Effects of External Influences on GC Results
September 1st 2017Small differences in process gas chromatography (GC) results from the same sample stream over time can indicate corresponding changes in target analyte concentrations, or the fluctuations might be due to external influences on the instrument. This instalment of ”GC Connections” explores ways to examine such results and better understand their significance.
LC–MS Characterization of Mesquite Flour Constituents
September 1st 2017Using a liquid chromatography–mass spectrometry (LC–MS) method in conjunction with two complementary types of chromatographic retention modes-reversed phase and aqueous normal phase-various compounds present in mesquite flour extracts were identified. Because of the diverse types of chemical constituents found in such natural product extracts, a single chromatographic mode may not be sufficient for a comprehensive characterization. However, the combination of reversed-phase and aqueous normal phase LC can encompass a wide range of analyte polarity. This characterization of the composition of mesquite flour could be used in future studies to elucidate the beneficial health effects of its consumption.
Results Correlation with External Influences
September 1st 2017In the previous instalment, we presented a case of periodically fluctuating data that did not lend itself well to trend analysis with conventional statistical methods. The data did appear to have a strong regular fluctuation, but its relationship to other observations was not clear. This instalment addresses methods for teasing out external influences on trending data.
Highlights from HPLC 2017 Symposium
September 1st 2017The 45th International Symposium on High Perfomance Liquid Phase Separations and Related Techniques (HPLC 2017), cochaired by Michal Holc€apek and František Foret, was held 18–22 June in Prague, Czech Republic. This instalment covers some of the highlights observed at the symposium, including advances in large-molecule separations, multidimensional chromatography, and areas of growing application of high performance liquid chromatography (HPLC). In addition, trends and perspectives on future developments in HPLC noted from the conference are presented.
Rapid Perfluorinated Alkyl Acid Analysis by LC–MS/MS Increases Sample Throughput
September 1st 2017Perfluorinated alkyl acids are man-made fluorochemicals used as surface-active agents in the manufacture of a variety of products, such as firefighting foams, coating additives, textiles, and cleaning products. They have been detected in the environment globally and are used in very large quantities around the world. These fluorochemicals are extremely persistent and resistant to typical environmental degradation processes. As a result, they are widely distributed across the higher trophic levels and are found in soil, air, groundwater, municipal refuse, and landfill leachates. The toxicity, mobility, and bioaccumulation potential of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), in particular, pose potential adverse effects for the environment and human health.
Analyzing Multisegmented Block Copolymers by SEC-MALS-IV
September 1st 2017“Click” chemistry is a class of efficient and selective reactions that is characterized by quantitative yields, tolerance to a broad range of functional groups, facile experimental setup, and minimal synthetic workup. This class of reactions combines particularly well with controlled radical polymerization methods, such as atom transfer radical polymerization (ATRP), and the two techniques have been prolifically employed for the synthesis of a wide variety of novel polymeric materials, including (multi) block copolymers, stars, brushes, and gels. This note describes the analysis of multisegmented block copolymers prepared by click-coupling of block copolymers synthesized by ATRP.
Identifying Post-Translational Modifications in Monoclonal Antibodies
September 1st 2017Identifying Post-Translational Modifications in Monoclonal Antibodies Analyzing post-translational modifications-such as glycosylation, oxidation, and deamidation-at different levels can reveal different types of information.
Liposome Size, Concentration, and Structural Characterization by FFF-MALS-DLS
September 1st 2017Liposomes are often used as nanocarriers to encapsulate in their cores hydrophobic or highly toxic drugs, and deliver these drugs safely to target tissue. During drug nanocarrier research and development as well as production quality control, it is of great importance to monitor liposome size distributions accurately while also verifying drug encapsulation. FFF-MALS-DLS, consisting of field-flow fractionation (FFF) combined with multi-angle light scattering (MALS) and dynamic light scattering (DLS), is a powerful tool for characterizing the size, concentration, and structure of large nanoparticle ensembles.
SEC-MS Analysis of a Bispecific Antibody
September 1st 2017Modern therapeutic antibody formats, such as bispecific antibodies (bsAbs), are on the rise. Bispecific antibodies are artificial proteins that recognize two different epitopes and can simultaneously bind to two different types of antigen. They can be used to redirect T cells to tumour cells, block two different signalling pathways simultaneously, dually target different disease mediators, and deliver payloads to targeted sites.
Novel Metabolomics GC Method for Olive Oil Analysis
August 22nd 2017A method to determine the quality of olive oil has been developed using a novel atmospheric pressure chemical ionization (APCI) source in combination with gas chromatography (GC) coupled to hybrid quadrupole time-of-flight mass spectrometry (QTOF-MS) and a metabolomics strategy.