Manganese lettuce

In this work the Eurachem guide [1] was used for the estimation of uncertainties involved in the determination by electrothermic atomic absorption spectrometry (EAAS) of manganese in digested lettuce leaves. The total uncertainty estimation was calculated assuming a 100% digestion efficiency with negligible uncertainty. The experimental precision was compared with an estimated one for the purpose of validation of the proposed method of evaluation. After this validation the uncertainty estimation was used in an accuracy test and in routine analysis with the support of a spreadsheet programme. 

The proposed uncertainty validation method was applied to the dry-base determination of manganese in digested lettuce leaves by electrothermic atomic absorption spectrometry. The proposed quality control scheme was also applied. 

Copper.—Cu, a.n. 29 a.w. 63-57. An invariable microconstituent of plants and animals. In plants the copper value is, roughly, one-fifth that of manganese and one-fifteenth that of iron. It ranges from 0-25 mg. Cu per litre of potato juice up to 40 mg. per kgm, in dried lettuce leaf. Leguminous plants and their seeds are rich in the metal. 

Manganese in Foodstuffs.— From the surveys of Peterson (1928), Richards (1930), the richest sources are liver, kidney, pancreas, muscle, lettuce, spinach and unmilled cereals. Wheat germ, which contains about 39 mg. Mn per 100 gm. dry material, offers an abundant supply (Sluiter, 1933 Von Oettingen, 1935). 

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