Spike Recovery Studies Research Articles

Investigations of a reduced palladium chemical modifier for graphite furnace atomic absorption spectrometry

Palladium is a very useful chemical modifier for graphite furnace atomic absorption spectrometry. It can be used to stabilise many elements several hundred degrees higher than is possible with current methods. Its performance as a modifier is strongly affected by the sample matrix. The addition of a reducing agent provides for more consistent performance. The main purpose of the reducing agent is to “modify” the form of the palladium, guaranteeing that palladium is reduced to the metal early in the temperature programme. Differences were seen in the behaviour of the palladium modifier depending on the reduction method used. A comparison of palladium modifier methods in spike recovery studies of thallium was carried out to investigate differences between the reduction methods. It was suspected that differences in the physical form of palladium contributed to the variability in results. Scanning electron micrographs were used to investigate the physical form of palladium on the graphite surface. A method using the palladium modifier for the determination of selenium was compared with a commonly used procedure in spike recovery studies.

Rapid Digestion and Flameless Atomic Absorption Spectroscopy of Mercury in Fish: Collaborative Study

A collaborative study of the determination of mercury in fish has been completed in which wet oxidation of fish tissue in nitric acid, using vanadium as a catalyst, is compared with the AOAC official final action digestion technique, 25.103-25.105, involving a nitric-perchloric acid mixture. The study used tuna fish samples of known mercury content and included spike recovery studies in which methyl mercury solutions of known composition were provided to each laboratory. The study was designed to provide recovery information that bracketed the regulatory level of mercury in fish. The results indicate that the proposed digestion method is at least as precise and accurate as the AOAC method. The proposed method is also more rapid and less hazardous. It has been adopted as official first action.