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A nitrogen-cooled and an argon-cooled hydrogen flame have been used for the determination of sulfur containing species in solids by molecular emission cavity analysis (MECA). The argon-cooled flame is much more sensitive for the determination of SO₄²⁻. In a solid mixture containing S₈, S²⁻, SO₃²⁻, and SO₄²⁻, the presence of one or more of these sulfur containing species can be determined with the argon-cooled flame. The nitrogen-cooled flame can be useful, for example, in the determination of a mixture of S₈ and SO₃²⁻ in a solid matrix. All these sulfur containing species can be quantitatively determined in the argon-cooled flame in the concentration range from about 10 ppm to 5000 ppm. The variation from 10 percent to 30 percent in the reproducibility of these measurements has been attributed to the non-homogeneity of the solid materials and the small sizes required. Sulfur dioxide has been used for the reduction of ammoniacal copper(II) solutions to solutions containing various copper(I) compounds. These copper(I) compounds can be reduced further to copper metal by varying the solution conditions. The mechanisms of the reactions involved must be understood before they can be successfully used for the large scale production of copper. Porth et al.'s method was followed for the synthesis of Cu(I) intermediates. Several compounds were isolated and their compositions determined. The changes in the relative concentrations of Cu(I) and Cu(II) are also important for unraveling the kinetics and mechanisms of these reactions. A simple spectrophotometric method using 2,9-dimethyl-1,10-phenanthroline was developed to monitor the Cu(I) concentration in solution. The sensitivity of the method is sufficient to determine 10⁻⁵ M Cu(I) in the presence of Cu(II); SO₂, however, interferes with the method. Other possible methods including the use of a mixture of EDTA and 2,9-dimethyl-1,10-phenanthroline were also examined. Evidence is presented for the formation of a ternary complex of copper(I), 2-9-dimethyl-1,10-phenanthroline, and EDTA. The possibility of using a mixture of Cu(II) and 2,9-dimethyl-1,10-phenanthroline to determine SO₂ was tested. Oxygen was found to interfere with this method.

Excessive levels of sulfur in the ecosphere are generally found to be detrimental to man and his environment. Four inorganic forms of sulfur are singled out as common constituents of natural and pollutant systems: sulfide (S²⁻), elemental sulfur (S⁰), sulfite (SO₃²⁻), and sulfate (SO₄²⁻). Progress toward characterizing the chemical interactions and toxicity of these species is retarded by the lack of suitable analytical procedures for determining the forms of sulfur in complex solid matrices. An extensive survey of the literature reveals that conventional analyses for sulfur are numerous, but that most techniques are restricted to solutions containing only one type of sulfur. A few complex and cumbersome analytical schemes have been devised, however, for the determination of mixtures of sulfur species in solution. Solubilization of the sample prior to analysis not only adds a step to the procedure, but it also increases the number of variables and the uncertainty associated with the results. The direct determination of sulfur in solids is an alternative to extraction which avoids many of its pitfalls. A critical review of the methods available discloses a paucity of analytical techniques capable of determining individual sulfur species in solid mixtures. X-Ray methods such as X-ray fluorescence and X-ray photoelectron spectroscopy rank the highest as potentially useful probes for eliciting information concerning the oxidation state of sulfur in solids. Routine quantitative work is impeded by the inability to examine bulk properties and the relative lack of sensitivity inherent in X-ray techniques. This apparent analytical void has led to the development of a new technique which can be applied to the determination of inorganic sulfur in solids: time resolved molecular emission spectrometry (TRMES). Solid samples are placed in a small, quartz-lined cavity at the end of a stainless steel rod and the rod is positioned in a low temperature flame, in line with the entrance slit of monochromator. The resulting molecular sulfur emission is monitored at 383.6 nm and is linearly related to sulfur content between at least 10⁻⁵ to 10⁻⁷ g. Qualitative identification of sulfide, elemental sulfur, sulfite, and sulfate is afforded by the separate, time dependent emission responses which are observed. Detection limits are species dependent and theoretically, in a 1.5-mg sample, range from 0.2 pg for sulfite to 8ng for sulfate. In practice, quantitation at these low levels is hindered by inhomogeneous standards. Effects due to different bulk matrices, the presence of two or more sulfur species in a sample, or interferences from counterions are minimal or have not been detected. TRMES provides an alternative to aspirating the sample into the flame and greatly reduces the amount of sample that is required. In addition, the cavity serves to confine the sample and the resultant emission to a small, predetermined region of the flame. This enhances sensitivity and allows one to choose the optimum sample position in the flame. Standard flame emission instruments may be readily adapted to this technique by the addition of a simple, easily fabricated sample introduction device. The utility of TRMES is demonstrated by the determination of sulfur species in several complex matrices, including: coal (S₂²⁻); copper and lead smelter particulates (S²⁻, SO₃²⁻, SO₄²⁻); deep-sea ferromanganese nodules (S⁰); and geologic materials (S²⁻, SO₄²⁻).