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routines automatically optimised acquisition parameters for collection of the highest quality data, including laser power, integration time, and spectral averaging. For comparison, 785 nm and 1064 nm Raman spectra were collected with MIRA DS and a commercially available handheld Raman device, respectively.


Mixture analysis with XTR


Figure 3 contains overlaid 785 nm and XTR spectra that illustrate both the extraordinary ability of MIRA XTR DS to eXTRact Raman data from a mixture of highly fl uorescent hydrocarbons and the resolution that permits visual confi rmation of both solvent and solute. MIRA XTR DS yields high information content with excellent peak resolution. The characteristic fl at baselines contribute to excellent signal-to- noise and are superior to spectral processing using baseline- correction. In contrast, 785 nm laser excitation without XTR is dominated by fl uorescence emission across the spectrum, which obscures weaker Raman signals.


Figure 2. Fluorescence in the Raman spectrum.


In terms of instrumentation, the detector cannot distinguish between Raman scattered light and fl uorescence. Very large and expensive Raman systems can be built that use the time difference of Raman scattering (instantaneous) and fl uorescence (nanoseconds) to separate the signals [7]. However, this is impractical for handheld Raman systems.


XTR. (which stands for ‘Raman eXTRaction’) is Metrohm Raman’s patent-pending proprietary method to differentiate the signals stemming from fl uorescence and Raman scattering and bin them into two distinct spectra. MIRA XTR DS produces a fl uorescence spectrum with its corresponding intensity and shape, and it generates a pure Raman spectrum of just the Raman scattered light.


MIRA XTR DS


The appropriate instrument for diverse on-site applications balances integrated design and functional features. While progress has been made in the performance of portable Raman devices, compact and cost-effective solutions for fl uorescence mitigation are still lacking. MIRA XTR DS fi lls this gap with a handheld Raman system that uses a low cost, low power 785 nm laser with silicon detectors for sensitive fl uorescence-free detection.


MIRA XTR DS rapidly eXTRacts the Raman signal from spectra complicated by fl uorescence with advanced, patent-pending algorithms. Built on the MIRA DS platform, MIRA XTR DS maintains all the benefi ts of its predecessor for chemical and material identifi cation.


Fluorescence-free material identifi cation


Test materials evaluated for fl uorescence mitigation with MIRA XTR DS included hazardous chemicals, illicit drugs, ingredients and products commonly used in the food and beverage industry, and an assortment of manufactured materials. Liquids were examined in glass vials using the vial-holder attachment, and solids were directly interrogated with the iUA- intelligent Universal Attachment. Proprietary SmartAcquire


Figure 4. MIRA XTR DS demonstrates improved signal and resolution over traditional handheld 785 nm and 1064 nm systems.


Figure 3. Each component in a methamphetamine and diesel fuel mixture can be distinguished in the MIRA XTR DS spectrum.


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