Speciation of organolead compounds in water samples by GC-AAS after in situ butylation with tetrabutylammonium tetrabutylborate.

A simple and reliable analytical method for the determination of organolead compounds in water samples has been developed by means of a gas chromatographic-atomic absorption system (GC-AAS). The derivatization of the organolead cations, necessary before their determination, was directly achieved in the water samples by the reagent tetrabutylammonium tetrabutylborate. Hexane/pentane was used to extract the butylated tetraorganolead compounds. The organic layer was dried and purified with sodium sulfate, concentrated by evaporation and injected into a GC-AAS system. The effects of various parameters on the derivatization and extraction procedures were studied and discussed.

A FIA-system for As(III)/As(V)-determination with electrochemical hydride generation and AAS-detection.

A flow-injection system with electrochemical hydride generation and atomic absorption detection for As(III)/As(V) determination is described. A simple electrolytic flow-through cell has been developed and optimized. Several cathode materials like Pt, Ag, Cu, C and Pb have been tested. The influence of the electrolysis current, concentration of sulfuric acid, carrier stream, flow rate, sample volume and interferences by other metals on the arsenichydride generation have been studied. For the determination of total inorganic arsenic, As(V) is reduced to As(III) on-line by postassium iodide or L-cysteine at 95 degrees C. The influence of the temperature and the reduction medium on this pre-reduction step has been tested. The calibration curve is linear in the range of 5 to 50 microg/L for As(III) and total inorganic arsenic and shows a higher sensitivity than in case of reduction with sodium tetrahydroborate. The detection limit is 0.4 microg/L for As(III) and 0.5 microg/L for total inorganic arsenic at a sample volume of 1 mL.

Biomimetic oxidation of plant protecting agents.

The suitability of two in vitro oxidation systems as chemical models for the biological degradation of plant protecting agents has been investigated. As representative herbicides diclofop, fenoxaprop, isoproturon, linuron and monolinuron have been oxidised by two systems, the Fentons' reagent and the ascorbic acid oxidation system (AAOS) and the results compared to those of the known metabolic pathways of these compounds. The herbicides have been oxidised by Fentons' reagent (hydroxy radicals). The main products were isolated by preparative scale HPLC and identified with (1)H-NMR and MS. Some of the products have been identified by comparing their retention times and UV/Vis-spectra to those of standard compounds. Several products known from biological degradation are also found after chemical oxidation, however, notable differences between the two pathways have been observed, for instance in the case of diclofop. Oxidation by the AAOS leads to comparable results. Reaction rates for the oxidation with the AAOS have been studied and compared with data known from degradation studies of the herbicides in soil. Compounds which are slowly degraded in soil are oxidised more slowly in the biomimetic process than those with a fast degradation in soil.

Neurobehavioral effects of a long-term exposure to tetraalkyllead.

Employees of a factory producing antiknock additives for gasoline were examined psychologically after an exposure of an average of 14 years. A neurobehavioral symptom questionnaire, tests of single and choice reaction time, a cancellation task and a digit symbol test were the neurobehavioral variables. Total lead in urine and trimethyllead in urine showed different patterns of correlation with the neurobehavioral measures. Intellectual abilities (logical reasoning), age, and job years were controlled by partial correlation statistics as possible confounders. Referring to the low level of 21 micrograms lead per 100 ml blood and regarding the dose-response relations reported in the literature, the results support the hypothesis of a special neurotoxicity of the alkyllead compounds.

Exertional dyspnea as initial manifestation of Takayasu's arteritis--a case report and literature review.

BACKGROUND: Takayasu's arteritis is a chronic systemic inflammatory disease that usually affects the aorta, its primary branches and occasionally the pulmonary and coronary arteries. Female gender in reproductive age and Asian origin are known factors associated with higher disease prevalence. The clinical manifestations vary considerably and are typically caused by limb or organ ischemia illness and fever. The estimated incidence rate in the western world is 2.6 cases per million persons per year. Occasionally, exertional dyspnea can be the sole primary clinical manifestation of Takayasu's arteritis. CASE PRESENTATION: We report the case of a 57-year-old woman who was referred to our institution with increasing exertional dyspnea caused by pulmonary artery involvement in Takayasu's arteritis. In a review of the literature we discuss demographic data, clinical and radiographic findings and available therapeutic options. CONCLUSIONS: Dyspnea due to pulmonary artery involvement can be the initial symptom of Takayasu's arteritis. Simple clinical tests, including a complete pulse-status and blood pressure measuring at both arms can lead to the right diagnosis and should always be done beyond the auscultation of the heart and lungs in patients with dyspnea.

