and the amount of crystallization water in sodium bicarbonate were calculated.
[0034]
The amount of free water, the amount of crystal water of sodium carbonate monohydrate, and the amount of crystal water of sodium sesquicarbonate were 30 ppm, 29 ppm, and 288 ppm, respectively. From this, the amount of sodium carbonate monohydrate and the amount of sodium sesquicarbonate were quantitatively analyzed as 200 ppm and 1810 ppm, respectively.
[0035]
Comparative Example 1
100 g of sodium bicarbonate of Example 1 was set in a desiccator containing calcined zeolite at room temperature, and the water content in the sodium bicarbonate was determined from the reduction of sodium bicarbonate after 24 hours. As a result, the water content was 0.1% or less and could not be quantitatively analyzed.
[0036]
Comparative Example 2
The conditions of Example 1 were followed except that 0 μg (no addition), 50 μg, 100 μg, 500 μg, and 1000 μg of water were added to 4 g of sodium bicarbonate in Example 1 and the heating temperature in the sample part was 20 ° C. ± 0.5 ° C. The amount of free water in sodium bicarbonate, the amount of crystal water of sodium carbonate monohydrate, and the amount of crystal water of sodium sesquicarbonate were quantitatively analyzed. The measured results are shown in Table 1. Crystallized water could not be quantitatively analyzed. Although the added water could be quantified as free water, its analytical accuracy was poor.
[0037]
[Table 1]

Comparative Example 3
Sodium bicarbonate was added under the same conditions as in Example 1 except that water (0 μg (no addition), 50 μg, 100 μg, 500 μg, 1000 μg) was added to 4 g of sodium bicarbonate in Example 1, and the heating temperature in the sample part was 100 ± 0.5 ° C. The amount of free water, the amount of crystallization water of sodium carbonate monohydrate, and the amount of crystallization water of sodium sesquicarbonate were quantitatively analyzed. The BL value increased due to the decomposition of sodium bicarbonate and was not stable, and could not be quantitatively analyzed.
[0038]
Example 2
0 μg (no addition), 50 μg, 100 μg, 500 μg, and 1000 μg of water were added to 4 g of sodium bicarbonate in Example 1, and the amount of free water in sodium bicarbonate and the amount of crystallization water of sodium carbonate monohydrate and sodium sesquicarbonate under the conditions of Example 1 The amount of water of crystallization was quantitatively analyzed. Table 2 shows the measurement results. It was confirmed that the added water was quantitatively analyzed accurately as free water.
[0039]
[Table 2]

Example 3
0 μg (no addition), 5 μg, 10 μg, 50 μg, 100 μg, 500 μg, and 1000 μg of sodium sesquicarbonate were added to 4 g of sodium bicarbonate of Example 1, and the amount of free water and sodium carbonate monohydrate in sodium bicarbonate under the conditions of Example 1. The amount of crystal water of the product and the amount of crystal water of sodium sesquicarbonate were quantitatively analyzed. The results are shown in Table 3. It was confirmed that the crystallization water of the added sodium sesquicarbonate was quantitatively analyzed with high accuracy.
[0040]
[Table 3]

Example 4
4 g of sodium bicarbonate monohydrate was added to 4 g of sodium bicarbonate of Example 1 at 0 μg (no addition), 5 μg, 10 μg, 50 μg, 100 μg, 500 μg, and 1000 μg, respectively, and free water content and sesquicarbonic acid in sodium bicarbonate were added under the conditions of Example 1. The amount of crystallization water of soda and the amount of crystallization water of sodium carbonate monohydrate were quantitatively analyzed. The results are shown in Table 4. It was confirmed that the crystal water of the added sodium carbonate monohydrate was quantitatively analyzed with high accuracy.
[0041]
[Table 4]

【The invention's effect】
As is apparent from the above description, according to the present invention, a trace amount of water in baking soda can be accurately and quantitatively analyzed in a short time by a simple apparatus and method for controlling the heating temperature and the carrier gas flow rate. Furthermore, free water present in trace amounts in sodium bicarbonate, water of crystallization such as sodium carbonate monohydrate and sesquicarbonate sodium carbonate (dihydrate), which has been impossible in the past, are each accurately separated and determined in a short time. Can be analyzed. Therefore, it is very useful for process control and quality control.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of the apparatus of the present invention.
FIG. 2 is an example of quantitative analysis of water in sodium bicarbonate according to the present invention. In FIG. 2, the X axis (horizontal axis) is the time (min) during which the gas is circulated, the left side of the Y axis (vertical axis) is the moisture generation rate during measurement (unit: μg / min), Y The right side of the axis (vertical axis) is the integrated water generation amount during measurement (unit: μg).
[Explanation of symbols]
1: Gas drying device 2: Sample part 3: Moisture quantitative analysis means 4: Flow pipe for guiding gas to the gas drying apparatus 5: Flow pipe for guiding dry gas to the sample part 6: Heating for leading the moisture-entrained gas to the moisture quantitative analysis means Distribution pipe 7: Distribution pipe 8 for guiding gas discharged from the moisture quantitative analysis means 8: Gas 9: Dry gas 10: Moisture entrained gas 11: Exhaust gas

