| Malachite green（MG）is a typical kind of triphenylmethane dye,which has teratogenic,carcinogenic and mutagenic high toxicity as an illegal drug of aquaculture in China.Because it has significant inhibitory effect on the incidence of water mold,and it is still illegally applied by some farmers.During aquaculture,the dominant malachite green can enter the fish body and can be transformed into a leucomalachite green,which is more harmful to the human’s health than it’s former.In addition,histamine residue is one of the important food safety topic of aquatic food,when the human body ingests excessive histamine,it will cause allergic symptom,and even endanger human life.For the detection of malachite green and histamine level in aquatic product,high performance liquid chromatography,liquid chromatography-mass spectrometry and ELISA protocols were established in the past decades.Although the above methods have the advantages of good analytical performance,however,these methods were characterized with cumbersome handling,dependence on complex instruments and high cost,which are not easily applied into rapid food safety detection.Therefore,based on thin-layer chromatography and read-out coloring materials,this paper developed rapid semi-quantitative method for the malachite green,histamine in aquatic products direct reading color semi-quantitative method.The specific research contents are as follows:（1）In order to realize the direct reading color development of TLC to detect the histamine content in aquatic products,in the histamine analysis chapter of this study,nano-material was firstly prepared based on the sol-gel method and the ninhydrin@titanium dioxide nanocomposite was printed on the TLC band to form a self-visualization zone,where is corresponding to the specific shift value（Rf）of histamine.The n-butanol:acetone:ammonia water development system was used to perform rapid thin-layer direct read-out visualization detection on the aquatic product extract,and the image strips were also analyzed by Image J software.The results showed that all amino acids and biogenic amines coexisted in histamine and aquatic products could be effectively separated under the optimized conditions.It is concluded that there is a clear linear correlation between histamine concentration and coloration grey depth（R2=0.98）,so it is reliable to use naked eye to evaluate.The method is established to the detection of histamine content in aquatic products,the linear range of detection is 37.5-1200 mg·kg-1,and the limit of detection is18.75mg·kg-1.In addition,the detection results were verified by HPLC method,and proved that the results were reliable.This paper provides useful reference for rapid detection of malachite green,it also provides a reference for further color analysis of other biogenic amines in aquatic products.（2）In order to establish a direct rapid read-out visualization detection and semi-quantitative method for malachite green based on TLC approach,nano-material was firstly prepared based on the sol-gel method and the potassium iodate@titanium dioxide nanocomposite was printed on the TLC band to form a self-visualization zone,where is corresponding to the specific shift value（Rf）of leucomalachite green.Furthermore,an acidic aqueous solution of potassium iodide was applied as a visualization supporting solution,and analysis was accomplished by the aid of Image J software.For the analysis of aquaculture water sample,the malachite green is firstly transformed into colorless leucomalachite green by using reducing agent,then a serials of visualization detection steps were described in this paper in detail.It is concluded that there is a clear linear correlation between the concentration of leucomalachite green and coloration grey depth（R2=0.99）.Thus,it is possible to use naked eye to evaluate,and even semi-quantitative direct read-out visualization detection of total malachite green in aquaculture water was realized.For aquaculture water,the linear range of detection is 2.5-160μg·L-1 with the limit of detection（LOD）is 1.6μg·L-1.For aquatic products,the linear range of detection is 5.0-320μg·kg-1,and the LOD is 3.2μg·kg-1.In addition,the analysis results were also verified by HPLC-MS method,proving the results were reliable.This paper provides useful reference for rapid detection of malachite green,and provides theoretical basis for direct read-out visualization analysis of other triphenylmethane dyes. |
