Triethyl Lead Research Articles

Simultaneous measurements of Cr, Cd, Hg and Pb species in ng L−1 levels by interfacing high performance liquid chromatography and inductively coupled plasma mass spectrometry

Toxicity, mobility, bioavailability and biofunctions of chromium, cadmium, mercury and lead are heavily dependent upon their specific chemical forms, leading to a high demand to metal speciation analysis rather than total quantification. Simultaneous speciation analysis of multiple metal(loid)s is attractive to a large sample capacity containing unstable analytes due to its economic and environmental advantages over the conventional single elemental strategies. In this work, an analytical method integrating online solid phase extraction into high performance liquid chromatography interfaced with inductively coupled plasma mass spectrometry (ICP-MS) to simultaneously preconcentrate and quantify Cr, Cd, Hg and Pb forms in pg L−1 levels in water was developed. Cr(III + VI), Cd(II), Hg(II), Pb(II), methylmercury (MeHg), ethylmercury (EtHg), and trimethyl (TML) and triethyl lead (TEL) were captured by the C18 adsorbent (equilibrated with 10 mL of 1.0 mM 2-hydroxyethanethiol at 10 mL min−1) and eluted by mobile phase (5.0 mM Cys at pH 2.0), then completely separated on the C18 column within 8.0 min and eventually determined by ICP-MS. Low limits of detection (0.001–0.007 ng L−1) and quantification (0.003–0.023 ng L−1), good relative standard deviations (<4%) and high enrichment factors (827–2656 folds) were obtained with good linearities. Three reference materials of total cadmium (GBW08602), total mercury (GBW08603) and total lead (GBW08601) in water were analyzed by the developed method to validate the accuracy with good agreement with certified values and satisfactory recoveries (92–100%). This method was proved feasible by the determination of Cr, Cd, Hg and Pb compounds in drinking water, river water, pond water and tap water.

Comparison of two extraction methods for the determination of organolead compounds using sodium tetrapropylborate as derivatization reagent

Two extraction methods of accelerate solvent extraction (ASE) and supercritical fluid extraction (SFE) were used to the extraction of trimethyl lead (TML) and triethyl lead (TEL), which were detected by gas chromatographer coupled with mass spectrometry. Sodium tetrapropylborate, as the derivatization reagent, was applied for the detection of gas chromatography. The recovery rate of ASE were about 88.2% (TML) and 86.4% (TEL) with 15 min consuming. The recovery rate of SFE were about 93.7% (TML) and 94.1% (TEL) with 40 min consuming. Two extraction methods of ASE and SFE were optimized, which were also analyzed in recovery, repeatability, accuracy, limit of detection (LOD) and other aspect. Both ASE and SFE exhibited rational recovery efficiency. The established methods were also applied to the real soil samples. SFE had better extraction effect according to time consumption, recovery rate, LOD and accuracy. However, ASE had more advantages in automated extraction, which could be applied to the pretreatment of large amounts of samples. • Trimethyl lead and triethyl lead of soil environment are extracted and measured. • ASE / SFE - GC system is established for the assessment of trimethyl lead and triethyl lead. • Experimental parameters of ASE and SFE are evaluated and optimized. • Difference and efficiency of ASE and SFE are analyzed for practical application.

Simultaneous enrichment of inorganic and organic species of lead and mercury in pg L−1 levels by solid phase extraction online combined with high performance liquid chromatography and inductively coupled plasma mass spectrometry

