Detection Of Chlorpheniramine In Chicken Manure And Its Effect On Soil Microbial Diversit

In this study,a rapid method was developed for the determination of robenidine residue in soil and the degradation characteristics of robenidine was investigated by simulating microcosm.Finally,the effects of robenidine on soil microorganisms and soil enzymes were studied by 16 S r RNA sequencing and soil enzyme activity assay.The determination of robenidine residue in chicken manure and muck was as follows: Robenidine in chicken manure was detected according to the method established by this research group in the previous period.Robenidine in muck was extracted using 2% EDTA water:2% formic acid acetonitrile(1:4,v/v),cleaned up with N-propyl ethylenediamine.Target analyte was detected by high performance liquid chromatography diode array detector with gradient elution using methanol and5 mmol/L aqueous ammonium acetate solution(containing 0.5% formic acid)as mobile phase.The methodological validation results show that the linear regression of the method is good,the detection limit was 0.06 μg/g and the quantification limit was0.20 μg/g.The average recoveries of robenidine in muck quantified by external standard method at three spiked levels of 0.20 μg/g,1.00 μg/g and 2.00 μg/g ranged from 92.21% to 94.73%,and the relative standard deviations within and between batches ranged from 2.2% to 4.5% and 4.0% to 5.1%,respectively.The method has good accuracy and precision.According to the excretion pattern of robenidine after feeding chickens,the degradation test of robenidine in soil was conducted at a low concentration of 40 μg/g and a high concentration of 400 μg/g excreted with manure 1d after drug withdrawal.The results showed a long degradation half-life of 14.74 d and 21.26 d,respectively.The 16 S rRNA sequencing results showed that soil bacterial species diversity and richness decreased with increasing robenidine concentrations,and the effect increased with time.The stress of robenidine significantly reduced the relative abundance of the major bacterial community Firmicutes(P < 0.01)and significantly increased the relative abundance of Proteobacteria(P < 0.05),resulting in a significant change in the soil bacterial community structure.At 8 mg/kg robenidine concentration in soil the abundance of harmful bacteria(Comamonadaceae)increased from 1.59% to 24.97%.However,the abundance of beneficial bacteria(Bacillaceae,Pseudograilibacillus,Arthrobacter and Gemmatimonas,etc.)decreased from 21.14%,21.47%,11.02% and 15.36% to 0.09%,0.07%,0.97% and 1.12%,respectively.Under the stress of robenidine,carbon and nitrogen cycling in the soil were inhibited by the changes of microorganisms.