Evaluation of mollusks as biomonitors to investigate heavy metal contaminations along the Chinese Bohai Sea

Two gastropod species (Rapana venosa and Neverita didyma) and three bivalve species (Mytilus edulis, Crassostrea talienwhanensis and Ruditapes philippinarum) were collected from eight sites along the coastline of the Chinese Bohai Sea for the investigation of heavy metal contaminations. Cd, Co, Cu, Ni, Pb and Zn were analyzed by using pressure nebulization-inductively coupled plasma-mass spectrometer. Two certified reference materials Dogfish mussel (DORM-2) and Mussel (GBW 08571) were used to validate the methods and the obtained results proved to be in good agreement with the certified values. The results of the present study showed that Crassostrea talienwhanensis possessed a much greater ability for bioaccumulation of Cu and Zn than did the other species. Rapana venosa manifested the most bioaccumulation capacity of Cd. Among the five species, the Ruditapes philippinarum possessed the highest content of Ni. Furthermore, Cd, Cu and Zn contents in some gastropods and oysters samples exceeded the maximum permissible levels established by WHO. Due to their special bioaccumulation capacity of Cd and Ni, Rapana venosa and Ruditapes philippinarum had the potential of being used as biomonitors to control the aquatic contaminations of heavy metals.

Gas chromatography/mass spectrometry applied for the analysis of triazine herbicides in environmental waters

The excess use of triazine herbicides in agriculture causes severe contamination to the environment especially for ground water. Gas chromatography coupled with mass spectrometry (GC/MS) was used to analyze simazine, atrazine (ATR), cyanazine, as well as the degradation products of ATR such as deethylatrazine and deisopropylatrazine in environmental water samples. These compounds were baseline separated by the established GC method. The water samples were pre-concentrated by solid-phase-extraction (SPE) and analyzed by ion trap MS at sub- to low-ppt levels. Recovery of ATR by the SPE pre-concentration using a C18 cartridge was determined as 90.5 +/- 3.5%. Detection limit of the method using selected ion monitoring technique for ATR was 1.7 ppt when one liter water was analyzed. The relative analytical error for ATR fortified water samples at 200 ppt was -12.5% (n=12) with triple analysis and the relative standard deviation was 3.2%. Trace levels of ATR at 3.9 and 9.7 ppt were determined in water samples collected from a reservoir and a river in Hong Kong.

Determination of atrazine, deethylatrazine and simazine in water at parts-per-trillion levels using solid-phase extraction and gas chromatography/ion trap mass spectrometry

Methods for trace analysis of atrazine and simazine in water have been developed by using stable-isotope dilution with detection by gas chromatography/mass spectrometry. D(5)-Atrazine was used as the internal standard for the determination of atrazine and deethylatrazine, while (13)C(3)-simazine was used for simazine analysis. Water samples were fortified with known amounts of the internal standards and submitted to solid-phase extraction with a C(18) bonded-silica cartridge. A gas chromatograph coupled with an ion-trap mass spectrometer was used to analyze the water sample extracts. Method detection limits were 38 parts-per-trillion (ppt) for atrazine and deethylatrazine and 75 ppt for simazine. The accuracy of the method, represented by relative analytical errors, was less than 15%, and the method precision was less than 5% (relative standard deviation, n = 9). The method was successfully applied to analyze surface water samples collected from a reservoir and a river at ppt levels.

Small-scale survey on the contamination status of butyltin compounds in seafoods collected from seven Chinese cities

Tributyltin (TBT) and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), in the commercial sea products collected from seven Chinese cities were measured to evaluate the extent of contamination and the potential adverse effect on health. Universal existence of butyltins was found in these samples, and the concentrations of TBT ranged from <6.9 to 17175 ng of Sn g(-1) of wet weight. The accumulation ratios of the pollutant in these organisms were as high as 10(3) or more compared with the previously reported data in corresponding water. The existing different accumulation capabilities of pollutants among the various seafood species were studied. It was observed that the butyltin compounds were comparatively stable during cooking or processing procedures in the manner of usual Chinese cooking way. The occurrence of butyltin compounds in sea products indicated a potential danger for the health of people who consumed seafood in these areas.

Identical flow injection spectrophotometric manifold for determination of protein, phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds or premixes

A simple procedure using an identical manifold was developed for determination of nitrogen (protein) phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds and feedstuffs. By changing appropriate reagents and detection wavelength, these 8 elements were determined successively with a simple identical double-line flow injection (FI) manifold. Fl spectrophotometric determinations were made by the blue indophenol reaction for ammonium, the molybdenum blue method for phosphate, the cresolphthalein complexone procedure for calcium, and the mercuric thiocyanate procedure for chloride. The chromogenic reagents for copper, iron, manganese, and zinc determination were bis(cyclohexanone)oxalydihydrazone (Cuprizone), 1,10-phenanthroline, formaldoxime, and xylenol orange, respectively. Sample digestion catalyst, Fl manifold, and some chemical parameters were optimized. The proposed procedure had a sampling rate of 90/h for each analyte. The determination ranges (mg/L) were 10-60 for N, 1-15 for P and Ca, 540 for Cl, and 0.5-15 for Cu, Fe, Mn, and Zn, respectively. Results of the analyses of animal feed and feedstuff samples by this procedure did not differ significantly from those obtained by proven manual methods.

