What are the possible reasons for the sample to turn a faint pink when the bromcresol-green methyl red indicator is added instead of the normal blue-green color?

Dokument-ID

Dokument-ID TE103

Veröffentlichungsdatum

Veröffentlichungsdatum 08.01.2019
Frage
What are the possible reasons for the sample to turn a faint pink when the bromcresol-green methyl red indicator is added instead of the normal blue-green color?
Zusammenfassung
Alkalinity indicator has unexpected faint pink color and not blue-green color
Antwort
The total alkalinity indicator bromcresol-green methyl red will turn the sample blue-green in color. If the sample turns a faint pink color then the sample contains an interference. The most common interference to the alkalinity titration methods is chlorine above 3.5 mg/L. Chlorine at this concentration will bleach the normal color of the indicator.

To remove the chlorine interference, pretreat the sample by adding 1 drop of the Sodium Thiosulfate Standard Solution, 0.1N, 100 mL MDB (Product # 32332) per 100mL sample, before adding any other reagents.

For more information on common alkalinity interferences, please reference What are some common interferences in the alkalinity titration methods?

Hat dir diese Antwort geholfen?

Wird gesendet...
Vielen Dank für Ihr Feedback.
Beim Senden ist ein Fehler aufgetreten. Versuchen Sie es erneut.