Improvements in the determination of eight polycyclic aromatic hydrocarbons through a stepwise interlaboratory study approach

A summarising account of a systematic stepwise approach based on interlaboratory studies carried out by a number of laboratories from European Union and EFTA countries is given. This approach has been designed to improve the analytical state of the art in the determination of selected polycyclic aromatic hydrocarbons in different environmental matrices. The approach resulted in a certification exercise to produce a sewage sludge as Certified Reference Material (CRM). The results of the programme showed that HPLC and GC are equally reliable for PAH analysis at submicrogram to microgram per gram levels in various environmental matrices. Major improvements were achieved during the programme, resulting in reduced coefficients of variation and between-laboratory differences. Several recommendations emerging from the programme experience are presented.

The certification of a reference material for the evaluation of the ISO method for the detection of Salmonella

A reference material (RM) containing Salmonella typhimurium was certified as CRM 507 by the Standards, Measurements and Testing Programme of the European Commission. The material consists of a gelatin capsule filled with artificially contaminated milk powder. The material is certified for the evaluation of presence/absence methods based on the ISO 6579 procedure for the detection of Salmonella. In the certification study 11 laboratories determined the presence/absence of Salmonella from each of 50 capsules. They also determined the mean number of colony-forming particles (cfp) and the homogeneity of the batch of RM according to an enumeration procedure. Certified values were calculated for both procedures separately. Based on the presence/absence procedure a fraction of capsules in which no Salmonella could be detected of 2.7% (one-sided 95% confidence upper limit 4.4%) was certified, for the enumeration procedure this fraction was 0.61% (one-sided 95% confidence upper limit 1.6%). The certified mean number of Salmonella cfp in one capsule is 5.9 (two-sided 95% confidence interval 5.3-6.4). Data on the preparation, identification, stability (at storage and higher temperatures) and homogeneity of the material are presented.

[Oligo-elements of the amniotic fluid from normal, hypotrophic and trisomy 21 fetuses]

Oligo-elements concentrations were measured between 16-18 weeks of normal pregnancy in the amniotic fluid of 84 women who delivered children with a normal weight, 16 women who had term delivery of hypotrophic children, and 7 women who delivered trisomic children (5 trisomy 21, one trisomy 18 and one trisomy 10p). Copper, zinc, bromine, lead, rubidium assays were carried out using fluorescence X spectrophotometry with dispersion of energy. The oligo-elements levels are not different in the three groups of amniotic fluid: hypotrophic, trisomic or normal fetuses. These results are compared with those previously reported.

[Disorders of plasma trace elements in diabetes. Relation to blood glucose equilibrium]

The influence of glycaemic control and diabetes characteristics on plasma concentrations of magnesium, zinc, copper, selenium, rubidium and bromine has been evaluated in 44 diabetics (30 insulin-dependent, 14 non insulin-dependent), and the results obtained were compared to those of 309 control subjects of the same mean age. Diabetics had reduced plasma magnesium concentrations (P less than 0.01) but normal erythrocyte magnesium levels. Plasma zinc and selenium concentrations were reduced, whereas those of copper were increased and those of bromine and rubidium were normal. Correlation between glycaemic control, evaluated by measurement of glycosylated haemoglobin levels, and each of the parameters studied was only demonstrated with magnesium in insulin-dependent diabetics (r = -0.561; P less than 0.02). No correlation was found with the other clinical or anthropometric characteristics of the diabetic patients studied. Diabetes seems to be associated with numerous abnormalities of plasma trace elements and magnesium, but the mechanism of these abnormalities has not yet been elucidated. A decrease in zinc and selenium concentrations and an increase in copper concentrations might be additional factors of atherogenicity.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy-dispersive x-ray fluorescence. 3. Routine analysis

We applied the energy-dispersive x-ray fluorescence technique to determination of trace elements in human bronchoalveolar lavage fluids. Our analysis of more than 200 samples allowed us to determine normal reference values, to be used in characterizing occupational exposure. These values are expressed both in nanograms per 1000 cells (of all kinds) and nanograms per 1000 macrophages to correlate lavage efficiency and dust content of the alveoli. The result expressed in milligrams per liter is not sufficient, because some healthy volunteers showed high concentrations of iron but normal values when expressed vs the number of cells. Some examples of abnormal compositions of broncho-alveolar lavages are reported and the fully automated spectrometer developed for clinical and biological investigations is described.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy-dispersive x-ray fluorescence. 3. Routine analysis

