A quantitation method for gaseous formaldehyde based on gas chromatography with metal-organic framework cold-trap sorbent as an effective alternative for HPLC-based standard protocol

Abstract

The suitability of a zirconium metal-organic framework (MOF: UiO-66) as a sorption medium for the cold-trap analytical system was explored for trace analysis of gaseous formaldehyde (FA) using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). A dual-bed cold trap containing UiO-66 (or MOF-5 (zinc MOF)) with Tenax (R) TA was prepared to run adsorption of FA at -25 degrees C and its desorption at 300 degrees C to acquire the maximum relative recovery up to 100%. The TD-GC/MS system equipped with a UiO-66 + Tenax (R) TA cold trap yielded a low method detection limit of gaseous FA (0.27 ng in 100 mL (2.17 ppb FA)) with good linearity and reproducibility. With the use of UiO-66 as a cold-trap medium for GC-MS analysis, the breakthrough of FA was not observable to a significantly extended sampling range (e.g., up to 800 mL of 1250 ppb (1143 ng)). In contrast, MOF-5 tested as a reference medium suffered from immediate (12.7%) breakthrough (at 250 mL) to restrict a maximum sampling only up to 50 mL. As such, the proposed method based on UiO-66 MOF is found as a highly efficient option to overcome the limitations of virtually all GC-based quantitation methods introduced previously for ambient FA. As such, this method can be used as an effective alternative method for high-performance liquid chromatography (HPLC)-based quantitation approach.