Determination of heavy metal concentration in feed and permeate streams of polymer enhanced ultrafiltration process

Polymer enhanced ultrafiltration (PEUF) is a newly developed method for the removal of heavy metals from aqueous solutions. This method was applied for the removal of mercury and cadmium with the presence of polyethyleneimine (PEI) as a water soluble polymer. After ultrafiltration experiments for metal–polymer mixtures, two separate streams, namely, retentate and permeate, former of which contains mainly metal–polymer complex and free polymer molecules while latter of which mainly contains free metal ions, were obtained. At the end of PEUF experiments, performance of operation was determined by concentration analyses which was achieved by atomic absorption spectroscopy (AAS) applied in a different way for permeate and retentate streams considering the effect of presence of polymer. For mercury analysis, cold vapor AAS was applied. It was observed that the presence of PEI did not affect the atomic absorption signal when 10% HCl was added to the sample solutions. For calcium and cadmium, flame AAS was used. It was observed that change in PEI concentration results in change in measured concentration of calcium and cadmium. Therefore, two new approaches were developed for accurate measurement of concentrations of calcium and cadmium. It was also observed that presence of other metals did not affect the accuracy of the measurement of a particular metal in the concentration range studied.     

Determination of Y,Sm, Eu,Gd, Dy,Ho, Er in high purity terbium oxide by ICP-AES

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was employed to determine Y, Sm, Eu, Gd, Dy, Ho and Er in high purity terbium oxide. Terbium oxide was dissolved in 0.5 mol/l HNO₃ and nebulized into the plasma generated by a 56 MHz RF generator at 1.5 kW output power. Using a Jobin-Yvon 1-m Czenry-Turner high resolution, high dispersion scanning monochromator, lines mutually interference-free as well as free of interference from the matrix Tb were chosen for the seven analytes. A set of standards containing the analytes in the concentration range 0.01–1.0 gmg/ml with 1 mg/ml Tb was used for calibration. It was necessary to apply background correction to the gross analyte line intensities in order to obtain linear calibration plots for the analytes.     

亚稳态能量转移发射光谱法测定镉的研究

本文提出了一种测定镉的亚稳态能量转移发射光谱法。利用低功率交流介电法获得活化氮。采用电热蒸发微量进样装置进样,在波长为326.1nm处,测得镉的检出限为0.2 ng/mL。     

Photoacoustic Spectrometry Investigation and Determination of Rare Earth Ions Ho3+ and Nd3+ in a Solution

A home-made high sensitive photoacoustic transducer was used to determine the photoacoustic signal in a solution. The photoacoustic spectra of Ho in different solvents were measured and comparedwith its absorption spectrum. The affection factors of photoacousticsensitivity are discussed. The trivalent rare earth ions Ho3+ and Nd3+in an aqueous acetonitrile solution were determined. The detection limit is 5×10-8 mol/L for Ho3+ and 1.0 ×10-7 mol/L for Nd3+, and corresponds to the absorbance of 1.5×10 and 6.3×10-7.respectively.     

Application of laser ablation–inductively coupled plasma-mass spectrometry (LA–ICP–MS) to investigate trace metal spatial distributions in human tooth enamel and dentine growth layers and pulp

Human tooth enamel provides a nearly permanent and chronological record of an individuals nutritional status and anthropogenic trace metal exposure during development; it might thus provide an excellent bio archive. We investigated the micro-spatial distribution of trace metals (Cu, Fe, Mg, Sr, Pb, and Zn) in 196×339 m² raster pattern areas (6.6×10⁴ m²) in a deciduous tooth using laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS). Ablated areas include prenatal and postnatal enamel, the neonatal line, the dentine–enamel junction (DEJ), dentine, and the dentine–pulp junction. Topographic variations in the surface elemental distribution of lead, zinc, strontium, and iron intensities in a deciduous tooth revealed heterogeneous distribution within and among regions. ⁴³Ca normalized elemental intensities showed the following order: Sr>Mg>>Zn>Pb>Fe>Cu. Elevated zinc and lead levels were present in the dental pulp region and at the neonatal line. This study demonstrates the ability of LA–ICP–MS to provide unique elemental distribution information in micro spatial areas of dental hard tissues. Elemental distribution plots could be useful in decoding nutrition and pollution information embedded in their bio apatite structure.Presented in part at the 2002 Winter Conference on Plasma Spectrochemistry, Scottsdale, AZ, January 6–12, 2002. The poster was selected as an outstanding poster presentation.     

The measurement of high proton affinities for a variety of metallic compounds: a new approach by flame-ion mass spectrometry

