A new method for chemical identification based on orthogonal parallel liquid chromatography separation and accurate molecular weight confirmation

Recent advances in the theory and application of orthogonal LC separation have allowed for the establishment of a more effective method for the chemical identification of target compounds in complex samples, especially structurally similar compounds. In this study, a new chemical identification method based on orthogonal parallel separation and accurate molecular weight confirmation was developed. An orthogonal separation system consisting of an XTerra MS C(18) column, a home-made Click OEG column, and a Click CD column was established for separation and identification. In addition, 82 flavonoids were selected as references, to be used for the construction of a library. Retention times of each reference flavonoid on each column and accurate molecular weights were recorded and imported into a searchable library as "tags" for the unknown screening. For the method validation, two complex mixtures, fractions of Dalbergia odorifera T. Chen and Scutellaria baicalensis Georgi, specifically, were separated and identified. In total, nine compounds were unequivocally identified by retention time and confirmation of accurate molecular weight, demonstrating that this method is suitable and efficient for the chemical identification of complex samples.     

Gas chromatographic peak identification for polybrominated diphenyl ethers under different temperature programs

A method has been developed for gas chromatographic peak recognition of polybrominated diphenyl ethers (PBDEs) under different temperature programs. On the basis of an identification database of retention parameters (A, B values) of gas chromatography and retention times of the selected internal standards, the retention times of BDEs can be accurately estimated. In comparison with the experimental retention values, the predicted retention times have been proved to be very accurate. In addition, owing to only a part of BDE analytical standards are available, using 40 BDEs as a training set, the quantitative relationship between retention parameters of BDEs and molecular connectivity indexes has been found. The correlation coefficients are greater than 0.997. The A, B values of all the remaining 169 BDE congeners have been predicted.