Low TE buffer is a modified version of standard TE (Tris-EDTA) buffer in which the EDTA concentration is reduced tenfold, from 1 mM down to 0.1 mM, while Tris remains at 10 mM and pH stays at 8.0. The purpose is straightforward: keep enough chelating power to protect nucleic acids from degradation by stray nucleases, but avoid carrying so much EDTA into downstream reactions that it starves enzymes of the magnesium and other divalent cations they need to work. That tradeoff between protection and interference shapes nearly every decision about when to reach for low TE versus its full-strength counterpart.
What Standard TE Does and Why EDTA Gets Reduced
Standard TE buffer has two jobs. Tris buffers the pH at 8.0, which keeps DNA in its stable, double-stranded form and discourages the slow acid-catalyzed damage that can nick or fragment strands over time. EDTA’s job is different: it grabs divalent metal ions, especially magnesium and calcium, pulling them out of solution. That matters because most nucleases (the enzymes that chew up DNA and RNA) need a divalent cation in their active site to function. Strip the metal away and the nuclease goes quiet.
At 1 mM EDTA, standard TE is aggressive enough to shut down nuclease activity in stored samples even if a bit of contaminating enzyme is present. But that same aggressiveness becomes a liability the moment you want to do something with the DNA. Polymerases, ligases, and restriction enzymes all rely on magnesium. If you pipette DNA dissolved in 1 mM EDTA straight into a PCR reaction, the carryover EDTA can chelate enough magnesium to weaken or block the polymerase. Researchers examining common PCR inhibitors found that EDTA is among the compounds that interfere with Taq polymerase function, affecting the amplification curve rather than the DNA template itself.1Journal of Forensic Sciences. An investigation of PCR inhibition using Plexor®-based quantitative PCR and short tandem repeat amplification In standard TE, one microliter of sample brings along enough EDTA to matter when reaction volumes are small.
Low TE solves this by dropping the EDTA to 0.1 mM. That tenfold reduction means far less chelator carries over into each downstream tube. In a typical 25-µL PCR reaction, a couple of microliters of low TE contributes so little EDTA that the reaction’s magnesium supply is barely touched. You still get some nuclease-suppressing benefit during short-term handling, but not enough chelation to sabotage the enzymes you actually need.
When Low TE Makes a Practical Difference
The choice between standard TE and low TE usually comes down to what you plan to do with the nucleic acid and how soon you plan to do it.
- Long-term archival storage: Standard TE is often preferred for DNA banks and biorepositories, where samples sit for months or years and no one is worried about EDTA carryover yet. The extra chelation provides a wider safety margin against nuclease contamination over time.
- Working stocks for frequent use: Low TE suits DNA that gets pulled out of the freezer regularly for PCR, quantitative PCR, library preparation, or cloning. You can pipette directly into reactions without first diluting or purifying the buffer away.
- Low-input applications: When starting material is scarce, every cleanup step risks losing sample. Researchers preparing next-generation sequencing libraries from very small amounts of DNA have resuspended purified samples in low EDTA TE specifically to avoid an extra purification step before library construction.2PubMed Central. Microfluidic platform for next-generation sequencing library preparation with low-input samples
- Sensitive fluorometric quantification: As discussed in the section below, even the modest ionic strength of TE can influence how fluorescent dyes bind DNA. Low TE carries the same Tris and salt contribution as standard TE, so it performs similarly in quantification assays without the extra chelation risk.
If your workflow involves eluting DNA off a column or beads and then immediately feeding it into an enzymatic reaction, low TE is almost always the better default. If you are banking extracted DNA from a clinical study and will not touch it again for a year, standard TE earns its keep.
