Pattern recognition of respirable dust particles by a back-propagation artificial neural network.

A back-propagation neural network was used as a pattern recognition tool for LAMMA mass spectral data. Standard EPA source profiles were used as training and test data of the net. The elemental patterns (10 elements) of the sum of 100 mass spectra of fine dust particles were presented to the trained nets and satisfactory recognition (> 50%) was obtained.

The chemical composition of African haze.

The LAMMA technique (Laser Microprobe Mass Analyzer) is a valuable and powerful technique for the analysis and characterization of particulate air pollutants. At seven sites in Zimbabwe, Africa, dust particles were collected and 200 single particles were analyzed for each sampling point. The main chemical species present in the particles are Na+, K+, Cl, NO3+ and SO4(2-). Beside these, soot particles, containing carcinogenic polynuclear aromatic hydrocarbons were found. Biomass burning was identified as the major source of the dust particles what is in accordance with the assumed air quality for our sampling period.

Speciation of selenium compounds with ion-pair reversed-phase liquid chromatography using inductively coupled plasma mass spectrometry as element-specific detection.

For selenium speciation analysis, the hyphenation of chromatographic separation with element-specific detection has proved a useful technique. A powerful separation system, which is capable of resolving several biologically and environmentally important selenium compounds in a single column, is greatly needed. However, that has been difficult to achieve. In this paper eight selenium compounds, namely, selenite [Se(IV)], selenate [Se(VI)], selenocystine (SeCys), selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), selenocystamine (SeCM) and trimethylselenonium ion (TMSe+), were separated by using mixed ion-pair reagents containing 2.5 mM sodium 1-butanesulfonate and 8 mM tetramethylammonium hydroxide as a mobile phase. The separation of these anionic, cationic and neutral organic selenium compounds on a LiChrosorb RP18 reversed-phase column took only 18 min at a flow-rate of 1.0 ml/min with isocratic elution, and baseline separation among the six organic Se compounds was achieved. Inductively coupled plasma mass spectrometry (ICP-MS) was employed as element-specific detection. A comparison of ICP-MS signal intensity obtained with a Barbington-type nebulizer and with an ultrasonic nebulizer (USN) was made. Different signal enhancement factors were observed for the various selenium compounds when a USN was used. The speciation technique was successfully applied to the study on chemical forms of selenium in a selenium nutritional supplement. Selenomethionine was found to be the predominant constituent of selenium in the supplement.

Arsenic speciation in human urine reference materials using high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection.

Six arsenic compounds including arsenocholine, arsenobetaine, dimethylarsinic acid, methylarsonic acid, arsenous acid and arsenic acid were separated by high-performance liquid chromatography (HPLC) on a Hamilton PRP-X100 anion-exchange column using isocratic elution and detected by inductively coupled plasma mass spectrometry (ICP-MS). This analytical procedure was applied to the speciation of arsenic compounds in human urine. The influence of urine matrix on the separation of arsenic compounds was evaluated and the determination of arsenic compounds was not hampered by the ArCl interference which has often been encountered in ICP-MS. Three human urine reference materials, SRM 2670 normal level, SRM 2670 elevated level and Lyphocheck urine metal control 1, were analyzed with respect to arsenic compounds by HPLC-ICP-MS. The results were found to be in good agreement with the certified total arsenic concentration in the reference materials. Six arsenic compounds were detected. Arsenobetaine was found to be present in all of the investigated human urine reference materials.

The interaction of particulate matter and gaseous automobile exhaust in the city of Graz, Austria.

Aerosol particles collected at urban locations contain a significant portion of automobile exhaust emissions, especially lead and zinc. The most important emitted gases, carbon monoxide (CO), hydrocarbons (HC), and the nitrogen oxides (NOx) play an important role in the formation of photochemical smog in urban areas. Nitrate formation through heterogeneous reactions on dust particles may provide a removal mechanism for the nitrogen oxides in the atmosphere. As a consequence dust can reduce ozone formation rates by up to 25%. At 47 sites within the city of Graz, Austria dust particles were collected. Two hundred particles with a diameter of about 1 microns were analyzed with a Laser Microprobe Mass Analyzer (LAMMA) for each sampling point: one half for laser generated cations and the other half for anions. The frequencies of occurrence of elements in 100 particles were used as a measure for the air quality. Isolines (lines of equal element frequencies) were employed to outline polluted regions and identify the sources of dust particles. A summation method was used to monitor nitrogen oxides. Particulate nitrate correlates well with lead frequencies in aerosols as well as with NOx levels. This indicates that the NOx emitted by traffic exhaust is at least partially deposited on particulate matter.

