[Show abstract][Hide abstract] ABSTRACT: Concentrations of HCH isomers, DDT, and its metabolites have been measured in 63 soil samples collected in the urban area and outskirts of Beijing City. HCHs and DDTs were observed in all samples and their geometric mean levels were 5.78 and 38.21 ng g(-1), respectively. The spatial distribution of OCPs in Beijing was clearly showed by the contour map, suggesting the sites with the higher level of OCPs are located in the west and the south region and urban areas within the study regions." Furthermore, a t-test showed a significant difference of the level of some compounds between urban and outskirts areas. The temporal distribution of HCHs and DDTs suggested that the historical application of OCPs has a great effect on the residual level. The ratios of (alpha-/gamma -HCH (p,p'-DDE+p,p'-DDD)/p,p'-DDT, and o,p'-DDT/p,p'-DDT indicated the present of lindane and impure dicofol besides technical HCHs and technical DDTs in Beijing. The potential risk of HCHs and DDTs was assessed on the basis of some current guideline values for soil. The level of OCPs in our study area was compared with other studies.
Full-text · Article · Nov 2006 · Archives of Environmental Contamination and Toxicology
[Show abstract][Hide abstract] ABSTRACT: Forty-five pooled subsoil samples, collected from the outskirts of Beijing at the depths of 1.5–1.8 m, were analyzed for 17 polycyclic aromatic hydrocarbons (PAHs) using gas chromatography and mass spectrometry (GC–MS) to determine their total contents and distribution patterns. The sum of 17 PAHs concentrations varied from not detected to 0.982 μg g−1 in subsoil. The higher total contents of PAHs were observed in the southeast areas where there are some industries. PAHs in most of the subsoil were lower than those in the topsoil (0.016–3.884 μg g−1). PAHs concentrations displayed no relationship with the organic materials. In subsoil, the dominated PAHs were perylene>benzo(a)pyrene>benzo(g,h,i)perylene>indeno(1,2,3-cd)pyrene. It was notable that the content of 8 carcinogenic PAHs represented 47% of the total priority PAHs and the concentration of benzo(a)pyrene in the subsoil was comparable to that in the topsoil, which was much higher. The distribution of target compounds especially perylene and the fluoranthene/pyrene ratio shows that the sources in the subsoil are characterized by combustion such as traffic and incorporation of the diagenetic PAHs.
[Show abstract][Hide abstract] ABSTRACT: Interest in the analysis of alpha-hexachlorocyclohexane (alpha-HCH) enantiomers as an alternative or complementary approach to elucidating isomer ratios of alpha/gamma-HCH has grown in recent years because it can provide useful information to evaluate the influence of different degradation and transformation processes. In this paper, a simple and rapid method for the determination of alpha-HCH enantiomers in biota samples is described. The method developed consists of ultrasonic extraction, sulfuric acid silica gel cleanup, solid-phase extraction (SPE) column fractionation, and final determination with chiral high-resolution gas chromatography. Ultrasonic extraction greatly shortens the extraction process time, and the sulfuric acid silica gel and SPE cleanup perfectly remove lipids and other interference compounds in the lipid-rich samples. The method is found to be simple, less time-consuming, and easy to operate, thus providing a useful alternative method to assess the enantioselective breakdown of alpha-HCH in biota system.
No preview · Article · Apr 2005 · Analytical and Bioanalytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: A method for separation of four environmentally important compounds (three alkylphenols and bisphenol A) by cyclodextrin-modified reverse-migration micellar electrokinetic chromatography (CD-RM-MEKC) has been optimized. On-line concentration, stacking using reverse-migrating micelles and a water plug (SRW), was used to improve the limit of detection. Two main factors affecting the efficiency of enhancement by SRW, injection sample length and water-plug length, are discussed in detail. Compared with the normal 2-s injection, more than 121-fold enhancement of peak area and more than 71-fold enhancement of peak height were achieved with 120-s sample injection after 120-s water-plug injection. With this optimized separation method and SRW technology, limits of detection were found to be 0.089, 0.030, 0.0091, and 0.033 mg L−1 for 4-nonylphenol, 4-tert-octylphenol, bisphenol A, and 4-tert-butylphenol, respectively. Calibration plots (R
2 ≥ 0.9968) and relative standard deviations (RSD, %) of corrected peak areas and migration time were also satisfactory. Combined with off-line concentration by solid-phase extraction (SPE) this method might be used to determine these contaminants at ppb levels in groundwater samples.