Assuming that you are using column/membrane purification of the dna from blood A common reason for poor results is adding too much blood....this does not lead to more dna but does give dirtier dna. Try purifying smaller volumes of blood. The samples that you already.have could be further purified either by column or phenol extraction. Whether your samples will amlify depends on the primers (luck) or what enzyme you are using for the amplification. Many companies now sell genetically modified polymerases that can amplify from whole blood samples so should work with cleaner but still rather impure dna.( KAPA polymerases for instance)

Muhammad Najeeb Ullah The low A260/A280 ratio (~0.65) indicates protein or phenol contamination, which can inhibit ARMS PCR despite good DNA yield and gel quality. To improve DNA purity, perform a cleanup using a column-based kit, magnetic beads, or phenol/chloroform extraction followed by ethanol precipitation. Treating with Proteinase K and RNase can also help. If purification isn't possible, dilute the DNA and add BSA or DMSO to the PCR to reduce inhibition. For accurate concentration, use Qubit instead of NanoDrop.

A low A260/A280 ratio strongly suggests protein contamination . While the DNA bands appear good on the gel, the low ratio could negatively affect ARMS PCR, which depends on clean, specific DNA templates.

Here’s how you can proceed and improve DNA quality:

1. Purify the DNA Further

Use one of the following cleanup methods to improve purity:

• Phenol-chloroform extraction + ethanol precipitation
• Commercial DNA cleanup kits (e.g., QIAquick PCR Purification Kit, Zymo DNA Clean & Concentrator)

2. Re-check with NanoDrop

3. Test PCR on a Small Scale First

• Try ARMS PCR using cleaned DNA from 1–2 samples.
• Include a positive control with known good-quality DNA.
• Optimize MgCl₂ concentration or try adding BSA (0.1 mg/ml) to help neutralize inhibitors.