Many scientists analyze samples with a spectrophotometer. Spectrophotometers measure the interaction of light—such as absorbance, reflectance, transmittance, and fluorescence—with a sample in order to provide a chemical signature. Spectrophotometers can cover various ranges of electromagnetic radiation such as ultraviolet (UV), visible (Vis), infrared (IR), and more. Many scientists and engineers—in biochemistry and physics as well as pharmaceutical and other industries—rely on this technology. Here, experts provide guidelines to use when shopping for a new instrument.

For an overview of this area, visit Biocompare’s spectrophotometer page. Even a quick look reveals the diversity of instruments: single-beam, double-beam, split beam, and beyond.

Meet the experts and their products

Sudhir Dahal—molecular spectroscopy product manager at Shimadzu Scientific Instruments—points out that Shimadzu makes three types of spectrophotometers: UV-Vis-NIR, Fourier-transform infrared (FTIR), and fluorescence.

“The UV-Vis-NIR spectrophotometers are used to characterize samples’ absorbance, transmittance, and reflectance in the ultraviolet, visible, and near-infrared region,” Dahal says. “FTIR spectrophotometers help characterize and identify samples based on their interactions in the infrared region, and fluorescence spectrophotometers measure the fluorescence profile of samples to identify and characterize them.”

From DeNovix, market development manager Andrew Jones explains that the company makes spectrophotometers that combine UV-Vis and fluorescence measurements. “UV-Vis is performed either as microvolume measurements where the sample is retained between two measurement surfaces and light is transmitted directly through the sample, or alternatively plastic or quartz cuvettes can be used,” he says. Typically, the microvolume measurements use sample volumes of 1 microliter or less, and fluorescence measurements are made with 0.5 milliliter, thin-wall PCR tubes with a sample volume of 1–20 microliters. “All DeNovix instruments are driven by on-board software—no additional PCs required—and are fully networked to allow easy exporting of data to network folders, printers, or email,” Jones adds.

Exploring applications

Spectrophotometers can be used in many ways. In discussing Shimadzu’s products for example, Dahal says, “The most common applications of these spectrophotometers are to characterize and identify unknown samples and their amount.”

These devices can also be used in a research environment or for industrial quality assurance or quality control. “For example, spectrophotometers can be used to identify the amount of protein in a given sample, quantitate denatured DNA caused by heat or other chemical processes, identify contaminants in pills, and determine concentrations of various species for medical and biological uses,” Dahal explains. “In addition, spectrophotometers are also used to characterize known and unknown samples in the field of material science to help develop scientific equipment, medical devices, and sensors.”

When asked about the benefits of spectrophotometers, Dahal points out three: “they require minimal or no sample preparation prior to measurement compared to most analytical instruments; the measurements are often quick—in some cases under a minute; and they are easy to use and highly accurate while being one of the most affordable instruments in most analytical or research labs.”

For the spectrophotometer line from DeNovix, “scientists typically use these instruments to assess the quantity and quality of DNA, RNA, or protein samples, and this can be achieved through either absorbance or fluorescence,” Jones says. “Absorbance and fluorescence both encompass a wide range of assays within the life science and biochemical fields.”

A key feature of DeNovix spectrophotometers is the combination of three measurement modes: microvolume UV-Vis, cuvette, and fluorescence. Plus, Jones notes that the company’s SmartPath Technology “combines unique software and mechanical components to ensure that the optimum pathlength is used for every sample.” He adds, “SmartPath Technology does not require calibration for the lifetime of the instrument.”

Buying tips

With so many options, how does a scientist or engineer pick just one? To help scientists make the right purchase for their research needs, Jones provided the following list.

  • Does the instrument have a range of built-in applications or customizable software that fits the current and future needs of the user?
  • Does the system meet the accuracy and precision specifications required for the application?
  • Is there an option to run fluorescence assays?
  • Does the instrument require routine re-calibration?
  • Can the instrument be upgraded to include additional measurement modes, such as fluorescence?
  • Can the instrument be tested in your lab? Head-to-head comparisons and hands-on user experience using real-life samples are important in assessing the options now available in this market.
  • How will users handle the data? Are there options to network, store, and backup data?
  • If the lab requires performance validation, is there an installation qualification/operational qualification package available?

Dahal also adds some helpful guidance. “First, a potential buyer should consider discussing their need with the manufacturer to help find the right spectrophotometer,” he says. “Spectrophotometers are designed for various types of applications and for various types of uses, and we will help match your needs to the right model, because the most expensive—or the least expensive, for that matter!—may not always be the best match for a customer’s needs.”

There is a lot to consider as a customer delves into a product’s features. “It is so easy to get lost within the specs and details,” Dahal explains. “Therefore, we highly suggest speaking to a real person—your local rep—after you’ve done some research.”

Still, there’s more to do before making a purchasing decision. “The buyer should request application notes, technical notes, and possibilities for doing a demo with their typical samples,” Dahal explains. “Finally, it is extremely important to check for the availably of technical support and services to help with training and peace of mind after purchase.”

These comprehensive tips are a good starting point on your purchasing journey. Do your research and don’t rush the decision. The right spectrophotometer should last a long time and make meaningful contributions to your research or industrial processes. So, make the most of your shopping.

Image: The mitochondria in this heart cell appears red when illuminated with ultraviolet light. Image courtesy of National Heart, Lung and Blood Institute, NIH