[Histonet] Formalin pH

[Tony Henwood]

Hew-Shue (1991) has described a useful pH indicator for working neutral buffered formalin solutions. Bromocresol purple, when added to formalin solutions, serves as an indicator of pH as well as, from a safety aspect, labelling the solution as formalin making redundant the dangerous “smell” test. At an acidic pH (5.2) the intense indicator colour is yellow whereas at pH 6.8, the colour is purple. A saturated solution of the dye is prepared, and 2 to 4 drops are added to 10 litres of neutral buffered formalin. Other advantages are that the fixative is more readily distinguished from other colourless solutions such as saline, thus preventing accidental misuse, and formalin spills are more easily recognised.

Hew-Shue N (1991) “Bromcresol Purple as a Colored Marker and pH Indicator for Ten Percent Neutral Buffered Forrnalin” J Histotechnol 14(4):257-260.


Regards,

Tony Henwood MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) (Retired)
Principal Scientist, the Children’s Hospital at Westmead (Retired)
Adjunct Fellow, School of Medicine, University of Western Sydney.

From: Bacon, Charles via Histonet<mailto:histonet at lists.utsouthwestern.edu>
Sent: Thursday, 14 September 2023 6:42 AM
To: ewj at pigs.ag<mailto:ewj at pigs.ag>
Cc: HistoNet<mailto:histonet at lists.utsouthwestern.edu>
Subject: Re: [Histonet] Formalin pH

We pull the COA from the vendors website. Some are better than others but the are usually listed by lot number. I keep them in a network shared folder so they can be pulled by anyone that is asked for the evidence during inspection.

Sent from my iPhone

> On Sep 13, 2023, at 8:22 AM, "ewj at pigs.ag" <ewj at pigs.ag> wrote:
>
> Sooner or later the people have got to rise up
> and tell those brain-dead paper-shuffling regulators
> to just stuff it.  Their mindless interference is
> just wasting time and interfering with people's
> ability to keep their own garden.
>
> -----Original Message-----
> From: Cooper, Brian via Histonet
> Reply-To: Cooper, Brian
> To: Paula Sicurello, HistoNet
> Subject: Re: [Histonet] Formalin pH
> Date: Today 10:19 AM
>
> Ask your vendor to send a certificate of analysis that includes the pH. That's what we did and now they come with each lot. We do have to bug them for them occasionally.
>
> I'm betting your vendor has at least heard about this from other customers so it should be on their radar at the very least.
>
>
> Thanks,
>
>
>
> Brian D. Cooper, HT (ASCP)CMQIHCCM| Histology Supervisor
>
> Department of Pathology and Laboratory Medicine
>
> Children's Hospital Los Angeles
>
> 4650 Sunset Blvd MS#43- Los Angeles, CA 90027
>
> Ph: 323.361.3357<tel:+13233613357>
>
> bcooper at chla.usc.edu<mailto:bcooper at chla.usc.edu>
>
> ________________________________
> From: Paula Sicurello via Histonet <histonet at lists.utsouthwestern.edu>
> Sent: Tuesday, September 12, 2023 7:12:05 PM
> To: HistoNet <histonet at lists.utsouthwestern.edu>
> Subject: [Histonet] Formalin pH (EXTERNAL EMAIL)
>
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> This email came from outside CHLA. Do not open attachments, click on links, or respond unless you expected this message and recognize the email address: histonet-bounces at lists.utsouthwestern.edu.
>
> Hello Histoteckies,
> What are y'all doing regarding the CAP requirement to monitor the pH of formalin?
> We buy tons and tons of the 5 gallon cubitainers and we are still debating over how to check the pH.
>
> Looking forward to your replies.
> Toodles!
> Sincerely,
>
> Paula Sicurello
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