C NMR as an analytical tool for the detection of carbonic acid and pK determination.

NMR spectroscopy has become a standard technique in studies both on carbon capture and storage. C NMR allows the detection of two peaks for carbonated aqueous samples: one for CO and another one for the species H CO , HCO , and CO -herein collectively named H CO . The chemical shift of this second peak depends on the molar fraction of the three species in equilibrium and has been used to assess the equilibrium between HCO and CO .

Improving hydrodynamic injection in capillary electrophoresis by using the integral of pressure.

A careful analysis of the typical devices and conditions used during hydrodynamic injection in capillary electrophoresis shows that the Hagen-Poiseuille model for the laminar flow is valid, even during the transitions of pressure. Therefore, the monitoring of pressure becomes a reliable approach to evaluate the effective injected volume, because the volume is proportional to the integral of pressure (IoP) over time. A piezoresistive sensor was used to monitor the air pressure at headspace of the sample vial.

Qualitative and quantitative aspects of time-, charge-, and mobility-based electropherograms.

The migration process in capillary electrophoresis is obtained by using a high-voltage power supply, and the basic idea is to keep the control on the migration velocity of the analytes by controlling either the applied voltage or current. The effectiveness of this control has impact on the resulting electropherogram and, thus, in the identification and quantification of the analytes. Although the usual electropherogram is the record of the detector signal as a function of time, other two domains should be considered: charge and mobility.

Stability-indicating method development for quantification of bromopride, its impurities, and degradation products by ultra-high performance liquid chromatography applying Analytical Quality by Design principles.

A comprehensive forced degradation study for bromopride was carried out in accordance with International Conference on Harmonization (ICH) recommendations followed by the identification and prospecting of the major degradation products. The analytical quality by design (AQbD) concepts were used to develop a stability-indicating method for bromopride and five organic impurities quantitation by ultra-high performance liquid chromatography with UV detection (UHPLC-UV). Two screenings and one optimization design were performed, including a Monte Carlo simulation to assess the Method Operable Design Region (MODR).

Determination of primary aromatic amines from cooking utensils by capillary electrophoresis-tandem mass spectrometry.

This paper describes a fast, sensitive, environment-friendly method for the determination of 19 primary aromatic amines (PAAs) in cooking utensils by capillary zone electrophoresis coupled with tandem mass spectrometry. The best electrophoretic separation of PAAs was obtained in 0.1 mol l formic acid (pH 2.

Indirect calibration for capillary electrophoresis with conductivity detection.

There is a growing interest in conductivity detection for capillary electrophoresis; especially because of capacitively coupled contactless conductivity approach. This robust and general-purpose detector has another lesser-known feature: sensitivity does not depend on the very chemical nature of the analyte, but only on its effective charge and effective mobility. Therefore, the calibration curve prepared for a given species may be used to quantify another one of same charge and mobility.

Simulated microgravity accelerates aging in Saccharomyces cerevisiae.

The human body experiences physiological changes under microgravity environment that phenocopy aging on Earth. These changes include early onset osteoporosis, skeletal muscle atrophy, cardiac dysfunction, and immunosenescence, and such adaptations to the space environment may pose some risk to crewed missions to Mars. To investigate the effect of microgravity on aging, many model organisms have been used such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and mice.

A sensitive multiresidue method for the determination of pesticides in marijuana by liquid chromatography-tandem mass spectrometry.

A multiresidue method based on QuEChERS extraction followed liquid chromatography coupled with tandem mass spectrometry was developed and validated for the determination of 42 pesticides in marijuana. Less than 6 min is required for detection of all species. By using original QuEChERS, the sample preparation is also fast and simple.

Capillary electrophoresis with dual diode array detection and tandem mass spectrometry to access cardiovascular biomarkers candidates in human urine: Trimethylamine-N-Oxide and l-carnitine.