Quantification of ultra-trace inorganic and organic species of lead and mercury in unpolluted environmental water is crucial to estimate the mobility, toxicity and bioavailability and interactions. Simultaneous pre-concentration of Pb and Hg species in pg L−1 levels followed by multi-elemental speciation analysis makes great sense to a large set of unstable samples because of time advantages. Herein simultaneous enrichment and speciation analysis of ultra-trace lead and mercury in water was developed by online solid-phase extraction coupled with high performance liquid chromatography and inductively coupled plasma mass spectrometry (SPE-HPLC-ICP-MS) for this aim. Pb(II), trimethyl lead (TML), triethyl lead (TEL), Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) were baseline separated in 11 min under gradient elution using 5 mM l-cysteine (Cys) at pH 2.5 in the 0–1 and 4–15 min and 5 mM Cys + 0.5 mM tetrabutyl ammonium hydroxide solution at pH 2.5 in the 1–4 min. Lead and mercury species in 10 mL intact water samples were adsorbed on a 1 cm C18 enrichment column pre-conditioned with 10 mL of 1 mM 2-mercaptoethanol at 10 mL min−1, and then directly desorbed by the mobile phases. High enrichment factors (459 for Pb(II), 1248 for TML, 1627 for TEL, 2485 for Hg(II), 1984 for MeHg and 1866 for EtHg) were obtained with good relative standard deviations (<5%), leading to low LODs (0.001–0.011 ng L−1) and LOQs (0.004–0.036 ng L−1). Good accuracy of this method was validated by two certified reference materials of total lead in water (GBW08601) and total mercury in water (GBW08603) along with spiked recoveries (89–93%). The method was applied to analyze trace lead and mercury species in river, lake, tap and rain water, and purified and mineral water. Inorganic lead of 13–68 ng L−1 and inorganic mercury of 21–49 ng L−1 were measured in the nine water samples whereas TML, TEL and MeHg were not detected with 2–5 ng L−1 EtHg presented only in one river water and tap water.

Determination of Lead Species in Algae by Capillary Electrophoresis-Inductively Coupled Plasma-Mass Spectrometry

A method of capillary electrophoresis (CE) coupled with inductively coupled plasma-mass spectrometry (ICP-MS) was established to determine lead ion [Pb(II)], trimethyl lead (TML), and triethyl lead (TEL). An extraction technology for lead with different species in algae was proposed and optimized for qualitative and quantitative analyses. Experimental results showed that these three lead compounds could be effectively separated within 20 min by CE-ICP-MS in a buffer solution of 70 mM H3BO3 and 17.5 M Na2B4O7 (pH 8.9). This method had good reproducibility for migration time (relative standard deviation (RSD) < 4%) and peak area (RSD < 5%). On the basis of this, the three lead compounds were detected in the linearity range of 10–200 μg L−1 with the correlation coefficient over 0.90. The detection limits for Pb(II), TML and TEL (S/N = 3, Pb) were 0.091, 0.023 and 0.030 μg L−1, respectively. The fractional extraction rate of Pb exceeded 80%, and the recoveries of Pb(II), TML, and TEL in algae samples were 103.6%, 95.7% and 90.6%, respectively. The detection results of lead content in laver and kelp samples showed that Pb in algae mainly existed in the form of Pb(II). Given its simplicity, high efficiency, and low sample consumption, the method could provide technical support for the quality control of marine algae and other marine products.

Development of a methodology for the simultaneous determination of inorganic and organolead compounds using supercritical fluid extraction followed by gas chromatography–mass spectrometry and its application to environmental matrices

A method for the extraction of triethyl lead (TEL +), trimethyl lead (TML +), and Pb 2+ from sand was developed using supercritical modified CO 2–CH 3OH extraction and in situ complexation with sodium diethyldithiocarbamate (NaDDTC) using a 2 5 factorial exploratory design is described. The screened variables were (i) pressure (69–193 bar), (ii) temperature (40–150 °C), (iii) ligand amount (0–100 mg), (iv) methanol volume (0.0–0.5 mL) and (v) static time (0–45 min). The optimum extraction conditions found were as follow: pressure, 193 bar; temperature, 40 °C; amount of NaDDTC, 100 mg; methanol volume, 0.5 mL; static time 45 min; and CO 2 flow rate, 1 mL min −1. Under these conditions the following recoveries were obtained (TML + 97 ± 2%, TEL + 70 ± 5%, and Pb 2+ 100 ± 4%). The presence of NaDDTC is not necessary for the extraction of TML + and TEL +, but it is a very significative parameter for Pb 2+. A second experimental design 2 2 + star for temperature and pressure was realized, but the results were not better than those of the first model. SFE extract derivatization was achieved with pentylmagnesium bromide, and target analyte determination was carried out by gas chromatography–mass spectrometry. Detection limits in the full-scan mode were 4, 10, and 39 pg as lead for TMPeL, TEPeL and PbPe 4, respectively. The method was validated with urban dust containing TML + (CRM 605. Pb 7.9 ±1.2 μg kg −1) and river sediment containing inorganic lead (GBW08301. Pb 79.0 ± 12.0 mg kg −1) as reference materials. The proposed method was applied to lead analysis in sand collected from an oil-polluted beach in Chile.