Combined effects of shiftwork and environmental hazards (heat, noise, toxic agents).

The paper deals with the results of studies or discussions concerning the problem of nightwork combined with other adverse working conditions. Special emphasis is laid on the untoward effect of high temperature during nightwork, as well as on noise and exposure to chemicals. It is shown that there is no substantial influence of heat stress on the circadian rhythm of adrenaline excretion under sitting working conditions with the subject performing a difficult mental task at warm climates up to 30 degrees C BET. Shiftwork and noise induce independent different effects which can be explained in terms of activation for shiftwork and in terms of tension for noise. The combination of both adverse exposures is therefore partly subtractive but partly additive as night work and noise negatively affect daysleep. Practical experience in the field of combined effects of shiftwork and chemical agents is lacking, but theoretical speculations lead to the conclusion that there may exist a time of day dependence of some chemicals, used at workplaces.

Transport processes through track-etch membrane filters in a reagent delivery cell.

A reagent delivery cell with a track-etch membrane filter for on-line dilution of concentrated salt solutions is described. The influence of several system parameters such as concentration of the stock solution, temperature. transmembrane pressure and the dependence on the diffusion coefficients of several salt components on the dilution was evaluated. As an application example, the use of the reagent delivery cell for on-line calibration of an atomic absorption spectrometer was studied. Fluxes through the membrane filter of 10 to 50 nL mm(-2) min(-1) with relative standard deviations of 0.8% within a day and 1.9% from day to day were achieved. The permeation experiments with the track-etch membrane filter for the dilution of aqueous solutions of several chlorides and sodium salts confirm a diffusion process. Flux rates can be estimated mathematically using Fick's first law with an agreement between measured and calculated dilution factors within 86 to 113%.

A sensitive method for simultaneous determination of airborne organolead compounds. Part I: Chromatographic separation and chemical reaction detection.

Reversed phase high performance liquid chromatography coupled to a sensitive chemical reaction detector has been developed for the separation and detection of inorganic lead and organolead compounds. The separation of Pb2+, Me3Pb+, Et3Pb+, Me4Pb, and Et4Pb can be achieved within 50 minutes. The eluate from the column flows continuously through a system of mixing coils where the lead species are transformed into compounds which undergo complexation with 4-(2-pyridylazo)resorcinol. The red-coloured complex is detected spectrophotometrically at 546 nm. In the lower measuring range of 0.3 to 1.5 nmol (abs.) for the five compounds linear calibration curves are obtained. The requirements and characteristics of the separation and post-column reactions are illustrated and the linearity, reproducibility, and sensitivity of the system area discussed.

Membrane-controlled reagent-delivery systems--a new approach for the continuous production of reagent and standard solutions.

A new simple and robust system for the production of standard solutions, based on the mass-transfer of analytes through membranes, is described. The device consists of a cone-shaped reservoir vessel, filled with a concentrated solution of the analyte and separated from a liquid acceptor stream by a membrane. Mass-flow from donor to acceptor solution is controlled by the mass-transfer-affecting properties of the active membrane area, which is determined by the hole in a template (diameter 0.8 mm) placed between the membrane and the acceptor-channel. Using nitrate as model analyte and a track-etched membrane filter (pore size 0.1 microm) dilution factors up to 2,400,000 with long-term reproducible accuracy of < 2% have been achieved. Adjustment of a requested concentration is possible by varying either the flow rate of the acceptor stream or the concentration of the reservoir solution.

Use of erythrocyte ghosts for preconcentration in element speciation.

