A spectrophotometer measures how much light a sample absorbs or transmits at specific wavelengths. Because absorbance relates directly to concentration (the Beer-Lambert law), it's a central tool for quantifying nucleic acids and proteins, running colorimetric assays, and monitoring reactions. Matching the instrument to your applications keeps measurements accurate and your workflow efficient.
Visible vs. UV-Vis
The wavelength range you need is the biggest decision. Visible spectrophotometers (roughly 320–1000 nm) handle routine colorimetric work such as protein assays and OD600 cell density. UV-Vis instruments (about 190–1100 nm) add the ultraviolet range required to measure DNA, RNA, and proteins directly at 260/280 nm. If nucleic acid quantification is in your future, choose UV-Vis.
Key factors to consider
- Wavelength range and accuracy: Ensure it covers your assays, with good wavelength accuracy and reproducibility.
- Optical design: Single-beam instruments are economical and compact; split-beam and double-beam designs correct for lamp drift and give greater stability for demanding quantitative work.
- Spectral bandwidth: A narrower bandwidth improves resolution and the ability to distinguish closely spaced peaks.
- Sample format: Standard cuvette holders, micro-volume (a few microliters) for precious samples, and flow cells for continuous or high-throughput reading — pick what fits your samples.
- Software and data handling: Onboard methods, stored standard curves, and easy export (USB/PC) speed up analysis and reporting.
Tips for reliable readings
Always blank against the correct reference, use matched, clean cuvettes (quartz for UV work), and let the lamp warm up and stabilize before measuring. Keep samples within the instrument's linear range — dilute highly concentrated samples rather than reading off-scale. Small disciplines like these are what separate trustworthy data from noisy results.
Browse our Laboratory Spectrophotometers to find the right instrument for your assays.