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Abstract: A novel method for preparation of ammonium‐free seawater, which is used as a carrier solution and matrix for standard solutions, was designed. These standard solutions are used for calibration curve in flow analysis to detect trace quantities of ammonium in seawater. The system, which consisted of only a peristaltic pump and a hydrophilic‐lipophilic balance (HLB) cartridge, was simple, convenient, and easy to operate. The original seawater used in the method could be collected from the coastal regions. And appropriate quantities of o‐phthaldialdehyde (OPA) and sulfite solution were added to the original seawater (The molar proportions of ammonium : OPA : sulfite were 1 : 200 : 80). After allowing it to set for more than 16 h, the seawater was pumped through the HLB cartridge. The reaction product of ammonium (present in the matrix), OPA and sulfite was retained by the HLB column and the solution coming out of the cartridge was ammonium‐free seawater. The ammonium in the original seawater was efficiently removed and also its concentration in the ammonium‐free seawater prepared by this method was much lower than that of the seawater collected from the surface of the South China Sea. The difference in the salinity of the seawater before and after the process was negligible, and also the pH was slightly increased. Moreover, ammonium‐free seawater could be prepared whenever required, and contamination due to transportation and storage could be prevented. [ABSTRACT FROM AUTHOR]

Phosphate is a typical limiting nutrient in oligotrophic oceans and its concentration can be as low as the nanomolar level, especially in surface seawater. Different techniques for nanomolar level phosphate determination have been studied, most of which are automatic and high throughput methods based on flow analysis. However, these techniques need expensive commercial or laboratory-made instruments, and experienced operators. This study reports an operationally convenient, sensitive and practical method for the determination of nanomolar dissolved reactive phosphorus in aqueous samples, based on classic phosphomolybdenum blue chemistry and solid phase extraction methodology. Under acidic conditions, the formed phosphomolybdenum blue can be preconcentrated on a hydrophilic-lipophilic balance solid phase cartridge, eluted with 0.2 M NaOH, and detected at 700 nm after color recovery with the addition of more reagents. After optimization of the recovery reagents volumes, the effectiveness of the method was evaluated. This simple manual method is sensitive (detection limit of 3.0 nM using 50 mL sample, which can be lowered to ∼ 1 nM by preconcentrating more sample), reproducible (relative standard deviation of 2.6%, n = 81, with different operators), free of interferences from salinity (0-35), silicate (up to 200 μM) and arsenate (up to 100 nM) and suitable for different aqueous matrixes. The effects of a series of phosphorus-containing compounds ( n = 13) were evaluated, with more than half showing hydrolysis during the experiment. This method was applied to determine the phosphate concentration in samples collected from the Western Pacific. [ABSTRACT FROM AUTHOR]

A novel analytical method has been established for on-line simultaneous determination of fluorene and acenaphthene, chrysene and benzo[a]anthracene (B[a]A) by polarization synchronous fluorometry (PSF) coupled to high performance liquid chromatography (HPLC). The detection limits were: 0.039, 0.046, 0.016 and 0.042 mgL- 1 for fluorene, acenaphthene, chrysene and B[a]A, respectively. The proposed method has been successfully applied to simultaneous determination of these PAHs in environmental air and marine sediment samples. [ABSTRACT FROM AUTHOR]

In this study, samples of 18 wet precipitations (WPs) and 38 aerosols were collected around a coal-fired power plant (CFPP) located in Xiamen, southeast China, which was equipped with a seawater flue gas desulfurization system. Total particulate mercury (TPM) in aerosol samples, and total mercury (WP-TM), dissolved mercury (WP-DM) and particulate mercury (WP-PM) in WP samples were analyzed for the natural isotopic compositions of mercury. For the first time, both mass dependent fractionation (MDF) and mass independent fractionation of odd (odd-MIF) and even (even-MIF) isotopes of WP-DM and WP-PM were reported and discussed. Both WP-TM and TPM displayed negative MDF and slightly positive even-MIF. Negative odd-MIF was observed in TPM and WP-PM, whereas positive odd-MIF was observed in WP-TM and WP-DM. It was found that the mercury budget in WP-PM samples was mainly controlled by atmospheric particles. Potential sources of mercury in samples were identified via analysis of mercury isotopic signatures and meteorological data with the NOAA HYSPLIT model. The results showed that TPM and WP-PM in solid samples were homologous and the isotopic compositions of WP-TM depended on those of WP-DM. The ratios of Δ 199 Hg/Δ 201 Hg resulting from photochemical reactions and positive Δ 200 Hg values (from -0.06‰ to 0.27‰) in all samples indicated that the mercury coming from local emission of the CFPP together with long-distance transportation were the two main contributing sources. [ABSTRACT FROM AUTHOR]

