NanoDrop

The NanoDrop is a commonly used laboratory spectrophotometer. The reduced preparation and cleanup time compared to what is required for reading a single sample in a traditional cuvette means that multiple samples can be measured in less than a minute. The NanoDrop performs well across a broad optical spectrum, covering both ultraviolet (UV) and visible light ranges. It is designed to measure 0.5-2 microliter samples with high precision and reproducibility. The NanoDrop operates based on Beer’s Law, which states that when monochromatic light (light with a specific wavelength) passes through a solution, there is typically a quantitative relationship between the concentration of solutes and the intensity of light transmitted. In other words, the higher the concentration of the sample, the less light is transmitted through it.

To convert OD (optical density) to the concentration of unknown nucleic acid samples, the following conversion factors are used:

A260 dsDNA = 50 µg/ml

A260 ssDNA = 33 µg/ml

A260 ssRNA = 40 µg/ml

Before acquiring the NanoDrop spectrophotometer, we were accustomed to using cuvettes and all associated procedures. However, the simplicity of using the NanoDrop for measuring RNA and DNA is remarkable. The sample volume of just one microliter results in tremendous savings in reagents. This is particularly important when working with RNA extracted from tissue biopsies, making every nanogram of RNA valuable. Additionally, since the sample can be easily removed by wiping the droplet from the measurement surface, a large number of samples can be analyzed in a relatively short time.

Unlike other small spectrophotometers, the NanoDrop is capable of scanning samples across a range of 220-750 nm. This is a beneficial feature as it can provide important analytical information (such as assessing the efficiency of a dye). For some users, the need to connect the NanoDrop to a computer can be seen as a drawback, primarily due to the space required to set up the entire system. However, the ability to archive measurements graphically compensates for this limitation. Occasionally, we encounter strange error messages during measurement; however, we have found that restarting the computer usually resolves the issue.

Overall, the NanoDrop is a powerful and advanced device for measuring DNA and RNA concentrations. For laboratories with high demand for sample analysis, this tool provides a cost-effective solution that quickly pays for itself in a short amount of time.