Contamination Control in Trace Element Analysis

Abstract

Contamination problems inherent in analysis at the ultratrace (<1 µg/g) element level are reviewed. Suggestions for controlling systematic errors in the following parameters are offered: the sample, the laboratory, containers, and reagents. The addition of the blanks contributed from each of these sources comprises the total analytical blank in an analysis. Inasmuch as high blanks invalidate most ultratrace analyses, reduction in the size and variability of the blank components is a major step in attaining higher accuracy.

General aspects of trace analytical methods-VI. Acid pressure decomposition in trace element analysis

“…Owing to this resistence, but also because of its low content of trace metals when compared with other synthetic materials, PTFE is one of the materials preferred for the manufacture of apparatus used in trace element analysis (ref. 4).…”

“…PTFE is practically completely resistent to hydrofluoric acid (ref. 4). Because in the polymerization process 'metalfree' peroxide catalysts are employed, the main impurities encountered which give rise to blank values, particularly when first using a new pressure decomposition vessel, probably originate from the machining process.…”

“…These are presumably 'conglomerations' copolymerized into the PTFE which are set free during surface attack by the decomposition acid (ref. 4). In order to keep these blank values low, vessels of the smallest suitable capacity, and with the smallest possible inner surface area should be used.…”

“…Of some significance is the slight gas permeability of PTFE due to which noticeable amounts of nitrogen oxides, water or acids (ref. 4) and also traces of iodine and mercury (refs. 18, 31) …”

Simple and Micro Determination of Manganese in Serum by Graphite Furnace Atomic Absorption Spectrometry

“…For the determination of ultratrace mangamese in serum, it should be essential to minimize the contaminations from other sources: such as reagents, sampling method and devices, laboratory wares and laboratory environment. 3,[7][8][9] In the present paper, the simple and micro procedure for the determination of manganese in serum is described using 200 µl of sample. Special techniques to avoid contamination in an ordinary laboratory as well as possible contamination sources in an old method are also described.…”