Atmospheric aerosol studies in southern Norway using size-fractonating smapling devices and nuclear analytical techniques

Atmospheric aerosol samples were collected during spring sampling campaigns in 1988 and 1989 at Birkenes and Nordmoen in southern Norway. The aerosol collectors used included stacked filter units (SFUs), a low volume sampler (referred to as ILVS), which consists of a filter preceded by three impaction stages, and an 11-stage Berner low-pressure impactor (LPI). All samples were analyzed for up to about 40 elements by INAA and PIXE. The resuls obtained from parallel samplings were intercompared in terms of ratios ILVS/SFU and LPI/SFU, whereby these ratios were calculated separately for the coarse and fine size fractions. For the ILVS/SFU parallel samplings, excellent agreement was observed between the results for the fine fraction, with the overall mean average ratio (based on 21 samples and 22 elements) being 0.99±0.10. For the coarse fraction, the overall mean ILVS/SFU ratio (based on 21 elements) was 0.75±0.13. This low result is explained by different upper-particle-size cut-offs of the two samplers. For the parallel samplings with LPI and SFU, the agreement was poorer, but still reasonable. The atmospheric concentrations observed at the two sites in the two campaigns and also the LPI size distributions for the various elements are discussed briefly.     

Microwave-assisted extraction of metal elements from glass fibrous filters for aerosol sampling

Atmospheric aerosols are generally collected on filters according to the International Monitoring System (IMS) designed in the Comprehensive Nuclear-Test-Ban Treaty (CTBT). More information could be revealed when the filter sample is pretreated rather than measured directly by g-ray spectrometer. Microwave-assisted extraction (MAE) is a suitable method that gives higher recoveries of elements from glass fibrous filters under different conditions. The results indicate that the MAE is a highly efficient and robust method for the treatment of glass fibrous filter samples. The recoveries of potential fission products from glass fibrous filter samples by microwave-assisted extraction meet the efficiency of the extraction by both aqua regia and 2% HCl.     

Development of variance‐filtered instrumental transfer methods for high‐resolution NMR spectroscopy

The introduction of a variance‐filter to both direct standardization (DS) and piece‐wise direct standardization (PDS) instrumental transfer methods for the analysis of NMR spectral data is described. The variance‐filter modification allows for the identification of regions in the NMR spectra that are not adequately represented by the limited number of transfer calibration samples used during the calculation of the instrument‐to‐instrument transfer matrix. For these spectral frequencies, the corresponding portion of the transfer matrix is replaced by identity (or scaled identity) prior to the secondary instrumental data sets being transferred to the target instrument response. The spectral matching performance of the variance‐filtered instrumental transfer method as applied to high‐resolution ¹H NMR spectra is presented along with possible uses and limitations. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of superabsorbent polyacrylate dust in workplace atmospheres after derivatization with ethanol and using HPLC with pulsed electrochemical detection

Superabsorbent polyacrylates (SAPs) have been used in the hygiene industry for many years. A derivatization and analytical method was developed for routine analysis of trace levels of SAP dust in workplace atmospheres. In comparison with existing methods, which are based on the sodium content or the ion exchange properties of the polymer, this method is more specific. It has the advantage of not being influenced by any sodium containing contaminants. Air samples are collected on Teflon filters using air monitoring sampling cassettes. The filters are subsequently placed in quartz vials and a reaction mixture containing hydrochloric acid in ethanol is added. The hydrochloric acid-ethanol solution, when heated, converts the carboxylic acid groups on the backbone of the insoluble polyacrylate into ethyl esters. After reaction, the excess of ethanol and hydrochloric acid is completely removed under vacuum. The sample is then treated with aqueous sodium hydroxide at 80 degrees C to release the bound ethanol. The solution is analyzed by HPLC on an anion exclusion stationary phase using dilute perchloric acid as mobile phase. Ethanol is identified and quantified with a pulsed electrochemical detector. Several environmental samples in addition to laboratory spiked samples were successfully analyzed with this technique. Recoveries averaged > 85% for spiked blank filters at levels from 5 to 50 micrograms per filter with relative standard deviations up to 7%. The instrument's limit of detection (LOD) for ethanol was 0.1 mg l-1. The LOD for derivatization and analysis corresponds to 3 micrograms of SAP per filter (assuming an esterification factor of 0.30 microgram of ethanol per microgram of SAP).     

