Hydrochloric Acid Extraction Procedure for Determination of Inorganic Elements in Foods of Animal Origin

Abstract

Application of hydrochloric acid extraction procedure for determination of inorganic elements (K, Mg, Ca, Zn, Mn, Cu, Fe and P) in animal foods (raw skipjack, boiled and semi-dried whitebait ("shirasuboshi"), boiled and dried sardines ("niboshi"), loin of pork and pig liver) was described. Potassium, Mg, Ca, Zn, Mn, Cu and Fe were determined by atomic absorption spectrophotometry (AAS) and P was determined by vanadomolybdate spectrophotometric method. The results were compared with those obtained by dry ashing method using platinum dish or wet digestion method using HNO3-HClO4 as pre-treatment. (1) Potassium, Mg, Ca, Mn and Zn in animal foods were extracted with 1% and 3% HCl solution at room temperature (20-25°C), and Cu was extracted with 3% HCl solution at room temperature (20-25°C). (2) Iron in pig liver and "shirasuboshi" were extracted at 80°C with 3% HCl, but extraction of iron in the other animal foods was incomplete, ranged between 37 and 68%. (3) APDC-DIBK extraction of Fe, Cu and Zn followed by AAS determination could be applied to 3% HCl extracted solution as same as dry ashing or wet digested sample solution. (4) Extraction of phosphorus in animal foods with dilute HCl was incomplete, ranged between 70 and 89%.