Automatic Sample Preparation for Scintillation Counting

The quality of sample preparation is crucial for the validity of any result quantifying ³H and ¹⁴C in labelled samples. Sample preparation can be tedious and time-consuming – particularly for plant materials, oils, fats, tissues, blood, soil samples – where color can also exert an influence on the final result. To ensure accurate quantification of these labelled isotopes within samples, the recommended technology is sample oxidation through combustion. This allows the ³H and ¹⁴C to be trapped and isolated into individual scintillation vials without the influence of quench. To enable high-throughput, automation is therefore a necessity and our new robotic system “Robox” has been specifically designed to allow the automated preparation of 120 samples per day.

The samples are initially located on barcoded sample boats and these are fed systematically into the biological sample oxidizer by a robot. The samples are placed into the furnace of the oxidizer at a very high temperature and are completely combusted in a controlled oxygen flow. The combustion produces gaseous ¹⁴CO₂ and ³H₂O which is transferred to individual scintillation vials that have been previously filled with scintillation cocktail and then automatically capped. Each vial then has a unique identifier applied to the surface of the sealed lid through laser printing of a barcode and is finally placed in scintillation counter racks ready for analysis.

The Robox system offers distinct advantages in that there is no user contact with the radioactive samples or critical chemicals such as scintillation cocktails or toxic vapors. In addition, the unattended operation allows the user to be utilized for other important laboratory tasks. The system also guarantees a full sample audit trail through barcoding to meet all laboratory reporting requirements.