A new boronate affinity monolithic material was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE). The porous boronate affinity sorbent was prepared by in situ copolymerization of 3-acrylamidophenylboronic acid (APB) and divinyl benzene (DVB). To achieve optimum extraction performance for benzoylurea pesticides, several parameters, including desorption solvent, pH value, ionic strength in sample matrix, extraction and desorption times, were investigated in detail. At the same time, a simple, sensitive and environment friendly method for the determination of benzoylurea pesticides in water and juice samples was developed by the combination of SCSE-APBDVB with HPLC equipped with a diode array detector. Under the optimized experimental conditions, the limits of detection (S/N = 3) for target analytes were 0.055-0.11 μg/L in water and 0.095-0.31 μg/L in juice. The precision of the proposed method was evaluated in terms of intra- and inter-assay repeatability calculated as RSD, and it was found that the RSDs were all below 9.0%. The developed method was successfully applied to the determination of benzoylurea pesticide residues in water and juice samples and satisfactory recoveries of spiked target compounds were in the range of 75.6%-109%. The results well demonstrate that the new sorbent can extract benzoylurea pesticides effectively through multi-interactions including boron-nitrogen coordination, hydrogen-bond and hydrophobic interactions between sorbent and analytes.

A simple, efficient and sensitive method for the simultaneous determination of nitrofurantoin (NFT), furazolidone (FZD) and nitrofurazone (NFZ) in feed and water samples was developed by stir bar sorptive extraction (SBSE) coupled to high performance liquid chromatography with diode array detection. The SBSE based on poly (vinylimidazole-divinylbenzene) (VIDB) monolithic material as coating was used to concentrate the three target analytes. To obtain the optimum extraction performance, several VIDB-SBSE parameters were investigated and studied, including pH value, ionic strength of sample matrix, extraction and desorption time. Under the optimized experimental conditions, the linear ranges were 0.5-200 microg/L for FZD, 0.25-200 microg/L for NFT and NFZ. The limits of detection (S/N = 3) were in the range of 0.068-0.11 microg/L for the three analytes. The precision of the proposed method was evaluated in terms of intra- and inter-day repeatability calculated as RSD, and it was found that the RSDs were all below 6%. The developed method was successfully applied to the determination of nitrofuran residues in animal feed and water samples. The satisfactory recoveries of the spiked target compounds were in the range of 80.6%-108%.

Matrix effect is an important interfering factor in LC-MS quantitative analysis. In this paper, matrix effects and retention efficiencies of 33 veterinary drugs spiked in river water were studied on hydrophilic-lipophilic balance (HLB) cartridges of 3 brands (Waters, Supelco, and CNW), using LC-MS/MS for detection and reverse osmosis (RO) water as the control under 500-fold concentration. In RO water, only the exogenous matrix effects were observed on three brands of HLB cartridges. Most quinolones and tetracyclines showed positive matrix effects. Estrogens showed negative matrix effects on two brands of HLB cartridges. Sulfonamides were not obviously affected by matrix effects. Chloramphenicols showed negative matrix effects on one brand of HLB cartridge. In river water, matrix effects were different from those of the RO water due to the combined exogenous and endogenous interfering substances. Sulfonamides showed slight matrix effects as those in RO water. Most quinolones and tetracyclines showed positive matrix effects. Chloramphenicols and estrogens showed negative matrix effects. Compared to the external standard method, matrix matched calibration method effectively overcame the matrix effects with better quantitative results. The recoveries of 33 target veterinary drugs spiked in river water at 50 ng/L and 200 ng/L levels were in the ranges of 40.3%-146.0% (Waters), 37.8%-104.2% (Supelco), and 52.9%-150.1% (CNW) with RSDs (n = 4) of 0.2%-14.6%. The results indicated that there was no significant difference in the retention efficiency between the 3 HLB cartridges with the matrix matched calibration method. This study provided supporting data for the HLB cartridge selection in multi-residual determination of the veterinary drugs in river water samples.

