A simple and rapid on-line separation system for micro amounts of calcium and magnesium in salt was developed. The 8-quinolinol (OX)-loaded active carbon (AC) column selectively separated calcium and magnesium which were presented in salt from sodium chloride as the matrix. The pH of the sample solution was adjusted to 9.5 because calcium and magnesium were retained as OX-complex on the OX-loaded AC column in the pH 9 to 11 region. The OX-loaded AC column could not easily release OX, no matter what type of 2M acids were introduced to the column. The column is so excellent in durability that it can be used at least 1,000 times. The composition of the mobile phase for ion chromatography was 2.5mM of EDTA in 10% methanol. The detection limit was 0.60 ppm for calcium and 1.00 ppm for magnesium in solid salt sample, respectively. The time period required for simultaneous determination of calcium and magnesium was about 20 min. The procedure was successfully applied to the determination of calcium and magnesium ion in several commercially available salts. The proposed preconcentration and separation method for calcium and magnesium based on the OX-loaded AC column is slightly influenced by contamination because it is a closed system and has a good reproducibility.

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Solvent extraction was studied for the recovery of lithium from the wastewater of Li₂CO₃ precipitation. A kerosene solution containing α-perfluoroalkanoyl-m-dodecylacetophenone (XI51) and tri-n-butyl-phosphate (TBP) was used as the extracting reagent. A large synergistic effect was obtained for the Li extraction with the extracted species of Li (XI51)(2TBP). Lithium ions were quantitatively extracted in the pH range between 10 and 12.5, while the separation of lithium from the other alkali metal ions was best at pH 9.1. The lithium ions in the organic phase were back-extracted quantitatively by shaking for 40 min with a 1M HCl solution. The decrease in lithium extractability was slight by the seventh repetition of extraction and back-extraction. The recovery of lithium from the wastewater of Li₂CO₃ precipitation was 97% by double extraction with the extracting reagents, while the extractability of sodium was very low (1%).

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A flow-injection analysis (FIA) system is presented for simple and rapid determination of ammonia at sub-ppm levels in seawater and concentrated sodium chloride solution. The system consists of a direct on-line coupling of the gas diffusion separation using porous polytetrafluoroethylene (PTFE) membrane tubing and subsequent spectrophotometric detection of ammonia by the formation of indophenol blue dye with sodium hypochlorite and 1-naphthol in a continuous flow system. Sodium citrate added to the alkaline medium which is essential to convert ammonium ion to ammonia proved to be very effective in preventing magnesium and calcium in the seawater sample from precipitating in this FIA system, thus enabling the direct injection of seawater sample. No laborious complicated manual operation for separation and detection is required. The limit of detection was 0.008 ppb and satisfactory precision of 1% relative standard deviation was also obtained. The analytical readout is available within 6 min after sample injection.

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