Coherent’s novel Transmission Sampling Accessory is capable of analyzing samples by transmission Raman spectroscopy through the implementation of the TR-Probe THz-Raman® platform, which can be particularly beneficial for the analysis of coatings or other materials that can affect backscatter measurements, such as those present in pharmaceutical tablets or pills. Transmission Raman is a multiple scattering process that provides an average measurement that covers the entire volume of the sample.
Transmission Raman Sample Accessory Mounted to TR-PROBE Module
The Transmission Sampling Accessory chamber is equipped with a set of holders that can accommodate pills or tablets of varying sizes that is versatile for use with standard HPLC vials. The fiber-coupled Coherent CleanLineTM Laser source provides excitation to the system from the TR-PROBE module. By unplugging the module from the Excitation port of the probe, which places the system in backscatter mode, and then plugging it back into the front of the transmission accessory, which is also known as the transmission mode of the system. A comparison between these two modes can be easily identified without causing any movement to the sample as shown in the figure.
Easily switchable with other sample holders via the universal dovetail mount. Various sample inserts enable many common sample dimensions
The Transmission Sampling Accessory is easily removable from the probe, and can even be replaced with other TR-Probe accessories through the dovetail mount on the front of the probe as required by the user. The sampling accessory is compatible with all TR-PROBE models including the 532 nm, 785 nm, 808 nm, 976 nm and 1064 nm probes.
Some additional features of this accessory include:
- Sample chamber accommodates pill/tablet holders or vitals
- Excitation of the system is provided by a fiber-coupled CleanLineTM Laser source from TR-PROBE module
- Applicable for both transmission or backscattering measurements on the same sample
- Pill/tablet holders capable of accommodating common pill/tablet sizes
- Includes laser interlock with override capability
Comparison of backscatter and transmission measurements on an Advil tablet. The backscatter signal (blue trace) is dominated by the tablet coating, and the spectrum of the Ibuprofen present in the bulk is not detected. Transmission Raman signal (green trace) including the THz-Raman® spectrum demonstrates increased SNR in the THz-Raman region compared to the fingerprint region, further reducing acquisition times.
THz-Raman PLUS Fingerprint Region Measurement
All TR-Series THz-Raman® modules are ultra-compact in their size and can be connected easily to almost any spectrometer or Raman system. A high-power, wavelength-stabilized, single-frequency laser source is matched to the ultra narrow-band ASE, beamsplitter and notch filters to ensure a maximum throughput and attenuation of the excitation source. THz-Raman® modules are available in 532 nm, 633 nm, 785 nm, 850 nm, 976 nm and 1064 nm excitation wavelengths.
The novel, compact and robust THz-Raman® TR-PROBE provides both in-situ reaction and process monitoring as required by the user. Configuration of the probe can be achieved by various sample interface accessories such as immersion or contact probe tips, a convenient vial/tablet holder or a steerable non-contact optic. A separate CleanLineTM laser provides AS-free excitation through a multimode fiber that allows the probe to operate in harsher environments where the electrical connections may not be permissible. All THz-Raman® modules can be utilized with any commercial Raman system or spectrometer. Coherent can recommend or integrate an appropriate spectrometer and deliver the complete system.
This information has been sourced, reviewed and adapted from materials provided by Coherent.
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