Characteristics, sources and health risk assessment of trace metals and polycyclic aromatic hydrocarbons in PM2.5 from Hefei, China.

Trace metals (TRs) and polycyclic aromatic hydrocarbons (PAHs) are major toxic components of fine particulate matter (PM2.5) and related to various health adverse outcomes. The study aims to get a better understanding of the contents, sources and risks of PM2.5-bounded TRs and PAHs in Hefei, China, during the period of 2019-2021. We collected 504 samples and measured twelve TRs and sixteen priority PAHs by inductively coupled plasma mass spectrometry and high-performance liquid chromatography. The annual mass concentrations of PM2.5 was fluctuated in the year of 2019-2021 at 50.95, 47.48 and 59.38 µg/m3, with seasonal variations in rank order of winter > spring > autumn > summer. The median concentrations of PM2.5-bounded Æ©TRs and Æ©PAHs were also fluctuated, 132.85, 80.93 and 120.27 ng/m3 for Æ©TRs, 2.57, 5.85 and 2.97 ng/m3 for Æ©PAHs, in the year of 2019, 2020 and 2021, respectively. Seasonal variations of Æ©TRs and Æ©PAHs show the highest concentration in winter. Positive matrix factorization was used for identified pollution emission sources, and TRs mainly originated from coal combustion, traffic emission and fugitive dust, while PAHs stemmed from biomass, diesel, gasoline and coal combustion. Health risk assessment indicated that adults were more vulnerable than children, the carcinogenic risk assessment of As and Cr manifested a certain degree of cancer risk (1.0 × 10-6 < CR < 1.0 × 10-4) in adults group, and health risks of TRs were higher than PAHs in Hefei. These findings suggest that PM2.5-bounded TRs and PAHs should be considered when making emission control strategies for air pollution, and winter, combustion sources and adults should achieve more policy attention to decrease exposure risks in Hefei.

[Simultaneous spectrophotometric determination of certain beta-lactam antibiotics in rabbit serum using multivariate calibration methods].

Cefuroxime sodium, ceftriaxone sodium, cefotaxime sodium and cefazolin sodium have absorption in ultraviolet region, and their absorption spectra are overlapping. So they can not be determined individually by spectrophotometry without prior separation. In this paper, the chemometric multivariate calibration method was applied to the simultaneous determination of these four compounds in a Britton-Robinson buffer solution (pH 2.09), and the analytical results were compared with those by classical least squares (CLS), principal components regression (PCR) and partial least squares (PLS). The linear ranges of cefuroxime sodium, ceftriaxone sodium, cefotaxime sodium and cefazolin sodium are 1.0-20.0, 2.0-20.0, 2.0-20.0 and 1.0-18.0 microg x mL(-1), respectively. The proposed procedure was successfully applied in the determination of these drugs in rabbit serum, and the result obtained from spectrophotometry was compared with the one by HPLC with no significant difference found.