Detection of iron and copper ions based on gold nanorod etching colorimetry
In an acidic environment,Fe3+and Cu2+reacted with KI solution to oxidize I-to I2,and I2 was used to etch Au nanorods(AuNRs)to produce a blue shift of the longitudinal surface plasmon resonance(LSPR)absorption peak of AuNRs to achieve the detection of Fe3+and Cu2+.At a reaction temperature of 50 ℃,0.8 mL HCl(0.1 mol L-1),2 mL KI(20 mmol L-1),and 2 mL AuNRs solution were added in 2 mL 500 μmol·L-1 of Fe3+or 30 μmol·L-1 of Cu2+solution,and the Fe3+or Cu2+solution could etch AuNRs until the LSPR absorption peak of AuNRs disappeared af-ter 25 or 90 min.The concentrations of Fe3+and Cu2+had a good linear relationship with the LSPR absorption peak shift of AuNRs,and the R2 was above 0.99.This method has excellent selectivity and accuracy for the detection of Fe3+and Cu2+,with a maximum error of only 0.69％and 2.6％,respectively.For the detection of Fe3+and Cu2+coexis-tent system,the addition of an appropriate amount of F-in Fe3+solution to form a complex[FeF6]3-can chemically mask Fe3+,which can eliminate the interference of Fev in the coexistence system.The results showed that in a Cu2+concentration range of 0-20 μmol·L-1,the LSPR absorption peaks of AuNRs before and after the addition of Fe3+-F-masking system were blue-shifted 217 and 210 nm,respectively.There was a good linear relationship between the Cu2+concentration and the LSPR absorption peak shift of AuNRs,and the R2 was above 0.99.It can be concluded that the accurate detection of Cu2+in the mixed system can be achieved by chemically masking the Fe3+in the coex-isting ions.
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