Spectroscopic evaluation of interactions among trace elements and biogenic carbonates in the marine environment.

The interactions between trace elements and biogenic carbonates (marine mussel shells) in aqueous media were evaluated. The behaviour of Mn, Cu, Co, and Cd was investigated using spectrometric techniques (electrothermal atomic absorption, inductively coupled plasma atomic emission and electron paramagnetic resonance). The results obtained show that the metals considered do not form a distinct precipitated phase on the shell surfaces, but that they interact with the CaCO3. This study aimed to provide more information on the mechanisms involved in the storage of trace elements by the shells of marine bivalves. This would allow the use of mussel shells as an alternative to soft tissues for trace metal analyses in biological monitoring programmes.

Interaction of carboplatin with carrier human erythrocytes.

The antineoplastic drug Carboplatin (CBDCA) was encapsulated in human erythrocytes by means of transient hypotonic hemolysis, followed by isotonic resealing. Up to 5 mg/ml of packed cells could be entrapped, with about 70% cell recovery. In vitro incubation of the CBDCA-loaded erythrocytes in autologous plasma caused a very slow release of the drug from the cells (12% approximately in 3 h). The encapsulation conditions, performed at a low hematocrit, in order to obtain high amounts of the drug inside the carriers, impaired the metabolic properties of the loaded erythrocytes significantly. In particular, an almost complete disappearance of GSH was observed. Analysis of the intraerythrocytic metabolism of CBDCA showed that, in spite of its relatively high stability in aqueous solutions, in hemolysates and in the loaded erythrocytes a significant percentage of CBDCA is rapidly converted to other species that still retain an antiproliferative activity in vitro. This fast conversion could be extensively inhibited by previous conversion of oxyhemoglobin to methemoglobin or carbomonoxyhemoglobin, suggesting an important role of heme iron in this process. Encapsulation of CBDCA in selectively targeted human erythrocytes may represent a therapeutic strategy for increasing the drug concentration in specific organs, notably liver.

The speciation of trace amounts of organometallics in marine organisms by gel-permeation high-pressure liquid chromatography with PAR derivatization.

A high-pressure liquid chromatograph equipped with an off-column calorimetric reactor was used for the determination of metallorganic compounds such as metallothioneins. The stainless-steel gel-permeation column used was first tested with ultraviolet detection of a standard protein mixture. The metallothioneins were determined by absorbance measurements at 520 nm after an off-column reaction of the metal-containing eluates with a buffered 4-(2-pyridylazo)resorcinol (PAR) solution. The eluates were also tested by flame and electrothermal atomic-absorption spectrometry; a correlation between AAS and ICP results and the peak areas of the calorimetric detection was also made. A zinc-inhibiting reagent was also added to the PAR solution in order to find the calorimetric error due to the presence of other metals such as copper or cadmium.

Seasonal variation of thallium, lead, and chromium concentrations in airborne particulate matter collected in an urban area.

In November 1985 a research program started, with the aim to evaluate seasonal variations in the concentrations of organic and inorganic pollutants in the atmosphere of Genoa. The program provided for the collection of samples of airborne particulate in five different areas with distinct urban characteristics. First results for chromium, lead, and thallium concentrations in an industrial and in an urban area are reported. Lead showed the highest concentration at both locations (geometric mean: 1.037 and 0.476 microgram/m3, respectively) and appeared to be little affected by seasonal variation. Private traffic was confirmed as the main source of this pollutant. Chromium and thallium geometric mean concentrations were 0.006 and 0.014 microgram/m3 in site A and 0.017 and 0.015 microgram/m3 in site B, respectively. In the urban location a good negative linear correlation was found between chromium and thallium concentration and mean ambient temperature; the domestic heating plants were suspected as important emission sources of these two compounds.

The distribution of arsenic and cobalt in patients with laryngeal carcinoma.

The objective of this study was to evaluate tissue and plasma concentrations of arsenic and cobalt in an attempt to discover the role of these elements in the malignant process. Using neutron activation analysis, arsenic and cobalt levels were determined in plasma and in non-malignant and malignant human tissues in 15 patients with laryngeal carcinoma. Arsenic and cobalt levels were about 60% higher in tumor than in adjacent non-malignant tissue (P less than 0.001): arsenic 72.4 +/- 18.0 ng/g versus 43.1 +/- 9.4 in non-malignant tissues, and cobalt 68.7 +/- 7.3 ng/g versus 39.6 +/- 7.0 in non-malignant tissues. Mean plasma arsenic and cobalt levels were also significantly higher in patients with laryngeal carcinoma than in healthy control subjects.

Plasma and tissue levels of some lanthanide elements in malignant and non-malignant human tissues.

Lanthanum (La) levels in plasma, in erythrocyte hemolysate and in tissue from healthy subjects and patients with laryngeal carcinoma were determined by neutron activation analysis. Plasma lanthanum levels were significantly higher in laryngeal carcinomas than in either healthy controls or in subjects suffering from localized inflammation (e.g. epicondylitis of the elbow) (p less than 0.001). The mean La concentration in malignant tissue samples was 57.5 +/- 7.2 ng g-1; the corresponding level in normal adjacent tissue from the same organ was 94.6 +/- 12.0 ng g-1. This 61% decrease in the concentration of La in malignant tissues was highly significant (p less than 0.001). In patients with laryngeal carcinoma we did not observe any detectable level of lanthanum in erythrocyte hemolysate; the mean La erythrocyte hemolysate level in healthy controls and in patients suffering from localized inflammatory condition was 14.3 and 33.2 ng ml-1, respectively. Further studies are in progress to evaluate whether or not this element can serve as a marker for diagnosis or prognosis in cancer.

Chemical analysis of uranium and titanium niobotantalate metamict minerals by ion-exchange chromatography and spectrophotometric procedures.

An ion-exchange separation followed by spectrophotometric determinations is applied to some metamict minerals. These minerals, containing very high amounts of elements which present some problems to the analyst, such as uranium, titanium, niobium and rare-earth elements, are fused with potassium bisulphate, and the cooled melts dissolved in sulphuric acid. The solutions are passed through a series of three ion-exchange columns to separate those mineral-forming elements for which the colorimetric procedures suffer interference from the elements listed above. The procedure has been tested with a synthetic solution and with solutions of the minerals.

Determination of trace amounts of zirconium in silicates by cation-exchange chromatography and spectrophotometry with xylenol orange.

An ion-exchange scheme and colorimetric determination with Xylenol Orange are used for estimating traces of zirconium in silicate rocks.

Determination of trace amounts of barium in silicate rocks and minerals by ion-exchange Chromatography and atomic-absorption spectrophotometry.

Trace amounts of barium are determined in the standard silicate rocks and minerals, W-1, AGV-1, BCR-1, DTS-1, GSP-1, G-2 of the U.S. Geological Survey and BR, GA, GH, GR, UB-N, DR-N, BX-N, DT-N, VS-N, FK-N, GS-N of the Centre de Recherche Petrographique et Geochimique de Nancy and the Association Nationale de la Recherche Technique. After an ion-exchange separation, the analyses are carried out by atomic-absorption spectrophotometry. The separation is performed to eliminate interferences due to matrix effects.