AN 24 - Picarro's Combustion Module-CRDS Quickly Distinguishes Between Renewable and Fossil Fuel Plastics
A fast screening method for supply chain management and QA/QC.
Plastics derived from annually renewable (bio-based or plant-based) carbon are used in a growing variety of products – from disposable cutlery and cups to chip bags and soft drink bottle products. So-called bioplastics (bio-based plastics, organic plastics, renewable plastics) are purported to provide significant reductions in greenhouse gas emissions and energy use1. The market for bioplastics was estimated at 360,000 metric tons for 2007 and growing by 38% annually2.
Current methods to test for bio-based content (ASTM D6866-083) require radiocarbon (14C) analysis through liquid scintillation counters (LSC) or accelerator mass spectrometers (AMS). LSC is generally considered a low precision tool and typically requires extensive sample prep, such as dissolving plastics in a chemical ‘cocktail’. Although AMS is considered a high-precision instrument, the capital and operating costs required to run an AMS unit are prohibitive to most users. For both techniques, per sample costs ($250 - $400) are considerably higher than typical per sample costs for stable isotope analyses ($20 - $100).Picarro’s Combustion Module-Cavity RingDown Spectroscopy (CM-CRDS) platform can be used to test for bioplastic content in raw materials and finished products such as disposable cups and forks. The CM-CRDS relies on the measurement of the stable (non-radioactive) carbon isotopes, 12C and 13C. The measurement process is simple. Small amounts of any solid or liquid can be placed in a tin capsule and dropped into the Combustion Module. The carbon in the sample is converted to 12CO2 and 13CO2 which are then analyzed using Picarro’s time-based, high-precision spectroscopic analyzer to provide the ratio of 13C to 12C. This value, δ13C, is a measure of the plant to fossil fuel content of the carbon in the material.