Content of strontium, lithium and calcium in selected milk products and in some marine smoked fish.

The strontium, lithium and calcium contents have been determined in 87 samples of five kinds of milk-fermented products, as well as in 93 samples of ten kinds of marine smoked fish. The samples were purchased on the local market. The representative samples were dry ashed in quartz crucibles and the ash was treated with suitable amounts of conc. HCl and a few drops of conc. HNO3. The obtained sample solution was then used for the determination of Sr, Li and Ca by the flame atomic absorption spectrometry (AAS) method. Ca and Li were determined using the air-acetylene flame and Sr with nitrous oxide-acetylene flame, according to the manufacturer's recommendations. The contents of Sr in the fermented milk products ranged from 0.21 to 0.79 (mean 0.44 +/- 0.07) and in the marine smoked fish from 0.02 to 4.63 (mean 1.16 +/- 0.24) mg/kg of the edible form of both products. Li contents in the milk products ranged from 0.01 to 0.50 (mean 0.07 +/- 0.04) and in the smoked fish from 0.00 to 0.58 (mean 0.11 +/- 0.08) mg/kg. The calcium was highest in the milk products and ranged from 1,010 to 2,020.0 (mean 1,377 +/- 143) mg/kg. In the smoked fish calcium varied strongly and ranged from 40 to 1,052 (mean 303 +/- 53) mg/kg of the edible form. The calculated average ratio of strontium to calcium (mg Sr/1 g Ca) in the milk beverages and yogurts amounted 0.32 and in the smoked fish was 12 times as high and amounted 3.84. The main purpose of this work was to present Ca, Sr and Li together. This is justified because Sr and to some extent also Li are able to modulate Ca metabolism and vice versa.