Benzene synthesis method coupled with passive sampling technique for 14C measurements in the atmospheric CO2

The present study focuses on the measurements of specific activity levels of 14C in the atmospheric CO2 using the passive sampling technique coupled with benzene synthesis method. The purity of benzene, synthesized from atmospheric CO2 was measured using the gas chromatography technique, and it was found that the purity of benzene was 99%. The Liquid scintillation counter was calibrated with a benzene sample synthesized from the NIST Oxalic acid standard, and the efficiency of the system is found to be 70.2% ± 0.8%. The passive sampling method was used to sample the atmospheric CO2. The atmospheric CO2 absorbed in 2N sodium hydroxide (NaOH) solution. The average amount of carbon absorbed in 2N NaOH solution is 5.27 ± 0.20 g for the sampling duration of 7 days. The measured specific activity 14C levels in the atmospheric CO2 varied from 240.9 to 250.0 Bq/kg C with an average specific activity of 246.3 ± 2.5 Bq/kg C.