Chemical characteristics of water-soluble ions in particulate matter in three metropolitan areas in the North China Plain.

PM2.5 and PM10 samples were collected simultaneously in each season in Beijing, Tianjin and Shijiazhuang to identify the characteristics of water-soluble ion compositions in the North China Plain. The water-soluble ions displayed significant seasonal variation. The dominant ions were NO3(-), SO4(2-), NH4(+) and Cl(-), accounting for more than 90% and 86% to the mass of total water-soluble ions in PM2.5 and PM10, respectively. The anion/cation ratio indicated that the ion acidity of each city varied both between sites and seasonally. Over 50% of the ion species were enriched in small particles ≤1 µm in diameter. The [NO3(-)]/[SO4(2-)] ratio indicated that vehicles accounted for the majority of the particulate pollution in Beijing. Shijiazhuang, a city highly reliant on coal combustion, had a higher SO4(2-) concentration.

[Simultaneous analysis of 14 short- and long-chain perfluorinated compounds in water by liquid chromatography-tandem mass spectrometry using solid phase extraction].

A solid phase extraction (SPE)-ultrahigh pressure liquid chromatography (UPLC) method coupled with tandem mass spectrometry was developed for the simultaneous analysis of the 14 short- and long-chain perfluorinated compounds (PFCs) in water. Water sample was concentrated and purified through WAX mixed-mode SPE cartridges. The separation of PFCs was performed on a BEH C18 column with gradient elution using methanol-5 mmol/L ammonium acetate as mobile phases. The PFCs were quantified by internal standard method in multiple-reaction monitoring mode. The calibration curves of the 14 PFCs were linear in the range of 0.1-50 µg/L with the correlation coefficients > 0.99. The limits of detection (S/N = 3) and quantitation (S/N = 10) of the method were 0.09-1.15 ng/L and 0.29-3.85 ng/L, respectively. The average recoveries of eight PFCs at three spiked levels of 2, 10 and 20 ng/L were 85.0%, 120.2% and 117.4%, with the relative standard deviations of 9.2%, 9.0% and 6.6%, respectively. The recoveries of the rest six PFCs were low due to unavoidable strong adsorption on the bottle/tube walls during sample pretreatment. The method was applied in the determination of PFCs in real samples of a lake in South China. Four short-chain and five long-chain PFCs were detected with mass concentrations of 41.29-49.05 ng/L and 98.43-111.02 ng/L, respectively. The results show that the method is suitable for the simultaneous analysis of short- and long-chain perfluorinated compounds in environmental water.

[Determination of hexavalent chromium in atmospheric particles PM2.5 and PM10 by ion chromatography with inductively coupled plasma mass spectrometry].

An analytical method using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of hexavalent chromium (Cr(VI)) in atmospheric particles PM2.5 and PM10 was established. The Cr(VI) in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column (AG7, 50 mm x 4 mm) with 75 mmol/L ammonium nitrate solution (containing 0.22 g/L Na2EDTA, pH 7.0) as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 µg/L and the correlation coefficient was 0.999 9 for Cr(VI). The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr(VI) increased from 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 min. The limit of quantification (LOQ) of Cr(VI) was 0.000 4 ng/m3 when the sampling volume was 20 m3. The average recoveries of Cr(VI) in the spiked PM2.5 and PM10 samples ranged from 91.6% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr(VI) in atmospheric particles.

[Determination of five microcystins in water using liquid chromatography-diode array detection/ion trap mass spectrometry].

A method for the determination of five microcystins (MCs) in water was established using liquid chromatography (LC)-diode array detection (DAD)/ion trap mass spectrometry (IT MS). The five MCs in water were enriched and purified by solid phase extraction, and determined by LC-DAD/IT MS. DAD was used for both qualitative and quantitative analysis, and IT MS was used for qualitative analysis only. Under the optimized conditions, the detection limits of 5 MCs in water were 0.1 microg/L. The average recoveries of the three spiked levels (0.2, 0.8 and 5 microg/L) were 52.2% - 115.2% with the relative standard deviations (RSDs) of 1.2% - 10.0%. This method uses UV absorption spectrum and MS spectrum in the qualitative and quantitative analysis, and can be applied in the determination of various MCs in both surface water and drinking water.

[An overview on analytical method of volatile organic compounds in water].

Various methods on monitoring of volatile organic compounds in water in domestic environmental monitoring field were overviewed recently. In order to better understand the advantages and characteristics of various instruments, such as laboratory, emergency, and automatic on-line instrument, analytical methods of volatile organic compounds in water were reviewed and evaluated through specific instruments and experiments. This will enable these methods to play a more effective role for future research.