Sample collection,filtration and preservation protocols for the determination of 'total dissolved' mercury in waters

The objective of the work carried out was to recommend protocols for the collection, filtration (0.45 microm) and preservation of surface water samples for the subsequent determination of total 'dissolved' Hg. Cold vapour (CV) ICP-MS was employed to determine Hg; samples were acidified to a strength of 4 mol l(-1) HCl and 1% NaBH4 was used as the reducing agent in-line. Four types of 125 ml bottles were studied (Teflon, fluorinated ethene propene copolymer, FEP; high density polyethylene, HDPE; polyethylene terephthalate copolyester, PET; polypropylene, PP), together with three cleaning methods (EPA Methods 1631, 1638 and a rinse with reverse osmosis deionised water, 'MilliQ'). The transmission properties of the four materials were also studied to evaluate the potential for contamination from atmospheric Hg0. Results of this bottle study (n = 195), all below the detection limit of 0.5 ng l(-1), indicate that the bottles of choice, from an economic and time-saving perspective, are HDPE and PP, the latter being preferable if the sample is to be stored in a contaminated atmosphere. The bottles would be used on a once-only basis, negating the need for labourious and costly cleaning on repeat use. A simple rinse with MilliQ water would suffice prior to use. Twelve 0.45 microm filter systems (mostly Millipore and Gelman) were studied for (a) their potential Hg contamination properties and (b) their retention of Hg, possibly in colloidal form, during filtration. Ottawa River water, spiked at 50 ng l(-1) Hg, was used as a control sample. Again blank values were all negative, indicating contamination was not a concern but different recoveries of Hg were obtained across the different systems. The optimum systems to use, in that they provided maximum recovery (ca 80%) of Hg, are the Millipore Sterivex capsule and the Millipore Millex disc, both based on the hydrophilic Durapore membrane. The lowest recoveries (23-36%) were found with the Gelman AquaPrep systems and the Millipore HN nylon filter. Four control samples, Ottawa, Rideau and Gatineau Rivers, and a MilliQ blank, were used to study three preservation approaches, in the media: 0.5% BrCl, 2% HCl and 0.04% K2Cr2O7 in 1% HNO3. Mercury was stable for 28 days in a medium of 0.5% BrCl in all four samples but the other two media showed a loss of up to ca 20% Hg over this time frame, the loss being sample and time dependent. This may be a species transformation which is not detected by CV-ICP-MS from an HCl medium but this requires further investigation. Mercury was stable over the 28 days in the spiked blank MilliQ sample for all three preservation media.     

Design and construction of an ultra-low-background 14-crystal germanium array for high efficiency and coincidence measurements

Physics experiments, environmental surveillance, and treaty verification techniques continue to require increased sensitivity for detecting and quantifying radionuclides of interest. This can be done by detecting a greater fraction of gamma emissions from a sample (higher detection efficiency) and reducing instrument backgrounds. A current effort for increased sensitivity in high resolution gamma spectroscopy will produce an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and useful coincidence efficiencies. The system design is optimized to accommodate filter paper samples, e.g. samples collected by the Radionuclide Aerosol Sampler/Analyzer (RASA). The system will provide high sensitivity for weak collections on atmospheric filter samples, as well as offering the potential to gather additional information from more active filters using gamma cascade coincidence detection. The current effort is constructing an ultra-low-background HPGe crystal array consisting of two vacuum cryostats, each housing a hexagonal array of 7 crystals on the order of 70% relative efficiency per crystal. Traditional methods for constructing ultra-low-background detectors are used, including use of materials known to be low in radioactive contaminants, use of ultra pure reagents, clean room assembly, etc. The cryostat will be constructed mainly from copper electroformed into near-final geometry at PNNL. Details of the detector design, simulation of efficiency and coincidence performance, HPGe crystal testing, and progress on cryostat construction are presented.     

Inhibition of bacterial degradation of EtG by collection as dried urine spots (DUS)

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are direct alcohol consumption markers widely used nowadays for clinical and forensic applications. They are detectable in blood and urine even after consumption of trace amounts of ethanol and for a longer time frame, being detectable even when no more ethanol is present. The instability of EtG against bacterial degradation in contaminated urine samples and/or the possible postcollection synthesis of this metabolite in samples containing, e.g., Escherichia coli and ethanol, may cause false identification of alcohol uptake. Therefore, it is of paramount importance to constrict these error sources by inhibition of any bacterial growth causing hydrolization or synthesis of EtG. This study evaluates a new method of collecting urine samples on filter paper, dried urine spots (DUS), for simultaneous detection of EtG, EtS and creatinine, having the great advantage of inhibiting bacterial activity. In addition, a method validation for the determination of EtG and EtS in DUS was performed according to the FDA guidelines. Sterile-filtered urine was spiked with EtG and EtS, inoculated with E. coli and incubated. Liquid and dried urine samples were collected after various time intervals up to 96 h. Liquid samples were frozen immediately after collection, whereas aliquots for DUS were pipetted onto filter paper, allowed to dry and stored at RT until analysis 1 week after. The specimens were analyzed by LC–ESI–MS/MS. As expected, degradation of EtG, but not of EtS, was observed in contaminated liquid urine samples. However, the specimens collected on filter paper and stored at RT showed no degradation during storage. Therefore, collecting urine samples on filter paper for EtG and EtS analysis turns out to be a reliable method to avoid bacterial degradation of EtG and EtS, and consequently, stabilization of these ethanol metabolites is achieved. In addition, simultaneous measurement of creatinine content as an indicator of urine dilution helps to interpret the results. Method validation for EtG and EtS in DUS was satisfactory, showing the linearity of the calibration curves in the studied concentration range, good precision, accuracy and selectivity.     