Simultaneous Determination of Trimethyl- and Triethyllead in Urban Dust by Species-specific Isotope Dilution/Gas Chromatography-Inductively Coupled Plasma Mass Spectrometry

Both (206)Pb-labeled trimethyllead (TML) and triethyllead (TEL) were synthesized from (206)Pb-enriched metallic Pb certified reference material (NIST SRM 983) and iodomethane or iodoethane through a one-process reaction in a closed system using centrifuge tubes, respectively. Organolead compounds in an urban dust reference material (BCR CRM 605) were extracted with an acetic acid/methanol (1:1) solution, which was mechanically shaken for 24 h. After adjusting the pH of the extracted solution to pH 5, the extracted organolead compounds were derivatized by tetrabutylammonium tetrabutylborate (TATB) and measured with GC-ICPMS. The analytical results of TML and TEL for BCR CRM 605 were 8.22 +/- 0.04 microg kg(-1) (mean +/- standard deviation, n = 3) and 1.12 +/- 0.06 microg kg(-1), respectively. The analytical results of TML agreed well with the certified value (7.9 +/- 1.2 microg kg(-1)).

Role of cathode identity in liquid chromatography particle beam glow discharge mass spectrometry

A detailed evaluation of the role of cathode identity on the analytical and spectral characteristics of various organic, organometallic and metal analytes using liquid chromatography–particle beam/glow discharge mass spectrometry (LC–PB/GDMS) has been carried out. A d.c. discharge, operating with argon as the support gas, was used throughout this work. In this study, Cu which has a relatively high sputtering rate, Ni which has moderate sputtering rate and Ta which has very low sputtering rate, are taken as cathode materials to study the ionization, fragmentation, and analytical characteristics of organic (caffeine, epigallocatechin gallate, peptide as representative compounds), organometallic (selenomethionine, triethyl lead chloride as representative compounds) and metal (Fe, La, Cs and Pb) species. A range of discharge gas pressures (26.6–106.4 Pa) and currents (0.2–1.5 mA) were investigated with the test cathodes to determine their influence on the spectral composition and overall analytical response for the various test species. Calibration plots were obtained for all of the species for each of the three cathodes to determine the respective limits of detection. Relative detection limits in the range of 0.02 to 15 ng mL − 1 (0.002–1.5 ng, absolute) for the test species were found to be in the order of Cu > Ni > Ta; which follows the order of the sputtering characteristics of the respective cathodes. These studies rendered information about the respective discharge parameters' role in choosing the most appropriate cathode identity in PB-GDMS for application in the areas of organic, organometallic and inorganic species analysis.

Feasibility study for the remediation of groundwater contaminated by organolead compounds

The aim of this research was to assess the effectiveness of chemical oxidation, Advanced Oxidation Processes (AOPs) and adsorption on granular activated carbon (GAC) for the ex situ remediation of a groundwater contaminated by organolead compounds, including tetraethyl lead (TEL), triethyl lead (TREL) and diethyl lead (DEL). The groundwater of concern was collected from the site of a former tetraalkyllead producing company in Trento (Italy), and showed an average total organic lead (TOL) content about 95.1 μg/L (TEL 0.5 μg/L, TREL 86.4 μg/L, DEL 8.3 μg/L). The main target of the study was to find out which method was more effective in reducing the pollutant content. For this purpose, several laboratory tests were performed, including chemical oxidation tests with different reactants (hydrogen peroxide, modified Fenton's reagent, potassium permanganate, activated potassium persulfate, oxygen and combinations of potassium permanganate and modified Fenton's reagent), AOPs with ozone, UV radiation and hydrogen peroxide and filtration on granular activated carbon. A combination of chemical and physical treatments was also tested, with GAC filtration followed by chemical oxidation. According to the results achieved, the treatments which showed the best remediation performances were: chemical oxidation with modified Fenton's reagent, AOPs with hydrogen peroxide and ozone (perozone), AOPs with hydrogen peroxide and UV radiation, and the combined treatment with activated carbon filtration followed by chemical oxidation with perozone. All these treatments showed a 90% TOL removal, with excellent removals of both TEL and TREL, and final DEL concentrations below 5 μg/L.

