[Analysis of Non-polar Organic Compounds in PM2.5 by Rapid Thermo-desorption Method Coupled with GC/MS].

Non-polar organic compounds (NPOCs) associated with PM2.5 in the atmosphere were analyzed by automated thermo-desorption (TD) coupled with gas chromatography/mass spectrometry (TD-GC/MS). The analyses for a total of 72 NPOCs were reviewed, including 34 PAHs, one Debenzothiophene, 27 alkanes (C10-C34), 5 hopanes and 5 steranes. Through this improved TD method, operation of filter loadings, TD condition and sample introduction were optimized. The MDL were 0.01-1.0, 0.1-8.0 and 0.50-2.0 ng·m-3 for PAHs, alkanes, hopanes and steranes, respectively. Calibration curve linearities were above 0.9 for all compounds. The TD efficiencies were 95%-100% for PAHs, 81%-100% for alkanes and 83.1%-100% for hopanes and steranes. PM2.5 samples were pretreated by TD and ultrasonic extraction methods separately and analyzed by GC/MS in two laboratories. Results from these two methods were comparable, as the relative biases were less than 30% for most compounds. Analysis results of PM2.5 samples from Linan and Shanghai showed that NPOCs were higher in winter than that in summer. Alkanes were predominant among NPOCs, followed by PAHs. Source analysis by PAH characteristic ratios indicated that fossil fuel burning and coal burning were the main sources of NPOCs in the two sites during the sampling periods.

Associations between thyroid autoantibody status and abnormal pregnancy outcomes in euthyroid women.

We investigated whether thyroid autoantibody status influences pregnancy outcomes in euthyroid women, by comparing abnormal pregnancy outcome rates between those who tested positive for thyroid autoantibodies (Ab+) and those who tested autoantibody-negative (Ab-). Euthyroid pregnant women (n=7,641) underwent tests for serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb). The subjects were divided into 4 groups according to thyroid antibody status: TPOAb-/TgAb- (92.9%); TPOAb+/TgAb- (3.2%); TPOAb-/TgAb+ (2.0%); and TPOAb+/TgAb+ (1.9%). The incidence rates of the following abnormal pregnancy outcomes were compared among the 4 groups and analyzed by Fisher's exact test: gestational diabetes, gestational hypertension, placenta previa, placental abruption, premature rupture of fetal membrane (PROM), intrauterine growth restriction, fetal distress, fetal anomalies, stillbirth, preterm birth, and low birth weight. Among the 4 groups, there were no significant differences in age, gestational age, or in the incidence rates of abnormal pregnancy outcomes, except for PROM and low birth weight. The highest incidence rates for PROM and low birth weight were in the TPOAb-/TgAb+ and TPOAb+/TgAb+ subjects, respectively. TgAb positivity and TPOAb positivity were associated with PROM and low birth weight, respectively. Underlying factors that govern the association between thyroid autoantibodies and PROM and low birth weight require further investigation.