Research & Development - October 2014

X-rays Provide Higher Energy Resolution

X-ray spectroscopy is widely used to determine the elemental and chemical composition of materials. However, Lawrence Livermore National Laboratory and

STAR Cryoelectronics LLC’s Superconducting Tunnel Junction (STJ) X-ray
Spectrometer offers more than 10 times higher energy resolution than current
x-ray spectrometers based on silicon or germanium semiconductors. This higher
resolution is made possible through the use of a superconducting sensor that
excites 1,000 times more free charges than is possible in a semiconductor-based
sensor. This allows for the clear separation of characteristic x-ray lines, even at
low energies and in complicated multi-element samples. The team’s
development of an automated liquid-cryogen-free cryostat allows for
operation of the instrument at the required temperature of 0.3

K, and they solved acquisition time limitations by using up to 112 sensors on a single array. The improved precision of the STJ x-ray spectrometer over current technology, along with its ease of operation, will make high-accuracy x-ray fingerprinting available to non-expert users.

◗ Lawrence Livermore National Laboratory, www.llnl.gov

Greater Peak Detection
for HPLC

HPLC and UHPLC are ubiquitous laboratory tools with enormous libraries of established separation methods for a vast array of compounds, deployed in diverse fields. The concern and challenge for any analyst considering a new technology for their application involves the effort required to adapt, transfer or recreate an already established method in a way that preserves the utility of the original method. Excellims Corp.’s IA3100 integrated, compact high-performance ion mobility spectrometry (HPIMS) detector for high-performance liquid chromatography (HPLC) systems provides complete separation and detection of complex mixtures, particularly when adding the IA3100 capabilities to existent LC hardware, and can complement or serve as a replacement for an end user’s present LC detector.

The core technology of the IA3100 uses advanced HPIMS to separate ions introduced via electrospray ionization from the corresponding HPLC eluent. HPIMS demonstrates higher performance over conventional IMS by offering ion mobility base separation having resolving power comparable to HPLC. Capitalizing on Excellims’ patented instrument design, the most important technology advancement is the HPIMS which achieves 60 to 120 resolving power, comparable to the HPLC/UHPLC method coupled to it and two to 10 times better than conventional IMS, maintaining the fidelity of the original chromatographic separation. The HPIMS separation also occurs in just milliseconds with total acquisition times of seconds per sample, so the detection is only limited by the elution time from the HPLC or UHPLC.

◗ Excellims Corp., www.excellims.com

A Wide Angle on Chemical Sensing

Detection and measurement of trace gases at low concentrations, in the presence of dynamically changing contaminants and at significant standoff distances, has important applications in both the civil and defense spaces. The detection and localization of gas releases, such as methane from leaking natural gas pipelines or nitrogen oxides from falling electrical equipment, requires high sensitivity to the target gas and insensitivity to other atmospheric contaminants, and, ideally, can be performed at long ranges. MIT Lincoln Laboratory’s Wide-Area Chemical Sensor (WACS) system uses a tuned, broadband laser coupled to a lossless, spectrally discriminating receiver to detect gases at sensitivities as good as typical local detectors, at ranges up to tens of kilometers, while compensating for atmospheric contaminants and instrument drift.

WACS’s enabling technology, a single lossless optical resonant cavity (Fabry-Perot etalon), spectrally separates light that sees the gas of interest from light that doesn’t by tuning the cavity to coincide with the gas absorption. All light encountering the cavity transmits through it or reflects off of it; comparison of these two light intensities allows measurement of the gas-induced absorption, which varies over the bandwidth of the optical cavity’s spectral response for time-varying, but spectrally constant, losses caused by atmospheric scintillation and other atmospheric contaminants.

◗ MIT Lincoln Laboratory, www.ll.mit.edu

Regenerating Suppressor Design

Suppressors, first invented in 1975 by Hamish Small, are used in ion chromatography (IC) to convert the eluent to a weakly dissociated form so the analyte ions can be detected with high sensitivity. Early suppressors were, from a regeneration perspective, batch mode devices that subsequently evolved to a continuous mode device that was regenerated with chemical reagents. Today, electrolytic regeneration is the preferred means of providing regenerated ions. The technology uses the electrolysis reaction to generate the ions required for suppression. Further, the use of suppressed eluent for providing the water required for electrolysis resulted in significant ease of use.

Thermo Fisher Scientific’s Thermo Scientific Dionex ERS 500 Electrolytically Regenerated Suppressor is a significant leap in electrolytic suppressor product design. The Dionex ERS 500 is the first fully regenerated high-capacity membrane suppressor that eliminates traditional gaskets and the need for frequent off-line regeneration. The new design, comprising two ion exchange membranes and two flanking regenerate channels, allows for operation at high pressures not feasible with current suppressors. The device has a unique fluid channel design that preserves column efficiency and is compatible with 4-µm particle IC columns for fast and high-resolution separations.