Re: [DIYbio] Non-Platinum Electrophoresis Electrodes That Don't Degrade

An FYI - ions generated from stainless steel, zinc metals, chromium, lead, copper, etc. during electrophoresis degrade RNA and DNA by attacking the phospohodiester backbone. If you are planning on cutting out DNA bands from your gel for cloning or other work - only platinum, gold or graphite electrodes would work. 
Conductive plastic?

On Thursday, October 22, 2015 at 3:31:26 PM UTC-7, John Griessen wrote:
I had an urge to search for a while, and found some practical info about electrodes that could help.

1.  The bigger they are  --  http://www.sciencemadness.org/talk/viewthread.php?tid=1519
        Has amateur chemists talking about
        driving reactions with electricity and high voltage.  They say that current density is what causes graphite to
        decay, not how high the voltage is.

        So, with big area of an electrode as a guide,  ebay China sellers offer fat electrodes 150mm long for $1.25 --
        http://www.ebay.com/itm/5-pcs-99-99-Graphite-Electrode-Cylinder-Rod-Length-150mm-Diameter-5mm-U6C-7-/181566352494

2.  The harder they come --  http://link.springer.com/article/10.1007%2Fs10800-008-9518-2?LI=true       paywalled paper
        A guide just from the abstract:
        "This work studied the voltammetric response of graphite reinforcement electrodes made of different pencil
        lead hardness. The studies showed that harder graphite leads, regardless of their manufacturer, are more
        appropriate as electrode material for voltammetric purposes due to their higher peak currents,
        increasing sensitivity and reproducibility"

        So, hard drafting pencil leads might be good for electrophoresis:
        9H is super hard, and available from aliexpress --
        http://www.aliexpress.com/item/KOH-I-NOOR-2-0-mm-Mechanical-Lead-Graphite-Lead-Black-9H-7H-6H-5H-4H/32393524530.html
        $6 for 12 pieces 120mm long

3.   Pt alternatives  --  Not a low cost answer, but on   http://www.sciencemadness.org/talk  --
        Someone mentioned iridium as electrode lasts for decades in production use and costs same as Pt.

4.   Nano surfaced  pencil graphite  --
http://www.linknovate.com/publication/mwcnt-modified-composite-pencil-graphite-electrodes-fabricated-by-direct-dripping-and-electrophoretic-deposition-methods-a-comparison-study-1480071/
        This article is available free for this week because the publisher is letting down their paywall
        as a promotion.  You can wade through how to get it, or ask me to resend it.  has nice SEM photos
        of 6H  (hard) pencil lead and 2B (soft) before and after coating with CNTs.

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