A small amount (≤ 10⁻⁶ mol fraction) of four alkaline earth metals, tin and yttrium were introduced into five, premixed, fuel-rich, H₂–O₂–N₂ flames at atmospheric pressure in the temperature range 1820–2400 K. Aqueous salt solutions of the metals were sprayed into the premixed flame gas as an aerosol using an atomizer technique. Ions in a flame were observed by sampling flame gas through a nozzle into a mass spectrometer. The concentrations of the major neutral metallic species present in the flame were calculated from thermodynamic data currently available. The principal metallic ions observed were AOH⁺ (A = Mg, Ca, Sr, Ba, Sn) and A(OH)₂⁺ (A = Y), formed initially by proton transfer to AO and OAOH from H₃O⁺, a natural flame ion. Except for Mg, the ions were also produced by chemi-ionization processes. By adjusting the concentration(s) of the salt solution in the atomizer, it was found that a pair of ions could be brought into equilibrium within the time scale of the flame; the pairs included H₃O⁺ with a metal ion or two metallic ions. Because water is a major product of combustion, a very large difference in proton affinity PA⁰(AO) − PA⁰(H₂O) ≤ 490 kJ mol⁻¹ (117 kcal mol⁻¹) could be attempted for the proton transfer equilibrium. Using PA⁰(H₂O) = 691.0 kJ mol⁻¹ (165.2 kcal mol⁻¹) as a reference base to anchor the proton affinity scale, ion ratio measurements led to proton affinity PA⁰ values of 766, 912, 1004, 1184, 1201, and 1222 kJ mol⁻¹ (183, 218, 240, 283, 287, and 292 kcal mol⁻¹) corrected to 298 K for OYOH, SnO, MgO, CaO, SrO, and BaO, respectively; of these, only the value for OYOH has not been reported previously. If it is assumed that the neutral thermodynamic data are correct (although some appear to be in error), the uncertainties in the PA results reported here are ± 21 kJ mol⁻¹ (5 kcal mol⁻¹). The realization that these equilibria can be achieved in flames provides a new approach to consolidate and build the high end of the proton affinity ladder, primarily of metallic species which are not accessible at lower temperatures.     

Quantitative millimetre wavelength spectrometry at pressures approaching atmospheric: II. Determination of oxygen at atmospheric pressure

A millimetre wavelength (MMW) Fabry-Perot cavity spectrometer described in earlier work has been applied to the measurement of oxygen absorption at 60 GHz and atmospheric pressure in a gas matrix of nitrogen. The spectrometer has also been modified such that the MMW source is stabilised by a sub-harmonic microwave signal transmitted by an infrared carrier on a single mode telecommunications fibre optic. This is a step towards developing an instrument comprising minimal electronic components that can perform MMW spectrometry remotely. Oxygen determinations were achieved by monitoring the change in the quality factor (Q) of a resonant Fabry-Perot cavity due to the presence of an absorbing sample. The MMW absorption of the sample was determined by incrementing the frequency modulation (FM) deviation of the source frequency scanning the cavity resonance profile. The response curve of absorption signal versus fraction of oxygen in nitrogen was found to be linear throughout the working range of 1-100% O₂ (v/v) in N₂ with a slope of (1.407±0.007)×10⁻⁴ m⁻¹ (% O₂)⁻¹. The detection limit (3× standard deviation of the background) was found to be ∼0.8% (v/v). The MMW technique employed is advantageous since, unlike common MMW techniques, there is no vacuum requirement. Application of this method, to the monitoring of oxygen in gas mixtures of practical importance, is proposed. Values of the oxygen spectral absorption coefficients of lines between 55 and 60 GHz were measured at reduced pressure and found to be within ±2% of previous literature values. A pressure correction coefficient for O₂ absorption at 60 GHz in the 45-121 kPa range was obtained and found to be (1.354±0.014)×10⁻⁴ m⁻¹ kPa⁻¹.     

Electrospray tandem mass spectrometric analysis of zeaxanthin and its oxidation products

Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caused by free radicals. Under conditions of normal oxidative stress the carotenoids serve as protective antioxidants; however, when the oxidative stress exceeds the antioxidant capacity, carotenoids can be oxidized into numerous cleavage products. The determination and identification of oxidized carotenoids in biological samples remains a major challenge due to the small sample size and low stability of these compounds. We investigated the reaction of various zeaxanthin cleavage products with O-ethyl hydroxylamine to evaluate their levels in a biological sample. For this, a sensitive and specific electrospray tandem mass spectrometry (ESI-MS/MS) was developed, avoiding the classical lower sensitive and specific HPLC-UV and fluorescence absorption methods. Protonated molecules [M + H](+) of carotenoids upon collision-induced dissociation produced a number of structurally characteristic product ions. A series of complicated clusters of product ions differing in 14 (CH(2))and 26 (C(2)H(2))Da was characteristic of the polyene chain of intact carotenoids. All carotenoid ethyl oximes of zeaxanthin cleavage products were characterized by the losses of 60 and 61 Da in their MS/MS spectra. Through the application of the LC/MS/MS method, we identified two oxime derivatives of 3-hydroxy-beta-ionone and 3-hydroxy-14'-apocarotenal with protonated molecules at m/z 252 and m/z 370 respectively, in a human eye sample.     

安眠镇静药物的串联质谱分析方法

气相色谱以及气相色谱／质谱联用经常被用来分析生物体液样品中的药物。用这些方法分析时，需要在色谱分析前，进行长时间的样品制备和衍生化过程。本文描述了用地识别１６安眠镇静药物的ＥＩ／ＭＳ／ＭＳ过程，并且对两例服毒自杀者的尿样进行了检测。     

Mercury species immobilized on sulphydryl cotton: A new candidate reference material for mercury speciation

A batch of sulphydryl cotton microcolumns was prepared and charged with a mixed Hg standard solution (methyl-, ethyl- and inorganic Hg, 10 g l^–1 as Hg, 3 ml) and stored at 4 °C in a light-tight box. At regular time intervals over a 4 month period microcolumns were removed and Hg species were quantified by gas chromatography microwave-induced plasma atomic emission spectrometry (after elution, extraction and derivatization steps). It was found that analyte recoveries for methyl- and inorganic Hg were quantitative over the 4 month period while ethyl-Hg species appeared to be stable for up to 2 months.