NP40 (was Re: nucleus removal in Sf9 cells.)

Ian A. York iayork at
Mon Jan 5 11:44:38 EST 1998

In article <U55850.835.00129CA8 at>,
Arthur Wohlwill <U55850 at> wrote:
>Are NP-40 and Nonidet P40 the same thing?  Someone told me they were not.  If 
>so, what is the difference.

It seems to depend who you ask.  The Calbiochem catalogue uses them
synonymously (lists NP-40, and puts Nonidet P40 in brackets), but the
Sigma catalogue says under NP40 "This detergent is often mistaken for
Nonidet P40".  

The Calbiochem NP40 is octylphenoxylpolyethoxyethanol.  Sigma says that
NP40 is nonylphenoxy polyethoxy ethanol and Nonidet P40 is octylphenoxy
polyethoxy ethanol; thus according to Sigma Calbiochem is selling Nonidet
P40, not NP40.  On the other hand, Sigma also says that Nonidet P40 is no
longer sold, and that the equivalent product is igepal CA-630 ("chemically
indistinguishable from Nonidet P40").  My Calbiochem catalogue is '96-'97,
so perhaps this is updated.

Sigma says under NP40 that it's a solid at room temperature, so I suspect
that most of the "NP40" that's used is actually "Nonidet P40".  

It's all rather confusing, really.

    Ian York   (iayork at  <>
    "-but as he was a York, I am rather inclined to suppose him a
     very respectable Man." -Jane Austen, The History of England

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