The herbicide 2,4-D is being analyzed in plant matter usingtriphenylphosphate (TPP) as an internal standard. A calibrationsample is prepared by pipetting 10.0 µL of 119 µg/mL 2,4-D and 10.0µL of 100 µg/mL TPP into 1.00 mL of acetonitrile (ACN). (Hint: Whatis the total volume?) Separation by HPLC gave the peaks shown inthe table below. The sample was analyzed by homogenizing 5.196 g ofplant material and extracting the 2,4-D into 2.4 mL of ACN. 10.0 µLof 100 µg/mL TPP was added to the ACN extract before HPLC gave thepeak areas shown below.
Peak Areas   2,4-DTPP
Calibration Solution 28685 Â Â 15865
Plant Extract   2217   5816
Calculate the concentration of 2,4-D in the plant material inunits of ng/g (ppb).
ng/g
