{P4Mo6}-Based Complex Modified by Graphite Applied in Electrochemical Ultra-trace Detection of Nitro-antibiotics under Strongly Acidic Conditions

The electrochemical analytical technology at the molecular level is of great importance for the successive and simultaneous determination of ultra-trace antibiotics. Herein, a complex constructed by the {P4Mo6} unit has been synthesized under the hydrothermal condition with the formula [H2(3-AP)]6{Co[Mo6O12(OH)3(HPO4)2(PO4)2]2} (3-AP = 3-ammethylpyridine) (1). Complex 1 was modified by different ratios of graphite powder (GP) to produce the 1/GP composites via a physical method. The results showed that the optimal ratio of 1 to GP is 1:2.6, which was denoted as the 1/GP-2.6 composite. The 1/GP-2.6 composite as a superior electrochemical sensor has achieved the ultra-trace electrochemical detection of metronidazole (MDZ), dimetronidazole (DTZ), nitrofurantoin (NFT), and nitrofurazone (NFZ) under the best condition. Moreover, the 1/GP-2.6 composite demonstrated high sensitivity and anti-interference ability. In addition, the possible electrochemical detection mechanism of four nitro-antibiotics has been analyzed.