How Buffer Choice Affects DNA Quantification
One of the less obvious reasons to care about your resuspension buffer is its impact on DNA concentration measurements. Researchers comparing fluorometric (Qubit) and spectrophotometric (NanoDrop) readings found that diluting DNA in TE buffer gave consistent Qubit values that tracked well with spectrophotometric estimates, while diluting the same DNA in distilled water caused the Qubit readings to diverge and underestimate the true concentration.3PLOS ONE. Pitfalls of DNA Quantification Using DNA-Binding Fluorescent Dyes and Suggested Solutions
The culprit turned out to be ionic strength. When those researchers tested sodium chloride solutions of varying concentration, they found that DNA dissolved in 1 mM NaCl or above gave stable Qubit readings, matching the TE buffer results. Below 1 mM NaCl, the double-stranded DNA appeared to shift into a slightly different conformation that the fluorescent dye bound less efficiently, dragging the apparent concentration down.4PLOS ONE. Pitfalls of DNA Quantification Using DNA-Binding Fluorescent Dyes and Suggested Solutions Standard TE contributes roughly 3 mM of sodium ions; low TE contributes a similar amount from the Tris component. Both provide enough ionic strength to keep the DNA helix in its normal conformation for dye binding.
This matters in practice more than it might sound. If you elute DNA into nuclease-free water to avoid EDTA entirely, and then use a fluorometric method to decide how much template to add to your sequencing library or genotyping reaction, you could be systematically underloading. Low TE sidesteps both problems at once: low enough EDTA to be enzyme-friendly, high enough salt to keep your quantification honest.
Freeze-Thaw Cycles and Storage Stability
Even in a good buffer, DNA does not survive unlimited freeze-thaw cycles. A study examining lambda DNA stored in Tris-EDTA buffer found roughly 10% degradation after a single freeze-thaw and about 75% degradation after 20 cycles, with the loss following an exponential decay pattern.5Nature Communications. DNA stability: a central design consideration for DNA data storage systems That degradation comes from mechanical shearing as ice crystals form and melt, and from the transient concentration spikes that occur as liquid water freezes out and solutes become more concentrated in the remaining liquid phase.
Low TE does not change the physics of ice crystal formation, so it does not magically protect against freeze-thaw damage. What it does do is make it more practical to aliquot your sample. Because you can pipette low TE directly into reactions, there is less reason to thaw the entire tube every time you need a few microliters. Aliquoting into single-use volumes before the first freeze is the simplest way to limit freeze-thaw cycles, and low TE removes the friction that might otherwise tempt someone to skip aliquoting (“I’ll just clean up the EDTA later”).
For truly long-term storage spanning years, some biorepositories still prefer standard TE because its higher EDTA concentration offers a broader protective margin. The thinking is that over very long time frames, even trace nuclease contamination can accumulate damage, and the slightly higher chelation is worth the later cleanup cost. For working stocks that get used within weeks or months, low TE is the more practical choice.
Chelation Chemistry and Nuclease Behavior
The relationship between chelators and nucleases is not always as simple as “remove the metal, kill the enzyme.” Research on a calcium-dependent nuclease found that the enzyme was not activated by free calcium but rather by calcium that was already chelated to EGTA (a close chemical relative of EDTA). Adding excess unchelated EGTA actually inhibited the enzyme, while the chelated calcium-EGTA complex kept it running.6PubMed Central. A Novel Nuclease Activity that is Activated by Ca2+ Chelated to EGTA
That finding is a reminder that chelators can have more than one effect in a biological mixture. In the case of EDTA in TE buffer, the dominant effect is straightforward: EDTA grabs free magnesium and calcium, deactivating the nucleases that need those ions. But in complex biological extracts, EDTA-metal complexes can occasionally serve as cofactors for unexpected activities. This is part of why molecular biologists tend to keep EDTA at the minimum effective concentration rather than loading up. Low TE reflects that philosophy: use enough to handle the common threats, but do not flood the system with chelator that could produce surprises in unusual sample types.
RNA Applications and Buffer pH
Low TE is primarily associated with DNA work, but RNA researchers face a related set of concerns. RNA is far less stable than DNA under most conditions, and both the buffering species and the pH of the storage solution influence how quickly messenger RNA loses integrity.7Journal of Pharmaceutical Sciences. Factors Affecting Stability of RNA – Temperature, Length, Concentration, pH, and Buffering Species Tris buffer at pH 8.0 works well for DNA but is slightly alkaline for RNA, which degrades faster under basic conditions because the 2′-hydroxyl group on each ribose sugar can attack the adjacent phosphodiester bond.
