Improvements on the Phenylboronic Acid Derivatization Method in Determination of 3-monochloropropane Fatty Acid Esters in Camellia Oil by N-(n-propyl)ethylenediamine Solid Phase Extraction

Abstract

Pollution of foods with chloropropanol fatty acid esters is a growing international food safety issue, especially contamination with 3-monochloropropane-1, 2-diol (3-MCPD) esters. Traditional GC/MS method using phenylboronic acid (PBA) as a derivatization reagent has been proven to be high selective. However, the disadvantage of this method is that excessive amounts of phenylboronic acid causes the formation of triphenylboroxin that may lead to instrument fouling and reduces the sensitivity of this 3-MCPD detection method. The objective of this study was to optimize a solid phase extraction method after the phenylboronic acid derivatization to illimate the triphenylboroxin formed form excess PBA treatment, and to provide an instrument-friendlier GC-MS method for the detection of 3-MCPD in camellia oil. Different solid phase extraction methods were compared, and (n-propyl)ethylenediamine (PSA) column was selected for its selective in the absorption of fatty acid of ethylenediamine-N-propyl (PSA). Good linearity for 3-MCPD esters detection was found within the concentration range of 0.2 to 10 mg/kg (r2 = 0.9992). The limits of detection (LOD) and the limits of quantification (LOQ) were 0.05 mg/kg and 0.10 mg/kg, respectively. The average recoveries of 3-MCPD esters spiked at 0.25 mg/kg, 1 mg/kg, and 5 mg/kg in pressed camellia oil ranged from 98.83 to 108.79% with a relative standard deviation less than 10%. When this method was applied to the detection of 3-MCPD esters in commercially available camellia oil samples, high amounts of 3-MCPD were present in refined camellia oil samples: the mean content was 1.33 mg/kg, ranging from < 0.034 to 5.47 mg/kg.