Analysis of alkyl phosphates in petroleum samples by comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection and post-column Deans switching

► GC×GC-NPD with post-column Deans switch to protect NPD from derivatization reagents. ► NPD bead life increased 200×. ► Quantification and speciation of alkyl phosphates in petroleum samples. ► LODs and precision significantly improved compared to ICP-OES method. ► Recoveries in real samples of 79-105% with RSD < 5%.