Gas chromatography-mass spectrometry signal enhancement of ortho-allylphenols by their cyclization

The most common method for enhancing the sensitivity of chromatographic analysis to the compound under study is its prior derivatization, typically achieved through silylation or acylation. Studies performed with the use of ortho-allylphenol and its derivatives, compounds possessing an alkene chain and a phenolic group, i.e. the moieties capable of the internal mutual reaction, prove that it is possible to increase their GC-MS signal not only by their silylation and acylation but also by their initial cyclization at the sample preparation stage. While the silylation of individual ortho-allylphenols, depending on the type and number of substituents in the ortho-allylphenol core, results in a 3- to 6-fold increase in their GC-MS signal, the signal enhancement caused by the cyclization of each of these compounds is significantly greater than that induced by silylation alone, ranging from 5- to 11-fold. The procedure for enhancing the GC-MS signal of ortho-allylphenols through their preliminary cyclization is simple, workable, and effective, as demonstrated by the results of their analyses in blood, urine, saliva, and various food and cosmetic products. The presented results suggest that the GC-MS signal strength of almost any molecule can be enhanced by cyclization if it has an appropriate structure (i.e. possesses an alkene chain and a phenolic group - moieties capable of internal mutual reaction) and undergoes cyclization in the MS ionization chamber (the energy required for cyclization is lower than the energy of electrons in the standard GC-MS EI source).