Quantitative Response for Fluorine-Chlorine in Inert Gas Shields

Direct emission spectrographic determination of fluoride in geological materials by formation and excitation of calcium fluoride in a direct current arc

“…The time requirements and the problems attendant to fusion processes are well-known. To avoid these, several reports (5)(6)(7)(8)(9)(10)(11)(12) have described an emission spectrometric analysis method which permits a direct measurement without sample dissolution. This method usually involves mixing the sample in powder form with an excess of calcium (usually as CaC03) and subjecting it to a dc arc to produce and excite CaF.…”

“…This method usually involves mixing the sample in powder form with an excess of calcium (usually as CaC03) and subjecting it to a dc arc to produce and excite CaF. An examination of the reports (5)(6)(7)(8)(9)(10)(11)(12) indicates that the CaF emission appears early in the discharge cycle implying that CaF is readily vaporized and that the molecular emission bands are easily excited. These observations have led to the general usage of low current discharges (-7-10 A) with the rationale that the CaF can be formed, vaporized, and excited under these conditions without deleterious dissociation of the molecule.…”

“…Although the data available have all been generally supportive of this, the studies have not typically examined the conversion, vaporization, and excitation processes in detail. Moreover, the resulting methods have generally lacked desirable levels of sensitivity; the determination of F at concentration levels below pg/g appears to be a borderline case (5)(6)(7)(8)(9)(10)(11)(12). The purpose of the present investigation was to carefully examine the parameters affecting the entire analytical process, to determine their effects on the prevalent mechanisms, and evaluate means for enhancing the analytical sensitivity.…”

“…These samples were mixed with CaC03 (50 wt.%) and analyzed by the procedures summarized in Table I or described in the text below. Previous studies have shown that several factors affect the CaF emission intensity (5)(6)(7)(8)(9)(10)(11)(12). For convenience, experiments designed to determine the optimum conditions are discussed individually below.…”