| In recent years,food poisoning incident and criminal cases related to phytotoxin occurred frequently,in which rapid and accurate qualitative identification is a prerequisite step for tracing the source of poisoning and taking correct treatment measures.However,standard methods are difficult to meet the needs of rapid detection in the fields of medical treatment and criminal identification because of the complexity and time-consuming of pre-processing.Therefore,it is of practical significance to develop and establish a high sensitivity,accurate,simple and rapid on-site analysis technology of phytotoxin in different matrixes related to food safety.In this study,two typical plant toxins,tropane alkaloids(TAs)and aconitines(ACs),were taken as examples to establish a rapid on-site analysis method of plant toxins based on surface enhanced Raman spectroscopy(SERS).The main work includes the following three parts:(1)One uniform,stable and reliable SERS substrate with high SERS activity was developed.By improving the conventional seed-growth method reduced by ascorbic acid,and optimizing the preparation of silver seeds and growth conditions,the Ag NPs with controllable size and good uniformity in the range of 50-150 nm were obtained.The relationship between the size of Ag NPs and the activity of SERS was systematically investigated.It was found that Ag NPs with the size of 100±10.0 nm had the best SERS activity.On this basis,by optimizing the preparation process,the batch difference of SERS enhanced performance could be controlled within 10.0%.After one year storage at 0～10 ℃,the SERS activity of Ag NPs is about 45.9%of the initial state,which shows that the particles have certain SERS stability.(2)The qualitative and quantitative analysis method of three typical TAs was established based on SERS technology.Firstly,by analyzing the interaction mechanism among SERS substrate,target molecule and aggregating agent in aqueous solution,the formation mechanism of "hot spot" with high SERS sensitivity was explored.Secondly,a rapid qualitative and semiquantitative analysis method of three TAs(scopolamine hydrobromide,methscopolamine bromide and scopolamine butylbromide)in foods was established based on SERS technology.Combining the position and relative strength of the characteristic peak,three TAs could be distinguished qualitatively,and the intensity of the specific peak could be used in semiquantitative analysis.The lowest detection concentrations of three TAs were 5.0,1.0 and 1.0 μg/L,and the linear ranges were 5.01000.0,1.0-1000.0 and 1.0-1000.0 μg/L,respectively.Without complex sample pretreatment,this method could realize rapid qualitative and quantitative analysis of TAs in different spiked food samples,such as drinking water,beverage,cooked food,etc.,and we explored the possible mechanism of simple dilution method effectively weakening matrix effect to improve the selectivity of SERS detection.On this basis,the rapid analysis of trace scopolamine hydrobromide in phenobarbital scopolamine tablets and compound scopolamine hydrobromide patch was successfully realized,which has the same quantitative analysis ability as the standard method.(3)The qualitative and quantitative analysis method of three typical ACs was established based on SERS technology.Firstly,by analyzing the SERS detection results of ACs,the formation mechanism of "hot spot" with high SERS sensitivity in(2)is further confirmed.Secondly,a rapid qualitative and semi quantitative analysis method of three ACs(aconitine,mesaconitine and hypaconitine)in food was established based on SERS technology.The intensity of characteristic peak could be used for semiquantitative analysis of total ACs.The lowest detection concentration of three ACs was 5.0 μg/L,and the linear range was 5.0-100.0μg/L.Without complex sample pretreatment,this method could achieve rapid qualitative and quantitative analysis of ACs in different spiked food samples,such as drinking water,beverage,cooked food,etc.,and realize rapid qualitative and quantitative analysis of TAs and ACs in different spiked samples. |
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