Air pollution by particulate matter in the industrialized city of Leoben, Austria.

At seven sites in Leoben, Austria, aerosol particles were sampled in two size fractions by a dichotomous sampler using virtual impaction: the fine fraction (alveolar aerosol) with an aerodynamic diameter dac < 2.5 microns (PM2.5), and the coarse fraction (tracheobronchial aerosol) with an dac between 2.5 and 10 microns. It is believed that these particles are able to reach the lower regions of the human respiratory tract, and thus be responsible for most of the adverse health effects associated with suspended particulate pollution. A second sampling procedure was made collecting the PM2.5 fraction and after leaching with nitric acid, lead, zinc, cadmium, copper, chromium and vanadium were determined with an inductively coupled plasma mass spectrometer (ICP-MS). For one sample point a third sampling was carried out and both fractions were subsequently leached with water and dilute hydrochloric acid. Pb, Zn, Mn, Fe, Cd, Ni, Cu, Rb, Sr, Mo, Cs, Ba and Tl were determined by ICP-MS.

The retention behavior of arsenic compounds on PRP-X100 column under alkaline condition.

A systematical investigation of the retention behaviour of arsenic compounds (arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, arsenobetaine etc.) on PRP-X100 column under alkaline condition was carried out. The dependence of the retention times of arsenic compounds on pH with two mobile phases: 20 mmol/L ammonium bicarbonate, 2.5 mmol/L p-hydroxybenzoic acid/1.0 mmol/L benzoic acid was studied, and the optimal separations of these five arsenic compounds were achieved.

Essential trace elements in humans. Serum arsenic concentrations in hemodialysis patients in comparison to healthy controls.

Serum arsenic concentrations of persons suffering from renal failure and undergoing hemodialysis treatment (n = 85) and of healthy controls (n = 25) were determined by hydride-generation AAS technique after microwave digestion. The results were evaluated by comparing the values of both groups, considering physiological factors and individual data, as well as comorbid conditions of the hemodialysis (HD) patients. Serum arsenic levels were diminished in the patient group compared with controls (mean values 8.5 +/- 1.8 ng/mL vs 10.6 +/- 1.3 ng/mL). Furthermore, additional diseases within the hemodialysis group, particularly injuries of the central nervous system (CNS), vascular diseases, and cancer, were correlated to occasionally markedly decreased serum arsenic concentrations. It was concluded that arsenic homeostasis is disturbed by HD treatment and certain additional diseases. Desirable arsenic concentrations in the body seem to be reasonable. This consideration results in the conclusion that arsenic could play an essential role in human health. Thus, reference arsenic concentrations in different human tissues and body fluids should be established in order to recognize not only arsenic intoxication, but also arsenic deficiency. Perhaps arsenic deficiency contributes to the increased death risk of HD patients, and therefore, arsenic supplementations for patients with extremely low serum arsenic concentrations should be taken into account.

Accumulation of heavy metals in animals. Part 1: Lead and cadmium contamination in some wild animals.

The accumulation of the heavy metals lead and cadmium in the liver of wild animals reveals when also not so alarming, an anthropogenic source of influence from industrial procedures. A great deal of the high mean values distributed in the literature appear to be more a problem of data evaluation, where few, but higher deviation values caused by sample contamination distorts the picture. Apart from samples with heavy lead deposits due to the gun shot, it is not necessary to advise against the consumption of venison.

Accumulation of heavy metals in animals. Part 3: Heavy metal contamination in small mammals at a waste disposal site.

Small mammals were captured at a waste disposal site; the kidneys of the animals were analysed for their content of lead, cadmium, copper and zinc. A control group was taken from the adjoining forest. Lead and copper clearly revealed higher values, no difference could be found for zinc, while the reverse was true for the cadmium content.

Accumulation of heavy metals in animals. Part 2: Heavy metal contamination of fish in Styrian waters.

The kidneys of fish from five different regions of Styrian waters were investigated for their content of cadmium, lead, copper and zinc. 72.6% of fish demonstrated a zinc content below 130 ppm, cadmium content lay with 69% under 750 ppb. Lead concentrations were slightly higher, however values above 1 ppm were demonstrated only in 27.4% of cases. The copper content in the kidneys of fish was significantly higher; revealing in 28.8% a copper content of above 8 ppm.