The gas density balance in the Quantitative analysis of gas mixtures, without prior seperation of components : The determination of silica

When a gas mixture with a major component A which has a molecular weight considerably different from those of all other components (these being close together about a molecular weight of m) is introduced into the gas density balance with a carrier gas also of molecular weight m, the integral response of the gas density balance is essentially proportional to the amount of A in the sample and independent of the concentration ratios between all other components. The applicability of this principle is demonstrated in the determination of silicon tetrafluoride in mixtures with hydrogen fluoride and water, which were formed by reactions between silica, ammonium hydrogen fluoride and sulfuric acid. A direct determination of silica in solid samples containing 10–40 mg SiO2 is possible with a relative standard deviation of 2.5%.