Aluminium and fluoride in hospital daily diets and in teas

Abstract

The levels of aluminium and fluoride have been determined in hospital daily diets including breakfast, dinner and supper, as well as in black teas and herbal teas purchased from the local market. In tea, aluminium was determined directly in a sample solution by atomic absorption spectroscopy using nitrous oxide and an acetylene flame. For analysis of the hospital diet, samples containing lower levels of aluminium were analysed using a spectrophotometric method which measured aluminium in the form of a 8-hydroxyquinoline complex. Decomposition of the samples was achieved using a mixture of concentrated acids [nitric (HNO3), perchloric (HClO4) and sulphuric (H2SO4)] in platinum dishes. Fluoride was assayed by spectrophotometry using a microdiffusion procedure with a mixture of concentrated HClO4 and silver sulphate, trace amounts of the released fluoride [as hydrogen fluoride (HF)] were trapped on the alkaline surface of a Petri dish and then determined in the form of an alizarin-fluoride complex. The mean level of aluminium found in hospital daily diets amounted to 21.3 +/- 12.3 mg and the mean level of fluoride was 1.38 +/- 1.12 mg per adult person. In the 16 samples of commerically available brands of black teas, the levels of aluminium and fluoride ranged from 445 to 1552 ppm (mean = 897 +/- 264 ppm) and from 30 to 340 ppm (mean 141 +/- 85 ppm), respectively. In six herbal teas, the mean levels of aluminium and fluoride were lower, and amounted to 218.9 +/- 150.7 ppm and 6.0 +/- 6.9 ppm, respectively. This study has shown that concern about a high intake of aluminium and fluoride from these foods is unfounded.

Tea and fluorosis

“…The range of the fluoride content in tea commodities were summarized in the following table, in which tea commodities were classified by their different manufactured methods and various appearances [3,[6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Many studies measured the fluoride content in tea commodities from USA, UK, Germany, Japan, China, Hong Kong and Taiwan in China, Poland, Turkey and so on, including most kinds of tea commodities in international markets [3,[6][7][8][9][10][11][12][13][14][15][16][17]. The range of the fluoride content in tea commodities were summarized in the following table, in which tea commodities were classified by their different manufactured methods and various appearances [3,[6][7][8][9][10][11][12][13][14][15][16][17].…”

Aluminium determination in foods by using spectrophotometric oxine and flame AAS methods

“…The samples were decomposed by mixture of concentrated acids [68% HNO 3 Results of aluminium determinations obtained by employment of N 2 O1C 2 H 2 flame AAS method and spectrophotometric oxine (SO) method in teas, fresh leaves of celery and some other food samples were compared. The samples were digested for few hours in teflon beakers with use of a mixture of concentrated acids (H 2 SO 4 + HNO 3 + HClO 4 ), and then transported for final destruction into platinum dishes for ashing.…”

“…The diets were taken from a hospital canteen and the remaining foods were purchased on the local market [2,3].…”