Speciation analysis of mercury and lead in fish samples using liquid chromatography–inductively coupled plasma mass spectrometry

A liquid chromatography–inductively coupled plasma mass spectrometric (LC–ICP-MS) method for lead and mercury speciation analysis was described. Sample containing ionic lead and mercury compounds was subjected to liquid chromatographic separation before injection into the direct injection high efficiency nebulizer (DIHEN, 170-AA). The species studied include inorganic lead (Pb(II)), trimethyl lead (trimethyl-Pb), triethyl lead (triethyl-Pb), inorganic mercury (Hg(II)), methyl mercury (methyl-Hg) and ethyl mercury (ethyl-Hg), which were well separated by reversed-phase liquid chromatography with a C18 column as the stationary phase and a pH 2.8 solution of 0.2% (v/v) 2-mercaptoethanol, 1 mg L −1 ETDA, 174.2 mg L −1 sodium 1-pentanesulfonate and 12% (v/v) methanol as the mobile phase. The lead and mercury species in biological tissues were quantitatively extracted, into 10 g L −1 EDTA and 0.2% (v/v) 2-mercaptoethanol solution taken in a closed centrifuge tube and kept on water bath, using microwaves at 65 °C for 2 min. The spike recovery of individual lead and mercury species determined by spiking the samples with suitable concentration of lead and mercury mixture standard were between 93% and 99%. The detection limits of the species studied were in the range 0.1–0.3 μg Pb L −1 and 0.2–0.3 μg Hg L −1. The procedure has been applied for the speciation analysis of two reference samples namely NRCC DOLT-3 Dogfish Liver and DORM-2 Dogfish Muscle and a swordfish sample obtained locally. The sum of the concentrations of individual species has been compared with the certified values for total lead and mercury to verify the accuracy of the method. The precision between sample replicates was better than 10% with LC–DIHEN-ICP-MS method.

Speciation of lead compounds in fish by capillary electrophoresis-inductively coupled plasma mass spectrometry

A capillary electrophoresis-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for lead speciation application is described. Sample containing ionic lead compounds were subjected to electrophoretic separation before injection into the micro-concentric nebulizer (CEI-100). The species studied include inorganic lead (PbII), trimethyl lead (TML) and triethyl lead (TEL). The separation has been achieved on a 70 cm length × 75 μm id fused silica capillary. The electrophoretic buffer used is 15 mmol l−1 Tris (pH 8.25) containing 10 mmol l−1 SDS (sodium dodecyl sulfate), 0.2 mmol l−1 EDTA and 2% v/v methanol, while the applied voltage is set at +26 kV. The lead species in biological tissues are extracted into 1% m/v EDTA solution taken in a closed centrifuge tube and kept on a water bath, using microwaves at 70 °C for 10 min. The extraction efficiencies of individual lead species added to the sample at 2 μg Pb g−1 level are between 97% and 102%. The detection limits of the species studied are in the range 0.2–0.6 ng Pb ml−1. The procedure has been applied for the speciation analysis of two reference materials namely dogfish liver tissue (NRCC DOLT-3) and oyster tissue (NIST SRM 1566a) and two real-world samples.

Histological and Histochemical Alterations in the Kidney Induced by Lead

Although lead intoxication is one of the most common forms of metal intoxication, the histochemical alterations in the renal tissues due to chronic lead exposure is limited and has not yet been well identified. A total of 60 male Wistar albino rats (Rattus norvegicus) were exposed to lead acetate trihydrate (0.0, 0.25, 0.5, 1.0 and 2% for 1 to 12 months) in drinking water to investigate the histological and histochemical alterations in the renal tissues due to lead. Chronic exposure to subtoxic doses of lead produced distinct progressive tubular, glomerular and interstitial damages. Tubular changes occurred earlier than glomerular and interstitial ones, and included anisokaryosis, nuclear pyknosis, karyomeglay, development of intranuclear and cytoplasmic inclusions together with tubular dilation, necrosis, vacuolization, tubular hyperplasia and solid tubular adenoma. The glomerular alterations were mainly mesangial hypercellularity, segmental proliferation, focal and segmental glomeruloscleriosis, glomerural hyalinization and glomerular tuft alterations. The findings indicate that lead produces significant histological and histochemical changes in the kidney that lead to severe complications.

