Method for measuring aluminum content by chrome azurol S spectrophotometry

Abstract

The invention discloses a method for measuring aluminum content by chrome azurol S spectrophotometry. The method comprises the following steps: digesting a sample, removing acid and fixing the volume to obtain a digestion solution; transferring the hydrolysate, adding a proper amount of sodium hydroxide solution, standing for a period of time, and centrifuging to obtain a first supernatant and a first precipitate; adding a proper amount of a sodium hydroxide solution into the first precipitate, vortex, transferring the vortex solution to a microwave digestion tank, carrying out microwave treatment, and centrifuging the solution again after microwave treatment to obtain a second supernatant and a second precipitate; combining the first supernatant and the second supernatant, adding a proper amount of nitric acid, and heating and concentrating to obtain a solution to be detected; according to the method, under the condition that food contains a large amount of iron, the content of aluminum can be accurately measured by adopting the chrome azurol S spectrophotometric method.

Description

technical field [0001] The invention relates to the technical field of aluminum content determination, in particular to a method for measuring aluminum content by chrome azure S spectrophotometry. Background technique [0002] When chrome azure S spectrophotometry is used to detect aluminum content in food, since chrome azure S can form colored complexes with various metal ions, the selectivity of the color developer of this method is not high, and iron, manganese, copper, Metal ions such as zinc can interfere with it, especially iron, but the method is still widely used due to its low cost, simple operation and high sensitivity. [0003] At present, there are many related reports on eliminating the interference of other metal ions on the determination of aluminum content in chromazurine S. Among them, the masking method is the most widely used. Commonly used masking agents include ascorbic acid solution, zinc EDTA solution, thioglycolic acid, etc. Adding a masking agent ca...

AI Technical Summary

Problems solved by technology

[0002] When using chrome azure S spectrophotometry to detect the aluminum content in food, since chrome azure S can form colored complexes with various metal ions, the selectivity of the chromogenic agent of this method is not high, common iron, manganese, copper, Metal ions such as zinc will interfere with it, especially iron. However, due to the low-cost instruments, simple operation and high sensitivity of chrome azure S spectrophotometry, this method is still widely used.

[0003] At present, there are many related reports about eliminating the interference of other metal ions on the determination of aluminum content in chrome azure S, among which the masking method is the most widely used, and the commonly used masking agents include ascorbic acid solution, ethylenediaminetetraacetic acid zinc solution, thioglycolic acid, etc. Adding a masking agent can indeed accurately measure the aluminum content within a certain range, but the masking ability of the masking agent is limited. If there are a large number of interfering ions in the sample, the effect of the masking agent will be greatly reduced, and the use conditions of the masking agent are harsh. , such as EDTA zinc solution with a pH of 4-6

In addition, the metal industry uses sodium hydroxide roasting to make aluminum form water-soluble metaaluminate, and then separate it from other metals. The roasting temperature of this method is high, and the measured aluminum is lost, and it is only suitable for the detection of aluminum in metals. It is not suitable for the detection of aluminum in food; there are also reports in the metal industry that after the sample is dissolved in acid, sodium hydroxide is added to separate aluminum from other metals, and then aluminum is detected, but this detection method is not chrome azure S spectrophotometry , chrome azure S spectrophotometric detection of aluminum, aluminum must be AL 3+ Alkaline state can be measured, and aluminum will co-precipitate with other alkali metals (magnesium hydroxide, calcium hydroxide, zinc hydroxide, etc.), resulting in aluminum no longer soluble in strong alkali, resulting in no detection of aluminum, this method is not correct its resolved

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