Selecting the Right Transmission Cell for Spectrophotometric Liquid Analysis


Posted on April 6, 2016

Transmission Cell Materials

Transmission cells, also known as cuvettes, come in both glass and plastic versions, each with their own benefits and limitations. Carefully considering your analytical needs, sample type, economic considerations, and laboratory environment will allow you to choose the cell material most compatible with your individual situation.

Glass Cells

Glass cells are considered the gold standard for measurement performance due to their clarity, durability, and heat resistance. Although the initial cost of glass cells is higher than plastic alternatives, with proper care, you can reuse them for years. HunterLab’s spectrophotometers are paired with custom manufactured glass transmission cells made of optical quality glass for the ultimate in analytical precision. Because all components are fused, not glued, solvents will not affect the material, making them ideal for use with all types of solvents. These cells are designed with two flat windows and an abraded U-shaped spacer to minimize internal reflectance and can be safely heated up to 275°C.

If you are working with higher temperatures, Pyrex glass cells are your best option. Because they are molded, these rugged transmission cells can safely handle hot solutions with greater capability than three-piece construction cells. It is important to note, however, that the performance of Pyrex glass is not as optimal as HunterLab glass cells.

Plastic Cells

Plastic transmission cells offer a durable and affordable alternative to glass cells, allowing them to be used on a disposable basis to avoid the risk of cross-contamination and the need for cleaning.1 Unlike fragile glass cells, plastic cuvettes do not pose a breakage risk, allowing for safer handling. Despite these advantages, plastic cells have several significant limitations; because they are made of clear acrylic, they do not have the clarity of glass cells, which can potentially compromise their performance. Additionally, plastic cells may not be heated and “many of the plastic cuvettes are not compatible with most organic solvents.”2 However, plastic cells are still appropriate for many applications.

Specialized Transmission Cells

Specialized cells are available to suit a variety of unique needs that expand your liquid analysis options and give you greater flexibility than offered by traditional options.

Glass Flow Through Cells

Flow through cells are designed to allow for continuous sampling of transparent liquid products. HunterLab offers an innovative flow through cell made of clear annealed borosilicate that can be heated up to 100°C. To minimize air bubbles, these flow cells are aligned vertically and fed from the bottom, optimizing analytical accuracy.

Small and Semi-Micro Volume Cells

Traditional cells often require a significant sample volume, compromising the ability of those working with scarce or expensive resources or miniaturized sample preparation protocols to obtain accurate readings using standardized equipment. To facilitate small sample analysis, HunterLab offers a specialized small volume transmission cell requiring a sample volume of only 4mL, allowing you to obtain accurate readings from minute amounts of material. Made of optically clear glass, this cell includes both an inject-a-cell top and solid propylene top to preserve valuable or scarce materials and facilitate the measurement of volatile samples. Additionally, both glass and plastic semi-micro cells are available for analysis of even smaller sample volumes, with some requiring only a 0.4mL sample to cover the viewed area.

Disposable Round Glass Vials

Disposable glass vials made of borosilicate glass give you the accuracy of glass and the robustness to handle corrosives, volatiles, and hot solutions. Because these cells are highly cost efficient, they can be employed on a single-use basis to avoid time-consuming cleaning and eliminate the risk of cross-contamination. The round design is ideal for material that must be centrifuged for mixing or separating, or if the materials need to be heated.

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