[Study of the Mn-doped ZnS quantum dots as the phosphorescence probes to detect the micro-quantity Hg2+].

In the present paper, the Mn-doped ZnS quantum dots were synthesized in water, and the MPA was used as the stabilizer. Utilizing the strong quenching effect of Hg2+ to the phosphorescence of the ZnS: Mn quantum dots, the method to detect micro-quantity Hg2+ in water was established by using the quantum dots as the phosphorescence probes. Compared to the fluorescence methods, the phosphorescence has longer lifetime and higher selectivity, and avoids the interference of the fluorescence and the scattering light. The result showed that under the optimum conditions, the relationship between the deltaP/P and Hg2 concentration was linearity which was ruled by the Stern-Volmer equation while the Hg2+ concentration was between 1.0 x 10(-5) and 1.0 x 10(-3) mol x L(-1), and the linear correlation coefficient was 0.998 8. The recovery of the method was between 85.2% and 106.1%, the RSD was 3.46%, and the detection limit was 9.7 x 10(-6) mol x L(-1). The mechanism of quenching of phosphorescence was discussed. The interferences of some metal ions could be effectively eliminated by adding appropriate masking agents in the solution.

[Study of CdTe quantum dots as fluorescence probe to detect trace amount of Pb2+].

The surface modified quantum dots (QDs) as fluorescence probe to quantitatively detect the Pb2+ in water phase was studied in the paper. Using the mercaptopropionic acid (MPA) as the stabilizer, the CdTe quantum dots were synthesized in water phase. Based on the quenching effect of the Pb2+ on the QDs fluorescence, the method for detecting trace Pb2+ using QDs as probe was established. The results showed that the relationship between the Pb2+ concentration and the quenching intensity of the QDs (Delta F) while the Pb2+ concentration ranged from 1.0 x 10(-8) to 1.0 x 10(-6) mol x L(-1) was fairly linear, and the correlation coefficient was 0.997 2. The detection limit was 9.3 x 10(-10) mol x L(-1). The RSD was 5.9%, and the recovery rate was between 86% and 110%. The study of the interference of the metal ions showed that the method was highly selective.

[Determination of trace elements hg and Rh in gelatin by inductively coupled plasma emission spectrometry--applying MSF model to improve the precision and detection limit].

Using ICP-AES, the method was developed to quantitatively determine the trace elements Hg and Rh in gelatin for the first time. The unknown samplers were processed with the wet digestion method. Multiple trace elements in gelatin could be quantitatively determined by ICP-AES at the same time. Applying the MSF model, the method to correct the spectral interference and the background was discussed. The result's precision and detection limit could be greatly improved by MSF model. The results of the experiment showed that the method features high accuracy, rapidity, high performance and a wide linear dynamic range, and the results were very satisfactory.

Silver nanoparticle-based ultrasensitive chemiluminescent detection of DNA hybridization and single-nucleotide polymorphisms.

A new nanoparticle-based chemiluminescent (CL) method has been developed for the ultrasensitive detection of DNA hybridization. The assay relies on a sandwich-type DNA hybridization in which the DNA targets are first hybridized to the captured oligonucleotide probes immobilized on polystyrene microwells and then the silver nanoparticles modified with alkylthiol-capped oligonucleotides are used as probes to monitor the presence of the specific target DNA. After being anchored on the hybrids, silver nanoparticles are dissolved to Ag+ in HNO3 solution and sensitively determined by a coupling CL reaction system (Ag+-Mn2+-K2S2O8-H3PO4-luminol). The combination of the remarkable sensitivity of the CL method with the large number of Ag+ released from each hybrid allows the detection of specific sequence DNA targets at levels as low as 5 fM. The sensitivity increases 6 orders of magnitude greater than that of the gold nanoparticle-based colorimetric method and is comparable to that of surface-enhanced Raman spectroscopy, which is one of the most sensitive detection approaches available to the nanoparticle-based detection for DNA hybridization. Moreover, the perfectly complementary DNA targets and the single-base mismatched DNA strands can be evidently differentiated through controlling the temperature, which indicates that the proposed CL assay offers great promise for single-nucleotide polymorphism analysis.

Selective determination of cysteine by resonance light scattering technique based on self-assembly of gold nanoparticles.

The interaction between cysteine and gold nanoparticles was studied. Through the covalent combination with the -SH group and the electrostatic binding with the -NH3+ group of cysteine, gold nanoparticles can self-assemble to form a network structure, which results in greatly enhanced resonance light scattering (RLS). The experimental results demonstrate that the RLS technique offers a sensitive tool for investigations of self-assembly of nanoparticles. On the other hand, the RLS method can be applied to selectively determine cysteine with high sensitivity and simple operation. The linear range of determination of cysteine is from 0.01 to 0.25 microg/mL with the detection limit of 2.0 ng/mL (16.5 nM, 3sigma). None of the amino acids found in proteins interferes with the determination.

[Quantitatively determining trace elements Co and Bi in gelatin by inductively coupled plasma atomic emission spectrometry method--applying IEC model to correct the spectral interference of Fe to Co].

By ICP-AES, the authors established the method to quantitatively determine the trace elements Co and Bi in gelatin. The authors processed the unknown sample with wet digesting method. Trace elements in gelatin could be quantitatively determined at the same time. To correct the spectral interference of Fe to Co at specific wavelength, the Interelement Correction(IEC) model was established. The results of the experiment showed that the IEC model could effectively erase the spectral interference of Fe to Co. The result of the spectral correction was greatly superior to the result where the spectral interference weren't corrected by the IEC model. The method was accurate, quick with high performance and wide linear range. The linear correlation coefficient of the tested elements was over 0.999 90. The relative standard deviation (RSD%) was less than 2.00%. The recovery rates were in the range of 98%-107%.

[Determination of micro-elements in couplers by inductively coupled plasma atomic emission spectrometry].

By ICP-AES, we established a method to quantitatively determine the micro-elements in couplers. We processed the unknown sample with wet digesting method. Nine micro-elements in the couplers can be quantitatively determined at the same time. Using the powerful chem.-station, we have discussed the method to eliminate physical interference and background correction. The results of the experiment showed that the method is accurate, quick, of high performance, and with all RSDs < or = 1.00%. The linear correlation coefficient of the tested elements is over 0.9999.