On-line coupling of solid-phase extraction to high-performance liquid chromatography for determination of estrogens in environment

A method based on on-line solid-phase extraction (SPE) coupling to high-performance liquid chromatography (HPLC) for the determination of estrogens has been developed. This method can continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pretreatment, which can then be analyzed by HPLC with a UV detector at 230 nm. A pre-concentration column was adapted with methanol/water for chromatographic separation and two kinds of sorbents were involved, which are octadecyl-bonded silica and cigarette filter. The condition of pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of both two sorbents were satisfactory. The on-line SPE system requires very low maintenance and just involved a switching-valve-filter system and a flow-inject pump, and the operation of the whole SPE-HPLC instrumentation is quite simple. The detection limits for pre-concentrating 50 mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ng L⁻¹. The enhancement factors were in the range of 197-326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112%. The precisions for nine replicate measurements of a standard mixture (5.0 μg L⁻¹) were in the range of 1.0-3.4%.     

The separation of platinum and palladium by selective extraction of H(2)Pt(SCN)(6) and H(2)Pd(SCN)(4) using a polyTHF-impregnated filter

Platinum and palladium are known to form complexes with the thiocyanate ion in solution. The isolation and separation of both platinum and palladium as thiocyanate complexes is demonstrated by passing them through an organic-impregnated filter (OIF) prepared with polyTHF. Simultaneous extraction is performed by converting both metals into the extractable form. Sequential extraction is achieved by exploiting the difference in the rates of formation for the extractable complexes of the two metals. The extraction of both metals is rapid with quantitative recoveries of platinum with flow rates as high as 600 ml min⁻¹ in small samples, while recoveries from larger volume samples were considerably lower. Once extracted, the metals can be removed from the OIF by conversion to a non-extractable form with a high pH eluting solution. The rapid separation, isolation and preconcentration of both platinum and palladium from aqueous samples is demonstrated.     

Determination of trace nitrite ion in water by spectrophotometric method after preconcentration on an organic solvent-soluble membrane filter

A simple and rapid preconcentration technique, based on collecting trace nitrite on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to its spectrophotometric determination in water. At pH 2.0, nitrous acid diazotizes with p-aminoacetophenone. which is then coupled with N-(1-naphthyl)ethylenediamine, at the same pH. The azo dye formed is collected on a 0.45 urn nitrocellulose filter at pH 4.7 as its ion associate with dodecyl sulfate. The ion associate and filter are dissolved in a small volume of 2-methoxyethanol (methylcellosolve), and acidized with 0.05 ml of 2 M hydrochloric acid and the absorbance of the resulting solution is measured at 555 nm against a reagent blank. Detection limits better than O.1 mug/dm(-3) as NO(2)(-) can be achieved. The ions normally present in water do not interfere when sodium metaphosphate is added as a masking agent. The proposed method has been applied to the analysis of water samples from several sources, the recoveries of the nitrite added to the samples are quantitative, and results found are satisfactory.     

Determination of Iron (II) in Water by a Spectrophotometric Method After Preconcentration on an Organic Solvent-Soluble Membrane Filter

Abstract

A solvent-soluble membrane filter is proposed for a simple and rapid preconcentration and spectrophotometric determination of iron (II), which was collected on a nitrocellulose membrane filter as an ion-associate of the cationic complex of iron (II)-1,10-phenanthroline with an anionic surfactant of dodecyl sulfate. The ion-associate collected was dissolved in 5 ml of 2-methoxyethanol together with the filter. The color intensity due to the ion-associate in the resulting solution was measured at 510 nm against a reagent blank. Beer's law is obeyed in the range 1–15 μg Fe (II) in 5 ml of solvent with excellent reproducibility, and detection limits better than 0.5 μg dm^?3 as Fe (II) can be achieved. The diverse components normally present in water do not interfere when proper masking reagent is added. The proposed method has been applied to the analysis of water samples from several sources such as river water, ground water and tapwater samples, the recoveries of the iron (II) added to the samples are quantitative, and results found are satisfactory.     

