Problem: Quantifying common biomolecules such as nucleic acids and proteins efficiently without significant loss of sample is a frequent problem encountered in laboratories that regularly perform molecular biology techniques. Conventional methods such as traditional cuvette based spectrophotometers and fluorescence-based plate reading require either too much material or too much time to quantify samples. Due to these limitations, investigators often forgo quality control steps to conserve sample, save time, or both. The overall demand from the scientific community is for reduction of the time and material needed for measurement without sacrificing data quality. As molecular techniques that use less material continue to be developed, take accurate measurements with minimal consumption of sample is of paramount importance.

Solution: By using fiber-optic technology and taking advantage of the inherent surface tension properties of liquid samples, NanoDrop microvolume instruments (Thermo Fisher Scientific) can accurately quantify a wide range of biomolecules using volumes as small as 1 microliter. The patented sample retention system enables absorbance measurements to be performed without traditional containment devices such as cuvettes or capillaries. The Thermo Scientific NanoDrop™ 8000 Spectrophotometer captures and holds up to eight 1 μl samples during the measurement cycle. Using a multi-channel pipettor, 1 μl samples are pipetted directly onto the lower array of optical pedestals. An upper-array optical pedestal automatically engages the sample, using surface tension to form a liquid column that determines the mechanically controlled path length.

Once the measurement is complete, the user prepares for the next set of samples by simply cleaning the optical surfaces with a standard laboratory wipe.

By removing the need for traditional containment devices, the NanoDrop 8000 can automatically change its path length from 1 mm to 0.2 mm during the same measurement cycle. This allows for a broad dynamic range of sample concentrations to be measured (2 ng/μl to 3700 ng/μl for dsDNA), essentially eliminating the need to perform dilutions. The multi-sample capability of the NanoDrop 8000 addresses the needs of higher-throughput environments such as biorepositories, sequencing laboratories and genotyping facilities. To improve the ergonomics of the system and reduce human error, the Sample Position Illuminator keeps track of which samples are to be drawn by lighting up the appropriate wells on a 96-well plate.

Overall, scientists who work with limited sample quantities or restricted time frames need simple, elegant solutions that give sound, quality controlled data with minimum consumption of sample. NanoDrop instrumentation offers a fast, simple alternative to conventional quantitation methods.

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