Square wave adsorptive stripping voltammetric determination of diazinon in its insecticidal formulations

The pesticide diazinon was determined in its insecticidal formulations by square wave adsorptive stripping voltammetry. The method of its determination is based on the irreversible reduction reaction at the hanging mercury drop electrode. The optimal signal was detected at -1.05?V vs. Ag/AgCl in Britton-Robinson buffer at pH?4.4. Various parameters such as pH, buffer concentration, frequency, amplitude, step potential, accumulation time, and potential were investigated to enhance the sensitivity of the determination. The highest response was recorded at an accumulation potential -0.4?V, accumulation time 60?s, amplitude 75?mV, frequency 100?Hz, and step potential 5?mV. The pesticide electrochemical behavior was considered under experimental conditions. The electroanalytical procedure enabled diazinon determination in the concentration range 4.0?×?10(-8)-3.9?×?10(-7)?mol?L(-1) in supporting electrolyte. The detection and quantification limit were found to be 1.1?×?10(-8) and 3.7?×?10(-8)?mol?L(-1), respectively. The method was applied successfully in the determination of the active ingredients in the insecticidal formulations Diazinon 10GR and Beaphar 275.     

4—（H—酸偶氮）—1—苯基—3—甲基吡唑酮光度法测定铜的研究及应用

合成了新试剂４－（Ｈ－酸偶氮）１－苯基－３－甲基吡唑酮（ＨＰＭＰ），研究了其和铜的显色反应。在ｐＨ＝７的ＮＨ４Ａｃ缓冲介质中，ＣＴＭＡＢ存在下，ＨＰＭＰ与Ｃｕ（Ⅱ）生成２∶１紫色络合物，λｍａｘ＝５８０ｎｍ，ε＝５．６８×１０４Ｌ·ｍｏｌ－１·ｃｍ－１。铜含量在０～０．６ｍｇ／Ｌ内符合比耳定律。方法用于水样和生物样品中铜的测定，结果令人满意。     

Optimization of pulp mill effluent treatment with catalytic adsorbent using orthogonal second-order (Box-Behnken) experimental design

Novel catalytic adsorbent (ruthenium on carbon) was employed for the treatment of pulp mill effluent in the presence of hydrogen peroxide. Mathematical model and optimization of the process regarding the most favorable COD (%), TOC (%) and color (%) removal rates was developed and performed with experimental design taking into account catalytic adsorption process kinetics. As the initial experimental design, 3(3-1) half-fractional factorial design (H-FFD) was accomplished at two levels to study the significance of the main effects, such as catalytic adsorbent (g l(-1)) and hydrogen peroxide (ppm) concentrations using the response surface methodology (RSM). Finally, a four factor-three coded level central composite design (CCD) with 28 runs was performed in order to fit a second-order polynomial model. Validation of the model was accomplished by different criteria including coefficient of determination and the corresponding analysis of variance. The achieved removal rates for TOC (up to 75%), COD (up to 73%) and color (up to 68%) were observed for the defined optimal conditions: 1g l(-1) of ruthenium on carbon, 7 ppm of hydrogen peroxide, pH = 4 and ambient temperature. The proposed method benefited significantly improved TOC, COD and color removal efficiency, regenerability and reusability of the catalytic adsorbent and unaltered initial pH of an effluent in comparison to traditional adsorption or oxidation processes.     

A highly sensitive spectrophotometric determination of micro amounts of vanadium(V) in environmental and alloy samples by using 3,4-dihydroxybenzaldehydeisonicotinoylhydrazone (3,4-DHBINH)

3, 4-Dihydroxybenzaldehydeisonicotinoylhydrazone was prepared, characterized with spectral analyses and used for developing a new method for the simple, sensitive and rapid spectrophotometric determination of vanadium(V) which gives maximum absorbance at wave length 360 nm. The metal ion gives a yellow colored complex with 3, 4-DHBINH in acetate buffer of pH 5.5 with 1:1 (metal:ligand) composition. The method obeys Beer's law in the range 0.5-5.3 mug mL(-1) of vanadium(V). The molar absorptivity and Sandell's sensitivity were found to be 1.29 x 10(4) L mol(-1) cm(-1) and 0.003949 mug cm(-2) respectively. The correlation co-efficient of the V(V)-3, 4-DHBINH complex was 0.992 which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) as 0.424% (n = 5), and its detection limit 0.01677 mug mL(-1) of vanadium(V). The instability constant of the method was calculated by Asmus' method as 4.1666 x 10(-3). The interfering effect of various cations and anions were also studied. The proposed method was successfully applied to the determination of vanadium(V) in environmental samples (water and soil) tobacco leaves and alloy samples. The validity of the method was tested by comparing the results with those obtained using an atomic absorption spectrophotometer.     