A capillary electrophoresis with diode array and tandem mass spectrometry detection (CE-UV-MS/MS) method has been developed for the targeted assessment of cardiovascular biomarkers candidates, trimethylamine-N-Oxide (TMAO) and l-carnitine, and creatinine in human urine samples. The dual detection was applied due to the high concentration of creatinine (monitored by UV detection at 200 nm) in relation to TMAO and l-carnitine (quantified by selected reaction monitoring (SRM) mass spectrometry), in human urine. All instrumental parameters, sheath liquid (SHL) and background electrolyte (BGE) compositions were optimized with a pool of urine provided by adult healthy volunteers and evaluated by signal-to-noise ratio (SNR) and peak shape of TMAO.

Application of capillary electrophoresis combined with conductometric and UV detection to monitor meteorite simulant bioleaching by Acidithiobacillus ferrooxidans.

The importance of microorganisms and biotechnology in space exploration and future planets colonization has been discussed in the literature. Meteorites are interesting samples to study microbe-mineral interaction focused on space exploration. The chemolithotropic bacterium Acidithiobacillus ferrooxidans has been used as model to understand the iron and sulfur oxidation.

Ultrafast capillary electrophoresis method for the simultaneous determination of ammonium and diphenhydramine in pharmaceutical samples.

Ammonium and diphenhydramine are active ingredients commonly found in the same pharmaceutical preparations. We report, for the first time, a sub-minute method for the simultaneous determination of ammonium and diphenhydramine. The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection.

Improving thermal control of capillary electrophoresis with mass spectrometry and capacitively coupled contactless conductivity detection by using 3D printed cartridges.

A 3D-printed cartridge was developed to improve the interface between a capillary electrophoresis instrument and a mass spectrometer. The thermostated airflow from the CE was guided to the entrance of the electrospray source keeping as much as possible the silica capillary in a proper Joule-heating dissipation environment. Hollow 3D-printed walls made of ABS covered by a 0.

Detection of coffee adulteration with soybean and corn by capillary electrophoresis-tandem mass spectrometry.

The detection of coffee adulteration with soybean and corn by capillary electrophoresis-tandem mass spectrometry was accomplished by evaluating the monosaccharides profile obtained after acid hydrolysis of the samples. The acid hydrolysis, using HSO as a catalyst, increases the ionic strength of the sample impairing the electrophoretic separation. Therefore, Ba(OH) was used to both neutralize the medium and reduce the content of sulfate by precipitation of BaSO.

Capillary electrophoresis tandem mass spectrometry determination of glutamic acid and homocysteine's metabolites: Potential biomarkers of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects both lower and upper motor neurons, leading to muscle atrophy, paralysis, and death caused by respiratory failure or infectious complications. Altered levels of homocysteine, cysteine, methionine, and glutamic acid have been observed in plasma of ALS patients. In this context, a method for determination of these potential biomarkers in plasma by capillary electrophoresis tandem mass spectrometry (CE-MS/MS) is proposed herein.

Amphetamine and derivatives in natural weight loss pills and dietary supplements by capillary electrophoresis-tandem mass spectrometry.

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for amphetamine (AM), phentermine (PTM), methamphetamine (MAM), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), and methylenedioxyethylamphetamine (MDEA) in commercial samples of homeopathic and phytotherapic medicines and dietary supplements is presented. The samples were submitted to a modified QuEChERS extraction procedure (at apparent pH 13) followed by electrophoretic separation in 0.1molL formic acid electrolyte (pH 2.

Fast analysis of terbutaline in pharmaceuticals using multi-walled nanotubes modified electrodes from recordable compact disc.

In this study, homemade disposable gold electrodes made from recordable compact disks were modified with carbon nanotubes for amperometric quantification of terbutaline sulfate in pharmaceutical products. A flow cell using an impingent jet of solution on the electrode surface was build and used for amperometric detection, and a series of experiments were carried out to find the best experimental conditions for the new electrode in a specially designed cell. A linear response for terbutaline was obtained in the range from 3.

A capillary electrophoresis system with dual capacitively coupled contactless conductivity detection and electrospray ionization tandem mass spectrometry.

