Biomonitoring of benzene and toluene in human blood by headspace-solid-phase microextraction

A simple and rapid method for the determination of benzene and toluene in whole blood by headspace-solid-phase microextraction (HS-SPME) is described. Using SPME fibres coated with 65 μm carboxene/polydimethylsiloxane, limits of quantification (LOQ) of 5 ng/L for benzene and 25 ng/L for toluene are achieved. As a result of its large linear range (i.e. 5–5000 ng/L for benzene) the method is suitable for biomonitoring of both occupationally and environmentally exposed people. The reproducibility of the determination of benzene is ≤ 8%. An interlaboratory comparison demonstrated that the method proposed here compares favorably with existing methods (dynamic headspace, purge and trap). Received: 9 February 1998 / Revised: 6 July 1998 / Accepted: 18 July 1998     

Adsorptive voltammetric procedure for the determination of platinum baseline levels in human body fluids

Summary An extremly sensitive procedure for the determination of platinum in human body fluids is presented. A high pressure decomposition of the samples is followed by adsorptive voltammetric measurement. A detection limit down to 0.2 ng Pt/l sample allowed baseline levels of platinum in body fluids (urine: 0.5–15 ng/l, blood and blood plasma: 0.8–6.9 ng/l) to be evaluated. The concentration ranges in body fluids of occupationally exposed people were determined to 21–2900 ng/l (urine), 32–180 ng/l (blood) and 95–280 ng/l (blood plasma).     

Determination of Mg,Al, P,Cu and Mn in biological fluids by neutron activation analysis

Thermal and epithermal neutron activation analysis has been applied to determine the concentrations of magnesium, aluminium, phosphorus, copper and manganese in two biological fluids: blood serum and market milk. Both epithermal neutron irradiation and radiochemical separation (a chromatographic column of HAP) were used to get rid of the interferences from 24-Na. Strongly acidic solutions of the irradiated samples were passed through the columns of HAP, where sodium was completely adsorbed while, Al, Cu, Mg and Mn were eluted with an efficiency of 99±1%. Since both Al and P were determined through the formation of²⁸Al (2.24 min) thermal and epithermal neutron activation have been applied in order to determine the contribution of each radionuclide to²⁸Al activity. The determination of Mg, Al and P in milk samples was done instrumentally, whereas in the case of blood serum with higher concentration of Na, a radiochemical separation is essential in both cases. The concentrations of Al, Cu, Mg, Mn and P in blood serum and market milk were found to be 0.24±0.02 and 1.85±0.09 g Al/ml, 1.35±0.04 and 0.068±0.005 g Cu/ml, 22.9±1 and 98.9±8.6 g Mg/ml, 22±3 and 16±2 ng Mn/ml and 167±13 and 865±32 g P/ml, respectively.     

Measurement of naltrexone in rat brain regions and serum by high performance liquid chromatography with electrochemical detection

Summary A method is described for the determination of naltrex-one in discrete rat brain regions and serum. Separation and quantitation are performed by reversed-phase high-performance liquid chromatography with electrochemical detection. The drug gave a linear response over the range of 12.5–100ng for either 1.0ml for cerebellar homogenate or 25l for serum (1.25–10ng on column). Recoveries of naltrexone, added to the homogenate or serum, were 94±7 and 86±6%, respectively, when compared with naltrexone dissolved in water. The mean between-run relative standard deviations were 5.8 and 6.8% for cerebellar homogenate and serum, respectively, over the concentration range studied. The within-run relative standard deviations for cerebellar homogenate (12.5ng/ml) or serum (12.5ng/25l) were 7.7%. The application of the method to an in vivo animal experiment is demonstrated.     

High Performance Liquid Chromatography Determination of Pcmx In Blood Plasma Using Electrochemical Detection

Abstract

A rapid and specific high performance liquid chromatographic (HPLC) procedure has been developed for the determination of p-chloro-mxylenol (PCMX) in blood plasma. the method is based on the extraction of PCMX from plasma with benzene in the presence of a known amount of dichloro-m-xylenol (internal standard). the benzene extract is evaporated to dryness and the residue dissolved in 200 μl of mobil phase. the HPLC system consisted of a reversed-phase column and a 65% methanol:35% ammonium carbonate 0.05% solution as a mobile phase. an electrochemical (EC) detector/glassy carbon electrode set a potential of +0.9V versus Ag/AgCl/3M NaCl is used to monitor the drug. the recovery of PCMX is approximately 98%, the limit of quantitation is 2 ng/ml of plasma for the HPLC-EC procedure. the coefficient of variation is 5.1% over the range of 10-1000 ng/ml of plasma. Data are presented to illustrate the practicality of this method for evaluation of PCMX plasma levels after a single intravenous administration of 500 mg dose of PCMX to five mongrel dogs.     

