New Optical pH sensing cuvettes turn spectrophotometers into drift-free pH meters  

Proprietary sol gel coating materials developed by Ocean Optics (The Netherlands) have enabled new technology for convenient, non-intrusive monitoring of biological samples. By encapsulating pH indicator dyes into coatings applied to its new Smart pH Cuvettes, Ocean Optics miniature fibre optic spectrometers and accessories can be used for optical pH sensing of 5.0-9.0 pH range samples. With Smart pH Cuvettes, pH readings can be taken quickly and accurately using existing spectrometer setups, negating the need for a dedicated pH meter. pH measurements are critical in applications ranging from DNA analysis, drug discovery, and blood analysis, to environmental monitoring and food and beverage production.

The Smart pH Cuvettes’ immobilized indicator dye is encapsulated into a robust sol gel matrix, allowing for the diffusion of ions while preventing leaching of the dye. Unlike traditional pH electrode meters, Smart pH Cuvettes can be used for monitoring low conductivity samples such as boiler water. In addition, fully integrated Smart Cuvette pH systems provide full spectral analysis to help eliminate errors from changes in turbidity, temperature and ionic strength. The physical properties of the immobilised indicator dye eliminate the need for frequent calibration.

Smart pH Cuvettes are 1-cm square, come in plastic Poly (methyl methacrylate) (PMMA) or quartz and are coated on their inner walls with a sol gel embedded with Bromocresol Green pH indicator dye. The cuvettes are available separately (in 8-, 50- and 100-cuvette packs) or as part of a fully integrated desktop or handheld spectrometer-based pH system.

The PMMA Cuvettes have a temperature range of -5 °C to 70 °C, while quartz is available for high-temperature applications. The PMMA Cuvettes are compatible with aqueous solutions, ethanol/methanol solutions, ammonia, peroxides and sodium hypochlorite solutions. The quartz cuvettes also can be used in acetone and concentrated acids (including nitric, sulfuric and acetic). Although PMMA cuvettes are designed to be disposable, they can be used multiple times depending on sample environments.