Determination of hanging white block in food

Here is an introduction to high performance liquid chromatography (according to "GB/T21126-2007 Determination of Sodium Formaldehyde Sulphoxylate Content in Wheat Flour, Rice Flour and Their Products")
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1.
Principle

In acidic solution, the sample remaining formaldehyde sodium sulfoxylate decomposition in aqueous formaldehyde is extracted, after extraction of formaldehyde with 2,4-dinitrophenylhydrazine addition reaction generates a yellow 2,4- Nitrophenylhydrazone , extracted with n-hexane , was separated by high performance liquid chromatography, qualitatively compared with the retention time of standard formaldehyde derivatives, and quantified by standard curve method
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Where X-the content of sodium formaldehyde sulfoxylate in the sample (calculated as formaldehyde), ug/g

m ₁ ——According to the peak area of ​​the derivative phenylhydrazone, the quality of formaldehyde is found from the standard working curve, ug

50——The volume of sample plus extracting solution, mL

2——The volume of the sample extract for determination, mL

m——sample mass, g

2.

Chromatographic column: chemically bonded C ₁₈ column, 4.
6mm×250mm; mobile phase: acetonitrile + water mixed solution;

Flow rate: 0.
8mL/min; UV detector wavelength: 355nm
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3.
Tips

This method is suitable for the determination of residual formaldehyde and sodium formaldehyde sulfoxylate in wheat flour, rice flour and their products
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