Characterization of a total diet reference material (ARC/CL HDP) for contents of essential and toxic elements

Summary A total diet reference material (RM) was prepared by employing material leftover from a nationwide Finnish hospital diet study. The material was carefully homogenized using Ti-blades, freeze-dried, rehomogenized with Ti-blades, passed through a 2 mm nylon sieve and carefully mixed in large glass cylinders. Homogeneity of the material divided into 20 g samples in polyethylene bottles was tested by taking ten 0.5 g samples from the beginning and end of the bottling line and analyzing them for Zn and Mg. The homogeneity was within 1.0% for both Zn and Mg. An interlaboratory comparison study involving reliable reference laboratories that employed a total of seven methods based on independent analytical principles was conducted on the contents of 14 mineral elements. After the exclusion of outliers the recommended concentrations (on a dry weight basis) expressed as the medians±95% confidence limits were established as follows: Ca=2.86±0.124 mg/g, Mg=785±25 g/g, K=9.42±0.30 mg/g, Na=7.87±0.57 mg/g, Fe=30.4±0.9 g/g, Mn=12.9±0.58 g/g, Zn=28.9±1.3 g/g, Cu=3.18±0.19 g/g, Mo=262±35 ng/g, Ni=271±38 ng/g, Se=181±17 ng/g, Pb=43±8 ng/g, Cd=21±3 ng/g and Hg=6.6±3.6 ng/g. All of the above recommended concentration ranges, except that for Ni, fell into category A, i.e. values recommended with a high degree of confidence according to the certification criteria established by Pszonicki.     

Novel coating for solid-phase microextraction: Electropolymerization of a molecular receptor functionalized with 2,2′-bithiophene for the determination of environmental pollutants at trace levels

A novel solid-phase microextraction coating based on the electropolymerization of a molecular receptor properly functionalized with 2,2′-bithiophene was developed for the determination of environmental pollutants in air and water samples. The 2,2′-bithiophene-based film was electrochemically deposed on the surface of a gold wire using cyclic voltammetry. The fibres showed a porous structure with an average thickness of 12 ± 3 μm (n = 5): a good intra-batch and inter-batch repeatability with RSD lower than 14% was also observed. The selective interactions via hydrogen bonding with organic molecules containing electronegative atoms was proved: LOD values in the low ng/l range allowed the determination of vinyl chloride and chlorobenzenes at trace levels in environmental matrices.     

Rapid and sensitive gas chromatographic determination of diacetylmorphine and its metabolite monoacetylmorphine in blood using a nitrogen detector.

A quantitative gas chromatographic method for the determination of plasma concentrations of diacetylmorphine and its metabolite monacetylmorphine using an alkali flane detector (nitrogen detector) is described. Plasma samples (pH 9.0) containing ethylmorphine acetate as internal standard are extracted with benzene. The dried benzene extracts are analysed as their corresponding acetylated derivatives following treatment with trifluoroacetic anhydride-benzent (1:5). The nitrogen detector permits quantitation of narcotic levels down to 100ng/ml with detection as low as 20 ng/ml. The higher sensitivity and selectivity of the nitrogen detector are compared to those obtained in flame ionization detection. Species differences in the rate of conversion of diacetylmorphine to monacetylmorphine in vitro in blood are also presented.     