A commercial system that is comprised of a CE coupled to an ESI triple quadrupole mass spectrometer was equipped with two capacitively coupled contactless conductivity detectors (C(4) Ds). The first C(4) D was positioned inside the original cartridge, and the second C(4) D was positioned as close as possible to the ESI probe entrance by using a 3D-printed support. The C(4) Ds electropherograms were matched to the ESI-MS electropherogram by correcting their timescales by the factor LT /LD , where LT and LD are the total capillary length and the length until the C(4) D, respectively.

Determination of biogenic amines in beer and wine by capillary electrophoresis-tandem mass spectrometry.

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.

Metalless electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips.

This paper describes the use of ionic solutions as sensing electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips. Initially, two channels were engraved in a PMMA holder by using a CO2 laser system and sealed with a thin adhesive membrane. PDMS electrophoresis chips were fabricated by soft lithography and reversibly sealed against the polymer membrane.

Determination of halosulfuron-methyl herbicide in sugarcane juice and tomato by capillary electrophoresis-tandem mass spectrometry.

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the determination of halosulfuron-methyl (HSU) residue in samples of sugarcane juice and tomato is introduced and validated. The samples were submitted to a QuEChERS extraction procedure followed by electrophoretic separation in NH4HCO3 electrolyte (adjusted to pH 8.5) and detection by electrospray-tandem mass spectrometry.

A simple approach to compensate the suction caused by the electrospray ionization source in capillary electrophoresis-mass spectrometry systems.

ESI sources continuously consume the liquid at the tip of the capillary, which causes the dragging of the BGE. The laminar nature of this flow causes the broadening of the peaks and loss of separation efficiency. The usual solution for this problem is to compensate this phenomenon by reducing the pressure at the inlet vial by either leveling of this vial or pumping off the air that is over it.

Ultra-fast determination of caffeine, dipyrone, and acetylsalicylic acid by capillary electrophoresis with capacitively coupled contactless conductivity detection and identification of degradation products.

Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) was used for fast, simultaneous determination of dipyrone (DIP), caffeine (CAF), and acetylsalicylic acid (ASA). In the same run and in less than 1min, the degradation products from DIP and ASA were also detected. In addition, the usage of the CE-C(4)D system allowed, for the first time, the detection of methylamine as a degradation product of DIP.

Miniaturized flow system based on enzyme modified PMMA microreactor for amperometric determination of glucose.

This paper describes the development of a microfluidic system having as main component an enzymatic reactor constituted by a microchannel assembled in poly(methyl methacrylate) (PMMA) substrate connected to an amperometric detector. A CO2 laser engraving machine was used to make the channels, which in sequence were thermally sealed. The internal surfaces of the microchannels were chemically modified with polyethyleneimine (PEI), which showed good effectiveness for the immobilization of the glucose oxidase enzyme using glutaraldehyde as crosslinking agent, producing a very effective microreactor for the detection of glucose.

Fast simultaneous determination of trimethoprim and sulfamethoxazole by capillary zone electrophoresis with capacitively coupled contactless conductivity detection.

The association of trimethoprim and sulfamethoxazole is a very effective with antibiotic properties, and commonly used in the treatment of a variety of infections. Due to the importance in diseases treatment of humans and also of animals, the development of methods for their quantification in commercial formulations is highly desirable. In the present study, a rapid method for simultaneous determination of these compounds using CE with capacitively coupled contactless conductivity detection was developed.

Determination of mono-, di-, and oligosaccharides by capillary electrophoresis with capacitively coupled contactless conductivity detection.

Saccharides and chitooligosaccharides can be separated in electrophoretic conditions by raising the pH of the medium, which renders the corresponding alcoholate forms. These anionic species can be separated and detected with capacitively coupled contactless conductivity detection as negative peaks because of their low mobilities when compared to the hydroxyl mobility, which is the main co-ion in the background electrolyte. Three methods for different matrixes are presented in this chapter.