Which agarose concentration should I use for my DNA fragments?

As a working rule, use 0.7 percent agarose for fragments of 1 to 10 kb, 1.0 percent for 0.5 to 7 kb, 1.5 percent for 200 to 3,000 bp and 2.0 percent for fragments below 500 bp. Higher concentrations resolve small fragments better but slow the run and reduce loading capacity. For very large fragments above 10 kb, use 0.5 to 0.7 percent with a lower voltage and a longer run time.

Should I use TAE or TBE buffer for agarose gels?

TAE gives better resolution for fragments above 1 kb and is the common choice for routine cloning checks, but it has low buffering capacity and should be recirculated or replaced for long runs. TBE has higher buffering capacity, resolves small fragments better and suits longer or higher-voltage runs, but borate can interfere with downstream enzymatic steps. Choose one, prepare it consistently, and do not mix the two within a single tank.

How should agarose and buffer concentrates be stored in Singapore?

Store agarose powder dry at room temperature in a sealed container away from humidity; a desiccator is useful in a Singapore laboratory where relative humidity is high. Store 50x TAE or 10x TBE concentrates at room temperature, and dilute working buffer with distilled water as needed. Discard working buffer that becomes cloudy or shows growth, and never top up a tank with fresh buffer without replacing it periodically.

Does JWRESEARCH supply precast gels and electrophoresis accessories?

Yes. JWRESEARCH supplies agarose powders in several grades, 50x TAE and 10x TBE concentrates, DNA and protein ladders, loading dyes, nucleic acid stains, precast agarose gels, casting trays, combs, gel tanks and power leads. We also supply nitrile gloves, lab film and gel documentation accessories, delivered across Singapore.

Gel Electrophoresis Supplies Singapore

Published: {{NEW_ARTICLE_DATE}} | By JWRESEARCH | Category: Laboratory Consumables

A gel that runs badly rarely announces why. The band smears, the ladder looks crooked, the small fragment disappears off the bottom, and the temptation is to blame the sample. In most cases the cause is upstream: the wrong agarose concentration, a buffer that has been reused too many times, or a gel poured too hot and set unevenly.

At JW RESEARCH SUPPLY, we supply agarose, buffer concentrates, ladders, loading dyes, stains and casting accessories to molecular biology, diagnostics and teaching laboratories across Singapore. This guide sets out the consumable specifications that actually change a gel result.

Consumables Compared

Item	Typical Specification	Role	Points to Watch
Agarose, standard	Molecular biology grade, EEO ≤ 0.15	Routine DNA and RNA gels	Check moisture content and lot-to-lot gel strength
Agarose, low melting	Gelling 26 – 30 °C, melting 65 °C	In-gel extraction, enzymatic reactions	Lower gel strength; handle carefully
TAE concentrate	50x, pH 8.0 – 8.3	Routine DNA electrophoresis	Low buffering capacity; replace for long runs
TBE concentrate	10x, pH 8.0 – 8.3	Small fragments, longer runs	Borate carryover can inhibit later steps
DNA ladder	100 bp, 1 kb or custom range	Size reference and yield estimate	Heat and freeze-thaw degrade the ladder
Loading dye	6x with bromophenol blue or xylene cyanol	Tracks loading and monitors the run	Dye front does not equal fragment size
Precast gel	0.8 – 2% agarose, single use cassette	Fast routine checks, teaching labs	Check expiry and storage temperature

Specification Reference

Parameter	Typical Range	What It Affects
Agarose concentration	0.5% – 3.0% (w/v)	Resolution window and run speed
Gel thickness	3 – 10 mm	Well capacity and handling strength
Well count and volume	8 – 20 wells; 10 – 50 µL	Samples per run and loading comfort
Applied voltage	5 – 10 V/cm of gel length	Resolution; excessive voltage causes smearing
Buffer volume	Just covers the gel by 2 – 5 mm	Heat dissipation and current stability
EEO rating	≤ 0.15 for standard molecular biology agarose	Electroendosmosis and band sharpness
Gel strength	≥ 1,200 g/cm² at 1% for standard grades	Whether the gel survives loading and handling
Stain	Ethidium bromide or safer alternatives	Sensitivity, safety and waste handling

Matching Agarose Concentration to Fragment Size

Concentration is the single most useful variable. A 0.8 percent gel separates fragments from about 800 bp to 10 kb cleanly; a 2 percent gel resolves fragments below 500 bp that would run together on a looser gel. If a band is faint and diffuse at the bottom of the gel, the fragments are probably smaller than the gel can resolve rather than absent.

Pour the gel at a consistent thickness and let it set undisturbed. A gel poured too hot, or moved while setting, produces a wedge that tilts every band. Use the same tray and comb combination each time so that well depth and spacing stay constant between runs.

Buffer Practice

Prepare working buffer from a concentrate with distilled water and record the date on the bottle. Reusing running buffer is acceptable for a small number of short runs, but the ions deplete and the pH drifts, which shows up as slow migration and fuzzy bands. For long or high-voltage runs, recirculate the buffer or replace it.

Keep TAE and TBE systems separate. Residues of borate from TBE can inhibit ligation and sequencing reactions if glassware or tanks are shared without rinsing. If your workflow includes both, label tanks clearly and rinse with distilled water between uses.

Loading, Ladders and Documentation

Ladder choice: pick a ladder that brackets your expected fragment sizes, and load the same amount on every gel so band intensity is comparable.
Ladder storage: aliquot to avoid repeated freeze-thaw; a ladder that has been thawed ten times gives uneven bands.
Loading dye: the dye front tells you how far the run has progressed, not how large the fragments are; do not stop the run purely on colour.
Staining: follow the stain manufacturer's concentration and time, and image within a consistent window so results are comparable across gels.
Documentation: capture an image with the ladder visible and record voltage, time, gel percentage and buffer lot.

Safety and Waste

Ethidium bromide is a mutagen and must be handled with gloves, in a designated area, with its own waste stream. Safer alternatives reduce the hazard but still require disposal according to your institution's procedure. Agarose gels containing stain should never go into general waste or down a sink.

Electrophoresis tanks use direct current at potentially hazardous voltage. Check leads and lid interlocks before each run, and never open a tank while the power supply is on.

Ordering Checklist

Fragment size range and required resolution
Agarose grade and concentration
Buffer system: TAE or TBE, concentrate volume
Ladder range and format
Precast gels or in-house casting supplies
Stain type and waste disposal route

Tell us your fragment range, throughput and buffer preference, and we will propose a consumable list with pack sizes that match your weekly gel count, delivered across Singapore.

Contact JWRESEARCH

JW RESEARCH SUPPLY — laboratory equipment and consumables, Singapore.
Telephone / WhatsApp: +65 8039 3660
Email: SINGAPORE@JWSHY.COM
Website: www.jwresearch.cn