Bestimmung von Fe, Co, Cu, Zn, Se, Rb und Cs in NBS-Ochsenleber, Blutplasma und Erythrocyten durch INAA und AAS

Zusammenfassung Der Gehalt von Fe, Co, Cu, Zn, Se, Rb und Cs wurde in Blutplasma und in Erythrocyten von sechs Normalpersonen mittels der instrumentellen Neutronenaktivierungsanalyse und der flammenlosen Absorptionsspektrometrie (Cu) bestimmt. Zur Überprüfung der Richtigkeit wurde der NBS-Standard 1577, Ochsenleber, verwendet. Die erhaltenen Resultate für Elemente mit höheren Gehalten (Fe, Cu, Zn) liegen weitgehend im Bereich der bisher veröffentlichten Daten. Bei Elementen mit kleineren Gehalten (Co, Se, Rb, Cs) liegen unsere Werte in dem unteren Bereich oder darunter. Für diese Elemente wurden in Blutplasma und in Erythrocyten (hier bezogen auf Trockenmasse) die folgenden Mittelwerte ermittelt: Für Co 0,22 ±0,14 ng/ml, 0,59±0,23 ng/g, für Se 103±18 ng/ml, 401±29 ng/g, für Rb 167±36 ng/ml, 12,1±2,5 g/g und für Cs 0,88±0,18 ng/ml, 13,0±5,7 ng/g.

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Determination of Fe, Co, Cu, Zn, Se, Rb and Cs in NBS Bovine Liver, blood plasma and erythrocytes by INAA and AAS

Summary The content of the above elements has been determined in blood plasma and in erythrocytes of six normal persons by instrumental neutron activation analysis and flameless atomic absorption spectrometry (Cu). The over-all accuracy of these techniques was checked by using the NBS standard 1577, Bovine Liver. The results obtained for elements of higher content (Fe, Cu, Zn) are essentially in the range of other published data. However, our results for elements occurring with lower contents (Co, Se, Rb, Cs) are in agreement with the lowest values of the published data and in some cases they are even significantly below these. For these elements, the following contents have been determined in blood plasma and in erythrocytes (here related to dry weight): for Co 0.22±0.14 ng/ml and 0.59±0.23 ng/g, for Se 103±18 ng/ml and 401±29 ng/g, for Rb 167 ±36 ng/ml and 12.1±2.5 g/g and for Cs 0.88 ±0.18 ng/ml and 13.0±5.7 ng/g, respectively.

Diese Arbeit wurde durch die Deutsche Forschungsgemeinschaft gefördert.Dem Kernforschungszentrum danken wir für den Erlaß der Bestrahlungskosten.Herrn Dr. med. K. Spenger sind wir für die Mitwirkung bei der Blutentnahme und für wertvolle Diskussion dankbar.     

Determination of acipimox in capsules by differential pulse polarography

A differential pulse polarographic (DPP) method has been developed for the determination of acipimox in its pharmaceutical formulations. Using Sörensen buffer pH 6.0 as supporting electrolyte a single, irreversible peak occurred at –0.79 V vs an Ag/AgCl reference electrode. The peak height vs concentration plot was found to be linear over the range of 10^–6 to 6 × 10^–4 mol/l. The detection limit is 60ng/ml. The analysis of a series of 10 Olbetam® 250 mg capsules showed an overall standard deviation of ± 4.18 mg and a S_rel of ± 1.66%, respectively.     

Determination of urinary t-t muconic acid as biomarker of environmental benzene intake and its interference factors

The target of our study was the determination of urinary t,t muconic acid concentration, as a biomarker of benzene intake in a population. Urinary samples of 101 subjects, males and females were obtained to whom. Information regarding modification and confounding factors were recorded by questionnaire. The samples were analysed by HPLC, after extraction of trans,trans muconic acid on strong anionic exchange cartridges. In these analytical conditions the detection limit with good care is 10 micrograms/l. A concentration range from 10 to 1300 micrograms/l was found. High levels found in the population could explained by confounding factors present. The obtained results were correlated with sex, age and smoking or non smoking. There was a significant difference in mean concentrations between heavy smokers (160 micrograms/l) and non smokers (110 micrograms/l), that showed tobacco as an interference factor. The study showed that it is strictly necessary carry out a thorough anamnesis before sampling with the objective of finding eventual interference factors such as smoking, diet and drugs taken.     

Biomonitoring of benzene and toluene in human blood by headspace-solid-phase microextraction

A simple and rapid method for the determination of benzene and toluene in whole blood by headspace-solid-phase microextraction (HS-SPME) is described. Using SPME fibres coated with 65 μm carboxene/polydimethylsiloxane, limits of quantification (LOQ) of 5 ng/L for benzene and 25 ng/L for toluene are achieved. As a result of its large linear range (i.e. 5–5000 ng/L for benzene) the method is suitable for biomonitoring of both occupationally and environmentally exposed people. The reproducibility of the determination of benzene is ≤ 8%. An interlaboratory comparison demonstrated that the method proposed here compares favorably with existing methods (dynamic headspace, purge and trap).     

