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Two-color DNA microarray platforms are widely used for determining differential amounts of target sequences in parallel between sample pairs. However, the fluorescence (or Forster) resonance energy transfer (FRET) between two fluorophores can potentially result in the distortions of the measured fluorescence signals. Here we assessed the influence of FRET on the two-color DNA microarray platform and developed a reliable and convenient method for the correction of FRET distortion. Compared to current methods of normalization based on the statistical analysis and the hypothesis that only a small part of target sequences are differentially presented between sample pairs, our FRET correction method can recover the undistorted signals by the compensation of fluorescence emission, without considering the number of target sequences differentially presented. The correction method was validated with samples at different target ratios and with microarrays spotted in different probe concentrations. We also applied the FRET correction method to gene expression profiling arrays, and the results show that FRET was present when the content of target sequence was beyond a threshold amount and that the process incorporating our FRET correction method can improve the reliability of the gene expression profiling microarray platform in comparison with the current process without FRET correction. 10.1021/ac100804p

A gas sensor was developed by using the chemiluminescence (CL) emission from the oxidation of ethyl ether by oxygen in the air on the surface of borate glass. Theoretical calculation, together with experimental investigation, revealed the main CL reactions: ethyl ether is first oxidized to acetaldehyde and then to acetic acid, during which main luminous intermediates such as C[H.sub.3]C[O.sup.*] are generated and emit light with a peak at 493 nm. At a reaction temperature of 245 [degrees]C, the overall maximal emission was found at around 460 nm, and the linear range of the CL intensity versus the concentration of ethyl ether was 0.12-51.7 [micro]g [mL.sup.-1] (R = 0.999, n = 7) with a limit of detection (3[sigma]) of 0.04 [micro]g [mL.sup.- 1]. Interference from foreign substances including alcohol (methanol, ethanol and isopropanol), acetone, ethyl acetate, n-hexane, cyclohexane, dichloromethane, or ether (n-butyl ether, tetrahydrofuran, propylene oxide, isopropyl ether and methyl tert-butyl ether) was not significant except a minimal signal from n-butyl ether (

Atmospheric pressure dielectric barrier discharge (DBD) plasma can be used to split low molecular weight organic compounds, and the DBD-split/excited species can be swept into luminol solution to induce chemiluminescence (CL) emission. Based on this observation, a novel optical detector was proposed and preliminarily tested as a potential gas chromatographic (GC) detector in this work. The advantages of this new type of detector include the following: direct detection, fast response, high sensitivity, versatility (sensitive to a broad range of volatile organic compounds), simple and easy instrumentation, compactness (3.0 mm i.d. x 4.0 mm o.d. x 20 mm length of the DBD device), and low power (less than 5 W). Twelve volatile organic compounds, including methanol, ethanol, propanol, formaldehyde, acetaldehyde, benzene, dichloromethane, trichloromethane, tetrachloromethane, tetrahydrofuran, carbon bisulfide, and ethyl ether, were tested with this detector, and each of them produced a large signal. It was found that the CL signal was proportional to the analyte concentration and affected by the DBD parameters. Under the optimized experimental conditions, the limits of detection down to the tens of nanogram level were achieved for methanol, ethanol, propanol, formaldehyde, and acetaldehyde. It was then preliminarily tested as a GC detector for the separation of formaldehyde, ethanol, and propanol. This is the new application of DBD in analytical chemistry, and CL was for the first time generated in this way. The new detector can be a potential GC detector suitable for a wide range of volatile organic compounds.

This paper describes a novel hydride atomizer based on atmospheric pressure dielectric barrier discharge (DBD) plasma. The plasma was generated with a 3700-V, 20.3-kHz, and 5-W electrical power supply and easily sustained with inert gases (He or Ar) at a flow rate of 250 mL*min-1 after optimization. However, it cannot be sustained with [N.sub.2]. This atomizer offers the advantages of low operation temperature and low power consumption in comparison with the currently used electrothermal quartz atomization operated at 900 [degrees]C with a power supply of several hundred watts. To confirm the utility of the proposed atomizer, four arsenic species (As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA)) were determined by the present atomization technique. A hyphenation of HPLC coupled to hydride generation AAS with the optimized DBD atomizer has been successfully used for the speciation of arsenic in order to demonstrate the potential of this atomizer in the present study. The characteristics of the DBD atomizer and the effects of different parameters (discharge gas, gas flow rate, voltage, HC1 concentration, KB[H.sub.4] concentration) are discussed in the paper. Compared with other hydride atomization techniques, the proposed method shows the following features: (1) small size (70 mm X 15 mm X 5 mm), which is preferable for the miniaturization of the total analytical system; (2) low power consumption ([less than or equal to] 5 W), which indicates the possibility of the development of portable, fieldable analytical instrumentation for in situ detection using battery as power supply; (3) low atomizer temperature (~70 [degrees]C), which is in favor of the compactness of the total instruments; (4) avoidance of residue moisture removal in comparison with the existed GD system, which leads to the facility of the system. The analytical figures of the present technique were evaluated. The detection limits of As(III), As(V), MMA, and DMA obtained with HG-DBD-AAS were 1.0, 11.8, 2.0, and 18.0 [micro]g*[L.sup.-1], respectively. The accuracy of the system was verified by the determination of arsenic in reference material of orchard leaves SRM 1571. The concentration of As determined by the present method agreed well with the reference values. The speciation of arsenic in the freeze-dried urine SRM 2670 were carded out, and the results obtained were in agreement with the results of HPLC--ICPMS and the reported values by other laboratories.

A novel aerosol chemiluminescent (CL) detector coupling to capillary electrophoresis (CE) for the detection of saccharides is reported. This CL detector is composed of a postcapillary nebulizer and porous alumina as catalyzer in quartz tube. The CL emission could be generated due to the catalyzing oxidization of saccharides on the surface of porous alumina. The saccharides such as sucrose, a-lactose, maltose, raffinose, galactose, xylose, and glucose with only weak UV absorbance can be successfully detected. The linear ranges of those saccharides are from 30-2000 to 50-2000 mg/L; relative standard deviations range from 2.1 to 3.7% (200 mg/L, n = 11). Compared with the traditional UV detector currently used in CE, this novel detector shows the advantage of high sensitivity to the compounds with only weak UV absorption. Thus, it could be an important supplement of CE detectors for UV-lacking compounds.

This paper describes a novel aerosol chemiluminescence-based detector, which can be coupled to liquid chromatography for the determination of the chemicals with weak optical absorbance in the UV-visible region. This aerosol chemiluminescence (CL)-based detector, in which HPLC effluent is converted to aerosol and then generated CL emission on the surface of porous alumina, is composed of three main processes: nebuliztion of HPLC effluent, CL emission on surface of porous alumina material, and optical detection. To demonstrate the utility of the aerosol chemiluminescence detector, some compounds such saccharides, poly(ethylene glycol)s, amino acids, and steroid pharmaceuticals are determined by the present aerosol chemiluminescence detection method. Compared with an evaporative light scattering detector, the proposed detector shows the following features: (a) extensive CL emissions on porous alumina by many compounds tested, which leads to the potential application for the determination of volatile and nonvolatile chemicals with or without UV-visible absorbance; (b) a CL mechanism based on the catalytic oxidation of analytes, not on the light scattering, which suggests the present detector be free from the interference of the inorganic and nonvolatile mobile-phase modifiers. The CL characteristics and effect of different parameters, such as temperature and nebulizer gas flow rate, were also discussed in this paper. Furthermore, this aerosol chemiluminescence-based detector was successfully applied to the determination of raffinose, glucose, sucrose, maltose, and [alpha]-lactose.