Multielement analysis of biological samples by inductively coupled plasma-mass spectrometry. II. Rapid survey method for profiling trace elements in body fluids

A rapid survey of the elements in biological materials, covering most of the elements in the periodic table, is possible by using available software for semi-quantitative analysis (SEMI-QUANT) by inductively coupled plasma-mass spectrometry. The procedure takes 5 min after sample preparation and gives results with a precision (CV) of approximately 20%. At a 10-fold dilution, 13 elements can be consistently and reliably detected in serum and 15 elements in whole-blood samples. At present the most important limitation of this method is mass overlap by polyatomic species for some elements of interest (e.g., Cr, Mn, and V). However, for the set of elements that can be reliably determined at endogenous concentrations, including Li, B, Mg, Fe, Cu, Zn, Rb, and Sr, the rapid scanning capability may be useful. Although matrix effects limit the direct interpretation of the semi-quantitative output, reasonable estimates of concentration are attainable by using matrix-matched standards or by adding a multielement standard to an aliquot from one sample in the set. We also present an example of determination of 25 elements in saliva from a patient with extensive dental work: Components of many of his dental alloys were readily identified. The method may also prove useful for screening multiple toxic exposures to heavier elements, such as Pb, Tl, Cd, and Hg.

The Selection and Evaluation of Internal Standard Elements Based on Elemental/Instrumental Covariance

The selection of internal standards for elements analyzed by a multielement direct-current argon plasma emission spectrometer was made by studying the elemental covariance of a multielement standard. Principal components factor analysis of many analytical determinations of this standard indicated that the elemental covariance clustered into two main groups. These groups were a function of instrumental variation, mainly plasma shape. The first principal factor accounted for 43.4% of the variance and had high loadings for strontium, barium, boron, manganese, nickel, titanium, silicon, calcium, and cadmium. The second principal factor accounted for an additional 36.7% of the variance and had high loadings for lithium, vanadium, magnesium, potassium, and aluminum. Compared with an external standard, internal standards dictated by the principal components factor analysis results gave improved precision. Internal standards not correlated with response variations degraded both the accuracy and the precision of the analysis.

The Practical Analysis of High-Purity Chemicals. VI. Emission Spectrographic Analysis of High-Purity Acids

The spectrographic analysis of volatile acids in a high-purity form is reviewed and a procedure presented that involves evaporation of a 100-g sample under temperature controlled contamination-free conditions and emission spectrography using dc-arc excitation under controlled atmosphere. In the evaporation, graphite (10 mg) is added as a collector, sulfuric acid to convert to less volatile sulfates (with acetic, hydrochloric, and nitric acids), and also mannitol to retain boron (with hydrochloric and hydrofluoric acids). Indium is added as a internal standard. Spectra are examined for 33 elements against a multielement standard in graphite containing indium as an internal standard. For the concurrent analysis of three samples, the elapsed time is 4–10 h and the actual working time 3–5 h. Recovery studies are reported as well as the use of the procedure in the assessment of the leaching of borosilicate glass by concentrated mineral acids.