Utility of cefixime as a complexing reagent for the determination of Ni(II) in synthetic mixture and water samples

A simple, sensitive, and accurate UV spectrophotometric method has been developed for the determination of nickel in synthetic mixture and water samples. The method is based on the complexation reaction of nickel ion with cefixime, thus leading to the formation of Ni–cefixime complex in ethanol-distilled water medium at room temperature. The complex showed the maximum absorption wavelength at 332 nm. Beer’s law is obeyed in the working concentration range of 0.447–4.019 μg?mL^?1 with apparent molar absorptivity of 7.314?×?10³?L?mol^?1?cm^?1 and Sandell’s sensitivity of 0.008 μg/cm²/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.016 and 0.054 μg?mL^?1, respectively. The factors such as cefixime concentration and solvent affecting the complexation reaction were carefully studied and optimized. The method is validated as per the International Conference on Harmonisation guideline. The method is successfully applied to the determination of Ni(II) in synthetic mixture and wadi water samples collected from Al Rustaq. The same water samples are also analyzed by atomic absorption spectrophotometry. Both methods determined the amount of Ni(II) in water sample and found to be approximately the same.     

Pool of mobile and immobile phosphorus in sediments of the large, shallow Lake Peipsi over the last 100?years

Temporal variations in sediment phosphorus (P) composition and mobility were estimated in surface sediments of accumulation (core PS509 44?cm) and erosion (core PS2009 30?cm) areas of the shallow, large Lake Peipsi sensu stricto (s.s.; 2611?km(2), unregulated water level). The P pool in sediments including buried and mobile P is evaluated for the first time, which will provide baseline data for the future modelling of internal loading in L. Peipsi. Five sedimentary P fractions (including inorganic and nonreactive P) were separately quantified: loosely adsorbed and pore-water P (NaCl-P); redox-sensitive fraction P (NaBD-P); P bound to oxides of non-reducible Fe and Al (NaOH-P); calcium-bound P, mainly from apatite minerals (HCl-P) and refractory, mainly organic P (Res-P). Concentrations of P fractions varied during the 100?years with the highest values around 2007-2008 and 1923-1935. The P in "active" layers that are available for bacteria and algae or those undergoing changes and diagenetic transformations in the sediment could follow sediments with the water content of ～88%. Potentially mobile P is not decreased in the sediments deposited 50-100?years ago and makes up ca 63?mg?m(-2)?y(-1) (with range 8.3-23.7% of the total P (TP)) in the accumulation area, and ca 0.047?mg?cm(-3) (with range 1.3-22.4% of TP) in the erosion area. The result shows that 13-60% of TP contained in the surface sediment (from 34 to 398?mg P m(-2) y(-1)) has been remobilised during accumulation and could be exported to the overlying water.     

Determination of hydrogen peroxide in workplace air: interferences and method validation

A dynamic system for the generation of stable hydrogen peroxide test atmospheres was applied to the evaluation of samplers used for the determination of hydrogen peroxide in workplace air. The system is able to generate gas mixtures of between 0.1 and 10 ppm at different combinations of relative humidity (20-80%) and temperature (10-30 degrees C). Gaseous hydrogen peroxide is sampled on glass filters impregnated with Ti(IV) chloride and sulfuric acid and analyzed by UV spectroscopy. An interference was observed due to the acid catalyzed decomposition of peroxyacetic acid to hydrogen peroxide. This was significantly reduced by applying high sample flow rates and by lowering the concentration of sulfuric acid. The performance of the sampler and sources of uncertainties were tested according to the European Standard EN 1076.     

Cloud point extraction–atomic absorption spectrometry for pre-concentration and determination of cadmium in cigarette samples

A new complexing agent, 2-((2-((1H-benzo[d]imidazole-2yl)methoxy)phenoxy)methyl)-1H-benzo[d]imidazole (BIMPI), was used in cloud point extraction and applied for selective pre-concentration of trace amounts of cadmium in cigarette samples. Cadmium was complexed with BIMPI in a buffer solution (pH?=?10) using Triton X-114 as surfactant and quantitatively extracted into a small volume of the surfactant-rich phase after centrifugation. Under optimized conditions (pH?=?10.0, 0.8?×?10^?4?mol?L^?1 BIMPI and 0.08 % (w/v) Triton X-114), calibration graph was linear in the range of 34.0–1,670.0 μg?L^?1. The proposed method was applied to the determination of Cd in various cigarette (tobacco) samples which gave satisfactory results.     

