Synthesis of MoO3- x nanosheets and its application in ascorbic acid detection of fruit and vegetables

A new method combining ultraviolet (UV) spectrophotometry and MoO_{3- x} nanosheets was developed for the rapid and accurate determination of ascorbic acid (AA) content in fruit and vegetables in this study. MoO_{3- x} nanosheets were prepared by the liquid exfoliation method using AA as the reducing agent, and the content of AA can be determined by a UV spectrophotometer. Experimental conditions for the MoO_{3- x} nanosheet method, including grinding time, ethanol concentration, sonication time, and water bath temperature were also optimized. The morphology of MoO_{3- x} nanosheets was characterized by atomic force microscope. The results showed that the average thickness of MoO_{3- x} nanosheets was 2.1-5.8 nm. The MoO_{3- x} nanosheets method had a good linearity in the AA concentration range of 0.01-0.05 mg/ml (R²  = 0.9996). The limit of detection was 0.031 µg/ml, and the limit of quantitation was 0.095 µg/ml. The spiked recoveries were in the range of 88.79%-116.76%. The MoO_{3- x} nanosheets method was validated for the determination of AA content in five different fruit and vegetables samples with relative standard deviations less than 2%.