Yunrui Huang

Development of micro-solid phase extraction with titanate nanotube array modified by cetyltrimethylammonium bromide for sensitive determination of polycyclic aromatic hydrocarbons from environmental water samples

This paper described a simple and novel analytical technique for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. A micro-solid phase extraction (μ-SPE) was developed utilizing cetyltrimethylammonium bromide modified ordered TiO(2) nanotube array. The experimental results indicated that modified TiO(2) nanotube arrays demonstrated an excellent merit on the preconcentration of PAHs, and there were excellent linear relationships between peak area and the concentration of PAHs in the range of 0.2-100 μg L(-1) and 1.0-100 μg L(-1), respectively. The detection limits of proposed method for the targeted PAHs were in the range of 0.026-0.82 μg L(-1) (S/N = 3). The real-world environmental water samples were used to validate the applicability of the proposed method and good spiked recoveries were in the range of 75.0-114%. All these results demonstrated that this new μ-SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples.

Investigation of the applicability of highly ordered TiO2 nanotube array for enrichment and determination of polychlorinated biphenyls at trace level in environmental water samples

Present study investigated the applicability of ordered TiO(2) nanotube arrays for the enrichment and determination of polychlorinated biphenyls (PCBs) in water samples. A new and reliable method was developed for the preconcentration and determination of PCBs by micro-solid phase equilibrium extraction in combination with gas chromatography and electron capture detection (GC-ECD), which exploited the special physical and chemical properties of ordered TiO(2) nanotube arrays. The experimental results indicated that low LODs were easily achieved in the range of 0.02-0.10 μg L(-1) for PCB-28, PCB-52, PCB-101, PCB-153, PCB-138, and PCB-180. The proposed method was validated with several real water samples, and good spiked recoveries have been obtained in the range of 95.8-110.5%. The experimental results demonstrated that TiO(2) nanotube arrays could be reused for over 200 times without the lost of the extraction efficiency. All these showed that TiO(2) nanotube arrays would be very useful in the enrichment and determination of trace pollutants.

Development of sensitive determination method for fungicides from environmental water samples with Titanate nanotube array micro-solid phase extraction prior to high performance liquid chromatography

Fungicides have been widely used throughout the world, and the resulted pollution has absorbed great attention in recent years. Present study described an effective measurement technique for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil and tebuconazole in environmental water samples. A micro-solid phase extraction (μSPE) was developed utilizing ordered TiO(2) nanotube array for determination of target fungicides prior to a high performance liquid chromatography (HPLC). The experimental results indicated that TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of fungicides, and excellent linear relationship between peak area and the concentration of fungicides was obtained in the range of 0.1-50 μg L(-1). The detection limits for the targeted fungicides were in the range of 0.016-0.086 μg L(-1) (S/N=3). Four real environmental water samples were used to validate the applicability of the proposed method, and good spiked recoveries in the range of 73.9-114% were achieved. A comparison of present method with conventional solid phase extraction was made and the results exhibited that proposed method resulted in better recoveries. The results demonstrated that this μ-SPE technique was a viable alternative for the analysis of fungicides in complex samples.

Determination of trace organophosphorus pesticides in water samples with TiO2 nanotubes cartridge prior to GC-flame photometric detection.

This article described a new method for the sensitive determination of organophosphorus pesticides in water samples using SPE in combination with GC-flame photometric detection. In the procedure of method development, TiO(2) nanotubes were used as SPE adsorbents for the enrichment of organophosphorus pesticides from water samples. Several factors, such as eluent and its volume, sample pH, sample volume, sample flow rate, and concentration of humic acid, were optimized. Under the optimal conditions, the proposed method had good linear ranges as 0.1-40 microg/L for each of them, LOD of 0.11, 0.014, and 0.0025 microg/L, and LOQs of 0.37, 0.047, and 0.0083 microg/L for chlorpyrifos, phorate, and methyl parathion, respectively. The proposed method was validated with real environmental water samples and the spiked recoveries were over the range of 86.5-115.1%. All these results indicated that TiO(2) nanotubes, as a new SPE adsorbent, would be used widespread for the preconcentration and determination of environmental pollutants in the future.

Analysis of benzoylurea insecticides in water samples with TiO2 nanotube array micro-solid phase extraction coupled to high performance liquid chromatography

A rapid, easy to operate, and sensitive method was developed for the trace determination of benzoylurea insecticides based on a micro-solid phase extraction with highly ordered TiO2 nanotube arrays as the adsorbent prior to high performance liquid chromatography. The experimental results indicated that a good linear relationship was achieved between the peak areas and the concentrations of benzoylurea insecticides in the range of 0.1–40 μg L−1. The limits of detection (LODs) of diflubenzuron, chlorbenzuron, triflumuron and chlorfluazuron were 0.082, 0.026, 0.049 and 0.076 μg L−1, respectively. The proposed method was successfully used to determine the benzoylurea insecticides in environmental water samples. The spiked recoveries in the range of 76.5–102.4% were achieved. All these results demonstrated that the proposed method was of great value and would have great potential in the enrichment and determination of trace pollutants in the future.

Enrichment and analysis of typically persistent organic pollutants at trace level using micro-solid phase extraction based on titanium dioxide nanotube arrays

In present study, a micro-solid phase extraction with highly ordered titanium dioxide nanotube arrays as the adsorbent was developed for the enrichment and determination of eight persistent organic pollutants including heptachlor, heptachlor-epoxide, α-endosulfan, dieldrin, endrin, β-endosulfan, endosulfan sulfate and methoxychlor. The optimal conditions were as follows: elutant solvent, dichloromethane; cetyltrimethyl ammonium bromide (CTAB), 900 μL; extraction time, 40 min; desorption time, 5 min: sample pH, pH 7. The results showed that eight target persistent organic pollutants were successfully enriched and good limits of detection in the range of 0.018–0.19 μg L−1 were achieved. The precision of the proposed method was in the range 4.6–8.5% (RSD, n = 6). Analysis of genuine environmental water samples resulted in good spiked recoveries in the range of 75.1–107%. Based on these results, the titanium dioxide nanotube array demonstrated its advantages for enrichment and separation, and we predict it will be of great value in the development of new preconcentration and determination methods for other pollutants.

TiO2 nanotube array micro-solid phase equilibrium extraction for the determination of bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol at trace levels with high-performance liquid chromatography

This paper reports on research to establish a micro-solid phase equilibrium extraction using a highly ordered titanium dioxide (TiO2) nanotube array for the pre-concentration and determination of environmental endocrine disruptors. The analysis was performed using high-performance liquid chromatography (HPLC) with fluorescence and ultraviolet detection. The experimental results showed that method detection limits (MDL) with fluorescence detection were 0.012, 0.033, 0.036 μg L−1 and MDL with ultraviolet detection were 0.022, 0.049, 0.093 μg L−1 for bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol, respectively. The proposed method was successfully applied to the analysis of the target compounds in several environmental water samples. Good spiked recoveries in the range of 75.4–103.4% and 74.8–106.2% were obtained by using HPLC with fluorescence and ultraviolet detectors, respectively. These results showed that TiO2 nanotube arrays would be useful in the enrichment and determination of trace pollutants.