Rapid and Sensitive Determination of Available Phosphorus in Soil by Capillary Electrophoresis with On-line Preconcentration and Contactless Conductivity Detection

KeyWord:contactless conductivity detection  ?field-amplified sample injection  ?on-line preconcentration  ?capillary electrophoresis  ?available phosphorus  ?soil

Abstract:

      A new method for the rapid separation and sensitive determination of available phosphorus in soil by capillary electrophoresis£¨CE£© with field-amplified sample injection£¨FASI£© and capactively coupled contactless conductivity detection£¨C4D£© was developed£®Parameters affecting the CE separation and FASI efficiency were investigated in detail£¬including the composition and pH value of running buffer solution£¬separation voltage£¬sample injection voltage and time£®The analyte was well separated and sensitively detected within 8 min in a fused-silica capillary under the optimum conditions of 35 mmol/L acetic acid - 2 mmol/L ammonium acetate as running buffer£¬with separation voltage of £­14 kV£¬electrokinetic injection of £­11 kV ¡Á 10 s£®The calibration curve showed good linearity in the range of 16£­800 ¦Ìg/L£¬with a limit of detection of 5 ¦Ìg/L£®As a result£¬FASI showed significant increase of sensitivity with an enhancement factor of 580£®The intra- and inter-relative standard deviations£¨RSD£© were below 5.0%£®The co-existed inorganic anion£¨Cl£­£¬SO2?442-£¬NO?33-£© and organic acid did not interfere with the detection of available phosphorus in soil£®Contents of available phosphorus in soil samples could be easily determined without complex sample pretreatment£®This proposed method could meet the requirements for the fast screening and sensitive detection of available phosphorus in soil samples£®