Folic acid, ascorbic acid and sodium selenite restore the motility of Dictyostelium discoideum inhibited by triethyllead

The effect of triethyllead (TriEL) on motile activity, structure of cytoskeleton and chemotaxis of Dictyostelium discoideum amoebae in developing concentration gradients of folic acid (FA) and cAMP has been studied. It was observed that 3 μM TriEL had little or no effect on locomotion and chemotactic response of cells, whereas 5 μM TriEL strongly reduced the motile activity of Dictyostelium discoideum amoebae and inhibited their chemotaxis towards cAMP, but not towards FA. FA was found to restore the motile activity of Dictyostelium discoideum, inhibited by TriEL. A similar effect was observed in the presence of other antioxidants, i.e. ascorbic acid and sodium selenite, suggesting that oxidative stress may be involved in the action of TriEL. Moreover, the treatment of Dictyostelium amoebae with 5 μM TriEL caused disruption of microtubules while 3 μM TriEL had little effect on their structure. FA caused restoration of microtubules only in some cells within 1 h of incubation, i.e. when the directional movement of cells towards this chemoattractant was already observed. However, their organization was significantly different from that observed in the untreated cells, suggesting that microtubule undisturbed organisation may be not necessary for Dictyostelium discoideum amoebae locomotion and chemotaxis

Solid phase microextraction gas chromatography-glow discharge-optical emission detection for tin and lead speciation

A modified interface between a gas chromatograph (GC) and a hollow cathode (HC) radiofrequency (rf) glow discharge (GD) with detection by optical emission spectrometry (OES) has been investigated for elemental speciation studies. Solid phase microextraction (SPME), used for extraction and preconcentration of organic compounds, is here used for the introduction of the metal species under investigation into the injector of the GC, after preconcentration of metal species ethylated “in situ” with sodium tetraethylborate. Tin [monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT)] and lead species [trimethyllead (TML) and triethyllead (TEL)] were used as models and separated using a capillary column. Detection by rf-(HC)GD-OES was accomplished at 283.9 nm for tin and 283.3 nm for lead. After optimization of the parameters affecting the rf-(HC)GD signals (pressure, radiofrequency power and He flow rate used as plasma gas) and also the parameters affecting the SPME technique (adsorption time, desorption time, injector temperature and position of the fiber into the injector of the GC), the analytical characteristics were calculated. Good detection limits for the tin and lead species under study (0.021 µg L−1 for MBT, 0.026 µg L−1 for DBT, 0.075 µg L−1 for TBT, 0.03 µg L−1 for TEL and 0.15 µg L−1 for TML) were achieved. Finally, the accuracy of the proposed speciation methodology was tested by analysing a certified reference material (sediment PACS-2) from the National Research Council of Canada.

Determination of the speciation of organolead compounds in airborne particulate matter by gas chromatography–inductively coupled plasma mass spectrometry

The speciation of organolead compounds in airborne particulate matter was determined by gas chromatography–inductively coupled plasma mass spectrometry. The analytes were extracted from the sample using 0.5 M acetic acid in methanol. The ionic organolead compounds were extracted into hexane using diethydithiocarbamate at pH 9 in the presence of EDTA to complex inorganic Pb. Derivatisation of the organolead species was performed with butylmagnesium chloride. Separation and detection of the butylated trimethyllead (TML), dimethyllead (DML), triethyllead (TEL) and diethyllead (DEL) was achieved. Detection limits, as Pb, were 3.2 fg for TML, 2.4 fg for DML, 1.8 fg for TEL and 9 fg for DEL for a 1 μl sample injection. Typical precision of repetitive injections was 1.5–4% using tetraethyllead (TrEL) as internal standard. The method proposed was validated by the determination of TML in the reference material CRM 605 and was applied to the analysis of airborne particulate matter in the atmosphere of the city of Oviedo. DML, DEL and methylethyllead (MEL) were detected at pg m −3 levels.

Speciation of trimethyllead and triethyllead by in-tube solid phase microextraction high-performance liquid chromatography electrospray ionization mass spectrometry

An analytical method has been developed for the determination of the trimethyl- (TML) and triethyllead (TEL) species in aqueous samples. In-tube solid phase microextraction (SPME) and high-performance liquid chromatography (HPLC) are coupled to a quadrupole mass spectrometer (MS) using electrospray (ES) as an ionization interface. Optimization of the instrumental parameters is described, including the evaluation of three commercial GC capillaries for the in-tube SPME experiments. The elemental (208Pb+) and molecular forms TML and TEL (m/z 253 and 295, respectively) were monitored simultaneously to provide complete speciation information. Results from the in-tube SPME-HPLC-ESMS experiments indicate that complete separation and detection of TML and TEL can be achieved in less than 5 min. Precision is greater than 5% and estimated limits of detection are 11.3 and 12.6 ng ml−1, respectively, for TML and TEL at a solution flow rate of 450 µl min−1.