Claims (16)

A sample part capable of controlling the temperature to a constant temperature between 40 to 70 ° C. and capable of arranging baking soda powder, a moisture quantitative analysis means, and a mechanism for continuously flowing a water-entrained gas from the sample part to the moisture quantitative analysis means Equipped with a quantitative analysis device for moisture in baking soda that separates and quantifies the amount of free water in sodium bicarbonate, the amount of sodium carbonate monohydrate, and the amount of sodium sesquicarbonate . The quantitative analysis device for moisture in sodium bicarbonate according to claim 1, comprising a gas drying device and a mechanism for continuously flowing a drying gas from the gas drying device to the sample portion. The quantitative analysis device for moisture in sodium bicarbonate according to claim 1 or 2, further comprising a mechanism for heating the moisture-entrained gas. The apparatus for quantitative analysis of moisture in sodium bicarbonate according to any one of claims 1 to 3, wherein the moisture detection sensitivity of the moisture quantitative analysis means is 1 µg / min or less as a moisture supply rate supplied from the sample part. The apparatus for quantitative analysis of moisture in sodium bicarbonate according to any one of claims 1 to 4, wherein the moisture quantitative analysis means is a Karl Fischer moisture quantitative analyzer. Baking soda powder 0.05~20g placed on the sample unit, continuously circulating dry gas controlled to a constant temperature between 40 to 70 ° C. to the sample unit, the moisture entrained flowing out of the sample unit The amount of free water in sodium bicarbonate, the amount of sodium carbonate monohydrate, and the amount of sodium sesquicarbonate, wherein the gas is introduced into the moisture quantitative analysis means, and the moisture in the moisture entrained gas is measured over time by the moisture quantitative analysis means For quantitative analysis of moisture in sodium bicarbonate. The method for quantitative analysis of moisture in sodium bicarbonate according to claim 6, wherein the dry gas is dehydrated air or nitrogen gas. The method for quantitative analysis of moisture in sodium bicarbonate according to claim 6 or 7 , wherein the moisture content of the dry gas is 0.1 mg / liter or less. The method for quantitative analysis of moisture in sodium bicarbonate according to any one of claims 6 to 8 , wherein the flow rate of the dry gas is 100 to 300 N-cc / min. The method for quantitative analysis of moisture in sodium bicarbonate according to any one of claims 6 to 9 , wherein the moisture quantitative analysis means is a Karl Fischer moisture quantitative analyzer. Measure the time-dependent change in the amount of moisture in the gas accompanying moisture flowing out from the sample part, and determine the rate of water evaporation from the baking soda and the amount of water evaporation from the obtained results. The amount of free water, the amount of sodium carbonate monohydrate in The method for quantitative analysis of moisture in sodium bicarbonate according to any one of claims 6 to 10 , wherein the amount of sodium sesquicarbonate is subjected to fractional quantitative analysis. In the method of fractional quantitative analysis of the amount of free water, sodium carbonate monohydrate and sesquicarbonate in sodium bicarbonate , the following (1), (2), (3), (4), (5), (6) and (7) quantitative analysis method of sodium bicarbonate in water according to any of claims 6-11 using a formula.
[Formula 1]

(Wherein, C is the total amount of water of crystallization (ppm), C ₁ is the amount of crystallization water of sodium carbonate monohydrate (ppm), C ₂ is the amount of crystallization water of sodium sesquicarbonate (ppm), and A is the amount of sodium carbonate monohydrate. (Wt%), B is the amount of sodium sesquicarbonate (wt%), T is the total water content (ppm), F is the free water amount (ppm), D is the total water content (μg) until free water finishes, M Is the total water content (μg) until the crystallization water of sodium carbonate monohydrate is finished, H is the total water content (μg) until the crystallization water of sodium sesquicarbonate is finished, and BL is contained in the gas. Background water content (μg / min), T ₁ is the time until free water finishes out (min), T ₂ is the time until sodium carbonate monohydrate crystal water ends (min), T ₃ Is the time (min) until the crystallization of sodium sesquicarbonate finishes, We is the amount of sample (g) Is shown.) D according to claim _{12, M, H, BL,} T 1, T in determining the ₂ and _{T 3,} baking soda in the quantitative analysis method of moisture, characterized in that directly reads from the graph of the measurement data. D by detecting the inflection point of the water generation speed of the measurement _{data, M, H, BL, T} 1, T 2 and quantitative analysis method of sodium bicarbonate in water as claimed in claim 12 or claim 13 to determine the _{T 3} . D By approximating the measurement data in a plurality of _{functions, M, H, BL, T} 1, T 2 and quantitative analysis method of sodium bicarbonate in water according to any one of claims 12 to 14 to determine the _{T 3.} The method for quantitative analysis of moisture in sodium bicarbonate according to claim 15 , wherein the function is a normal distribution function.

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