Fully automated photocolorimetric method for dissolved silica in oil well water rich in sulfide and bicarbonate.
A fully automated photocolorimetric method for dissolved silica in oil well water rich in sulfide and bicarbonate is proposed; the method is based on yellow silicomolybdic heteropolyacid. To eliminate the interference of sulfide a treatment with bromate is utilized. The analytical range is 1-30 mg L(-1); with the automatically performed dilution it extends up to 300 mg L(-1), RSD 5.5%.
Differentiation of colloidal and dissolved silica: analytical separation using spectrophotometry and inductively coupled plasma atomic emission spectrometry
Abstract A method is described that differentiates between solutions containing silica-dominated colloids and solutions that are essentially free of colloids. Suspensions of tuff particles were treated to remove colloids by centrifugation, filtration or both. Agreement of silica concentrations determined by inductively coupled plasma atomic emission spectrometry and by a spectrophotometric method was taken as an indication of colloid-free solutions. For two tuffs, centrifugation was effective for removing colloids. For the third, highly altered tuff, filtration was more effective for removing colloids.
Potentiometric system for the continuous determination of low levels of chloride in high-purity power station waters
An analytical system for the continuous determination of low levels of chloride (0–150 µg 1–1) in high-purity power station waters has been developed that is based on the potential of a silver-silver chloride electrode versus a mercury-mercury(I) sulphate reference electrode, the electrodes being immersed in a buffered sample stream. The temperature of the electrode flow cell is controlled at 10 (±0.1)°C, at which level the sensitivity of 3.54 mV per 100 µg 1–1 is approximately 50% greater than that at 25 (±0.1)°C, and a linear response to changes in chloride concentration is observed over the range 0–150 µg 1–1. The standard deviations at 10 °C for nominal chloride concentrations of 50, 100 and 150 µg 1–1 are ±1.7, ±2.8 and ±2.8 µg 1–1, respectively. Substances normally present in these waters do not interfere appreciably.