Picomole-level Formaldehyde Determination in Gaseous and Beer Samples Using Flow Injection Chemiluminescence Analysis

Based on the linear enhancement of formaldehyde (FA) within 7.0 ∼ 1000 pmol l−1 on luminol—bovine serum albumin (BSA) chemiluminescence (CL) system, FA determination in air and beer samples using CL with flow injection (FI) was proposed. The detection limit was 2.5 pmol l−1 (3σ) and the relative standard deviations were less than 4.5% (n = 7). At a flow rate of 2.0 mL min−1, a whole analysis from sampling to washing only needed 32 s, offering a sample throughput of 112 h−1. This proposed method was successfully utilized to determine FA vapor pressure in liquid (121.8 ± 3.8 Pa), FA content in real air sample (8.93 ± 0.03 mg m−3), and FA levels in beer (199.5 ± 5.6 ∼ 225.2 ± 3.5 mg l−1), giving determination recoveries from 90.7% to 109.3%. The mechanism of BSA—FA interaction was also investigated, showing FA binding to BSA was a spontaneous process mainly through hydrogen bonding and van der Waals force by FI-CL, with binding constant K of 1.89 × 106 l mol−1 and the number of binding sites n of 0.86. Molecular docking analysis further revealed FA could enter into the pocket at subdomain IIA of BSA, with K of 1.71 × 105 l mol−1 and ΔG of -29.68 kJ mol−1.