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This MVP-Pro Star™ is a unique horizontal ATR mini-sampler, ideal for analyzing samples that are difficult to analyze by conventional FTIR spectroscopy methods. Such samples include solids such as coatings on slightly curved materials and paints and micro-liters of liquids or pastes.
The MVP-Pro Star™ utilizes all front-surface mirrors to focus the beam to and from the ATR crystal. The MVP-Pro Star features a monolithic diamond ATR prism. This provides a 1.5 mm diameter sampling area on the top of the diamond that can be used for spectroscopic measurements from the mid-IR to the FIR, with limited signal-to-noise in the 2300 cm-1 to 1850 cm-1 region.
The ATR crystal is mounted in a removable sampling plate for easy cleaning and crystal replacement. This sampling plate is part of the purge enclosure around the MVP-Pro Star™ that allows rapid sample exchange without interrupting the purge of the FTIR spectrometer. For applications requiring different penetration depths or chemical resistances, sampling plates with Ge, Si, and ZnSe hemispherical ATR crystals are also available.
Heatable sampling plates are also available for operation up to 200°C with diamond and ZnSe or up to 100°C with a Ge ATR crystal. The Heatable Sampling Plates feature a K-type thermocouple and cartridge heater. These are intended for operation with the Harrick's Temperature Controller.
For making contact with solid and powder samples, the MVP-Pro Star™ is equipped with a built-in pressure applicator with slip-clutch for consistent and reproducible results. For more fragile ATR crystals, i.e. ZnSe and Ge, a compatible low-torque slip-clutch is available. For more precise force measurements, a pressure applicator with built-in force sensor and display is offered.
For easy powder and liquid sampling, an optional Powder Retainer and Flow-Through Liquid Cell are available. Both attach to the sampling plates and are sealed with a Viton o-ring. The Powder Retainer contains the powder in a restricted volume and requires approx. 0.1 ml for operation. The Flow-Through Liquid Cell is a micro-cell with a volume of approx. 0.15 ml and Luer Lok fittings for sample introduction.
Representative infrared spectra recorded with the MVP-Pro Star™ are shown in Figures 1 through 4. Figure 1 shows the chemical changes in a corrosive cleansing agent as it dries. Over time, the water evaporates and the organic components and NaOH becomes concentrated.
Figure 1. ATR Spectra of Easy-Off™ Oven Cleaner Freshly Applied (top) and after 1 hr. of Drying (bottom).
Figure 2. ATR Spectra of an SOS™ Steel Wool Cleaning Pad, New (top), and Dried After Use (bottom).
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Figure 2 shows spectra of an abrasive cleaner. The pad is impregnated with soap, as shown by the black spectrum. The spectra show that the concentration of soap in the pad is lower after the pad has been used.
Figure 3 shows the ATR spectra of powdered dishwasher detergent. The detergent was a white powder with a low (<1%) concentration of green particles. A few grains of the green grains were separated from the bulk for analysis. The spectra show that the green material differs in composition from the bulk.
Figure 3. Normalized ATR Spectra of Green Specks in Cascade™ (top) and Cascade™ (bottom).
Figure 4. ATR Spectra of ChlorTrimeton™ antihistamine, inside of tablet (top) and outside of tablet (bottom).
Figure 4 shows infrared spectra of the inside and outside of an antihistamine tablet. The differences between the two are due to a coating on the outside of the tablet.
The MVP-Pro Star™ diamond ATR is excellent for examining a wide range of samples, including liquids, pastes and solids by FT-IR spectroscopy. It is ideal for analyzing samples that would damage other crystals - highly acidic or basic liquids and extremely hard solids.
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