I'm using the Qiagen Gentra Puregene DNA Extraction Kit. I'm getting qualities between 1.84-1.97. Is there an acceptable range? I recall someone telling me 1.7-1.9, but I'm not certain.
Pure DNA has a 260/280 ratio of 1.80, so if you are getting between 1.84 and 1.97 your DNA is doing great. Theoretically values higher than 1.80 could mean that you have some RNA with your DNA. If a small amount of RNA in your DNA could affect your downstream applications, which in most cases is not the case, you can always RNAse treat your DNA.