Problem- A standard solution containing 2.00 mg/L of vitamin E fluoresces with 374 units. A sample solution of vitamin E fluoresces with 643 units. The sample solution is spiked with 4.00 mg/L of vitamin E and the resulting is spiked with 4.00 mg/L of vitamin E and the resulting mixture fluoresces with 1092 units.

1- What's the concentration of vitamin E in the sample as determinded by standard addition?

2- Was the standard addition procedure needed?

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