抄録
The calcium carbonate coprecipitation method was studied for simplified determination of content of magnesium in cellulose fibers of cotton, ramie and rayon by flame atomic absorption spectrometry (F-AAS). All sample of cellulose fiber (about two grams) were dissolved with 200 ml of 70 % sulfuric acid, and 0.2-5 ml aliquots from sample solution were diluted to 100 ml with distilled water, following by adding dropwise of sodium hydroxide solution until the solution became neutralization by pH meter. A 15 ml of 8 gCa⁄l calcium chloride and 15 ml of 20 w⁄v% potassium carbonate were added to sample solution containing magnesium ion. Magnesium ion was quantitatively coprecipitated with calcium carbonate. The precipitate was collected onto a membrane filter (0.45 μm) and then dissolved with dipping for 15 min in 10 ml of HCl (1+11). The solution was made up to 100 ml with distilled water to prepare the sample solution for F-AAS. The detection limit for magnesium was 0.2 μg (3σ), and the lower limit of determination was 0.6 μg (10σ). This method was influenced neither neutralization of sulfuric acid nor coexistence materials (pectin, protein, ash, etc.) in fiber, and was satisfactorily applied to determine by F-AAS of magnesium ion in cellulose fiber. The removal rate of magnesium ion was ca. 50 % for scouring and bleaching yarn and ca. 90 % for acid treatment yarn based on raw cotton yarn.