A totally new biosorption concept has been tested. It involves the use of a biological membrane with given transport characteristics that encloses a reaction compartment chosen to bind incorporated substances irreversibly. Such a system is an erythrocyte ghost: erythrocytes that are hypotonically lysed can be filled with the desired media and resealed by warming up for 1 h. The transport system exploited is the predominant one in erythrocytes, i.e., the anion transport system with 10(6) channels/cell. Erythrocyte ghosts (in the following simply called ghosts) filled with ascorbate or cysteine as intracellular reductants were compared to unmodified human erythrocytes with regard to their ability to accumulate chromate specifically. Furthermore, the lifetime and behavior of the ghosts with respect to the influence of extracellular Cr(III) were tested. The great similarity found between the ghosts tested and unmodified erythrocytes clearly shows the general applicability of this new biosorption concept which offers possibilities for the biosorption of analytes that cannot be accumulated by unmodified erythrocytes.

Determination of trialkyllead species in water samples.

An analytical compound procedure is described for the determination of trimethyl- and triethyllead in water samples like rain, melted snow, and surface waters. The method consists of an enrichment step (adsorption onto and elution from silica gel), a chromatographic separation with column switching (HPLC including pre-column enrichment), and a spectrophotometric detection (chemical reaction detector). The detection limits for the whole procedure, starting with 500 ml sample volume, are 15 pg/ml and 20 pg/ml for trimethyl- and triethyllead resp. The standard deviation for repeated analysis of a sample containing 90 pg Et3Pb+/ml is calculated to +/- 4%. The method also covers the analysis of the chemically mixed trialkyllead species Me2EtPb+ and MeEt2Pb+. The investigation of several water samples taken from different locations shows the presence of trimethyl- and triethyllead in the concentration range of 20-100 pg/ml.

Experimental setup for the determination of analytes contained in ultrasonically levitated drops.

An automated technique for the determination of analytes in an ultrasonically levitated sample of 2 to 5 microL volume has been developed. Contactless dosing of reagents or solvents into an ultrasonically levitated drop was realized via piezoelectric micropumps. Drop size was continually controlled with a programmed CCD camera. A diode array spectrometer designed for the use with optical fibers was used for absorption and fluorescence measurements. Determinations via direct absorption measurements following the method of standard addition and acid-base titrations with an absorption indicator and a fluorescent indicator were carried out. The mean consumption of sodium hydroxide added via a piezoelectric micropump in five successive titrations with 18 nmol of sulfuric acid inside a levitated drop (indicator bromothymol blue) had a relative standard deviation of 0.7% and differed only by 0.2% from the expected value.

Application of rat mast cell incubates as a possible short-time test for sensitizing occupational chemicals.

The direct action of sensitizing occupational chemicals (formaldehyde, phenol, phenylhydrazine, p-aminophenol) on rat mast cells was investigated by determination of histamine using HPLC separation and fluorimetric detection. It turned out that dispensed mast cells from immunized and non-immunized Wistar-rats are more sensitive than small-cut lung tissue slices. Passive cutaneous anaphylaxis was negative after a fortnight sensitizing experiment with the here described occupational chemicals. Short-time tests with rat mast cells reflect anaphylactoid response and are suitable for the screening of sensitizing chemicals.

Comparison of two analytical procedures for the determination of free urinary catecholamines under the demands of shiftwork experiments.

A typical shiftwork experiment was chosen to prove the validity of an automated procedure for the analysis of free noradrenaline and adrenaline in urine. The method consists of a column switching technique with an adsorption/elution clean-up and a reversed phase high performance liquid chromatography followed by chemical reaction detection based on the trihydroxyindole method. The analysis of variance was performed using a second data set obtained by a semi-automated procedure for which the accuracy had already been confirmed. The analysis of covariance showed that for field studies, as well as for laboratory experiments in which the variances contributed by the experiments themselves are greater than 10% rel., the data sets of the two methods provide the same information.

Stability studies of arsenic, selenium, antimony and tellurium species in water, urine, fish and soil extracts using HPLC/ICP-MS.

The stability of arsenic, selenium, antimony and tellurium species in water and urine (NIST SRM 2670n) as well as in extracts of fish and soil certified reference materials (DORM-2 and NIST SRM 2710) has been investigated. Stability studies were carried out with As(III), As(V), arsenobetaine, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), phenylarsonic acid (PAA), Se(IV), Se(VI), selenomethionine, Sb(III), Sb(V) and Te(VI). Speciation analysis was performed by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Best storage of aqueous mixtures of the examined species was achieved at 3 degrees C whereas at -20 degrees C species transformation especially of selenomethionine and Sb(V) took place and a new selenium species appeared within a period of 30 days. Losses and species transformations during extraction processes were investigated. Extraction of the spiked fish material with methanol/water led to partial conversion of Sb(III), Sb(V) and selenomethionine to two new antimony and one new selenium species. The other arsenic, selenium and tellurium species were almost quantitatively extracted. For soil spiked with MMA, PAA, Se(IV) and Sb(III), recoveries after extraction with water and sulfuric acid (0.01 mol/L) were below 20%.

