A new experiment for improving A260/230s further from baseline

Why we tried this                  

Freshly collected EDTA blood usually cruises through Manta’s Blood DNA cartridges with textbook 260/280 and 260/230 ratios (≈ 1.8–2.0). But every now and then a tougher specimen shows up: samples that sat overnight, hemolysed draws, or tubes that took the scenic route to the lab. Those “seasoned” inputs sometimes carry a little more ethanol into the elution, nudging the 260/230 down. Rather than overhaul the chemistry, we tested a tiny process tweak: parking the beads on the magnet for an extra 30 seconds before elution to let residual wash buffer flash off.

The quick‑and‑dirty experiment

Unsealed cartridge controls are excluded from the averages. All the data above is average of a larger sample set.

What we saw

1. More DNA in the tube. Sample 1085 almost doubled (↗ 82 %). Sample 1086 got a modest 12 % bump.

2. Cleaner ratios. 260/230 jumped from 1.61 → 2.04 (blood sample 1085) and 2.10 → 2.28 (1086). 260/280 nudged closer to the textbook 1.8‑1.9 range.

3. Tighter reproducibility. Coefficient of variation on concentration crashed from 38 % to 8 % in the worst case.

So… does a 30‑second coffee break matter?

Apparently, yes. The extra half‑minute lets residual ethanol evaporate before elution, dragging fewer salts into the final pool. We expected nicer 260/230 values, but the jump in yield (especially on the lower‑input sample) was a pleasant surprise.

How we're rolling this out

✅Default in the Blood DNA (i4) protocol — the next Manta protocol release ships with the 30s magnet dry step baked in.

✅Firmware update— any Manta running our latest UI supports dwell‑on‑magnet commands. Earlier boxes will need a quick config push (takes ~2 min over Wi-Fi).

Got data of your own?

If you try the tweak, shoot your NanoDrop numbers to connect@cambrianbioworks.com — we'll fold community data into a living QC sheet.