Determination of lithium in biological samples by inductively coupled plasma mass spectrometry

Dried Blood Spots and Miniaturized Ultrasonic Nebulization Microplasma Optical Emission Spectrometry for Point-of-Care Testing of Blood Lithium

Despite the significant importance of blood lithium (Li) detection in the treatment of bipolar disorder (BD), its point-of-care testing (POCT) remains a great challenge due to tedious sample preparation and the use of large-footprint atomic spectrometers. Herein, a system coupling dried blood spots (DBS) with a point discharge optical emission spectrometer equipped with a miniaturized ultrasonic nebulizer (MUN-μPD-OES) was developed for POCT of blood Li. Three microliters of whole blood were used to prepare a dried blood spot on a piece of filter paper to which 10 μL of eluent (1% (v/v) formic acid and 0.05% (v/v) Triton-X) was added. Subsequently, the paper was placed onto the vibrating steel membrane of the ultrasonic nebulizer and powered on to generate aerosol. The aerosol was directly introduced to the μPD-OES for quantification of Li by monitoring its atomic emission line at 670.8 nm. The proposed method minimized matrix interference caused by high levels of salts and protein. It is worth noting that the MUN suitably matches the needs of DBS sampling and can provide aerosolized introduction of Li into the assembled μPD-OES, thus eliminating all tedious sample preparation and the need for a commercial atomic spectrometer. Calibration response is linear in the therapeutic range and a limit of detection (LOD) of 1.3 μg L-1 is well below the Li minimum therapeutic concentration (2800 μg L-1). Li in mouse blood was successfully detected in real-time using MUN-μPD-OES after intraperitoneal injection of lithium carbonate, confirming that the system holds great potential for POCT of blood Li for patients with BD.

Trace element reference values in serum determined by inductively coupled plasma atomic emission spectrometry

Serum reference values for Ba, B, Cd, Cu, Fe, Mn, Li, Se, Sr, and Zn in 141 healthy Norwegians were determined. The trace element concentrations were determined by the inductively coupled plasma atomic emission spectrometry technique that we have recently validated. The reference intervals were established according to the recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine. Also coverage intervals with coverage uncertainties were calculated according to the International Union of Pure and Applied Chemistry. The population studied consisted of 69 men and 72 women of the ages 21-87 years. The effects of gender, age, smoking, and oral contraceptives on serum levels of trace elements were investigated. Median concentrations of the different trace elements in (micromol/l) were as follows: Ba (0.44), B (1.50), Cd (0.004), Cu (17.1), Fe (21.4), Li (0.06), Mn (0.003), Se (1.26), Sr (0.17), and Zn (13.3). An increase in serum Ba and Sr was detected with age. These metals and Se were also significantly higher in women over 50 years of age in comparison to younger women. Women had higher serum Cu than men and those on oral contraceptives had higher serum Cu and Fe. Serum B tended to increase with age, while it was significantly reduced with smoking.

Sample collection guidelines for trace elements in blood and urine. IUPAC Commission of Toxicology

This paper presents an organized system for element-specific sample collection and handling of human blood (whole blood, serum or plasma, packed cells or erythrocytes) and urine also indicating a proper definition of the subject and sample. Harmonized procedures for collection, preparation, analysis and quality control are suggested. The aim is to assist scientists worldwide to produce comparable data which will be useful on a regional, national and international scale. The guidelines are directed to the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, lithium, manganese, mercury, nickel, selenium and zinc. These include the most important elements measured for their occupational or clinical significance, and serve as examples of principles that will guide development of methods for other elements in the future.

Monitoring of lithium levels in human serum after therapy with lithium preparations by capillary isotachophoresis

An isotachophoretic method for the evaluation of the level of lithium salts in serum samples was optimized. Use of operating systems containing polyethylene glycol permitted the separation of cationically migrating components from Li (i.e., Na, K and Ca). The pretreatment of serum samples involves only appropriate dilution with demineralized water depending on the concentration of the major components such as sodium. The lithium levels were studied both in model samples and serum from patients treated with lithium preparations.

Trace element reference values in tissues from inhabitants of the European Community. VII. Review of trace elements in blood, serum and urine of the Belgian population and critical evaluation of their possible use as reference values

The availability of accurate trace element reference values in human tissues represents an important indicator to the health status of the general population and occupational groups exposed to trace elements. The EURO TERVIHT project (Trace Element Reference Values In Human Tissues) aims to establish and compare trace element reference values in tissues from inhabitants of the European Community as baseline values for clinical/toxicological assessment studies (Sabbioni et al., 1992a,b). In this context one of the first steps considered is the critical evaluation (state of the art) of existing literature on trace element reference values in blood, serum and urine in the general population of each EC country. This paper reviews the Belgian situation.

RNAA as compared to ICP-MS for the analysis of normal human serum

The merits of radiochemical neutron activation analysis (RNAA) and inductively coupled plasma mass spectrometry (ICP-MS) are critically discussed for the determination of trace and ultratrace elements in normal human serum. For RNAA, two semiautomated procedures, allowing the determination of up to 18 elements, are briefly described. ICP-MS has a series of interesting features for the determination of trace elements. Matrix and spectral interferences can mostly be avoided or corrected for. After a simple 5- or 10-fold dilution and addition of an internal standard, more than 20 elements can be measured precisely and accurately.

Mass spectrometry of trace elements in biological samples

Mass spectrometry is a powerful analytical tool for determining the isotope ratios and concentrations of trace elements in various samples at levels ranging from major constituents to subparts per billion. Because isotope dilution is free from matrix effects, it has the potential of being incorporated into a definitive analytical approach that can provide reference values for concentrations in physiological and pathological conditions. In addition, isotope dilution mass spectrometry results are free from the constraints of quantitative recovery of the analyte, an essential requirement in other analytical techniques that is difficult to achieve with complex biological samples. A variety of mass spectrometric approaches have been used for determining the concentration of trace elements in biological samples. The more commonly used are thermal ionization mass spectrometry, inductively coupled plasma mass spectrometry, fast atom bombardment mass spectrometry, and gas chromatography mass spectrometry. This article reviews the work on trace element determination in biological samples using different mass spectrometric techniques and highlights the experiments performed by the authors in establishing gas chromatography mass spectrometry.

Bismuth in human serum: reference interval and concentrations after intake of a therapeutic dose of colloidal bismuth subcitrate

A sensitive method for the determination of the bismuth concentration in human serum is described. Analyses were carried out by inductively coupled plasma-mass spectrometry (ICP-MS), after a simple dilution of the samples with nitric acid. The detection limit of the applied method is 0.007 microgram/l whereas relative standard deviations varied from 5.7 to 13.6%. Determination of reference values in human serum of healthy adults gave a range from < 0.007 to 0.067 microgram/l (19 persons). Bismuth concentrations in serum were also measured before, during and after the intake of therapeutic doses of colloidal bismuth subcitrate (CBS). About 1.5-2 h after the intake of one tablet of CBS, the bismuth concentration in serum was found to have increased 51-1483 times (two apparently healthy volunteers and six hospitalized patients), showing that the serum bismuth concentrations can increase by several orders of magnitude during the intake of CBS. During the intake of four tablets of CBS per day by two apparently healthy volunteers, bismuth concentrations in serum after an overnight fast were found to be, respectively, 5.56 and 8.1 micrograms/l on day 15 and 4.28 and 13.6 micrograms/l on day 29. After stopping the therapy, the concentration of bismuth in serum slowly returned towards normal over a period of months.