Re: [ccp4bb] OFF_TOPIC: Should you be worried about BPA from plastics? Yes, if you store alkaline reagents in polycarbonate bottles!
Hi Last year there were a few reports in the chemical press (e.g. https://doi.org/10.1039/D1SC02708E, and references therein) of studies of glass catalysing reactions - it seems that it isn’t as benign as one might imagine. Of course, this will not be news to the old chemical hands on this BB... Harry > On 31 Jan 2022, at 10:09, Artem Evdokimov wrote: > > Interesting note - and a reminder that alkaline solutions are tricky :) By > personal preference, HDPE bottles are probably the best for storing strongly > alkaline solutions (XLPE also is very good, but harder to get lab-grade > bottles). > > Here's a handy chart for plastic vs stuff resistance. Note that HDPE is "E" > whereas PC (polycarbonate) is "N". > > https://www.calpaclab.com/chemical-compatibility-charts/ > > Glass is not recommended for alkali storage, although there are some glass > products that have A1 or better alkali resistance rating. They can get pretty > esoteric, especially if one requires near-complete passivity towards strongly > alkaline solutions. > > Artem > > - Cosmic Cats approve of this message > > > On Sun, Jan 30, 2022 at 1:02 PM Edward Berry wrote: > After using the same reagents for the Lowry assay and seeing the color yield > in the standard curve gradually decreasing year by year, we decided to make > new reagents last year. Sure enough the color yield was restored, but in the > next assay a few weeks later the blank was unusually high. after a month the > blank read nearly 1 AU. > > The problem was, we stored the alkaline reagent (NaOH + Na2CO3)in a > polycarbonate bottle. I like polycarbonate because it is transparent and hard > like glass, but lighter and less breakable. But polycarbonate is a polyester > of Bis-phenol A with carbonic acid. Apparently the high pH slowly hydrolyzes > the ester linkages, or the plastic retains some monomers that slowly leach > out, and (duh!) bis-phenol A gives a positive reaction with the > Folin-Ciocalto phenol reagent. > > > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing > list hosted by www.jiscmail.ac.uk, terms & conditions are available at > https://www.jiscmail.ac.uk/policyandsecurity/ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 > To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
Re: [ccp4bb] OFF_TOPIC: Should you be worried about BPA from plastics? Yes, if you store alkaline reagents in polycarbonate bottles!
Interesting note - and a reminder that alkaline solutions are tricky :) By personal preference, HDPE bottles are probably the best for storing strongly alkaline solutions (XLPE also is very good, but harder to get lab-grade bottles). Here's a handy chart for plastic vs stuff resistance. Note that HDPE is "E" whereas PC (polycarbonate) is "N". https://www.calpaclab.com/chemical-compatibility-charts/ Glass is not recommended for alkali storage, although there are some glass products that have A1 or better alkali resistance rating. They can get pretty esoteric, especially if one requires near-complete passivity towards strongly alkaline solutions. Artem - Cosmic Cats approve of this message On Sun, Jan 30, 2022 at 1:02 PM Edward Berry wrote: > After using the same reagents for the Lowry assay and seeing the color > yield in the standard curve gradually decreasing year by year, we decided > to make new reagents last year. Sure enough the color yield was restored, > but in the next assay a few weeks later the blank was unusually high. after > a month the blank read nearly 1 AU. > > The problem was, we stored the alkaline reagent (NaOH + Na2CO3)in a > polycarbonate bottle. I like polycarbonate because it is transparent and > hard like glass, but lighter and less breakable. But polycarbonate is a > polyester of Bis-phenol A with carbonic acid. Apparently the high pH slowly > hydrolyzes the ester linkages, or the plastic retains some monomers that > slowly leach out, and (duh!) bis-phenol A gives a positive reaction with > the Folin-Ciocalto phenol reagent. > > > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ > To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
[ccp4bb] OFF_TOPIC: Should you be worried about BPA from plastics? Yes, if you store alkaline reagents in polycarbonate bottles!
After using the same reagents for the Lowry assay and seeing the color yield in the standard curve gradually decreasing year by year, we decided to make new reagents last year. Sure enough the color yield was restored, but in the next assay a few weeks later the blank was unusually high. after a month the blank read nearly 1 AU. The problem was, we stored the alkaline reagent (NaOH + Na2CO3)in a polycarbonate bottle. I like polycarbonate because it is transparent and hard like glass, but lighter and less breakable. But polycarbonate is a polyester of Bis-phenol A with carbonic acid. Apparently the high pH slowly hydrolyzes the ester linkages, or the plastic retains some monomers that slowly leach out, and (duh!) bis-phenol A gives a positive reaction with the Folin-Ciocalto phenol reagent. To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
