Trace analysis of orthophosphates in seawater with solid phase extraction and spectrophotometry
Yuan, D. X.
Lin, Q. M.
- 海洋环境－已发表论文 
An ion pair compound of phosphomolybdenum blue (PMB) with cetyltrimethylammonium bromide ( CTMAB) can be extracted by solid phase extraction technique on C,8 column. Based on this, a novel method was established to determine trace orthophosphates in seawatei. Experimental parameters, including acid concentration of the eluant, the extracting flow rate, the reagent concentrations, the reaction time and temperature, were optimized. The effect, of salinity was also investigated. The results showed that PMB-CTMAB could be efficiently extracted, and the extraction was not influenced by the salinity within 25 and 45. Under the optimized conditions, using artificial seawater (35) as a matrix, the, linearity, the recovery and the detection limit of the proposed method were found to be 0. 18 to 4. 0 mu g/L P, 98.5% and 0. 05 mu g/L P, respectively. The RSDs ranged from 2. 7% to 5. 6% for the real seawater samples. Three seawater samples were analyzed with both the proposed method and magnesium hydroxide-induced coprecipitation ( MAGIC) method, and the results showed no significant difference with t test. The proposed method had the advantages of being more sensitive, faster and sampler saving.