Math may be frightening but cacodylate seems not... With a MW of 214 for the trihydrate
a 70 kg clone needs at the 0.5 g/kg LD50 to consume about 35 g of it, which is 0.16M. Of a 0.1M solution you'd therefore have to drink 1.6 L or almost 4 pints. So, prost, cheers, gsuffa, bescheid, slantje, na strovje etc! BR PS: it is really not 0.5mg/g for the LD50 - it is indeed 0.25 to 0.5 g/L - I checked. For waterflea it is lower though... PPS: I remember with horror from my inorganic Chemistry Lab taking place in Boltzmann's Labs (and with the same curriculum as I suspect now), a smell test (as in sniffing into the test tube) for As, called the Cacodylprobe (aka Krokodilprobe). As I am still around (although the As sniffing may explain a few things) panic appears unwarranted. ----------------------------------------------------------------- Bernhard Rupp 001 (925) 209-7429 +43 (676) 571-0536 b...@ruppweb.org hofkristall...@gmail.com http://www.ruppweb.org/ ----------------------------------------------------------------------- The road to scientific serfdom is paved with Nature papers ----------------------------------------------------------------------- -----Original Message----- From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Frank von Delft Sent: Friday, November 09, 2012 4:27 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] usefulness of cacodylate? Hi all - Anybody know a) how hazardous is cacodylate? b) does it really matter for crystallization screens? It seems by far the most hazardous component of the standard screens; this 2011 paper seems to think so (bizarrely, I can't access it from Oxford): http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2818.1977.tb01136.x/abstra ct and this is site says lethal dose is 0.5-5g/kg: http://cameochemicals.noaa.gov/chemical/4468 meaning 2ml of a 0.1M solution contains 1/10th lethal dose...? (Someone should check my maths...) [Coarse screens come mixed 2ml per condition.] Has anybody done careful experiments that showed it really mattered for a given crystal -- or even an entire screen? So I'm inclined to toss it out entirely rather than make crystallization screening a "hazardous activity". (We're being subjected to a safety review.) Thoughts welcome. phx
