Rapid Detection Of Trace Lead And Mercury In Sea Cucumber By Stripping Voltammetry

Sea cucumber?Stichopus japonicus?represent a healthy food choice for consumers,which is known for its nutraceutical and nutritional values.It ingest the sediment to extract organic matter and microorganisms.Because of its feeding behavior,it is easily exposed to heavy metals in the sediment.In that way,heavy metals could exert deleterious effects on animal and human health through being inevitably accumulated in food chain,especially Pb and Hg.Therefore,the determination of Pb and Hg in sea cucumber has practical significance for food safety.Electrochemical detection technology is widely used in the analysis and detection of heavy metals due to its advantages such as portable equipment,low price,fast analysis and so on.In this study,the parameters of microwave digestion were optimized by orthogonal design.Secondly two kinds of electrochemical sensors,?-CD/RGO/GCE and Ploy-T/NPG/AuE,were prepared.The methods for measuring Pb and Hg in sea cucumbers using the two sensors were developed by differential pulse adsorption stripping voltammetry.Finally the Pb and Hg in the dried sea cucumbers from A,B,C and D were analyzed.Combined with the map system,a visualization database of heavy metal in sea cucumber was established.The main contents are as follows:?1?Optimization of determination conditions of Pb and Hg in microwave-digested sea cucumber by orthogonal design.The pretreatment process of sea cucumbers is easy to produce errors,and has a great influence on the accuracy of the detection results.Therefore,recovery rate as an index to optimize the microwave digestion parameters,and the accuracy and recovery rate of the method are verified.The results showed that the optimal conditions for microwave digestion were control temperature 190°C,constant temperature time 25 min,the digesting agent ratio?nitric acid/hydrogen peroxide?6:1 and the pre-digestion time 10 h.The recovery rates of Pb and Hg were in range of 95.40⁹8.50%and 96.00¹00.10%with RSD of 2.02%and 4.60%,respectively.Proves that the method sensitivity has high detection sensitivity and reliable results.?2?Determination of Pb in sea cucumber by?-CD/RGO/GCE.Deprotonated?-CD could specifically adsorb Pb²⁺at pH of 10.0¹1.5,enhancing the selectivity of the sensor.According to this principle,RGO is modified on the surface of GCE by electro-reduction,and?-CD is electro-polymerized on the surface of RGO/GCE,to prepare electrochemical sensor?-CD/RGO/GCE.The Pb was quantitatively analyzed by differential pulse adsorption stripping voltammetry.The results showed that the linear range of?-CD/RGO/GCE was 1⁶0?g/L with the detection limit of 0.037?g/L.Finally,it was applied to the determination of Pb in sea cucumber.The relative error between the obtained test results and ICP-MS was less than 5%,and its anti-interference performance was good.The sample recovery rate was 95.83%¹02.79%.?3?Determination of Hg in sea cucumber by functional porous nano-gold materials based on T-Hg²⁺-T structure.Excellent electrochemical properties of 3-D porous nanogold and specific complexation of thymine with Hg²⁺.Based on this principle,NPG is prepared on the surface of AuE by the hydrogen bubble template method,and the aptamer Ploy-T was self-assembled on the surface of NPG/AuE,to prepare electrochemical sensor Ploy-T/NPG/AuE.Hg was determined by differential pulse adsorption stripping voltammetry.The results showed that the linear range of Ploy-T/NPG/AuE was 0.5³0?g/L with the detection limit of 0.021?g/L.Finally,it was applied to the determination of Hg in sea cucumber.The relative error between the obtained test results and ICP-MS was less than 5%,and its anti-interference performance was good.and the sample recovery rate was 95.56%¹01.73%.?4?Determination of Pb and Hg in sea cucumbers obtain from different producing areas by stripping voltammetry and.development of visual database.The prepared modified electrode combined with adsorptive stripping voltammetry was used to determine Pb and Hg in sea cucumbers from A,B,C,D.The results showed that the Pb and Hg contents in some samples exceeded the national standard and posed a threat to the safety and health of food.Then a visualization database of heavy metal content in sea cucumber was developed,which can visually display the metal element types and contents in sea cucumber samples at the collection location,so that consumers can understand the content information.In summary,based on optimization of parameters in sea cucumber for microwave digestion and two kinds of electrochemical sensors including?-CD/RGO/GCE and Ploy-T/NPG/AuE,rapid and effective methods for Pb and Hg determination in sea cucumber were developed.Furthermore,visualization database of heavy metal in sea cucumber was constructed to further detection.Thus qualitative or quantitative detection of heavy metals in aquatic products can be realized.