2
2.27
2
2.27
The RNA Purity Calculator evaluates the quality of your RNA sample using two key spectrophotometric ratios: A260/A280 for protein contamination and A260/A230 for organic contaminant assessment. High-quality RNA is essential for reliable results in qRT-PCR, microarray analysis, and RNA sequencing. This tool provides instant feedback on whether your RNA extraction protocol yielded sufficiently pure material for downstream applications.
Two purity ratios are calculated from three absorbance readings:
A260/A280 Ratio = A260 / A280
A260/A230 Ratio = A260 / A230
Inputs
Results
A260/A280 of 2.00 and A260/A230 of 2.27 indicate highly pure RNA suitable for all downstream applications.
Inputs
Results
A260/A280 of 1.50 indicates significant protein contamination. The RNA should be re-purified before use in sensitive applications.
The ideal A260/A280 ratio for pure RNA is approximately 2.0. Ratios between 1.8 and 2.1 are generally acceptable for most applications. Values below 1.8 suggest protein contamination, while significantly higher values may indicate degradation or buffer effects. Note that DNA has an ideal ratio of ~1.8, so a lower ratio in an RNA prep could also indicate DNA contamination.
Yes, pH significantly affects the A260/A280 ratio. Measuring nucleic acids in water (slightly acidic) can lower the ratio by 0.2–0.3 compared to measuring in TE buffer (pH 8.0). For reproducible and accurate purity assessment, always measure your samples in a slightly alkaline buffer such as 10 mM Tris-HCl pH 8.0.
If both ratios are suboptimal, consider re-extracting your RNA using a column-based kit (such as RNeasy) which generally yields cleaner RNA than organic extraction methods. Alternatively, perform an additional cleanup step: ethanol precipitation with sodium acetate can remove many contaminants, or use a commercial RNA cleanup column to polish the sample.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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