Hello Stefano,
I would quantify EDTA by titration with a standard Zn2+ ion solution using a Ca-selective electrode / reference electrode pair as end-point indicator. The typical Ca2+ ion-selective PVC membrane electrode is more selective towards Zn2+ ions than towards Ca2+ions. If the food contains already complexed Ca2+ ions the Zn2+ solution will displace the calcium at a pH-value of around 4 and thus will determine the total EDTA amount. An excess of the Zn2+-solution will shift the EMF several hundred mV more positive. NaOH can be determined by titration with a standard acid solution (sulfuric acid or HCl) using a pH-electrode as end-point indicator. To ensure that NaOH is the only base a control of the sodium content with flame photometry will verify the assumption.
- Badges
- Science method
- Similar topics
- Chemistry
- General Biochemistry
- Biochemical Techniques
- Analytical Chemistry