A simple low-cost flow-through light-scattering detector was developed for determining the particle mass concentration in colloidal suspensions. Employing a laser pointer as a light source and a photodiode IC as a light sensor, the detector was shown to have good sensitivity, yet was small and battery operated. The detector was demonstrated to be effective for the flow-injection nephelometric determination of sulfate by precipitation as barium sulfate.
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http://dx.doi.org/10.2116/analsci.19.1495 | DOI Listing |
Anal Chem
January 2025
Chemistry Department, Indiana University, Bloomington, Indiana 47405, United States.
Charge detection mass spectrometry (CD-MS) is an emerging single-particle technique where both the / and charge are measured individually to determine each ion's mass. It is particularly well-suited for analyzing high mass and heterogeneous samples. With conventional MS, the loss of charge state resolution with high mass samples has hindered the direct coupling of MS to separation techniques like size exclusion chromatography (SEC) and forced the use of lower resolution detectors.
View Article and Find Full Text PDFJ Chromatogr A
January 2025
Office of Pharmaceutical Quality Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, USA. Electronic address:
Asymmetrical flow field-flow fractionation (AF4) with multi-detection has continued to gain wider acceptance for characterizing complex drug products. An important quality attribute for these products is the measurement of the particle size distribution (PSD). Current limitations of established procedures (e.
View Article and Find Full Text PDFJ Chromatogr A
January 2025
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK. Electronic address:
Research into nanoparticle interactions with biomolecules has become increasingly important in nanomedicine. While lipid nanoparticles (LNPs) are widely used as drug delivery systems, there remains a gap in understanding their fate in circulation, which is crucial for selecting appropriate lipids during formulation development. This study is the first to use Asymmetric Flow Field Flow Fractionation (AF4) to compare two types of LNPs: MC3-LNPs and SM-102-LNPs, and their interactions with a model protein, bovine serum albumin (BSA).
View Article and Find Full Text PDFJ Sep Sci
January 2025
R & D Laboratory, TASNEE Technology and Innovation Centre, Al-Jubail Industrial City, Saudi Arabia.
In this study, a commercially available polypropylene homopolymer (H-PP) was blended with blow molding polyethylene (PE) grade via melt mixing using a compounding machine. The resulting blends were subjected to high-temperature size exclusion chromatography (SEC) analysis, coupled with infrared-5 (IR-5), viscometer (VISCO), and multi-angle laser light scattering (MALS) detectors. The molecular weight (MW) and MW distributions were investigated using SEC, and the exact blend compositions were evaluated using C nuclear magnetic resonance.
View Article and Find Full Text PDFJ Chromatogr A
February 2025
School of Pharmaceutical Sciences, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland. Electronic address:
Ion exchange chromatography (IEX) is an important analytical technique for the characterization of biotechnology-derived products, such as monoclonal antibodies (mAbs) and more recently, cell and gene therapy products such as messenger ribonucleic acid (mRNA) and adeno-associated viruses (AAVs). This review paper first outlines the basic principles and separation mechanisms of IEX for charge variant separation of biotherapeutics, and examines the different elution modes based on salt or pH gradients. It then highlights several recent trends when applying IEX for the characterization of biotechnology-derived products, including: i) the effective use of pH gradients, ii) the improvement of selectivity by using organic solvents in the mobile phase, multi-step gradients, or by combining ion pairing and ion exchange, and iii) the increase in analytical throughput using ultra-short columns or automated screening of conditions.
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