Fluorometric Determination of Nitrogen Dioxide in Atmosphere Sampled by the Liquid Droplet Technique

A new, simple, sensitive and selective fluorometric method for the determination of nitrite has been developed. The reaction of nitrite with hydralazine in acidic medium, heated on a boiling water-bath for 15 min, produced a tetrazolo (5,1-a) phthalazine (Tetra-P). The product formed was measured at _ex = 274 nm and _em = 345 nm. The fluorescence intensity was valid over a nitrite concentration range 0.067–60.3 ng mL^–1, with a detection limit of 0.0091 ng mL^–1. The reproducibility of the proposed method was determined by running a different concentration of nitrite, 13.4, 33.5, and 46.9 ng mL^–1. The % recoveries and the relative standard deviations were found to be 100.6 ± 0.9, 99.9 ± 0.5, and 99.4 ± 1.1%, respectively. The proposed method was applied successfully to the determination of nitrogen dioxide sampled from the atmosphere using the liquid droplet method. The nitrogen dioxide our wind tunnel was controlled by an NO _x analyzer based on a chemiluminescence analyzer detector (CLAD 1000). A linear graph was obtained for the nitrogen dioxide in the wind tunnel vs. NO₂ sampled by the liquid droplet method. The effect of interference substances in the determination showed that cations and anions did not disturb the process. The results obtained were satisfactory when compared with the reference method.     

The geochemistry of uranium in pore waters from lake sediments

The concentration of pore water uranium in six sediments from oligotrophic, mesotrophic, acidotrophic and dystrophic lakes was measured by inductively coupled plasma-mass spectrometry. Profiles of pore water U can be divided into two groups such as low (17±7 ng/l) and high concentration (69±30 ng/l). These values were 1–2 orders of magnitude higher than that of lake waters (6±4 ng/l) due to the release of U from the sediments by decomposition of organic materials. Variations in pore water U concentrations seem to relate to the differences in pore water pH, the association forms, and their contents of U in the lake sediments.     

Improved method for the immunological detection of malondialdehyde-modified low-density lipoproteins in human serum

Oxidized low-density lipoproteins (ox-LDL) such as malondialdehyde-modified LDL (MDA-LDL) play an important role in the pathogenesis of atherosclerosis. This study is aimed to establish a standard enzyme-linked immunosorbent assay (ELISA) for measuring serum MDA-LDL, and evaluate its usefulness by analyzing serum samples of diabetes mellitus (DM) patients. Serum sample stability, analytical sensitivity, intra- and inter-assay precision, dilution linearity, supplementation and recovery, and interfering substances were examined. Normal reference levels in 86 healthy subjects (33 males and 53 females; average age 34.4±7.8 years) with normal lipid profiles were also determined. MDA-LDL levels in blood and serum were unstable and gradually increased during storage. However, it could be stabilized by the addition of a reagent, which included sucrose. The detection limit of the assay was 6.3 U/l. Intra- and inter-assay imprecisions were <5.6 and <9.4%, respectively. Excellent dilution linearity was observed, and the average recovery was 105%. None of the test substances, for example, hemoglobin, lipid and bilirubin interfered with the assay. The normal reference levels of MDA-LDL and MDA-LDL/LDL-C in the 86 subjects with normal lipid levels were calculated as 58.8±17.9 U/l and 60.4±11.9 mU/mg, respectively. The both serum levels of MDA-LDL (122±62.8 U/l) and MDA-LDL/LDL-C (96.8±48.5 mU/mg) in the DM patients were significantly higher than those of controls (P<0.0001). Moreover, DM patients with atherosclerosis complications showed significantly higher MDA-LDL and MDA-LDL/LDL-C levels than those without complications, 174±81.3 versus 101±39.2 U/l, (P<0.01) and 138±59.0 versus 80.3±32.1 mU/mg, (P<0.005), respectively. These results suggest that the ELISA method for MDA-LDL described in this study fulfilled the sensitivity, reproducibility, and accuracy requirements for routine clinical assays and might therefore be a useful tool for evaluating atherogenicity.     

