[A Facile Nanogold Surface Plasmon Resonance Absorption Method for CO Tracing].

The detection of gas pollutants in atmosphere and indoor air is very important to human health and safety. Monoxide carbon (CO) is a common gas pollutant with high toxicity that mainly comes from the inadequacy oxidization of carbon such as oil, coal and petrol inadequacy combustion, auto-gas and some natural disasters whose limit value in air is lower than 6.0 mg·m-3 in the national standard. Due to its toxicity and uneasy detection, it is one of very dangerous component in the silent killer. Recently, several methods, including infra-red absorption, gas chromatography, potentiometry, Hg replacement, spectrophotometry, I2O5 and PdCl2 nake-eye, semiconductor sensor have been reportedly used for the detection of CO. To our best knowledge, there are no SPR absorption methods for CO, based on the NG SPR absorption. In this paper, the reaction between CO and HAuCl4 was studied with absorption spectrophotometry and transmission electron microscopy (TEM)while a simple and rapid SPR absorption method was developed for the determination of trace CO. In pH 7.2 phosphate buffer solutions, monoxide carbon reduced HAuCl4 to form nanogold (NG) particles with the size of about 45 nm that exhibited surface plasmon resonance (SPR) absorption peak at 540 nm and three energy spectral peaks at 1.70 keV, 2.20 and 9.70 keV for gold element. The analytical conditions were examined, and a pH 7.2 phosphate buffer solution with a concentration of 40 mmoL·L-1 PO3-4, a concentration of 40.0 µg· mL-1 HAuCl4 and a reaction time of 5 min was selected for use. Under the selected conditions, the SPR absorption peak value was linear to CO concentration in the range of 0.2～8.75 µg· mL-1, with a detection limit of 0.1 µg· mL-1 CO. According to the procedure, the influence of coexistent substances on the determination of 1.0 mg·L-1 CO was tested, with a relative error of ±5%. Results indicated that 200 times SO2-3, PO3-4, SO2-4, CO2-3 and NO-3, 100 times Zn2+, K+, BrO-3, Na2S, ethanol, methanol, 80 times Ni2+, Cr3+, Co2+, Ca2+, Mg2+, Fe3+, glucose, Pb2+, Al3+, SeO2-3, Na2S2O3, formaldehyde, 50 times Mn2+ do not interfere with the determination. It showed that this SPR method had good selectivity. The CO content in air samples was determined with the SPR method, with a relative standard deviation (RSD) of 1.8%～4.2%, the SPR method results were agreement with that of the gas chromatography (GC).

[A Hydride Generation-Catalytic Resonance Rayleigh Scattering Method for Detection of Trace Arsenic].

Arsenic is a toxic metal element and the establishment of a highly sensitive and selective method for As has great significance to human health and environment protection. In sulfuric acid medium, As(Ⅲ) was reduced by NaBH4 to form AsH3 gas that was trapped by the Ce(Ⅳ)-I- catalytic absorption solution to cause Ce(Ⅳ) concentration decreased and As particle increased, which resulted in the resonance Rayleigh scattering (RRS) and fluorescence increased at 370 and 351 nm respectively. The increased RRS and fluorescence intensities were linear to As(Ⅲ) concentration in the range of 0.006~0.76 and 0.006~0.28 mg·L(-1) respectively, with a detection of As of 3.0 µg·L(-1). The new hydride generation-catalytic RRS method was applied for detection of trace As(Ⅲ) in milk samples, and the results were in agreement with that of hydride generation-atomic absorption spectrometry.

[Determination of Trace Boron Based on Gold Nanorod Plasmonic Resonance Rayleigh Scattering Energy Transfer to the Coordinate].

B is a necessary trace element for human and animals, but the excess intake of B caused poison. Thus, it is very important to determination of B in foods and water. The target of this study is development of a new, sensitive and selective resonance Rayleigh scattering energy transfer (RRS-ET) for the determination of B. The combination of energy transfer with resonance Rayleigh scattering (RRS) has developed a new technology called RRS-ET, which can realize selective and sensitive detection of boric acid. The gold nanorods in diameter of 12 nm and length of 37 nm were prepared by the seed growth procedure. In pH 5. 6 NH4 Ac-HAc buffer solution and in the presence of azomethine-H (AMH), the gold nanorod particles exhibited a strong resonance Rayleigh scattering (RRS) peak at 404 nm. In the presence of boric acid, it reacts with AMH to form AMH-boric acid (AMH-B) complexes. When the complexe as a receptor close to the gold nanorod as a donor, the resonance Rayleigh scattering energy transfer (RRS-ET) take placed that resulted in the Rayleigh scattering signal quenching. With the increase of the concentration of boric acid, the formed complexes increased, the scattering light energy of gold nanorod transfer to the complexes increased, resulting in the Rayleigh scattering intensity linearly reduced at 404 nrn. The decreased RRS intensity responds linearly to the concentration of boron over 10~750 ng . mL-1 B, with a regress equation of ΔI404 nm =3. 53c+24 and a detection of 5 ng mL-1 B. The influence of coexistence substances on the RRS-ET determination of 2. 3 X 10(-7) mol . L-1 B was considered in details. Results showed that this new RRS-ET method is of high selectivity, that is, 4 X 10(-4) mol . L-1 Mn2+, Cd2+, Zn2+, Bi+, Na+, Al3+, glucose, Hg2+, IO3-, F-, SO(2-)3, SiO3-, NO3-, CIO4-, H2O2, mannitol, glycerol, and ethylene glycol, 4X 10(-5) mol . L-1 L-tyrosine, and 2 X 10(-4) mol . L-1 L-glutamic acid do not interfere with the determination. Based on this, a new sensitive, selective, simple and rapid RRS-ET method has been developed for the determination of trace boron in six mineral water samples that contain 24. 9, 29. 3, 57. 9, 59. 0, 84. 9, and 105. 1 ng . mL-1 B, with relative standard deviation of 1. 6%~ 4. 1% and recovery of 95. 61~9. 6%.