A new stir bar sorptive extraction (SBSE) coating based on molecularly imprinted polymer (MIP) with diethylstilbestrol as replaced template molecule was prepared. The influences of the contents of template molecule and monomer in the polymerization mixture on the extraction performance of MIP-SBSE were investigated thoroughly. The MIP was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to evaluate the usability of the new coating, the MIP-SBSE was combined with high performance liquid chromatography (HPLC) and diode array detector (DAD) with dienestrol (DS) and hexestrol (HS) as detected solutes. To achieve optimally selective extraction performance for DS and HS, several parameters, including extraction and desorption times, desorption solvent, ionic strength and pH value in sample matrix were investigated. The results showed that under the optimized experimental conditions, the present method has high selectivity and sensitivity. When drying-redissolving procedure was taken during sample preparation, the limits of detection for DS and HS were as low as 0.04 microg/L and 0.14 micorg/L, respectively. Good linearities were obtained for analytes with the correlation coefficients (R2) above 0.99. Finally, the proposed method was successfully applied to the determination of DS and HS in wastewater, honey and cow urine samples. The recoveries of spiked target compounds in real samples ranged from 61.3% to 120%. The developed method is simple, selective, sensitive and applicable for the analysis of trace DS and HS in complicated samples.

A method for the simultaneous determination of 87 commonly used pesticides in China including 24 organophosphorous pesticides, 15 organochlorine pesticides, 12 azoles, 9 pyrethroids, 7 amides and anilines, 5 carbamates and other 15 pesticides in river water and seawater was established using solid phase extraction (SPE)-gas chromatography-mass spectrometry (GC-MS). GC-MS parameters influencing separation and sensitivity were optimized, and the effects of sample volume, pH and salinity on SPE were investigated. The purification was performed using NH2 SPE cartridge. An internal standard and 5 surrogates were used for data analysis and quality control. The results indicated that under the optimized conditions the limits of detection were in the range of 0.1 - 6.6 ng/L. For most target pesticides, recoveries were between 60% and 120% with relative standard deviations (RSDs, n = 4) of 0.01% - 9.7% at the spiked levels of 5 ng/L and 20 ng/L in real river water and sea water matrices. The method was successfully applied to monitor multi-class pesticides in surface water in Fujian Jiulong estuary, and 20 pesticides including 5 organophosphorous pesticides, 3 amides, 4 azoles, 3 carbamates, 2 pyrethroids and 3 other pesticides were detected in the mass concentration range of 1.18 - 660.93 ng/L. The proposed method can meet the requirement for the determination of trace pesticide residues in water samples.

Stir bar sorptive extraction (SBSE) is an environmentally-friendly technology of sample preparation which combines extraction, cleanup and enrichment together, and it has been developed rapidly and widely applied to the trace enrichment of various target analytes in environmental, food and biological samples. Based on our research, the advance of SBSE, especially, the development of new coatings, are reviewed. At the same time, the possible development orientations of SBSE are discussed.

A new stir bar sorptive extraction (SBSE) based on molecularly imprinted polymer (MIP) with bisphenol A as template was prepared. Based on it, a simple, selective and sensitive method for the determination of bisphenol A (BPA) was developed combined with high performance liquid chromatography (HPLC) with diode array detection. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, the nature of desorption solvent, pH value and contents of inorganic salt in the sample matrix, were investigated. The optimized parameters for the extraction of BPA from water matrix with the MIP-SBSE are as follows: extraction and desorption time were 120 min and 10 min, respectively; the pH value of matrix was 10.0; using acetonitrile (including 1% acetic acid) as desorption solvent; no salt was added in the matrix. Under the optimized experimental conditions, the method showed good linearity between 1.0-200 microg/L. The detection limit (S/N = 3) and quantification limit (S/N = 10) of the proposed method for the BPA was 0.28 microg/L and 0.94 microg/L, respectively. The proposed method was successfully applied to the determination of the target compound in water samples. The recoveries of spiked target compound in real samples ranged from 96.0%-108.7%. The results indicated that the developed method possessed the advantages such as high sensitivity, simplicity, low cost and environmental friendliness.