Identification of trimethyllead in urine by high-performance liquid chromatography with column switching and chemical reaction detection and by liquid chromatography-mass spectrometry.

Incorporated tetraalkyllead compounds are metabolized in the liver and the highly toxic trialkyllead species are excreted via the urine. The procedure for the determination of these metabolites in urine consists of solid-phase enrichment, reversed-phase pre-column high-performance liquid chromatography (HPLC) and chemical reaction detection. As urine is a very complex matrix, it must be questioned whether the retention time alone is a sufficient criterion for the identification of the analytes. For the trimethyllead ion the validity of the results was examined by selectivity checks of the chemical reaction detector, by the application of different stationary and mobile phases in single and dual pre-column HPLC systems and by the use of thermospray LC-mass spectrometry as an independent method. The results demonstrated that the recommended method is accurate for the determination of trimethyllead in urine samples.

Rotational vibrational-rotational Raman differential absorption lidar for atmospheric ozone measurements: methodology and experiment.

A single-laser Raman differential absorption lidar (DIAL) for ozone measurements in clouds is proposed. An injection-locked XeCl excimer laser serves as the radiation source. The ozone molecule number density is calculated from the differential absorption of the anti-Stokes rotational Raman return signals from molecular nitrogen and oxygen as the on-resonance wavelength and the vibrational-rotational Raman backscattering from molecular nitrogen or oxygen as the off-resonance wavelength. Model calculations show that the main advantage of the new rotational vibrational-rotational (RVR) Raman DIAL over conventional Raman DIAL is a 70-85% reduction in the wavelength-dependent effects of cloud-particle scattering on the measured ozone concentration; furthermore the complexity of the apparatus is reduced substantially. We describe a RVR Raman DIAL setup that uses a narrow-band interference-filter polychromator as the lidar receiver. Single-laser ozone measurements in the troposphere and lower stratosphere are presented, and it is shown that on further improvement of the receiver performance, ozone measurements in clouds are attainable with the filter-polychromator approach.

Influence of coffee on the excretion of noradrenaline and adrenaline in urine. A pilot study for the comparison of two methodical models.

In field studies, the excretion rate of urinary catecholamines is very often used as an indicator of strain. Interfering effects which are due to caffeine, for example, can only be quantified if the influence of coffee consumption on the excretion of catecholamines is known quantitatively. This was the aim of our study with five subjects, on five consecutive working days, and with a strict standardization of nutrition. The urine samples were specified with respect to the following parameters: sampling period, volume, urine status, density, creatinine, noradrenaline, and adrenaline. Adrenaline showed a significant correlation with coffee consumption, whereas noradrenaline did not. Moreover, it could be demonstrated that relating the concentration of catecholamines to the creatinine excretion is insufficient for work physiology studies, especially if the urine sampling periods are as short as 2h.

[General practice and home blood pressure measurement with fully automated device in long-term comparison]. / Praxis- und Heimblutdruckmessung mit Vollautomaten im Langzeitvergleich.

In this prospective cohort study on 43 patients, the blood pressure patterns measured fully automatically in the doctor's practice and at home were compared over an average period of eight months. In total, a highly significant correlation was found between professional and patient measurements for both systolic and diastolic values. However, over the entire study period, the values obtained in the doctor's practice were higher than the patient's measurements (systolic +17 mmHg, diastolic +9 mmHg). The values obtained in the practitioner's office exhibited a much greater fluctuation than the patient's measurements. The majority of the values measured in the practice were above the mean of the home measurements (65% systolic and 67% diastolic). On therapy, 28 percent of the patients showing hypertensive values in the practice measured normal pressures at home. In conclusion, the study shows a minor fluctuation and a better reproducibility of the patient's own measurements versus those taken in the practitioner's office.