Spectrophotometric method for the determination of chromium (VI) in water samples

A simple and sensitive spectrophotometric method for the determination of chromium has been developed. The method is based on the diazotization of Dapsone in hydroxylamine hydrochloride medium and coupling with N-(1-Napthyl) Ethylene Diamine Dihydrochloride by electrophilic substitution to produce an intense pink azo-dye, which has absorption maximum at 540 nm. The Beer's law is obeyed from 0.02-1.0 microg mL(-1) and the molar absorptivity is 3.4854 L mol(-1) cm(-1). The Limits of quantification and Limit of detection of the proposed method are 0.0012 microg mL(-1) and 0.0039 microg mL(-1) respectively. The method has been successfully applied for the determination of chromium in water samples and the results were statistically evaluated with that of the reference method.     

Determination of antimony in human blood with inductively coupled plasma-mass spectrometry

A method is presented for the determination of antimony in whole human blood samples with an ICP-MS instrument using a quadrupole mass analyzer. A nitric acid/hydrogen peroxide open digestion procedure was employed for the blood sample treatment and preparation for analysis. The precision and accuracy of the method were evaluated by analyzing several Seronorm trace elements whole blood reference materials. The precision of the method at various antimony levels was better than 4% RSD and the recovery was greater than 92% at all levels. The detection limit, calculated as three times the standard deviation of the blank (3sigma, n= 12), was 0.03 microg L(-1). The method was successfully applied for the determination of antimony in blood samples from school children in rural areas of Kwazulu/Natal, South Africa and adults from Dearborn, Michigan. Blood antimony levels ranged from <0.03 to 3.82 microg L(-1) in children and 1.40 to 4.35 microg L(-1) for adults.     

过氧化氢氧化-全自动石墨消解仪消解-阳极溶出伏安法测定海水中总铬

采用全自动石墨消解仪加热、在碱性条件下用过氧化氢氧化海水中的三价铬,优化了极谱法测定条件,方法检出限为0.20μg/L,加标回收率为82.8%~105%,相对标准偏差5%,且对有证标准样品测试的结果符合准确度要求。方法具有选择性好、灵敏度高、准确等特点,适用于海水中总铬的测定。     

石墨炉原子吸收光谱法测定环境空气中钴

采用超细玻璃纤维滤膜采集环境空气中钴,硝酸-过氧化氢-氢氟酸混合进行消解,采用硝酸镁和硝酸混合液作为基体改进剂,石墨炉原子吸收光谱法测定环境空气中钴。此方法对测定环境空气中钴的灵敏度、准确度都有很大的提高,方法的最低检出浓度为0.25μg/L,当采样体积为100 L,钴最低检出质量浓度为0.000 1 mg/m3。对实际样品进行分析,钴的加标回收率为91.0%~106.5%。     

发生氢气分离离子色谱法间接测定水中硫化物

利用ＫＢＨ４在酸性条件下分解产生的氢气为载气分离水中硫化物，用ＮａＯＨ—Ｈ２Ｏ２溶液吸收Ｈ２Ｓ，并将其氧化为ＳＯ２－４，用离子色谱法测定ＳＯ２－４。方法用于各种水样中硫化物的测定，相对标准偏差为１．５８％，回收率在９０．５％到９８．２％之间。方法适用于水中硫化物的测定     

Occurrence and fate of steroid estrogens in the largest wastewater treatment plant in Beijing, China

