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From: Jack Reidy <jreidy2**At_Symbol_Here**STANFORD.EDU>
Subject: Re: [DCHAS-L] Phenolphthalein or Replacement?
Date: Nov 11, 2025 15:28 UTC
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: <BYAPR02MB5686278E591B53FC33A351388CCFA**At_Symbol_Here**BYAPR02MB5686.namprd02.prod.outlook.com>
In-Reply-To: <CAFCR6uZ38qew20uN1qVSmN10ZBmt-5H6bwX2iBMCzRXv-tkzpQ**At_Symbol_Here**mail.gmail.com>
Hi all,
I’m not sure what our labs currently use, but I remember that when they were shipping lab kits out during COVID, they used
red cabbage as an indicator.
Sincerely,
Jack Reidy (he/him)
Research Safety Specialist & Chemical Hygiene Officer
Environmental Health & Safety
Stanford University
484 Oak Road, Stanford, CA, 94305
Tel: (650) 497-7614
I acknowledge that the land on which I live and work is the ancestral and unceded land of the
Muwekma Ohlone Tribe. As an uninvited guest on these lands, I am a beneficiary of the ongoing displacement of the Ohlone people. I pay my respects to the Native peoples, past and present.
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
On Behalf Of David EldrEdge
Sent: Monday, November 10, 2025 6:08 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] Phenolphthalein or Replacement?
Our School's EHS responded to a question that was brought up about phenolphthalein:
"I verified this with the wastewater district, and they confirmed that it [phenolphthalein] cannot be disposed of down the drain. I want to be cautious here if we start
discharging materials improperly, it could trigger a wastewater audit and potentially open Pandora’s box for the college."
What do you all do? Are you still using phenolphthalein or have you replaced phenolphthalein with something like bromthymol blue or something similar? Do you get the same results or better?
or...
Are you still using phenolphthalein, if so how do you deal with the waste? If collecting the waste, is it worth the cost of disposal?
Warm regards,
David EldrEdge
Co-Owner
NALTIC Industrials, LLC
888.891.0077 Main
435.503.4972 Cell
435.767.7714 Google Voice & Text
435.654.2727 Fax
ᐧ
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