For RNA storage, many labs use a citrate-based buffer or simply nuclease-free water, keeping the pH closer to neutral or slightly acidic. When Tris-based buffers are used for RNA, the pH is sometimes dropped to 7.0 or 7.5. Low TE at pH 7.5 exists as a commercial product for exactly this reason: enough buffering to prevent wild pH swings, low enough EDTA to be compatible with reverse transcription, and a slightly lower pH to slow alkaline hydrolysis. If you are storing RNA in any Tris-EDTA formulation, confirming the pH is at least as important as confirming the EDTA concentration.
When Water Alone Is Not Enough
Given the hassle of managing EDTA concentrations, some researchers skip the buffer entirely and elute or resuspend nucleic acids in nuclease-free water. This works in the very short term, especially if the sample goes straight into a reaction. But over days or weeks, unbuffered water creates real problems.
Dissolved carbon dioxide from the atmosphere gradually lowers the pH of pure water toward 5.5 or below. At acidic pH, depurination (the loss of adenine and guanine bases from the DNA backbone) accelerates, leading to strand breaks. Without any chelator present, even trace divalent cations from the tube walls or pipette tips can support nuclease activity. And as the quantification data described earlier showed, the near-zero ionic strength of pure water destabilizes the double helix enough to throw off fluorometric concentration readings.8PLOS ONE. Pitfalls of DNA Quantification Using DNA-Binding Fluorescent Dyes and Suggested Solutions
Low TE addresses all three vulnerabilities. The Tris component buffers pH against atmospheric COâ‚‚ absorption. The 0.1 mM EDTA provides a baseline of cation chelation. And the combined ionic contribution keeps DNA in its normal helical conformation. For anything other than immediate same-day use, low TE is a meaningful upgrade over water with minimal downsides.
Preparing Low TE Buffer
Making low TE in the lab is simple enough that most groups prepare it from stock solutions rather than buying it premade, though commercial versions are widely available and convenient for labs that want sterility certification.
The recipe starts with two stock solutions: 1 M Tris-HCl at pH 8.0 (or pH 7.5 for RNA applications) and 0.5 M EDTA at pH 8.0. To make 1 liter of low TE, you combine 10 mL of the 1 M Tris stock and 0.2 mL of the 0.5 M EDTA stock, then bring the total volume to 1 liter with ultrapure water. The result is 10 mM Tris, 0.1 mM EDTA. Autoclave or filter-sterilize, and store at room temperature.
A few practical details trip people up:
- pH of the EDTA stock: EDTA does not dissolve easily until the pH is brought up with sodium hydroxide. If your EDTA stock was not properly pH-adjusted, you will have undissolved crystals that throw off the final concentration.
- Autoclaving Tris: Tris solutions shift in pH when heated, then return close to their original pH upon cooling. Always check pH at room temperature after autoclaving, not while the solution is still hot.
- Labeling: Many lab mix-ups happen because standard TE and low TE look identical. Clear labeling with the EDTA concentration is worth the five seconds it takes.
Alternatives Beyond Tris-EDTA
TE variants dominate nucleic acid work, but they are not the only option. Some researchers have explored amino acid-based buffers as alternatives, particularly for workflows involving silica-based purification. Amino acid buffers can modulate how strongly DNA sticks to silica surfaces, with positively charged amino acids promoting stronger adsorption and negatively charged ones weakening it.9PubMed Central. DNA adsorption to and elution from silica surfaces: influence of amino acid buffers This is mostly relevant to miniaturized and microfluidic systems where controlling the binding and release of DNA from solid phases is the central engineering challenge.
For routine bench work, other common alternatives include plain Tris without any EDTA (sometimes called T buffer or Tris-only), which is used when even 0.1 mM EDTA is considered too much for a particularly sensitive enzyme. There are also proprietary elution buffers sold with commercial DNA purification kits, which are typically low-salt, mildly alkaline solutions that may or may not contain trace EDTA. If you are using a kit and the manufacturer supplies an elution buffer, checking its composition against your downstream protocol is worthwhile. Some kit elution buffers are essentially low TE under a different label; others are closer to dilute Tris alone.
The overarching principle across all these options is the same balancing act that defines low TE itself: provide enough buffering and ionic strength to keep the nucleic acid stable, while introducing as few reactive components as possible that could interfere with whatever you plan to do next. Low TE sits at a sweet spot on that spectrum for the majority of common molecular biology workflows, which is why it has become something close to a default elution and storage buffer in labs that do a lot of PCR, genotyping, or sequencing.