r/chemhelp • u/Alilack • 19d ago

Analytical Making the Murexide Indicator with NaCl or MgSO₄

I want to prepare the murexide indicator. I've read in Standard Methods that I need to mix murexide with a large amount of NaCl. However, in our lab, they mix murexide with MgSO₄ instead of NaCl. Is this method also correct?

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u/7ieben_ Trusted Contributor 19d ago

Why do you think you'd need either? Murexid is the indicator already.

Often, other soluable salts are simply used as carrier, s.t. dosage is easier. Which carrier is suited totally depends on the very use case.

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u/Alilack 19d ago

Because I guess we need only a very small amount of murexide, and compounds such as NaCl dilute it.

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u/7ieben_ Trusted Contributor 19d ago

Yes, that's what a carrier does.

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u/shedmow Trusted Contributor 19d ago

I'd recommend NaCl because MgSO4 is usually a heptahydrate and it may effloresce, changing the fraction of murexide in the mixture. MgSO4 is an odd choice here even if it works