The technology for flue gas desulfurization (FGD) with seawater is widely adopted by coal-fired power plants in coastal areas. SO2 in the flue gas is absorbed by alkaline seawater and transfered in aqueous phase as sulfite (SO3(2-)), and most SO3(2-) is transformed to sulfate (SO4(2-)) after an aeration process. The remaining SO3(2-) in the seawater discharged to sea area may be harmful to marine organism because of its biological toxicity, thus it is necessary to determine the concentration of SO3(2-) in the seawater for desulfurization. In this study, the method of determination of SO3(2-) in the seawater by ion chromatography was investigated. The separation was achieved on an IonPac AS14A column with 14 mmol/L NaOH-12 mmol/L Na2 CO3 solution as the mobile phase at a flow rate of 1.2 mL/min, and the detection was performed by a pulsed amperometric detector. Formaldehyde was added as a protective agent when sampling because the SO3(2-) is easy to be oxidized. To avoid the formation of Mg (OH)2 in the mobile phase with high pH value which might block the column, the Mg(2+) in seawater was precipitated by NaOH solution (pH 12.0) before sample determination. The method showed good linearity within the range of 0-100 mg/L with an average recovery of 116.8%. The method detection limit (MDL) reached as low as 0.05 mg/L. The relative standard deviations (RSD) for seawater matrix samples spiked at levels of 7.5, 25.0 and 75.0 mg/L were 2.1% 3.1% and 4.0% (n = 9) , respectively. The method has been applied for the determination of SO3(2-) in flue gas desulfurization seawater with the advantages of being fast, sensitive and selective.

Using HLB cartridge for extraction and cleanup, a method for simultaneous determination of 4 tetracycline and 6 quinolone antibiotics in environmental water samples was developed by ultra pressure liquid chromatography coupled with tandem mass spectrometry. Using river water and sea water as matrices and carbadox as surrogate, the recoveries and relative standard deviations (RSD, n = 4) were 94.0% - 117.0% and 2.0% - 9.7% for 4 tetracyclines at 20.0 ng/L and 100.0 ng/L spiking levels and 63.6% - 93.9% and 1.6% - 8.1% for 6 quinolones at 5.0 ng/L and 20.0 ng/L spiking levels, respectively. The detection limits were 20.0 ng/L for 4 tetracyclines and 0.4 ng/L for 6 quinolones. The method has been successfully applied to the survey of 10 target antibiotic residues in Jiulong River estuary, Fujian.

A method was developed for the simultaneous determination of 9 triazole pesticides in environmental water using C18 cartridge for the extraction and enrichment, NH2 cartridge for the clean-up and gas chromatography-mass spectrometry for the detection. The linear range of calibration curves for the 9 target pesticides was between 0.025 mg/L and 0.500 mg/L. The detection limits were in the range of 0.002 - 0.009 microg/L. The 9 target pesticides were measured in river water and sea water at 0.025 microg/L and 0.100 microg/L spiking levels, recoveries and relative standard deviations (RSD, n = 3) were 68.4% - 113.9% and 1.6% - 6.9% for river water and 70.3% - 115.2% and 0.8% - 8.2% for sea water, respectively. The method is simple, sensitive, selective and suitable for the qualification of pesticide multiresidue analysis. It has been successfully applied to the survey of 9 triazole pesticide residues in Jiulong River Estuary, Fujian.

1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) is usually used as a scale and corrosion inhibitor in recycle-cooling water for steel industry. The quick and accurate analysis of HEDP concentration in water is of importance to control the inhibitor adding program. However, the common method for HEDP analysis, which determines the total phosphate in water samples, may suffer the serious problem of incorrectly including degraded HEDP as the active HEDP reagent. In this study, the method of the determination of HEDP in recycle-cooling water by ion chromatography was investigated. The chromatographic parameters, including elution and detection, were optimized. The separation was achieved on an IonPac AS14A column with NaOH solution of 80 mmol/L as the eluent at a flow rate of 1. 0 mL/min, and the detection was performed by a suppressed conductivity detection mode with the injection volume of 25 microL. The method showed good linearity within the range of 0. 25 and 25 mg/L with an average recovery of 102%. The detection limit of the method reached as low as 0. 1 mg/L. The relative standard deviations for 0. 25 and 0. 5 mg/L HEDP standard solutions were 4. 7% and 3. 5% (n = 13) , respectively. The method has been applied for the determination of HEDP in recycle-cooling water samples with the advantages of being simple, fast, sensitive, and interference free.