Application method using polarography
After the degradation of biological samples (e.g. milk,
wool, etc.), it is often important to know the cystine/cysteine
ratio. The proposed method describes the simultaneous
determination of the two amino acids
by differential pulse polarography
at the dropping mercury electrode (DME).
Milk and sodium caseinate produced from milk have high
protein contents. They have to be analyzed in alkaline
solution to prevent precipitation of proteins on the
separation column. The determination limits are approx.
50 µg/L for cysteine and approx. 1 mg/L for cystine.
The polarographic determination of cystine and cysteine
with Metrohm’s devices is easy and straightforward:
Just choose the method in the built-in database
of your 797 VA Computrace and start the determination.
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Food
Analysis 
