An Innovative Breakthrough in Automated FTIR-ATR Sampling

The development of an automated attenuated total reflection (ATR) accessory on a non-micro scale has been elusive despite ATR being the most popular mid-IR sampling technique due to its ease-of-use and small fixed pathlength. The primary advantage of FTIR-ATR measurements is minimal sample preparation. However, cleaning of the ATR crystal after every measurement is mandatory and has hindered the development of a commercial automated ATR in the past. With new innovations these challenges have been met and the advantages of automation are realised with the introduction of the AutoATR by PIKE Technologies. This in-sample compartment automated ATR accessory is suitable for making ATR measurements of liquids, gels, pastes, casted films and more.

The AutoATR is ideal for comprehensive large studies and for high-throughput routine measurements. Fields of biology, medical, pharmaceutical and food could benefit from an automated ATR. An automated ATR high-throughput device increases lab efficiency and minimizes workforce requirements.

The AutoATR merges an exciting new ATR crystal developed via microtechnology with a microtiter plate platform offering precision mechanics and automated software control. Using a 24-well microtiter plate format enables 24 unique ATR measurements to be conducted within one run. At the heart of this accessory is a single reflection ATR crystal made from 500-µm thick silicon functionalised with multiple microprisms, which couples the light into the crystal. Silicon, in this thin 500-µm form, is an ideal multipurpose ATR element. It has an extremely inert sampling surface and is suitable for use with substances having a pH between 1-12. The changeable ATR crystals also offer the opportunity to store the samples and to prepare different samples at the same time (i.e. drying).

For traditional Si ATR crystals, the beam pathlength through the crystal is several millimeters in some cases, which results in complete absorption of the Si phonon bands in the fingerprint region (1500 - 400 cm-1). The beam pathlength through the thin profile of the Si ATR element minimises absorption from Si phonon bands and offers a full mid-IR spectral range (5000 - 400 cm-1). The absorbance and penetration depth are comparable to a standard diamond ATR. Absorbance band position, shape and magnitude are very similar. The efficiency of the accessory’s delivery optics and Si ATR element coupled with several microprisms results in exceptional throughput and reproducibility. Thus, high-quality spectra may be collected over a short time period.