A simple direct analysis in a real time-mass spectrometry (DART-MS) method was developed for the rapid determination of four Sudan dyes (I-IV) in chili powder. Simple liquid extraction by hexane without further clean-up was used for sample preparation. DART parameters were systematically optimized to achieve the best detection performance. A DIP-it sampler was used for automatic sampling. The matrix effect was measured by comparing the limit of detection (LOD) in matrix solution with that in pure organic solution.Eventually, the identification of the Sudan dyes was confirmed by MS/MS results and the LODs for four analytes in matrix solution were $0.5 mg mL À1 . The method showed good linearity with correlation coefficients (R 2 ) greater than 0.99 for concentrations ranging from 1 to 20 mg mL À1 . The whole analytical process could be completed within 15 minutes with good recoveries (88-116%) and satisfactory repeatability (<26%, n ¼ 3).

Li2O–MgO–TiO2 ternary system is an important microwave dielectric ceramic material with excellent properties and prospect in both scientific research and application. A phase diagram of the Li2O–MgO–TiO2 ternary system was established in this article, based on earlier research results and our present work. Microwave dielectric properties with compositions in different regions of the phase diagram have been analyzed. We found that the 0.33 Li2MgTi3O8–0.67 Li2TiO3 ceramics sintered at 1200°C exhibited excellent dielectric properties: Q × f value = 80 476 GHz (at 7.681 GHz), εr = 24.7, τf = +3.2 ppm/°C. We also designed two ceramic systems in the Li‐rich region of the Li2O–MgO–TiO2 ternary system, which received little attention in the past decades, because many excellent single‐phase ceramics, such as Li2MgTiO4, Li2MgTi3O8 and MgTiO3, have been found in the Ti‐rich region. The ceramic systems have low sintering temperatures but also relatively poor dielectric properties.

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