We applied the energy-dispersive x-ray fluorescence technique to determination of trace elements in human bronchoalveolar lavage fluids. Our analysis of more than 200 samples allowed us to determine normal reference values, to be used in characterizing occupational exposure. These values are expressed both in nanograms per 1000 cells (of all kinds) and nanograms per 1000 macrophages to correlate lavage efficiency and dust content of the alveoli. The result expressed in milligrams per liter is not sufficient, because some healthy volunteers showed high concentrations of iron but normal values when expressed vs the number of cells. Some examples of abnormal compositions of broncho-alveolar lavages are reported and the fully automated spectrometer developed for clinical and biological investigations is described.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy-dispersive x-ray fluorescence. 2: Determination of abnormal lavage contents and verification of the results

We applied energy-dispersive x-ray fluorescence to the determination of abnormally present elements or abnormal concentrations of elements in human broncho-alveolar lavage fluids. The low detection limits and the ability to perform multi-elemental analysis permit one to establish or confirm occupational exposure of workers. We also describe different methods used to check our method and our results. We report examples of abnormal compositions of broncho-alveolar lavages containing W, Ce, La, Nd, I, Fe, or Ni. We discuss the limits of the method for characterizing silicosis or asbestosis.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy-dispersive x-ray fluorescence. 2: Determination of abnormal lavage contents and verification of the results

We applied energy-dispersive x-ray fluorescence to the determination of abnormally present elements or abnormal concentrations of elements in human broncho-alveolar lavage fluids. The low detection limits and the ability to perform multi-elemental analysis permit one to establish or confirm occupational exposure of workers. We also describe different methods used to check our method and our results. We report examples of abnormal compositions of broncho-alveolar lavages containing W, Ce, La, Nd, I, Fe, or Ni. We discuss the limits of the method for characterizing silicosis or asbestosis.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy dispersive x-ray fluorescence. 1: Technique and determination of the normal reference interval

We have applied energy dispersive x-ray fluorescence to the analysis of broncho-alveolar lavage fluids, to determine the concentration of several elements simultaneously with manipulation of the sample minimized. A 20-microL sample of a homogenized lavage fluid, to which two internal standards (containing Y and V) have been added, is deposited on a polypropylene film, 4 microns in thickness, and analyzed by x-ray fluorescence. We report the analytical procedure, the detection limits, and the reproducibility. The normal concentration range for trace elements is reported for a selected population. The simplicity and rapidity of the method, and the possibility of automating measurements, make this procedure suitable for screening large numbers of lavage specimens and to establish the diagnosis of some pneumoconioses.

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy dispersive x-ray fluorescence. 1: Technique and determination of the normal reference interval

We have applied energy dispersive x-ray fluorescence to the analysis of broncho-alveolar lavage fluids, to determine the concentration of several elements simultaneously with manipulation of the sample minimized. A 20-microL sample of a homogenized lavage fluid, to which two internal standards (containing Y and V) have been added, is deposited on a polypropylene film, 4 microns in thickness, and analyzed by x-ray fluorescence. We report the analytical procedure, the detection limits, and the reproducibility. The normal concentration range for trace elements is reported for a selected population. The simplicity and rapidity of the method, and the possibility of automating measurements, make this procedure suitable for screening large numbers of lavage specimens and to establish the diagnosis of some pneumoconioses.

Simultaneous determination of trace elements in serum by energy-dispersive x-ray fluorescence spectrometry

Energy-dispersive x-ray fluorescence is applied in the analysis of human serum to determine the concentrations of several elements simultaneously with minimal manipulation of the sample. The analytical procedure has been developed with standard sera, and standardization, detection limits, and reproducibility have been established. A 50-microL sample of diluted serum, to which an internal standard has been added, is deposited on a thin (4-microns thick) polypropylene film and analyzed by x-ray fluorescence. We report the statistical distributions of the concentrations of Fe, Cu, Zn, and Br obtained in the population (103 samples) studied, and report detection limits for the other 22 elements studied. The simplicity of the method, the high throughput, and the possibility of automating the measurements make this procedure suitable for screening large numbers of sera.

Simultaneous determination of trace elements in serum by energy-dispersive x-ray fluorescence spectrometry

Energy-dispersive x-ray fluorescence is applied in the analysis of human serum to determine the concentrations of several elements simultaneously with minimal manipulation of the sample. The analytical procedure has been developed with standard sera, and standardization, detection limits, and reproducibility have been established. A 50-microL sample of diluted serum, to which an internal standard has been added, is deposited on a thin (4-microns thick) polypropylene film and analyzed by x-ray fluorescence. We report the statistical distributions of the concentrations of Fe, Cu, Zn, and Br obtained in the population (103 samples) studied, and report detection limits for the other 22 elements studied. The simplicity of the method, the high throughput, and the possibility of automating the measurements make this procedure suitable for screening large numbers of sera.