Semiconductor gas sensors using metal oxides, carbon nanotubes, graphene-based materials, and metal chalcogenides have been reviewed from the viewpoint of the sensitive, selective, and reliable detection of exhaled biomarker gases, and perspectives/strategies to realize breath analysis on a chip for disease diagnosis are discussed based on the concurrent design of high-performance sensing materials and miniaturized pretreatment components. Carbon-based sensing materials that show relatively high responses to NO and NH3 at low or mildly raised temperatures can be applied to the diagnosis of asthma and renal disease. Halitosis can be diagnosed by employing sensing or additive materials such as CuO and Mo that have high chemical affinities for H2S, while catalyst-loaded metal oxide nanostructure sensors or their arrays have been used to diagnose diabetes via the selective detection of acetone or by pattern recognition of sensor signals. For the ultimate miniaturization of a breath-analysis system into a tiny chip, preconditioning that includes preconcentration, dehumidification, and flow sensing needs to be either improved through the design of gas/moisture adsorbents or removed/simplified through the design of highly sensitive sensing materials that are less impervious to interference from humidity and temperature. Moreover, an abundant sensing library needs to be provided for the diagnosis of diseases (e.g. lung cancer) that are associated with multiple biomarker gases and for finding new methods to diagnose other diseases. For this aim, p-type oxide semiconductors with high catalytic activities, as well as combinatorial approaches, can be considered for the development of sensing materials that detect less-reactive large molecules, and high-throughput screening, respectively. Selectivity for a specific biomarker gas will simplify the system further. Breath analysis on a tiny chip using semiconductor chemiresistors with ultralow power consumption that is connected to the ‘Internet of Things’ will pave new roads for disease diagnosis and patient monitoring.

Toward breath analysis on a chip for disease diagnosis using semiconductor-based chemiresistors: recent progress and future perspectives

https://iopscience.iop.org/article/10.1149/1945-7111/ab729c/pdf

Editors’ Choice—Critical Review—A Critical Review of Solid State Gas Sensors

Crowd-sourced air quality studies: A review of the literature & portable sensors

Among a number of gas analyzers, portable gas chromatography (GC) systems created by the integration of microfabricated components are promising candidates for rapid and on-site analysis of a number of complex chemical mixtures. This Feature provides a snapshot of the progress made in developing micro gas chromatography (μGC) systems in the last 4 decades. In particular, we discuss the development of microfabricated preconcentrators, separation columns, and detectors. Furthermore, we review different stationary phase materials used to coat the separation columns and the major efforts toward the development of an integrated μGC.

Micro Gas Chromatography: An Overview of Critical Components and Their Integration

Liquid chromatography (LC) based techniques in combination with mass spectrometry (MS) detection have had a large impact on the development of new pharmaceuticals in the past decades. Continuous improvements in mass spectrometry and interface technologies, combined with advanced liquid chromatographic techniques for high-throughput qualitative and quantitative analysis, have resulted in a wider scope of applications in the pharmaceutical field. LC-MS tools are increasingly used to analyze pharmaceuticals across a variety of stages in their discovery and development. These stages include drug discovery, product characterization, metabolism studies (in vitro and in vivo) and the identification of impurities and degradation products. The increase in LC-MS applications has been enormous, with retention times and molecular weights (and related fragmentation patterns) emerging as crucial analytical features in the drug development process. The goal of this review is to give an overview of the main developments in LC-MS based techniques for the analysis of small pharmaceutical molecules in the last decade and give a perspective on future trends in LC-MS in the pharmaceutical field.

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Current developments in LC-MS for pharmaceutical analysis.

In recent years, the need for measurement and detection of samples in situ or with very small volume and low concentration (low and sub-parts per billion) is a cause for miniaturizing systems via microelectromechanical system (MEMS) technology. Gas chromatography (GC) is a common technique that is widely used for separating and measuring semi-volatile and volatile compounds. Conventional GCs are bulky and cannot be used for in situ analysis, hence in the past decades many studies have been reported with the aim of designing and developing chip-based GC. The focus of this review is to follow and investigate the development and the achievements in the field of chip-based GC and its components from the beginning up to the present.

Through the years with on-a-chip gas chromatography: a review

Miniaturization of liquid chromatography (LC) is at the leading edge of the research topics and offers a wide range of applications in chemistry, biology, pharmaceutical, clinical diagnosis, and food analysis. The state-of-the-art “lab-on-chip” or “micro-total analysis systems” gathered scientists all over the world to provide systems with the aim of portability, reliability, reduced analysis time and cost of operation and analysis. From the hardware equipment point of view, the LC system is made by the primary compartments of solvent reservoir, pump, injector, column, and detector. In this work, we surveyed the development of LC systems and advances in each of the integrated components (i.e. pumping systems, injectors, separation channels, and detector) and the materials used for their fabrication from the beginning up to now. Finally, we summarize the application of fully integrated LC systems and exemplify about the multidimensional LCs on a chip development.

Towards fully integrated liquid chromatography on a chip: Evolution and evaluation

Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

Binding interaction of spherical silver nanoparticles and calf thymus DNA: Comprehensive multispectroscopic, molecular docking, and RAPD PCR studies

A sensitive, selective and simple method for the simultaneous determination of carvedilol enantiomers in aqueous solution has been developed using stir bar sorptive extraction (SBSE) followed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. This method is based on the reaction of carvedilol enantiomers with (-)-menthyl chloroformate (MCF) after extraction by the SBSE method to produce diastereomeric derivatives. The separation was achieved by use of a C18 analytical column and the influence of mobile phase composition on the enantioseparation of carvedilol was studied. The applicability of two sorptive phases, poly(methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane, were tested for extraction of carvedilol enantiomers from aqueous samples. The obtained results showed excellent linear dynamic ranges and precisions for each of them. The least limit of detection for (S)- and (R)-carvedilol obtained 8 and 11 µg L(-1), respectively, using the PA-EG sorptive phase. Inter- and intra-mean recoveries were also satisfactory, ranging from 98 to 103%, with coefficient of variation in the range of 1-5% at three fortified levels using a PA-EG coated stir bar. The proposed SBSE (PA-EG)-MCF derivatization-HPLC-UV method was successfully applied to enantioselective analysis of carvedilol in water and pharmaceutical dosages, confirming the application of this method.

Farideh Haghighi

Papers

Through the years with on-a-chip gas chromatography: a review

Towards fully integrated liquid chromatography on a chip: Evolution and evaluation

Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

Binding interaction of spherical silver nanoparticles and calf thymus DNA: Comprehensive multispectroscopic, molecular docking, and RAPD PCR studies

Determination of Carvedilol Enantiomers in Pharmaceutical Dosages by SBSE–HPLC Based on Diastereomer Formation