How to Test the Purity of Ammonium Metatungstate Hydrate?

Detecting the purity of Ammonium Metatungstate Hydrate can be performed by a variety of methods. Commonly used methods include chemical analysis, spectral analysis, chromatographic analysis and so on. Chemical analysis method can deduce the purity of ammonium metatungstate hydrate by determining the content of specific elements in the sample, such as determining the purity of ammonium metatungstate by determining the content of tungsten. Spectroscopic analysis methods such as X-ray diffraction (XRD) and infrared spectroscopy (IR) can be used to determine the crystal structure and chemical composition of the sample to indirectly assess the purity of ammonium metatungstate hydrate. Chromatographic methods such as High Performance Liquid Chromatography (HPLC) can be used to separate and determine the impurity components in the sample to further assess the purity of Ammonium Metatungstate Hydrate. Detecting the purity of ammonium metatungstate hydrate usually involves multiple steps and methods, which are summarized below.

 

Determination of the amount of water insoluble matter (weighing method):

Reference standard

GB/T 23368.1-2009 “Method of chemical analysis of ammonium metatungstate Part 1: Determination of the amount of water insoluble matter by weighing method”.

Scope of determination

It is suitable for the determination of the amount of water-insoluble matter in ammonium metatungstate, and the range of determination is from 0.0025% to 2%.

Method Steps

After the test material is dissolved with water, the insoluble matter is separated by filtration.

After drying the insoluble matter, weigh its mass, which is the amount of water insoluble matter.

 

Determination of impurity element content

For the impurity elements in ammonium metatungstate, such as potassium, Co, Cr, Al, Ca, V, Cd, Mn, etc., inductively coupled plasma emission spectrometer (ICP-OES) can be used for determination.

ICP-OES has the advantages of low detection limit, high sensitivity and resistance to matrix interference.

Before measurement, ammonia and hydrogen peroxide are usually used to dissolve the sample and hydrochloric acid is used to remove the tungsten in the matrix to reduce matrix interference.

 

Other Detection Methods

For the detection of specific elements, such as Mo, S, P, etc., an atomic absorption spectrometer (e.g. AA-1800C) can also be used. When testing complex samples, a combination of methods and techniques, such as column switching techniques, may be required to accurately determine the impurity content of the sample.

 

Purity Calculations

The purity of ammonium metatungstate hydrate can be calculated based on the detected content of the impurity element, combined with the amount of water-insoluble material. The purity is usually expressed as the mass fraction of ammonium metatungstate, i.e. the mass of pure ammonium metatungstate as a percentage of the total mass.

 

Precautions

In the process of testing, it should be ensured that the reagents, equipment and analytical methods used are in accordance with the relevant standards and norms.

For high purity ammonium metatungstate hydrate, more stringent and precise detection methods and techniques may be required.

Attention should be paid to the preservation and treatment of the samples during the detection to avoid the introduction of new impurities or contamination.

 

In conclusion, the detection of the purity of ammonium metatungstate hydrate requires the comprehensive use of a variety of chemical analytical methods and instruments to ensure the accuracy and reliability of the test results.

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