Novel inorganic mesoporous material with chiral nematic structure derived from nanocrystalline cellulose for high-resolution gas chromatographic separations.

Chiral nematic mesoporous silica (CNMS) has attracted widespread attention due to some unique features, such as its nematic structure, chirality, large pore size, high temperature resistance, low cost, and ease of preparation. We first reported the use of CNMS as a stationary phase for capillary gas chromatography (GC). The CNMS-coated capillary column not only gives good selectivity for the separation of linear alkanes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and isomers but also offers excellent enantioselectivity for chiral compounds. Compared with enantioseparations on commercial ß-DEX 120 and Chirasil-l-Val columns, a CNMS-coated capillary column offers excellent enantioselectivity, chiral recognition complementarity, and the separation of analytes within short elution times. It can also be potentially applied in high-temperature GC at more than 350 °C. This work indicates that CNMS could soon become very attractive for separations.

Polybrominated diphenyl ethers and organophosphate esters flame retardants in play mats from China and the exposure risks for children.

A total of 41 play mats made from different raw materials, such as polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), chemical crosslinked polyethylene (XPE), and polyvinyl chloride (PVC), were obtained from Chinese markets and analyzed for flame retardants. Polybrominated diphenyl ethers (PBDEs) and their replacements, organophosphate esters (OPEs), were measured and the associated exposure risks for children were evaluated. The levels (range; median) of OPEs (6.6-7400; 200 ng g-1) were generally 1-2 orders of magnitude higher than those of PBDEs (0.13-72; 13 ng g-1), consistent with the production and usage trends of flame retardants. The concentrations of both PBDEs and OPEs were the lowest in XPE mats (0.13-5.6; 3.3 ng g-1 for PBDEs and 6.6-320; 47 ng g-1 for OPEs) compared to the other three types. Concentration comparison and compositional analysis suggested that PBDEs and OPEs in play mats were most probably from leaching of raw materials, during production, storage, and/or transport. Children's exposure to PBDEs and OPEs from play mats was estimated for three pathways, i.e., dermal contact, inhalation, and hand-to-mouth ingestion. The combined exposure was 5-6 orders of magnitude lower than the established reference dose values, suggesting no obvious health concern regarding the occurrence of PBDEs and OPEs in play mats. Nevertheless, selection of less contaminated, i.e., XPE mats among those under investigation, by consumers is strongly recommended to minimize any potential exposure risk.