Rapid Determination of Enoxacin in Herba Houttuyniae Injection by Surface-Enhanced Raman Spectroscopy with Silver Nanosol
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Graphical Abstract
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Abstract
Using the self-made silver nanosol as the substrate, the method for rapid determination of enoxacin in Herba Houttuyniae injection by surface-enhanced Raman spectroscopy with silver nanosol was proposed. 1 mL of 1% (mass fraction) silver nitrate solution was taken and placed in a beaker, and 200 mL of water was added. The mixture was mixed at a rotational speed of 8 000 r·min−1 and heated to boiling. 9 mL of 1% (mass fraction) sodium citrate solution was added dropwise until the solution turned yellow, and the heating was stopped until the solution turned milky white. The solution was cooled to room temperature, and centrifuged at a rotational speed of 3 000 r·min−1 for 1 min. The upper solution (40 mL) was collected into the centrifuge tube, and 5 mL of water was added. The solution was centrifuged at a rotational speed of 5 000 r·min−1 for 5 min, and the supernatant was discarded. 5 mL of water was added, and the mixture was ultrasonic treated for 5 min. The resulting silver nanosol was stored at 4 ℃. The 0.2 mL of sample was taken, and 0.1 mL of silver nanosol was added. The mixture was detected within 200-3 200 cm−1 using Raman spectrometer. As shown by the results, linear relationship between the corresponding response intensity at Raman shift of 1 469 cm−1 and mass concentration of enoxacin was found in the range of 0.5-100 mg·L−1, with detection limit (3S/N) of 0.043 mg·L−1. Test for recovery was made on blank sample by standard addition method at 3 concentration levels, giving results in the range of 86.1%-103%, with RSDs (n=5) of the determined values in the range of 3.0%-5.7%.
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