Product Focus: UV-VIS Spectroscopy

Improving sources and detectors expand the applications

Spectroscopy benefits both research and manufacturing. “UV-Vis spectroscopy spans about any chemical application, from color analysis all the way to semiconductors,” says Mark Talbott, product manager for molecular spectroscopy at Shimadzu Scientific Instruments (Columbia, MD). For high-tech research, Travis Burt, marketing manager for highend UV-Vis-NIR products for Agilent (Melbourne, Australia) says, “There’s a lot of work in advanced materials—such as biosensors and nanoparticles—that relies on UV-Vis-NIR spectroscopy.” The research applications also include the characterization of optical coatings, solar cells, and semiconductors. In manufacturing, the applications extend just as widely. As explained by Ursula Tems, Agilent’s Melbourne-based marketing manager for routine UV-Vis products, “In biotech and pharma, we see UV-Vis spectroscopy used in quality control and assurance, which usually involves simple measurements on routine instruments that can be used by anyone.”

Tricked-out technology

On the high end of spectroscopy, the technology— especially the detectors—keeps getting better. As Carl Peters, senior applications scientist at BMG LABTECH (Cary, NC) says, “There are improvements on existing techniques in terms of very fast high resolution in spectrometers that collect UV-Vis spectra of 1 nanometer resolution in under a second.” He adds, “That’s really useful for identifying the presence of nucleotides versus proteins and finding contaminants.”

The detectors are also getting more flexible. For instance, Burt points out that Agilent developed a sandwich detector that captures UV-Vis on top and NIR underneath. “With two detectors in one,” he says, “it avoids scanning problems when changing from one detector to another, and it speeds up using it.”

The light sources are also improving. As an example, Tems talks about flash-lamp technology. “The fastflashing lamp, which can typically last up to 10 years, lets users make measurements more quickly and with a lower overall cost of ownership,” she says. “It is also immune to room light, so you don’t need a dark sample area.” That allows this technology to collect data with a fiber-optic probe that can be used in more situations. “You can take the instrument to the sample rather than taking the sample to the instrument,” Tems says. “Also, you get rid of cuvettes, because you can have the sample in a beaker or test tube or even a microcentrifuge tube.”

Talbott agrees that flash-lamp technology works best in some applications. He says, “The lamps last longer than the ones traditionally used, and you can do rapid analysis.”

To make this technology fit so many applications, the devices must be easier to use. Consequently, today’s spectroscopy platforms also allow more automation and simplicity. As an example, Peters says, “Just a few years ago, I was doing multiple readings at different wavelengths and doing all of the calculations by hand to quantify DNA or nucleotides and look at purity, but now that can all be done automatically.”

Picking the product

Although this area of instruments offers a wide range of options, selecting the best one for the job often depends on the wavelength range. “That’s probably the case,” says Burt, “for a lab manager working in a contract lab that looks at optical coatings.” In addition, the dynamic range might need to exceed the necessary operating range because some accessories consume some of the absorption range.

The types of measurements and productivity should also be considered. “Some labs look at liquid solutions, so maybe they need a vendor that supplies an adaptable system that includes liquid handling as well,” Burt says. For many routine measurements, ease of use could even trump the detection range and other high-tech aspects. As Tems says, “The choice may not come down to the instrument’s performance and specs but really to how easily the measurements can be taken.”

The format of the sample might also matter. As Peters says, “For a while, we’ve had a microplate reader with a spectrometer within it, and that enables higher throughput of the samples.” He adds, “It performs all of the analysis that you can do with a spectrometer and does it on multiple samples in a short time.” As an example, he mentions screening large amounts of DNA for its quality.

Being able to change the sample format also comes in handy. In a YouTube video called “UV-Vis Spectrophotometer—Yale CBIC,” Eric Paulson, acting director of the Yale Chemical and Biological Instrumentation Center (CBIC) in New Haven, Connecticut, shows some of the variety of sample accessories that some platforms offer and how to install them.

Many companies provide quality spectroscopy platforms and accessories. As Talbott says, “Most of the instruments are solid. In fact, we have instruments that have been in the field for 20-plus years.”

Minor maintenance

For an instrument already in your lab, only minor attention keeps it humming along. Talbott says that you just need to “keep in mind cleanliness and monitor lamp life.” On the clean side, Talbott says, “Lots of instruments come in for repairs and it looks like a powder box inside.” So just keep the instrument in a clean place when possible. Also, it’s worth watching the lamp life. Talbott says, “Our instruments monitor that lamp, and if it falls below a certain output it tells you to change the lamp.” That’s worth doing, since a dimmer lamp generates less light and more noise.

The available instruments for UV-Vis spectroscopy reflect the breadth of applications of this technology. So shopping for a new device takes attention to detail, and it’s worth the effort because the device could live a long life.

For additional resources on UV-VIS spectroscopy, including useful articles and a list of manufacturers, visit www.labmanager.com/spectrophotometers