What Consumables Does Gel Electrophoresis Need?

# What Consumables Does Gel Electrophoresis Need?

If you have ever stood in the reagent room wondering which boxes actually belong to the gel rig budget, this one is for you. Gel electrophoresis looks like an instrument purchase, but the real spend, month after month, hides in consumables. I will walk through everything a typical run burns through, from the gel itself to the membrane downstream.

A run consumes the gel itself (agarose you pour, or a precast polyacrylamide cassette), running buffer such as TAE, TBE, or Tris-glycine, a DNA stain, loading dye, and a size ladder. Around those sit pipette tips, tubes, gel extraction supplies and, for protein work, blotting membranes and transfer buffer.

Each category has one or two small decisions that decide whether your bands come out sharp or smeared. Here is the full list, with the buying notes I wish someone had handed me earlier.

The gel itself: precast or hand-poured

For DNA work, most labs still pour their own. A hand-poured agarose gel consumes surprisingly little: agarose powder, running buffer, a conical flask, a casting tray, a comb, and lab tape to seal the tray. A routine plasmid check might be a 1.2% agarose gel in 0.5× TBE, which is 1.2 g of agarose per 100 mL of buffer. Ten minutes in the microwave, a cool-down to about 60 °C, and you are casting.

Protein work is different. Unpolymerized acrylamide is a neurotoxin, so many labs have moved to precast polyacrylamide cassettes. These arrive in sealed plastic with the stacking gel already poured, often as two-gel cassettes. What you consume per run is the cassette itself, plus buffer, and you skip the APS and TEMED entirely. If your lab still hand-casts, the shopping list grows: acrylamide/bis solution, ammonium persulfate (fresh, always), TEMED, SDS, and casting frames with glass plates.

The trade-off is shelf life. Precast gels expire, usually within weeks to a few months depending on chemistry, so ordering a year’s worth is how labs end up throwing money into biohazard bins. Buy for the month. The nucleic acid electrophoresis protocols from Sigma-Aldrich give a good side-by-side of what each gel format needs.

Buffers and stains: TAE vs TBE, reuse, and bulk storage

Running buffer is your biggest recurring line item, and the TAE-versus-TBE choice shapes the whole workflow.

TAE (Tris-acetate-EDTA) resolves large fragments well and keeps DNA friendly for downstream enzymes, so it is the default if you plan to cut bands out for cloning. Its weakness is buffering capacity: acetate gets exhausted, and in my experience a tank of TAE is good for roughly two to three runs before the bands start to look tired. TBE (Tris-borate-EDTA) holds its pH far longer, gives sharper bands under 2 kb, and tolerates three to five runs. One caution: borate interferes with ligation, so TBE gels are for viewing, not extracting. If your tracking dye front drifts yellow during a run, the buffer is acidified and done, no matter what the reuse schedule says. Stellwagen’s review on DNA electrophoresis in agarose and polyacrylamide gels covers how strongly matrix and buffer chemistry affect mobility, if you want the theory.

Stains sit next to buffers in the cold room. Ethidium bromide at 0.5 µg/mL still works and is cheap, but it is a mutagen, so many labs pay a bit more for safer dyes like SYBR Safe or GelRed and skip the segregated waste stream. Loading dye (typically 6×, with glycerol or ficoll plus bromophenol blue and xylene cyanol) and a DNA ladder in the right size range complete the set. One practical tip: pre-mixed 6× loading dye costs barely more than the components and removes a failure mode.

Storage is where glassware enters the picture. Most labs make 50× TAE or 10× TBE stock, store it in glass media bottles at room temperature, and dilute with a graduated cylinder on run days. Concentrated TBE eventually precipitates; once you see crystals or sediment, the stock is done. If you are stocking up, our reagent and media bottles guide covers bottle sizes, threads, and what survives autoclaving.

Pipetting consumables: the tips that quietly decide band quality

Tips sound like the boring part, and then a bad tip box ruins a gel. Cheap tips with rough mold seams or inconsistent orifices can shear large fragments and load unevenly, which shows up as smeared or smiling bands. Filter tips matter whenever you pipette buffer back out of a tank or handle the ladder, because the inside of a pipette is exactly where cross-contamination hides between runs.

