{P<sub>4</sub>Mo<sub>6</sub>}-Based Complex Modified\nby Graphite Applied in Electrochemical Ultra-trace Detection of Nitro-antibiotics\nunder Strongly Acidic Conditions

The electrochemical analytical technology at the molecular\nlevel\nis of great importance for the successive and simultaneous determination\nof ultra-trace antibiotics. Herein, a complex constructed by the {P<sub>4</sub>Mo<sub>6</sub>} unit has been synthesized under the hydrothermal\ncondition with the formula [H<sub>2</sub>(3-AP)]<sub>6</sub>{Co[Mo<sub>6</sub>O<sub>12</sub>(OH)<sub>3</sub>(HPO<sub>4</sub>)<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>]<sub>2</sub>} (3-AP = 3-ammethylpyridine)\n(<b>1</b>). Complex <b>1</b> was modified by different\nratios of graphite powder (GP) to produce the <b>1</b>/GP composites\nvia a physical method. The results showed that the optimal ratio of <b>1</b> to GP is 1:2.6, which was denoted as the <b>1</b>/GP-2.6\ncomposite. The <b>1</b>/GP-2.6 composite as a superior electrochemical\nsensor has achieved the ultra-trace electrochemical detection of metronidazole\n(MDZ), dimetronidazole (DTZ), nitrofurantoin (NFT), and nitrofurazone\n(NFZ) under the best condition. Moreover, the <b>1</b>/GP-2.6\ncomposite demonstrated high sensitivity and anti-interference ability.\nIn addition, the possible electrochemical detection mechanism of four\nnitro-antibiotics has been analyzed.