Concern over steroid estrogens has increased rapidly in recent years due to their adverse health effects. Effluent discharge from wastewater treatment plants (WWTPs) is the main pollutant source for environmental water. To understand the pollutant level and fate of steroid estrogens in WWTPs, the occurrence of estrone (E1), 17-β-estradiol (E2), estriol (E3), and 17-β-ethinylestradiol (EE2) was investigated in the Gaobeidian WWTP in Beijing, China. Water samples from influent as well as effluent from second sedimentation tanks and advanced treatment processes were taken monthly during 2006 to 2007. In influent, steroid estrogen concentrations varied from 11.6 to 1.1?×?10(2)?ng/l, 3.7 to 1.4?×?10(2)?ng/l, no detection (nd) to 7.6×10(2)?ng/l and nd to 3.3?×?10(2)?ng/l for E1, E2, E3, and EE2, respectively. Compared with documented values, the higher steroid estrogen concentrations in the WWTP influent may be due to higher population density, higher birthrate, less dilution, and different sampling time. Results revealed that a municipal WWTP with an activated sludge system incorporating anaerobic, anoxic, and aerobic processes could eliminate natural and synthetic estrogens effectively. The mean elimination efficiencies were 83.2%, 96.4%, 98.8%, and 93.0% for E1, E2, E3, and EE2, respectively. The major removal mechanism for natural estrogens and synthetic estrogen EE2 were biodegradation and sorption on the basis of mass balance in water, suspension particles, and sludge. In the WWTP effluent, however, the highest concentrations of E1, E2, E3, and EE2 attained were 74.2, 3.9, 5.1, and 4.6?ng/l, respectively. This is concerning as residual steroid estrogens in WWTP effluent could lead to pollution of the receiving water. Advanced flocculation treatment was applied in the WWTP and transformed the residual estrogen conjugates to free species, which were reduced further by filtration with removal shifting from 32% to 57% for natural estrogen, although no EE2 was removed.     

Tidally driven N, P, Fe and Mn exchanges in salt marsh sediments of Tagus estuary (SW Europe)

Short-sediment cores and flooding water were collected at 0, 5, 15, 25 and 50?min of tidal inundation in the two sites colonised by pure stands of Spartina maritima (low marsh) and Sarcocornia fruticosa (high marsh) from the Rosário salt marsh (Tagus estuary, SW Europe). Concentrations of NH (4) (+) , NO (3) (-) +?NO (2) (-) and HPO (4) (2-) , Fe and Mn were measured in tidal flooding water and pore water. Flooding water is enriched in nutrients, particularly ammonium due to local discharge of untreated urban effluents. Nevertheless, NH (4) (+) and NO (3) (-) +?NO (2) (-) concentrations in flooding waters at t?=?5?min (NH (4) (+) =?246?±?7?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. fruticosa and NH (4) (+) =?256?±?8?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. maritima) rose sharply at both vegetated sites. An increase was also registered for HPO (4) (2-) and total dissolved Fe although the subsequent decrease was smoother. Advective transport induced by the two daily pulses of inundation is several orders of magnitude higher than the diffusive fluxes during submerged periods. In addition, solutes are exported from the sediment with the inundation and imported in submerged periods. The exported amount of inorganic nitrogen during tidal inundation (export of 3,200?μmol?N?m(-2)?day(-1)to the water column), is not counterbalanced by the sink of -290?μmol?N?m(-2)?day(-1) occurred during the submerged period.     

Study of the voltammetric behaviour of the ethalfluralin and methalpropalin and its determination in environmental matrices at hanging mercury drop electrode

An electroanalytical method has been developed for the determination of the herbicides ethalfluralin[N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) bezenamine] and methalpropalin [N-(2-methyl-2-propenyl)-2, 6-dinitro-N-propyl-4 (trifluoromethyl) benzenamine] by differential pulse adsorptive stripping voltammetry (DP-AdSV) on a hanging mercury drop electrode (HMDE) with universal buffer as supporting electrolyte. The optimum adsorption conditions were found to be pH 6.0, an accumulation potential of -0.6 V (HMDE vs SCE), an accumulation time of 80 s. and scan rate 45 mVs(-1). Calibration curve is linear in the range 1.30 x 10(-9) to 1.32 x 10(-5) M of ethalfluralin and 1.13 x 10(-5) to 2.0 x 10(-8) M of methalpropalin with detection limits of 1.08 x 10(-9) and 1.87 x 10(-8) M, respectively. The relative SD and correlation coefficients were found to be 1.24%, 0.998 and 1.34%, 0.995, respectively for ten replicates. The method is applied to the determination of the ethalfluralin and methalpropalin in formulations and environmental matrices.     