[Fluorescence Determination of Trace Se with the Hydride-K13-Rhodamine 6G System].

Se is a necessary trace element for human and animals, but the excess intake of Se caused poison. Thus, it is very important to determination of Se in foods and water. The target of this study is development of a new, sensitive and selective hydride generation-molecular fluorescence method for the determination of Se. In 0. 36 mol . L-1 sulfuric acid, NaBH4 as reducing agent, Se (IV) is reduced to H2 Se. Usin3-g I solution as absorption liquid3, I- is reduced to I- by H2Se. When adding rhodamine 6G, Rhodamine 6G and I3- form association particles, which lead to the fluorescence intensity decreased. When Se(IV) existing, Rhodamine 6G and I3- bind less, And the remaining amount of Rhodamine 6G increase. So the fluorescence intensity is enhanced. The analytical conditions were optimized, a 0. 36 ml . L-1 H2SO4, 21. 6.g . L-1 NaBH4, 23.3 µm . L-1 rhodamine 6G, and 50 µmol . L-1 KI3 were chosen for use. When the excitation wavelength is at 480nm, the Rayleigh scattering peak does not affect the fluorescence recording, and was selected for determination of Se. Under the selected conditions, Se(IV) concentration in the 0. 02~0. 60 µg . mL-1 range and the increase value of the fluorescence intensity (ΔF) at 562 nm linear relationship. The linear regression equation is ΔF562 nm =12. 6c + 20. 9. The detecton limit was 0.01 µ.g . L-1. The influence of coexistence substances on the hydride generatin-molecular fluorescence determination of 5. 07 X10(-6) mol . L-1 Se(IV) was considered in details. Results showed that this new fluorescence method is of high selectivity, that is, 0. 5 mmol. L-1 Ba2+, Ca2+, Zn2+ and Fe3+, 0. 25 mmol . L-1 . Mg2+, 0. 05 mmol . L-1 K+, 0. 2 mmol . L-1 Al3+, 0. 025 mmol . L-1 Te(VI) do not interfere with the determination. The influence of Hg2+, CD2+ and Cu2+ that precipitate with Se(IV), can be eliminated by addition of complex reagent. This hydride generation-molecular fluorescence method has been applied to determination of trace Se in water samples,

[Resonance Rayleigh scattering determination of trace tobramycin using aptamer-modified nanogold as probe ].

Nanogold (NG) was prepared using NaBH4 reduction of HAuCl4. The NG was modified by the tobramycin-aptamer to obtain a stable Apt-NG probe for tobramycin. The three aptamers containing 15, 21 and 27 bases were examined, and results showed that the aptamer with 21 bases was best and was chosen for use. In pH 6. 8 PBS buffer solution and in the presence of NaCl, the Apt-GN probes were not aggregated. When tobramycin was added, it reacted with the Apt of Apt-NG probe to form a very stable Apt-Tbc complex and released NGs that were aggregated into big particles under the action of NaCl with three resonance Rayleigh scattering peaks at 285, 368 and 525 nm respectively. The resonance Rayleigh scattering peak increased at 368 nm due to the formation of big NG particles from the probe. The effect of pH buffer solution, its volume, and Apt-GN probe concentration on the ΔI value was considered. A 200 µL pH 6. 8 PBS buffer solution and 19. 1 nmol · L(-3) Apt-GN, giving max ΔI value, were chosen for use. Under the chosen conditions, the increased resonance Rayleigh scattering intensity ΔI368 nm was linear with Tbc concentration in the range of 1.9-58.3 ng mL(-3), with a regress equation of ΔI = 35.3c-23 and a detection limit of 0.8 ng · mL(-3) Tbc. A 10.0, 20.0 and 30.0 ng mL-3 Tbc was determined five times respectively, and the relative standard deviations were 6.8%, 5.0% and 4.4%. The influence of some foreign substances was examined on the determination of 38.9 ng · mL(-3) Tbc, within ±10% related error. Results showed that a 80 times of Zn2+, 40 times of L-glutamic acid, Cu2+, Mg2+ and Ca2+, 20 times of glucose and terramycin, 10 times of L-phenylalanine and glycin, 2 times of L-aspartic acid, and 6 times of bovine serum albumin (BSA) and human serum albumin (HSA) do not interfere with the RRS determination of Tbc. The results showed that this aptamer-nanogold RRS method is of good selectivity. Tbc in real sample was analyzed, and the analytical result was in agreement with that of reference results, with a relative standard deviation of 6.5%-7.6% and a recovery of 95.0%-107%.

