In order to achieve accurate quantitation of drugs and metabolites (analytes) in complex matrices, 2H- (and less commonly 13C-) labeled analogues of the analytes are now routinely adapted as the internal standards (IS) using linear calibration models to fit data generated by selected ion monitoring gas chromatography-mass spectrometry (GC-MS) protocols. In this study, the effects of cross-contr...

Oscillating chemical reactions are complex nonlinear systems, which can exhibit different dynamic regimes such as regular and irregular oscillations, as well as chaos under different conditions. Such sorts of behavior in chemical and biological systems offer many choices for application to analytical chemistry. So far, regular oscillating profiles have been applied widely for the determination ...

Based on ultraviolet spectral net analyte signals, this research has studied the determination of the two effective components, sulfamethoxazole (SMZ) and trimethoprim (TMP), contained in compound sulfamethoxazole tablets in acid environment. The linear ranges of SMZ and TMP were 0.48-7.84 microg/ml (the regression correlation coefficient r = 0.9981) and 0.12-1.5 microg/ml (r = 0.9986), the cor...

We demonstrate a fluorescence lateral flow system that has excellent sensitivity and wide dynamic range. The illumination system utilizes an LED, plastic lenses and plastic and colored glass filters for the excitation and emission light. Images are collected on an iPhone 4. Several fluorescent dyes with long Stokes shifts were evaluated for their signal and nonspecific binding in lateral flow. ...

The levels of post-source metastable ion decay (PSD) observed in several peptides and proteins ionized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF-MS) are measured utilizing both infrared (IR) and ultraviolet (UV) desorption wavelengths. A gridless deceleration ion optic is employed to temporally separate stable analyte ions from analyte metastable...

In this work we evaluate the influence of thermal desorber temperature on the analytical response of a swipe-based thermal desorption ion mobility spectrometer (IMS) for detection of trace explosives. IMS response for several common high explosives ranging from 0.1 ng to 100 ng was measured over a thermal desorber temperature range from 60 °C to 280 °C. Most of the explosives examined demonstra...

We created an immunosensing platform for the detection of proteins in a buffer solution. Our sensing platform relies on graphene oxide (GO) nanosheets conjugated with antibodies to provide quantitative binding sites for analyte proteins. When analyte proteins and standard fluorescein-labelled proteins are competing for the binding sites, the assay exhibits quantitative fluorescence quenching by...

Two paper-based microfluidic techniques, photolithography and wax patterning, were investigated for their potential to improve upon the sensitivity, reproducibility, and versatility of paper spray mass spectrometry. The main limitation of photolithography was the significant signal (approximately three orders of magnitude) above background which was attributed to the chemicals used in the photo...

Optical Fibers Aptasensors fiber has attractive characteristics of fine diameter, soft texture, light weight, intrinsic safety and high biocompatibility, as reported by Ya-nan Zhang, Yong Zhao, co-workers in article 2300137. Specific aptamers modified the optical sensing region can specifically capture target analyte blood environment, such cytochrome C. This biological binding event cause chan...