Study on determination of iron,cobalt, nickel,copper, zinc and manganese in drinking water by solid-phase extraction and RP-HPLC with 2-(2-quinolinylazo)-5-diethylaminophenol as precolumn derivatizing reagent

A new method for the determination of iron, cobalt, nickel, copper, zinc and manganese in drinking water by the reversed-phase high-performance liquid chromatography (RP-HPLC) with 2-(2-quinolinylazo)-5-diethylaminophenol (QADEAP) as precolumn derivatizing reagent was studied in this paper. The iron, cobalt, nickel, copper, zinc, and manganese ions react with QADEAP to form color chelates in the presence of cetyl trimethylammonium bromide (CTMAB) and acetic acid-sodium acetic buffer solution medium of pH 4.0. These chelates were enriched by solid-phase extraction with a Waters Nova-Pak C18 cartridge and eluted the retained chelates from the cartridge with tetrahydrofuran (THF). The enrichment factor of 100 was achieved. Then the chelates were separated on a Waters Nova-Pak C18 column (3.9 x 150 mm, 5 microm) by gradient elution with methanol (containing 0.2% of acetic acid and 0.1% of CTMAB) and 0.05 mol L(-1) acetic acid-sodium acetic buffer solution (containing 0.1% of CTMAB) (pH 4.0) as mobile phase at a flow rate of 0.5 ml min(-1), and monitored with a photodiode array detector from 450 approximately 700 nm. The detection limits (S/N = 3) of iron, cobalt, nickel, copper, zinc and manganese are 0.8, 1.1, 0.9, 1.1, 1.5 and 2.0 ng L(-1), respectively, in the original sample. This method can be applied to determination at the microg L(-1) level of iron, cobalt, nickel, copper, zinc and manganese in drinking water with good results.     

A nanosilver-based spectrophotometric method for determination of malachite green in surface water samples

A new spectrophotometric method is reported for the determination of nanomolar level of malachite green in surface water samples. The method is based on the catalytic effect of silver nanoparticles on the oxidation of malachite green by hexacyanoferrate (III) in acetate–acetic acid medium. The absorbance is measured at 610 nm with the fixed-time method. Under the optimum conditions, the linear range was 8.0?×?10^?9–2.0?×?10^?7?mol?L^?1 malachite green with a correlation coefficient of 0.996. The limit of detection (S/N?=?3) was 2.0?×?10^?9?mol?L^?1. Relative standard deviation for ten replicate determinations of 1.0?×?10^?8?mol?L^?1 malachite green was 1.86 %. The method is featured with good accuracy and reproducibility for malachite green determination in surface water samples without any pre-concentration and separation step.     

Uptake of heavy metals by some edible vegetables irrigated using wastewater: a preliminary study in Accra, Ghana

The heavy metals (Fe, Zn, Pb, Ni, Cr, Co, and Cd) burden in wastewater, soil, and vegetable samples from a wastewater irrigated farm located at KorleBu, Accra has been investigated. Flame atomic absorption spectrometry after microwave digestion using a combination of HNO₃, HCl, and H₂O₂ (for water), and HNO₃ and HCl (for soil and vegetables). The mean concentrations (in milligrams per kilogram) of heavy metals in the soil samples were in the order of Fe (171?±?5.22)?>?Zn (36.06?±?4.54)?>?Pb (33.35?±?35.62)?>?Ni (6.31?±?8.15)?>?Cr (3.40?±?3.63)?>?Co (1.36?±?0.31)?>?Cd (0.43?±?0.24), while the vegetables were in the order of Fe (183.11?±?161.2)?>?Zn (5.38?±?3.50)?>?Ni (3.52?±?1.27)?>?Pb (2.49?±?1.81)?>?Cr (1.46?±?0.51)?>?Co (0.66?±?0.25)?>?Cd (0.36?±?0.15). The bioconcentration factors suggest environmental monitoring for the heavy metals as follows: Cd (0.828), Cr (0.431), Ni (0.558), Co (0.485), and Fe (1.067). Estimated daily intakes were very low for both children and adults except Fe (0.767 mg/kg/day) in children. The population that consume vegetables from the study area were, however, estimated to be safe based on the results obtained from the health risk index, which were all?<?<1. The sodium absorption ratio according to FAO (1985) classifications indicate that the wastewater in the study area is unsuitable for irrigation purposes.     

HDNPTT与镉显色反应的研究

应用合成的新试剂 1- (2 -羟基 - 3 ,5 -二硝基苯 ) - 3 - (4 -苯基 - 2 -噻唑 ) -三氮烯 (HDNPTT) ,研究了在表面活性剂TritonX - 10 0存在下 ,它与Cd2 的显色反应。结果表明 ,在 pH 8 0～ 10 0范围内 ,Cd2 与该试剂形成的配合物 ,其最大吸收峰位于 5 35nm处 ,摩尔吸光系数为 1 89× 10 5L·mol-1·cm-1。Cd2 在 0mg/L～ 0 32mg/L范围内符合比尔定律。此法用于环境水样和人发样品中微量镉的测定 ,结果满意。