Ca Analysis by Atomic Absorption

Introduction

Ca exists in the natural world in various compounds such as carbonates in the form of marble and limestone, etc., in gypsum (CaSO₄), fluorites (CaF₂), and apatites (Ca₅(PO₄)₃F), etc. Ca forms silvery white-colored crystals and reacts at ambient temperature with oxygen and halogens. It also bonds with oxygen, carbon, nitrogen, silicon and phosphorus when heated. Calcium forms divalent compounds, many of which are white in color. Calcium has a wide variety of applications, such as in bleach and as a pool water treatment agent in the form of calcium hypochlorite (Ca(OCl)Cl), and in stomach antacid preparations in the form of CaCO₃ and Ca(OH)₂, etc. A substantial portion of the human body consists of calcium, comprising about 1 kg of a 70 kg adult, 99% of which is contained in hydroxy apatite in the bones, and in muscle at levels of 140 - 700 ppm, and in blood at about 61 mg/dL. Ca performs various critical roles in the body, in particular, as the primary structural component of bone, maintaining the stability and permeability of biological membranes, and for the contraction of muscles, etc. For example, it is essential that sufficient calcium and phosphate be provided for bone formation, and that the Ca concentration in blood plasma is maintained at about 10 mg/dL. The daily intake of Ca in an adult is 600 - 1400 mg, but if the Ca concentration in blood decreases, the muscles shrink and exhibit spasms due to neural excitation. In cases of Ca deficiency, CaCl₂ is given either orally or via intravenous injection. On the other hand, hypercalcemia can cause kidney calcification attended by uremia. Since the deficiency and excess of Ca can exert such a great influence in the human body, nowadays, various supplements and functional foods that maintain the Ca balance in the body are being developed and marketed. This Application News presents a type of interference that may occur in flame analysis of Ca, and an effective corrective action.

July 23, 2024 GMT