Imagine you could save the weight of a chocolate bar in plastic every time you conduct an experiment!
Today I want to convince you that this is certainly possible.
Let us discover how much waste we can save every time we prepare an SDS-PAGE, a rather short and straightforward protocol – nevertheless, there is a lot of potential for optimization!
Work Smart, Not Hard
Always create as many gels as possible and as few as necessary. This means that if you are planning to run multiple SDS-PAGEs within the next week, prepare 2 or 4 gels at a time.
-> Advantage: This will halve or reduce to a quarter the amount of waste and time used.
Following The Right Order
Use the following pipetting order from dedicated stocks to reuse one serological pipette instead of three (cutting your waste by one-third):
- Water
- Low molecular Tris buffer
- High molecular Tris buffer
- Acrylamide
Ensure the volumes for each are large enough to pipette conveniently.
-> You cut your waste by one-third and save the time required to exchange pipettes.
Note: Be sure to use best practices and expel the liquid completely. The risk of contamination is minimal since you only take up fluid (without mixing), and this wouldn’t be a concern anyway, as you use dedicated stocks. However, we still aim to work as carefully as possible.
For SDS, 10% | N,N,N′,N′-tetramethylethylenediamine (TEMED) | Ammonium persulfate (APS), you use a single tip for each.
Traditional Approach
- 10 mL serological pipette: 3x = 26.91 g
- P1000 tip: 1x = 0.755 g
- P200 tip: 2x = 0.329 g
Sustainable Approach
- 10 mL serological pipette: 1x = 8.97 g
- P1000 tip: 1x = 0.755 g
- P200 tip: 2x = 0.329 g
28.323 g vs. 10.383 g -> 63% reduction
Keep Them With You
Each time you reuse your Falcon tubes (Tris buffers, acrylamide – SDS is often stored in a single 15 mL tube, APS and TEMED in smaller tubes), you cut down your waste even further. For us, reusing them for half a year has never caused any issues. However, for simplicity, let’s assume you reuse them 10 times:
Traditional Approach
- 50 mL tube: 10x*3 = 384.9 g
Sustainable Approach
- 50 mL tube: 1x*3 = 38.5 g
384.9 g vs. 38.5 g -> 90% savings
= Combined, these measures save more than 350 g of plastic, equivalent to the weight of 3.5 chocolate bars – just in plastic waste!
Note: We need 2x 50 mL tubes to mix our gels, so for each approach, add 25.66 g of waste to the total.
Bonus Tip
How do you know when your gel has polymerized sufficiently?
Since it is advisable to prepare a bit of excess solution in case you spill something or your apparatus is not entirely sealed, keep this remainder in your preparation tube. You will know the gel has polymerized when the leftover solution sets.
(Of note, polymerized gel is much less toxic than the liquid form, so never discard it into the sink!)
You can then leave the gel in the tube or throw it out later and reuse the tube. If you remove the gel, just be gentle and ensure no clumps are left behind. If in doubt, it’s better to discard the tube!
Weight of Items We Used (varies by manufacturer)
- 10 mL pipette: 8.97 g
- P1000 tip: 0.755 g
- P200 tip: 0.329 g
- 50 mL tube: 12.83 g