Josh P. Roberts

Josh P. Roberts

Articles by Josh P. Roberts

  • Ultralow-Temperature Freezers: Antarctica in a Box

    Wednesday, February 25, 2015
    In most common parlance, ultralow-temperature freezers (ULT freezers) are containers capable of maintaining an interior temperature of about –80 °C, typically by mechanical means. While they come in different orientations and sizes, they are most often seen as upright floor-standing models similar ... read more

  • Product Intelligence: Mighty Readers for Microplates

    Monday, January 26, 2015
    The microplate reader is an essential tool for analyzing assays in many, if not most, life sciences laboratories. Yet like fruit, which can be anything from banana to tomato to compote, a microplate reader can be any instrument capable of accepting an SBS-formatted microplate and reading it in ... read more

  • Refrigerated Laboratory Centrifuges: Cold Spinners

    Thursday, September 18, 2014
    At their most basic, centrifuges are little more than a motor that spins around, effectively pushing objects out with a force exponentially proportional to their distance from the center of rotation. Some centrifuges sit on a desk and do little more than force liquid to the bottom of small tubes or ... read more

  • Photodiode Array Detectors: An Array of Possibilities for (U)HPLC Detection

    Tuesday, August 19, 2014
    Photodiode array detectors—variously abbreviated as “PDA detectors” or simply “DADs”—are essentially spectrophotometers that transiently measure the absorbance of light by a liquid flowing past. They are the dominant detector type used in applications such as liquid chromatography (LC) to yield ... read more

  • UV-VIS Spectrophotometers: Measuring the Rainbow

    Thursday, April 24, 2014
    A UV-VIS spectrophotometer, as the name implies, measures the intensity of light absorbed (or reflected) by, or transmitted through, a substance at specific wavelengths between about 190 and 900 nm—the ultraviolet and visible spectra. read more

  • GC Systems—Separating Compounds for Decades

    Friday, March 14, 2014
    Gas chromatography (GC), much like liquid chromatography (LC), is used to separate compounds by sending a mixture through a column with which the constituent compounds differentially interact, detecting them as they emerge. But while “LC compounds tend to be polar and usually in the liquid phase, ... read more

  • Differential Scanning Calorimetry—A Fundamental Thermal Analysis Tool

    Thursday, October 24, 2013
    A differential scanning calorimeter (DSC) is a benchtop instrument used to determine thermodynamic transitions and heat capacities of a variety of substances. A small sample—typically 5–20 mg, around the size of the tip of a #2 pencil—is placed in the instrument’s furnace, the temperature is ramped... read more

  • Portable XRF: Nondestructive Testing in Seconds

    Monday, July 01, 2013
    We are all familiar with X-rays, the short, highly energetic waves used by dentists to check for cavities, and by airport screeners to look for contraband. We experience fluorescence—the phenomenon by which something absorbs energy and in turn releases it at a different wavelength—from almost ... read more
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