Electrospray mass spectrometry of trimethyllead and triethyllead with in-tube solid phase microextraction sample introduction

A study of positive ionization electrospray mass spectrometry (ES-MS) was performed on trimethyllead (TML) and triethyllead (TEL). The system consisted of in-tube solid phase microextraction (SPME) coupled directly to an electrospray mass spectrometer. Fragmentation patterns of compounds were observed by applying different fragmentation voltages. High voltages produced sufficient fragmentation to elucidate the dissociation of the trialkyllead compounds. Electrospray mass spectrometry has been shown to be a suitable detection system for organolead speciation. Applying fragmentation energy programming, it might be possible to obtain in parallel the molecular and atomic signals of lead compounds. Copyright 1999 John Wiley & Sons, Ltd.

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Lead speciation in rainwater by isotope dilution-high performance liquid chromatography-inductively coupled plasma-mass spectrometry

A new method for lead speciation in rainwater by isotope dilution analysis (IDA) using directly coupled high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) is described and demonstrated. Samples containing trimethyllead (TML) chloride and triethyllead (TEL) chloride in the presence of large amounts of inorganic lead have been analysed by HPLC-ICP-MS using reverse phase ion-pairing chromatography. The detection limit for the procedure is 3 ng g −1 for TML as Pb and 14 ng g −1 for TEL as Pb, with a linear range exceeding 1000 ng g −1 and a relative standard deviation of 4% for TML in the range 50–1000 ng g −1. TML chloride isotopically enriched in the stable 206 isotope was prepared and used to enhance the accuracy of the method by isotope dilution analysis. The IDA-HPLC-ICP-MS method was successfully applied to the analysis of a sample of artificial rainwater used in a collaborative study.

Microbial degradation of tetraethyl lead in soil monitored by microcalorimetry.

Sieved agricultural soil samples were treated with the anti-knock agent tetraethyl lead (Et4Pb), and the resulting effects were analyzed by microcalorimetry. Et4Pb additions resulted in an increase of the heat production rate, provided that oxygen was present and that the soil was not autoclaved. The increased heat production rate was accompanied by degradation of Et4Pb, as verified by speciation analysis (GC-MS) of the remaining Et4Pb and its ionic degradation products (triethyl lead and diethyl lead cations). Conclusive evidence was obtained that these transformations were mediated mainly by microbes. At an initial Et4Pb concentration of 2 g Pb/kg dry weight the biodegradation rate was about 780 mumol day-1 kg dry weight-1, whilst the chemical decomposition was only 50 mumol day-1 kg dry weight-1. A fivefold rise of the initial Et4Pb concentration resulted in a decrease of the biodegradation rate to 600 mumol day-1 kg dry weight-1 and an increase of the chemical decomposition to 200 mumol day-1 kg dry weight-1. The biodegradation rate was not influenced by the addition of glucose, which means that no indication for a co-metabolic attack of Et4Pb was found.

A rapid method for detection of nongenotoxic carcinogens of environmental pollutants using synchronized V79 cells and flow cytometry

Synchronized V79 cells were treated before entering mitosis with known and suspicious mitotic arrestants and analyzed by flow cytometry and by light microscopy. Colcemid, nocodazole, vinblastine, diethylstilbestrol, triethyl lead and cadmium sulfate caused a dose dependent mitotic arrest of up to 80%, in comparison with 6% for the controls. Mixtures of polycyclic aromatic hydrocarbons and heterocyclic compounds induced a mitotic arrest of 50%–60%. Extracts of airborne particulates revealed a mitotic arrest of 10%–40%. In contrast, benzoquinone and hydroquinone led to a G2-block rather than to a mitotic arrest. Results of flow cytometry measurements correlated well with those obtained by light microscopy. Cell synchronization in combination with flow cytometry seems to be of considerable value as a rapid method for testing nongenotoxic agents with mitotic arresting activity.