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Super-hydrophobic silicic xerogel (SG) was prepared from methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS), and the optimized MTMS to DMDMS molar ratio was determined to be 3/2. To fabricate new effective nitrosamines sorbent in tobacco extract solution, SG was modified by epitaxial growth of mesoporous silica to form the coated composite named as MSGx with a large surface area (152-208 m 2 g -1 ) and pore volume (0.133-0.162 mLg -1 ), and the new sorbent could capture 54~59% of nitrosamines in tobacco solution, superior to zeolite and mesoporous silica. 1 IntroductionNitrosamines are deemed to be the widespread carcinogens characterized with N-nitroso group, including volatile nitrosamines (VNA), non-volatile nitrosamines and tobacco specific nitrosamines (TSNA). TSNA are a group of carcinogens found only in tobacco products. They can cause various cancers or tumors in laboratorial animals and possess the potential carcinogenicity to human though their content in tobacco and tobacco products is in the range of μg g -1 (ppm) or ng g -1 (ppb). Among various efforts controlling the pollution of nitrosamines in environment, one strategy is to adsorb TSNA in tobacco extract solution in order to reduce the injurant at source [1][2][3][4], and effective sorbent is the key. TSNA are oily molecules and their adsorption in tobacco extract solution is inevitably interfered by water [1], so the favorable separation performance between water and oil is vital. Nowadays, many porous hydrophobic materials have been extensively studied [5], including carbon based materials [6], metal oxide nanowires [7,8], biological nanometer fiber [9,10], organic polymer [11,12] and macroporous aerogel [13][14][15], etc. However, complex synthesis and high cost hinders their actual application.Recently, hydrophobic polymethylsilsesquioxane (PMSQ) materials have been synthesized by crosslinking polymerization of methyltrimethoxysilane (MTMS), in which mesopores and macropore could be produced through phase separation [16,17].Also, flexible marshmallow-like silicic aerogel/xerogel was synthesized from MTMS and dimethyldimethoxysilane (DMDMS) co-precursor [18]. This aerogel is expected to

Based on the synthesis of super hydrophobic silicic xerogel (SG) from methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS), siliceous hydrophobic nanoparticles were fabricated within the mesoporous channels of SBA-15, in order to enhance the efficiency of adsorbing tobacco specific N-nitrosamines (TSNA) in aqueous solution. The concentration of precursor solution was adjusted to master the distribution of hydrophobic particles and the mean hydrophobicity of resulting composite, 150% increasing the capacity of SBA-15 in liquid adsorption of TSNA.

Herein, an effective and rapid method involving microwave-assisted extraction (MAE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of maleic hydrazide residues in tobacco.