[Resonance Rayleigh scattering determination of trace ozone based on the cationic surfactant association particles].

In the presence of pH 4.0 HAC-NaAC buffer solution, using H3BO3-KI (BKI) as absorption solution, O3 oxidized KI to produce I2, and it reacted with excess I- to form I3- that combined with the cationic surfactant (CS) such as cetylpyridinium chloride (CPCl), tetradecyl pyridinium bromide (TPB), cetyl trimethyl ammonium bromide (CTMAB), and tetradecyl dimethylbenzyl ammonium chloride (TDMAC) to produce stable (CS-I3)n association particles, which exhibited a strong resonance Rayleigh scattering (RRS) peak at 470 nm. Under the chosen conditions, as the concentration of O3 (C) increased, the concentration of I3- increased, and the RRS intensity at 470 nm (1470 nm) increased due to more association particles forming. The increased RRS intensity I470 nm was linear with O3 concentration. For the four CS systems, the linear range was 15-50, 50-100, 5-25 and 1-50 micromol x L(-1) O3 respectively. The regression equation is delta I = 8.81c-4.01, delta I = 5.44c-3.11, delta I = 15.39c-1.55, and delta I = 16.88c + 0.51. The detection limit is 4.9, 12, 2.85 and 0.56 micromol L(-1) O3 respectively. The influence of some foreign substances was examined on the determination of 2.5 x 10(6) mol x L(-1) O3, within +/- 10% relative error. Results showed that a 4.0 x 10(-5) mol x L(-1) Hg2+, 8.7 X 10(-5) mol x L(-1) Fe3+, 5.0 x 10(-5) mol x L(-1) Ca2+, 2.5 x 10(-5) mol L(-1) Zn2+ and Cu2+, 2.8 x 10(-6) mol x L(-1) Pb2+ and Cr3+, 4.2 x 10(-5) mol x L(-1) Mg2+, Mn2+ and Ba2+ do not interfere with the RRS determination. This showed that this RRS method is of good selectivity. The TDMAC system is most sensitive, and was chosen to detect O3 in air samples. The analytical results were in agreement with that of spectrophotometry results. Further more, laser scattering technique was utilized to examine the particle size distribution of (TDMAC-I3)n system. Results indicated that the particle size located in the range of 190-531 nm, in the absence of O3. Upon addition of O3, the excess KI reacted with O3 to produce I3-, and I3- interacted with the TDMAC to form (TDMAC-I3)n associated particles with a size range of 1,106-3,091 nm. This test identified that there are associated particles in the TDMAC system.

[Resonance scattering detection of trace Hg2+ using herring sperm DNA modified nanogold].

In pH 7.0 tris-HCl buffer solutions and in the presence of 0.017 mol x L(-1) NaCl, herring sperm DNA was combined with gold nanoparticles in size of 10 nm to form stable complex, and the NaCl did not cause the aggregation of the gold nanoparticles. Upon addition of Hg2+, that reacted with DNA to form more stable complex of Hg(2+)-DNA, and the gold nanoparticles aggregated to from larger nanogold clusters that led to considerable enhancement of the resonance scattering intensity at 572 nm enhanced considerably. The effect of GN concentration, DNA concentration, NaCl concentration, incubation time, and temperature, and ultrasonic irradiation was considered respectively, the conditions of 3.87 microg x mL(-1) GN, 11.7 microg x mL(-1) DNA, pH 7.0 Tris-HCl buffer solutions, 17 mmol x L(-1) NaCl, and incubation 10 min at 37 degrees C under the ultrasonic irradiation were chosen for use. Under the conditions, the enhanced resonance scattering intensity at 572 nm was linear to the Hg2+ concentration in the range of 3.3-3 333.3 nmol x L(-1), with regress equation of delta572 nm = 0.019c+5.0, coefficient of 0.999 1, and a detection limit of 2.5 nmol x L(-1) Hg2+. Results of interference tests showed that 30 micromol x L(-1) Mn2+, 33 micromol x L(-1) Mg2+ and Zn2+, 100 micromol x L(-1) Cd2+, 200 micromol x L(-1) Fe3+, and 420 micromol x L(-1) Mo6+, Pb2+ and Cu2+ did not interfered with the determination of 0.33 micromol x L(-1) Hg2+. That is, this resonance scattering spectral assay is of good selectivity. This assay was applied to the detection of Hg(II) in water sample, with a relative standard deviation of 5.1%, and the results were in agreement with that of the cool vapor atomic absorption spectrophotometry.