Abstract: High performance liquid chromatography(HPLC) is one of the analytical techniques used most frequently. Its chief limitation lies in the need to avoid the overlap of chromatographic peaks as much as possible. In this paper, the overlapped chromatograms and spectra system of 1-chloro-2,4-dinitrobenzene and 3,5-dinitrobenzoic acid in the presence of 2,4-dinitrobenzoic acid were resolved by using the alternating trilinear decomposition(ATLD) combined with HPLC-DAD. Moreover, both were determined simultaneously, whose recoveries were(102.1±2.2)% and(97.6±3.6)%, respectively. The satisfactory results show that this experiment can be easily performed without paying out time-consuming and complicated procedures and quantifying accurately. It revealed the ATLD algorithm was one of the approaches to solve second-order calibration problem in HPLC-DAD.

Key words: Alternating trilinear decomposition algorithim, HPLC-DAD, Nitrobenzenes, Second-order calibration