Phenols contamination pre-existing in LC-MS system and sample preparation materials, and influence on quantitation accuracy in human urine

Abstract

Environmental phenols are widely used in various industries. These are present everywhere, and can contaminate the analytical HPLC system and sample preparation materials. This background contamination can affect the phenol quantitation accuracy, and is a notorious problem in the ultra-trace analysis of phenols. To solve this problem, we investigated the background contamination of 37 phenols in HPLC and sample preparation materials, and evaluated calculation methods for quantitation in human urine. The target analytes were analyzed by LC-ESI/MS/MS, and a delay column was employed to identify and distinguish the phenol contamination sourced from the HPLC and injected samples. Bisphenol A, nonylphenol, 4-nitrophenol, benzophenone-3, and bisphenol AF were confirmed as contaminants pre-existing in HPLC. Especially, the main contamination source of bisphenol A in HPLC system was elucidated as water in mobile phase. Nonylphenol, 4-nitrophenol, Propyl paraben, 4-tert-octylphenol and methyl paraben were identified as contaminants preexisting in the sample preparation materials. The main contamination source of nonylphenol and 4-tert-octylphenol were enzyme. To investigate the influence on quantitation accuracy and the optimal quantitation method, the NIST SRM urine samples were analyzed. The results revealed that the most effective quantitation method is the background subtract correction method without the delay column. Eventually, this is the first report evaluating background contamination in diverse phenols, providing essential information for accurate quantitation.