Spectrophotometer cuvettes

Cuvettes are optical containers used in spectrophotometers for quantitative and qualitative analyses of substances in solutions.

About this subject

Cuvettes are essential components in laboratories performing spectrophotometry, a technique that measures light absorption by a sample. They come in various materials, such as glass, plastic (polystyrene, polymethyl methacrylate), and quartz, each with distinct transmittance ranges. Quartz cuvettes, for instance, allow UV measurements down to 190 nm, while glass ones absorb UV and are suitable only for visible light. The most common path length is 1 cm, but variations for microvolumes exist.

In daily use, cleanliness is crucial to avoid contamination and result deviations. Disposable plastic cuvettes are practical for routine work, while quartz ones, more expensive, are reusable with care. Spectrophotometry with cuvettes is standard for protein assays (Bradford method), nucleic acids (260/280 nm), and enzyme kinetics. The Beer-Lambert law relates absorbance to concentration, and the cuvette ensures a fixed optical path.

A curiosity: flow-through cuvettes allow real-time analysis in chromatography. Recent advances include miniaturized cuvettes for microfluidics, reducing sample and reagent volumes.

Frequently Asked Questions

What is the difference between quartz and glass cuvettes?

Quartz cuvettes transmit UV light down to 190 nm, ideal for ultraviolet analyses. Glass cuvettes absorb UV and only work in the visible range (above 320 nm), but are cheaper.

How to clean spectrophotometer cuvettes?

Wash with distilled water and mild detergent, rinse thoroughly, and air dry or use soft tissue. For stubborn residues, use dilute nitric acid or organic solvent, avoiding abrasives that scratch the optical surface.

What are microvolume cuvettes used for?

They allow analysis of samples with volumes from 2 to 50 µL, reducing reagent and sample consumption. Common in instruments like NanoDrop, used to quantify DNA and RNA.