Determination of manganese in feedstuffs by flow injection spectrophotometry based on rapid formation of permanganate at room temperature

A simple and rapid flow injection spectrophotometric procedure was developed for determination of manganese. In the presence of pyrophosphate and acetate, manganese was immediately oxidized to permanganate by periodate at room temperature in slightly alkaline medium. Under optimized conditions, the determination was made with a sampling rate of 120/h, a linear range of 0-30 mg/L Mn(II), a detection limit (S/N = 3) of 0.08 mg/L, and a relative standard deviation of 0.6% (n = 11) at 10 mg/L Mn(II). The proposed method was used to determine manganese in trace mineral premixes and feedstuffs. Results agreed well with those obtained by the standard atomic absorption spectroscopy method.

Occurrence of butyltin compounds in the waters of selected lakes, rivers and coastal environments from China

The presence of butyltin compounds was investigated for the first time in selected lakes, rivers and coastal environments of China. Aqueous samples were pretreated by the technique of headspace solid phase micro-extraction after hydride generation with sodium tetrahydroborate (NaBH4). Quantitative measurement of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) concentrations were accomplished by capillary gas chromatography with flame photometric detector using quartz surface-induced luminescence. Experimental data demonstrated the widespread occurrence of butyltin compounds in the Chinese aquatic environment. In some locations, the concentrations of TBT were higher than the acute and chronic toxicity threshold of sensitive fresh water or marine organisms. Although DBT and MBT (which mainly come from the degradation of TBT), are less toxic, their occurrence can still affect the ecosystem over a long time frame.

Arsenic speciation based on ion exchange high-performance liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV photo oxidation

An on-line method capable of the separation of arsenic species was developed for the speciation of arsenite As(III), arsenate As(V), monomethylarsenic (MMA) and dimethylarsenic acid (DMA) in biological samples. The method is based on the combination of high-performance liquid chromatograph (HPLC) for separation, UV photo oxidation for sample digestion and hydride generation atomic fluorescence spectrometry (HGAFS) for sensitive detection. The best separation results were obtained with an anion-exchange AS11 column protected by an AG11 guard column, and gradient elution with NaH2PO4 and water as mobile phase. The on-line UV photo oxidation with 1.5% K2S2O8 in 0.2 mol L(-1) NaOH in an 8 m PTFE coil for 40 s ensures the digestion of organoarsenic compounds. Detection limits for the four species were in the range of 0.11-0.15 ng (20 microL injected). Procedures were validated by analysis of the certified reference materials GBW09103 freeze-dried human urine and the results were in good agreement with the certified values of total arsenic concentration. The method has been successfully applied to speciation studies of blood arsenic species with no need of sample pretreatment. Speciation of arsenic in blood samples collected from two patients after the ingestion of realgar-containing drug reveals slight increase of arsenite and DMA, resulting from the digestion of realgar.

Flow injection spectrophotometric determination of copper, iron, manganese, and zinc in animal feeds using a common manifold

A rapid and simple procedure was developed for the determination of copper, iron, manganese, and zinc in animal feeds using an identical flow injection spectrophotometric manifold but different chromogenic reagents and different detection wavelengths. Bis(cyclohexanone)oxalydihydrazone, formaldoxime, 1,10-phenanthroline, and xylenol orange were adopted as chromogenic reagents for Cu, Mn, Fe, and Zn, respectively. Detection conditions such as manifold parameters, buffer pH, reagent concentration, temperature, and acidity of sample solution were optimized. Analytical characteristics of the method and interference of metal ions commonly present in feeds were studied. By changing the reagents and detection wavelengths, which can be done quickly, the proposed low cost flow injection system can determine Cu, Fe, Mn, or Zn in the range of 0.5-10 mg/L with a sampling throughput of 120/h.

Direct Grignard pentylation of organotin-contaminated lard samples followed by capillary gas chromatography with flame photometric detection

During a recent investigation of the organotin-contaminated lard samples, a simple method was developed by direct Grignard pentylation of lard samples and capillary gas chromatography with flame photometric detection using quartz surface-induced tin emission. Using HP-1 capillary column with temperature programming and FPD detector, pentylated tri-, di-, monometyltin, dioctyltin and Sn(IV) can be base-line separated and detected within 20 min. The analysis of pentylated tin compounds by GC-MS confirmed the existence of methyltins and inorganic tin in lard samples, which was agreeable with the results obtained by GC-FPD. The content of organotin compounds was calculated by internal standard method in which methyltripropyltin (MeSnPr3) acted as internal standard. The results showed that these samples were heavily contaminated with mg/g levels of dimethyltin, microg/g levels of tri- and monomethyltin. Among them, one sample contained mg/g level of dioctyltin and one contained a little of inorganic form of Sn(IV). The recoveries of tri-, di- and monomethyltin were 95.7%, 105.5% and 105.7%, respectively.