have you thought about sephadex g25 or 50 or similar size exclusion column separation. it is very good for desalting and very quick and you can use simple columns like Pasteur pipettes blocked with glass wool at one end or spin columns

Thankyou Paul Rutland. I hadn't, but after more looking, I think I definitely will now. I will also purchase some glass wool because that'd definitely be a useful fall back.

if your lab uses spin columns for cleaning up sequencing (Sanger) reactions then these make good general desalting columns if your volumes are less than 50ul and the membrane is designed not to bind dna and can be refilled and reused a few times