Stand-off Raman detection using dispersive and tunable filter based systems

Small, transportable Raman systems are being developed for stand-off Raman measurements at intermediate ranges (e.g. <20 m) for planetary measurements. Four variations of stand-off Raman systems are described that use a small telescope for light collection that is either fiber-optic or lens-coupled to a detection system. The performance of an acousto-optic tunable filter for wavelength selection and spectral imaging is tested by comparing signal-to-noise ratio and throughput to similar measurements using a conventional spectrograph, and by measuring a variety of organic and inorganic mineral samples at distances up to 15 m. We also determine optimal ICCD gate widths for acquiring remote Raman spectra under high ambient light conditions.     

Particle sorting using a porous membrane in a microfluidic device

Porous membranes have been fabricated based on the development of the perforated membrane mold [Y. Luo and R. N. Zare, Lab Chip, 2008, 8, 1688-1694] to create a single filter that contains multiple pore sizes ranging from 6.4 to 16.6 μm inside a monolithic three-dimensional poly(dimethylsiloxane) microfluidic structure. By overlapping two filters we are able to achieve smaller pore size openings (2.5 to 3.3 μm). This filter operates without any detectable irreversible clogging, which is achieved using a cross-flow placed in front of each filtration section. The utility of a particle-sorting device that contains this filter is demonstrated by separating polystyrene beads of different diameters with an efficiency greater than 99.9%. Additionally, we demonstrate the effectiveness of this particle-sorting device by separating whole blood samples into white blood cells and red blood cells with platelets.     

Status report: preparing an ambient aerosol filter reference material for elemental analysis

Summary For the elemental analysis of aerosol filter samples by X-ray techniques there is a lack of adequate reference materials (RM). No genuine aerosol matrix is available, which has been collected on membrane filters from ambient aerosol and can be distributed in the same physical form. It is possible to collect high-volume ambient aerosol samples, with a uniformity of 5% to 15%, in the elemental deposit ranges of 10 ng/cm² to g/cm² within probed spots of only 4 mm diameter on suitable filter materials. An aerosol sampling campaign is being organized, aiming at the collection of large enough filter batches of aerosols of different origin, suitable for characterization by different analytical methods and compatible with X-ray fluorescence analysis (XRF). To a large extent, the production control - especially for the homogeneity of the elemental mass deposits - will be performed by particle-induced X-ray emission (PIXE) analysis on residual material without consuming any part of the candidate RM stock.Working under contract CBNM/ST/91-147     

卡尔曼滤波分光光度法用于钴、镍、铜、锌、镉的同时测定—5-Br-PADAP-CPB法

本文运用卡尔曼滤波(KF)递推算法,以2-(5-溴-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP),溴化十六烷基吡啶(CPB)同时测定了五组分混合物:Co、Ni、Cu、Zn和Cd中各元素百分含量,合成样分析结果良好。用模型数据可测百分含量相差50倍的离子混合物。     

Capillary-HPLC-ESI-MS/MS method for the determination of acidic products from the oxidation of monoterpenes in atmospheric aerosol samples

A method is presented for the determination of acidic products from terpene oxidation in filter samples of the atmospheric particle phase. Oxidation products of monoterpenes are believed to add a large fraction to the secondary organic aerosol (SOA) in the troposphere. Those products with structures containing one or more carboxylic acid groups have especially low vapour pressures and therefore they are believed to contribute substantially to the particle phase. Although many experiments were performed in simulation chambers to study the SOA generation by oxidation of terpenes, concentration measurements of products in the atmospheric particle phase are still rare. This is especially true for oxidation products of terpenes other than α- and β-pinene. Therefore, we developed a method for the quantification of acidic products from terpene oxidation in atmospheric aerosol samples. After passing a PM 2.5 (PM = particulate matter) pre-separator to remove coarse particles, fine atmospheric particles were collected onto quartz fibre filters. A backup filter was placed behind the first filter to estimate possible sampling artifacts. The filters were extracted in an ultrasonic bath using methanol. After enrichment and re-dissolving in water the samples were analysed using a capillary-HPLC-ESI(−)-MSⁿ set-up. The ion trap mass spectrometer could be used to gain structural information about the analytes and to enhance the selectivity of the measurements by using its MS/MS capability. A variety of products from different terpenes could be identified and quantified in samples of the ambient atmosphere using reference data from chamber experiments. Due to strong matrix effects quantification of samples from the real atmosphere had to be done by the standard addition method.     

