Collision CDP 840 is a key factor for MRM transition. Evaluation of product ions from one precursor ion at a range of collision energies is required. The relationship between peak area and collision energy for one target analyte, γ-HCH, is illustrated in Fig. S5 (see Supplementary data). The results highlight that collision energy can substantially impact the sensitivity of MRM transitions. For example, the MRM transition 180.9 > 145 for γ-HCH exhibits an abundance of 577,893 at collision energy of 16 eV, compared to 13,574 at collision energy of 45 eV. This corresponds to a 40 times lower instrument detection limit. However, according to the abundance data of MRM transition 189.9 > 145 for γ-HCH, there were no substantial differences in abundance (577,893, 557,645 and 532,231) at 16, 18 and 20 eV.
PCBs, OCPs, PCMs, NAMs, CBz and MTCS were monitored on the 60 m DB-5MS column, while BFRs, CFRs and BCPS were monitored on a 15 m HT-5MS column. Methoxychlor and 4, 4′-DDT did not produce linear responses when analyzed via the 60 m column. To avoid the apparent on-column degradation of these two compounds, they were analyzed together with BFRs and CFRs on the 15 m HT-5MS column. To maximize the sensitivity and obtain enough data points for good peak shape, twenty three time segments for 60 m column analysis and thirteen time segments for 15 m analysis were applied. Details regarding exact retention time, MRM transition, dwell time, and collision energy are summarized in Table 1 and Table 2.