A study on postsplenectomy changes of serum tuftsin level using a radioimmunoassay protocol

In this article, postsplenectomy changes of serum tuftsin level were studied on both human subjects and rabbits by using a self-established radioimmunoassay protocol. Antituftsin antibodies were raised in rabbits and roosters.¹²⁵I-tuftsin was prepared through an Iodogen method. The characteristics of the RIA were satisfactory with a detecting range of 0.5–100 ug/ml and the lowest detection limit of 400ng/ml. Serum tuftsin levels of splenectomized subjects were measured and compared with control groups. The serum tuftsin level from 30 postsplenectomy human beings was 406±179 ng/ml ( ± s) while that from a control group of 40 healthy blood donors was 557±256 ng/ml; the serum tuftsin level of 10 postsplenectomy rabbits was found to be 206±75 ng/ml while that of a control group of 10 normal rabbits was 318±96 ng/ml. The results showed that serum tuftsin level decreased markedly after splenectomy.     

The determination of strontium in human blood serum and packed blood cells by radiochemical neutron activation analysis

Strontium is a trace element whose distribution and metabolism are similar to those of calcium, its close chemical analogue. The element received scientific attention because of its potential beneficial effects in the treatment of osteoporosis andosteolytic metastatic bone lesions but also because of the possible problems associated with the retention of⁹⁰Sr from radioactive fall-out. In continuation of a series of experiments intended to establish reliable reference values for trace elements in human blood serum and packed blood cells, we set up a project to determine also strontium. The following values were obtained (mean±standard deviation): 22.2±4.8 ng/ml (serum) and 2.85±1.11 ng/g wet weight (packed blood cells).     

High levelab initio stabilization energies of benzene

Summary G2 theory is shown to be reliable for calculating isodesmic and homodesmotic stabilization energies (ISE and HSE, respectively) of benzene. G2 calculations give HSE and ISE values of 92.5 and 269.1 kJ mol^–1 (298 K), respectively. These agree well with the experimental HSE and ISE values of 90.5±7.2 and 268.7±6.3 kJ mol^–1, respectively. We conclude that basis set superposition error corrections to the enthalpies of the homodesmotic or isodesmic reactions are not necessary in calculations of the stabilization energies of benzene using G2 theory. The calculated values of the enthalpies of formation of such molecules containing multiple bonds such as benzene ands-trans 1,3-butadiene, which are found from the enthalpies of isodesmic and homodesmotic reactions rather than of atomization reactions, demonstrate good performance of G2 theory. Estimates of theH _f ^o value for benzene from the G2 calculated enthalpies of homodesmotic reaction (2) and isodesmic reaction (3) are 80.9 and 82.5 kJ mol^–1 (298 K), respectively. These are very close to the experimentalH _f ^o value of 82.9±0.3 kJ mol^–1. TheH _f ^o value ofs-trans 1,3-butadiene calculated using the G2 enthalpy of isodesmic reaction (4) is 110.5 kJ mol^–1 and is in excellent agreement with the experimentalH _f ^o value of 110.0±1.1 kJ mol^–1.     

Development of a highly efficient in-tube solid-phase microextraction system coupled with UHPLC-MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples

Hydroxyl polycyclic aromatic hydrocarbons are considered active mutagenic and carcinogenic substances and are found in extremely low levels (ng/g) in biological samples. As a result, their determination in urine and blood samples is challenging, and a sensitive and effective method for the analysis of trace hydroxyl polycyclic aromatic hydrocarbons in complex biological matrices is required. In this work, a novel macroporous in-tube solid-phase microextraction monolith was prepared via a thiol-yne click reaction, and a highly efficient analytical method based on in-tube solid-phase microextraction coupled with UHPLC-MS/MS was developed to determine hydroxyl polycyclic aromatic hydrocarbons with low detection limits of 0.137–11.0 ng/L in complex biological samples. Four hydroxyl polycyclic aromatic hydrocarbons, namely, 2-hydroxyanthraquinone, 1-hydroxypyrene, 1,8-dihydroxyanthraquinone, and 6-hydroxychrysene, were determined in the urine samples of smokers, non-smokers, and whole blood samples of mice. Satisfactory recoveries were achieved in the range of 83.1–113% with relative standard deviations of 3.2–9.7%. It was found that implementation of the macroporous monolith gave a highly efficient approach for enriching trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.