Neutron activation studies of trace elements in tree rings

The levels of twelve elements most of which are either considered essential to plant growth or have been detected in air filter samples in an air pollution survey, have been monitored in three transverse sections of trees, two elms (ring porous trees) and one cedar (a conifer). Two dimensional distributions of these elements around the tree rings of the section and radially from ring to ring, have been obtained to see if tree rings can be analysed for use as a record of historical pollution.     

Evaluation of relevant time-of-flight-MS parameters used in HPLC/MS full-scan screening methods for pesticide residues

An automatic screening method based on HPLC/time-of-flight (TOF)-MS (full scan) was used for the analysis of 103 non-European fruit and vegetable samples after extraction by the quick, easy, cheap, effective, rugged, and safe method. The screening method uses a database that includes 300 pesticides, their fragments, and isotopical signals (910 ions) that identified 210 pesticides in 78 positive samples, with the highest number of detection being nine pesticides/sample. The concentrations of 97 pesticides were <10 microg/kg, 53 were between 10 and 100 microg/kg, and 60 were at a concentration of >100 microg/kg. Several parameters of the automatic screening method were carefully studied to avoid false positives and negatives in the studied samples; these included peak filter (number of chromatographic peak counts) and search criteria (retention time and error window). These parameters were affected by differences in mass accuracy and sensitivity of the two HPLC/TOF-MS systems used with different resolution powers (15 000 and 7500), the capabilities of which for resolving the ions included in the database from the matrix ions were studied in four matrixes, viz., pepper, rice, garlic, and cauliflower. Both of these mass resolutions were found to be satisfactory to resolve interferences from the signals of interest in the studied matrixes.     

Fast analysis of high-energy compounds and agricultural chemicals in water with desorption electrospray ionization mass spectrometry

Novel sampling and detection methods using desorption electrospray ionization (DESI) are examined in the detection of explosives (RDX, TNT, HMX, and TNB) and agricultural chemicals (atrazine, alachlor and acetochlor) from aqueous matrices and authentic contaminated groundwater samples. DESI allows analysis of solid and liquid compounds directly from surfaces of interest with little or no sample preparation. Significant savings in analysis time and sample preparation are realized. The methods investigated here include (i) immediate analysis of filter paper wetted with contaminated water samples without further sample preparation, (ii) rapid liquid-liquid extraction (LLE), and (iii) analyte extraction from contaminated groundwater samples on-site using solid-phase extraction (SPE) membranes, followed by direct DESI analysis of the membrane. The wetted filter paper experiment demonstrates the maximum sample throughput for DESI analysis of aqueous matrices but has inadequate sensitivity for some of these analytes. Both the LLE and the SPE methods have adequate sensitivity. The resulting SPE membranes and/or small volume solvent extracts produced in these experiments are readily transported to off-site facilities for direct analysis by DESI. This realizes a significant reduction in the costs of sample shipping compared with those for typical liter-sized samples of groundwater. Total analysis times for these preliminary DESI analyses are comparable with or shorter than those for GC/MS and limits of detection approach environmental action levels for these compounds while maintaining a modest relative standard deviation. Tandem mass spectrometric data is used to provide additional specificity as needed.     

Spectrofluorimetric determination of dipyridamole in serum--a comparison of two methods

Two spectrofluorimetric methods for the determination of dipyridamole in plasma are described. The thin-layer chromatographic-fluoridensitometric method utilizes 1 ml of plasma which is extracted at pH 10 with diethyl ether-dichloromethane (80:20). The organic phase is evaporated to dryness, reconstituted in 250 microliter dichloromethane and 5 microliter are spotted on a silica gel 60 plate. The plate is developed in ethyl acetate-methanol-ammonia (85:10:5), dried, dipped in a paraffin wax solution, dried, and scanned using 380 nm as excitation wavelength, a 430 nm cut-off filter, and collecting all emitted light on the photomultiplier. Quantitation was done by the external standard method, peak heights being measured and a calibration graph constructed. For the spectrofluorimetric method 1 ml of plasma is extracted at pH 10 with 8 ml of hexane-isoamyl alcohol (95:5) and the organic phase used directly for the measurement of the fluorescence intensity (excitation 405 nm, emission 495 nm). Quantitation was done by measuring the fluorescence of standards that were treated as above and constructing a calibration graph of concentration versus fluorescence intensity. Concentrations of unknowns were found by interpolation from this graph. The two methods were found to exhibit good correlation but the spectrofluorimetric method proved to be more amenable to the analysis of a large number of samples.