The utility of qNMR to improve accuracy and precision of LC-MS bioanalysis

In LC-MS bioanalysis, samples and analytes are quantified against calibration solutions and curves which are derived via serial dilution from stock solutions that are prepared from dry reference standards. The analytical errors associated with the mass and volume measurements required for this preparation of stock solutions can culminate in a variance which might affect bioanalytical data accuracy. Especially in the case of extended studies with intermittent sample analysis, the multiple preparation of separate stock solutions can also adversely affect bioanalytical data precision. Discussed here is an illustrative case study where a single stock solution was utilized for a longitudinal study with multiple data points by means of an orthogonal and synergistic quality control via quantitative NMR methodology resulting in improved bioanalytical data

Terahertz split-ring metamaterials as transducers for chemical sensors based on conducting polymers: a feasibility study with sensing of acidic and basic gases using polyaniline chemosensitive layer

We report on the first application of terahertz metamaterials acting as transducers for chemical sensors based on conducting polymers. In our feasibility study aimed at sensing of gaseous hydrochloric and ammonia, a two-dimensional sensor metamaterial consisting of an array of split-ring resonators on the surface of undoped silicon wafer was prepared. The surface of the resonator was coated with a 150-μm layer of polyaniline. Binding of hydrogen chloride to polyaniline leads to distinct changes in the resonance frequency of the metamaterial. Measurements can be performed both in the reflection and transmission mode. A numerical simulation of the response revealed an increase of both the real and the imaginary components of the dielectric function of the polyaniline film. These changes are attributed to the transition from emaraldine base to emeraldine salt. The results demonstrate a new approach for formation of highly sensitive transducers for chemical sensors