Two specifics worth committing to: use low-retention tips for anything under 10 µL, since your ladder and stain volumes are tiny and every microliter left behind in the tip is money and accuracy lost. And keep a box of long, thin gel-loading tips by the tank; fighting to load a well with a standard 200 µL tip is how wells get punctured and lanes cross-contaminate. The same rule about DNA-safe tips applies to your PCR bench, as we covered in what consumables PCR and qPCR work needs. For a deeper dive on tip types, see what pipette tips labs actually need.

Downstream consumables after the run

What you buy after the gel depends on what the gel is for.

If you are extracting DNA, a gel extraction kit consumes spin columns, binding and wash buffers, plus a clean, sharp blade for excising the band. Two consumable habits make a real difference here: trim excess agarose away aggressively, and keep UV exposure short, since the light that lets you see the band also damages the DNA you are recovering.

If the gel feeds a western transfer, the shopping list grows. Blotting membranes come as PVDF or nitrocellulose, in 0.45 µm for routine work and 0.2 µm when your protein is small. PVDF needs a methanol activation step and is more durable; nitrocellulose skips activation and binds well but tears more easily. You also consume filter paper for the transfer sandwich and Tris-glycine transfer buffer. Thermo Fisher’s western blot membrane selection guide compares the two chemistries in detail, worth reading before you commit to one. We cover the whole downstream workflow in what consumables western blotting needs.

And a small confession with stakes attached: I once ran a protein gel where a precast cassette leaked during the run. By the time anyone noticed, buffer had drained to the point that the current path collapsed, and the ladder lane diffused into the sample lane next to it. The samples were irreplaceable. That single afternoon is why I now inspect cassettes for hairline cracks before every run and keep a spare box of the exact cassette type in the drawer.

Buying and storage: the unglamorous half that saves money

Most of these items are cheap individually and wasteful collectively. A few habits keep the spend honest.

Store concentrated stocks in dedicated buffer bottles, dilute with a graduated cylinder rather than “eyeballing” into the tank, and label every bottle with contents, concentration, and prep date. Stains and any light-sensitive dye go in amber glass or a dark cupboard, not the shelf by the window. Staining trays are consumables too if you stain in solution; a dedicated set of shallow trays saves you from staining gels in beakers, which is how breakages happen. A one-page summary:

Conclusion

Gel electrophoresis is not an expensive technique at the bench; it is a steady one. The gel format, the buffer you commit to, the tips in the box, and the membrane downstream are all consumables, and each one offers a cheap upgrade that shows up in band quality. If you only change one thing this week, check your buffer reuse habit, since exhausted TAE is the most common cause of gels that look “off” with no obvious bug. Then audit storage, because half of wasted consumables die on a shelf, not in a tank. When you are ready to look at neighboring workflows, our guides to PCR and qPCR consumables and western blotting consumables pick up right where the gel stops.

Frequently Asked Questions

Can you reuse TAE buffer?

You can, for about two to three runs, though TBE tolerates reuse better. Discard it if the pH has drifted, the dye front runs yellow, or you see any cloudiness. For sensitive work such as gel extraction ahead of cloning, fresh buffer every time is the safer call.

How much agarose do I need for a 1% gel?

One gram per 100 mL of running buffer. For a typical mini-gel you will use 40 to 50 mL total, so roughly 0.4 to 0.5 g of agarose. Weigh for the gel volume of your specific tray rather than guessing.

Which membrane should I choose for western blot, PVDF or nitrocellulose?

Either works for most chemiluminescent blots. PVDF is more durable and binds more protein but requires a methanol activation step; nitrocellulose skips activation and is easier to handle, though it tears more easily. Use 0.2 µm pore size if your target protein is under about 20 kDa.

Do I need filter tips for gel loading?

For loading wells, gel-loading tips without filters are fine and cheaper. Where filter tips earn their keep is handling stains, ladders, and anything you are pipetting out of a shared tank, because they stop aerosols and drips from contaminating your pipette between runs.