Matrix interferences in the analysis of benzene in urine.

The analysis of benzene in urine of the general population or of exposed workers can be performed with different methods using the 'purge and trap' or 'solid-phase microextraction' techniques in combination with gas chromatographic analysis and photoionisation or mass spectrometric detection. The published results, however, are deeply conflicting. Differences in sample preparation by different research groups and our own preliminary observations prompted us to investigate pre-analytical and analytical factors potentially capable of modifying the urinary benzene quantification results. Benzene concentrations were measured in 20 urine samples in relation to different conditioning conditions (at 24, 40 and 80 degrees C) and at basic or acid pH. Urinary protein concentrations were measured in the same samples. Urine heating at 80 degrees C yields benzene concentrations on average five times higher than at 24 degrees C. On acidification of urine, the benzene released increases up to 28-fold in comparison to that obtained at uncorrected 'physiological' pH. Despite a widely scattered data distribution, a statistically significant linear correlation was found between 'heat-released' and 'acid-labile' benzene values. There was no correlation between total urinary proteins present in 'physiological' concentrations (between 12 and 110 mg/l) and the different kinds of benzene in urine. Our results could perhaps be explained if it is supposed that part of the benzene in urine is absorbed onto sediment, or bound to specific proteins, or derived from parent molecules and is released with pH modification or heat administration. Our observations may also help to explain why the urinary benzene concentrations reported by different investigators vary considerably even when environmental levels are comparable.

Reference values of urinary 3,5,6-trichloro-2-pyridinol in the Italian population--validation of analytical method and preliminary results (multicentric study).

The interlaboratory validation of analytical procedures for the assay of urinary 3,5,6-trichloro-2-pyridinol (TCP) in the general Italian population is reported. The determinations were performed by high-resolution gas chromatography (HRGS) with electron capture detection and HRGS with mass spectrometry (MS) in 2 laboratories. The urine samples were from 42 participants from 3 regions of Italy. The results were evaluated by interlaboratory quality control. Urinary TCP concentrations were above the detection limit (1.2 micrograms/L) in 88% of the population, with a mean detectable concentration [GM (GSD)] of 2.8 (1.9) micrograms/g creatinine (creat). (GM, geometric mean; GSD, geometric standard deviation.) The Mann-Whitney U test showed that wine consumption was a statistically significant variable (p < 0.05) for urinary concentrations of TCP. Analysis of variance of the logarithm of urinary TCP versus wine consumption and diet showed a statistically significant fit. The model used explained 30% of the total variance: wine consumption and diet accounted for 37 and 17% respectively of the explained variance.

Urinary 1-hydroxypyrene as a marker of exposure to pyrene: an epidemiological survey on a general population group.

Urinary levels of 1-hydroxypyrene in a general adult population group are studied. Experimental data are not normally distributed; statistical analysis required a base 10 logarithmic transformation of data. The concentrations of urinary 1-hydroxypyrene measured were expressed as microgram g-1 urinary creatinine and are comparable with those reported by other authors, both for smoker and non-smoker subgroups. Multiple regression analysis shows that, for smokers, the number of cigarettes smoked per day and the body mass index (BMI) significantly influence the levels of urinary 1-hydroxypyrene expressed as microgram g-1 urinary creatinine, whereas no personal or behavioural variable (age, sex, alcohol consumption, dietary intake of pyrene, BMI) modified the 1-hydroxypyrene levels for non-smokers.

Determination of environmental reference concentration of six PAHs in urban areas (Pavia, Italy).

We propose a sampling strategy, using individual dosimetry to measure the daily inhaled quantity of PAHs in urban air. The method was applied to monitor 56 subjects living in an Italian town (Pavia; 80 000 inhabitants) and the Environmental Reference Concentration (E.R.C.) of six PAHs (classified as 'possible' carcinogenic agents for humans) was determined. The individual environmental samplings took place in two different seasons (winter and summer), for persons living in four different urban areas with different traffic density. Subjects were selected using a specific questionnaire designed to collect information on indoor and indoor+outdoor exposure times. The mean +/- S.D. value of Benzo[a]pyrene [BaP] was 0.37 +/- 0.15 ng m-3 in winter and 0.12 +/- 0.07 ng m-3 in summer. Assuming 18 m3 as the daily inhaled quantity the estimate of the BaP inhaled quantity was 6.66 ng/day in winter and 2.16 ng/day in summer.

Environmental and urinary reference values as markers of exposure to hydrocarbons in urban areas.

A study using individual dosimetry to evaluate the daily inhaled dose of sixteen aromatic and aliphatic hydrocarbons in three groups of primary school children, living in three Italian towns with 50,000 inhabitants or less, (Treviglio-Lombardy; Poggibonsi-Tuscany; Valenza-Piedmont) is presented. The simultaneous use of two passive samplers (radial diffusion) for each child, for a 24 h period, determined both the indoor and indoor + outdoor environmental reference concentrations. We measured the urinary levels of benzene, toluene, ethylbenzene and xylenes for each child and hence determined the urinary reference values for BTEX. We also considered the possibility of using benzene in urine as a biomarker of environmental exposure of the general population to this xenobiotic. We evaluated how both the environmental and biological measures were influenced by the presence of smokers in the surveyed children's houses. For the group of children living in Poggibonsi, we considered the influence of the living area and the traffic density on environmental concentrations of benzene (indoor and indoor + outdoor).

Preparation and characterization of deuterium-labeled glycosaminoglycans.

Heparin, NAcHep, DS, and CS were labeled with deuterium by N-reacetylating, with the deuterated acetic anhydride (CD3CO)2O, GAGs previously N-deacetylated (by hydrazinolysis) to the desired extent. Degrees of deuteration of the present preparations, as determined by 2H- and 1H-NMR were 15%, 51%, 49%, and 79% for heparin, NAcHep, DS, and CS, respectively. The NMR analysis (including the 13C spectra) of the labeled products indicated that deuterium labeling did not involve any substantial modification of the GAG structures. Also NMR signals associated with specific sequences of heparin for antithrombin and of DS for heparin cofactor II were essentially the same in the unlabeled and in the deuterated GAGs. The substantial retention of the original structure was confirmed by data on the degree of sulfation (by conductimetry) and on the electrophoretic mobility in acid buffer. On the other hand, HPLC/SEC data indicated some depolymerization of heparin and DS in the N-deacetylation step of the labeling reactions. HPLC/MS spectrometry permitted a clear identification of disaccharide and tetrasaccharide fragments obtained from deuterated GAGs by enzymic (heparinase, chondroitinase ABC) or chemical depolymerization (deaminative cleavage, Smith degradation), opening new prospects for studies of human pharmacokinetics, with differentiation of exogenous from endogenous GAGs.