Huang Xiao-Lan, Zhang Jia-Zhong
Ocean Chemistry Division, Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, FL 33149, USA.
Talanta. 2009 May 15;78(3):1129-35. doi: 10.1016/j.talanta.2009.01.029. Epub 2009 Jan 24.
A simplified, easily performed persulfate digestion method has been developed to process a large number of water samples for routine determination of total dissolved phosphorus. A neutral potassium persulfate solution (5%, w/v, pH approximately 6.5) is added to the samples (at 10 mg potassium persulfate per mL of sample), which are then digested at 90 degrees C in an oven for 16 h. This method does not require pH adjustment after digestion because neither an acid nor a base is added to the samples prior to digestion. The full color of phosphoantimonylmolybdenum blue from the digested samples develops within 8 min. Compared with the autoclave method, digestion at sub-boiling temperatures in an oven is safer, and a large number of samples can be heated overnight requiring no constant monitoring. The apparent molar absorptivity (epsilon) of nine organic phosphorus compounds and two condensed inorganic phosphates ranged from 1.17 x 10(4) to 1.82 x 10(4)L mol(-1)cm(-1) in both distilled water and artificial seawater matrixes. The average recovery of these phosphorus compounds was 94+/-11% for the DIW matrix and 90+/-12% for the ASW matrix. No significant difference in molar absorptivity was observed between the undigested and digested phosphate, especially in the seawater matrix. It is, therefore, suggested that a phosphate solution be directly employed without digestion as the calibration standard for routine determination of total dissolved phosphorus. This method was used to study the spatial distribution of total dissolved phosphorus in the surface waters of Florida Bay.
已开发出一种简化且易于操作的过硫酸盐消解方法，用于处理大量水样以常规测定总溶解磷。向样品中加入中性过硫酸钾溶液（5%，w/v，pH约为6.5）（每毫升样品加入10毫克过硫酸钾），然后在烘箱中于90℃消化16小时。该方法在消化后无需调节pH，因为在消化前未向样品中添加酸或碱。消化后样品中的磷锑钼蓝在8分钟内完全显色。与高压釜法相比，在烘箱中于低于沸点的温度下消化更安全，并且可以大量样品过夜加热，无需持续监测。在蒸馏水和人工海水基质中，9种有机磷化合物和2种缩合无机磷酸盐的表观摩尔吸光系数（ε）范围为1.17×10⁴至1.82×10⁴L·mol⁻¹·cm⁻¹。这些磷化合物在去离子水基质中的平均回收率为94±11%，在人工海水基质中的平均回收率为90±12%。未消化和消化后的磷酸盐之间在摩尔吸光系数上未观察到显著差异，尤其是在海水基质中。因此，建议直接使用未经消化的磷酸盐溶液作为常规测定总溶解磷的校准标准。该方法用于研究佛罗里达湾表层水中总溶解磷的空间分布。
