CHROMATOGRAPHY 49
obtain the same band broadening at high pH, the loading had to be increased more than 160 times.
Te advantage shown in Fig. 1. can also be explored for the purification of sample mixtures. Te results shown in Fig. 2. are based on the purification of crude tryptamine with the impurity eluting ahead of it. Te results highlight two preparative runs, with a 500 µL injection at a sample concentration of 13.3 mg/ml, one at pH 2.5 and the other at pH 11 using EternityXT C18 material.
Tese conditions are possible because with EternityXT C18, even at pH levels as high as pH 12, it is possible to run large- scale separations for an extended period of time maintaining the quality of the stationary phase.
As seen in the figure, at low pH, the impurity elutes under the main peak, which will impact the productivity and yield of the run. At high pH, the key compound and the impurity are much better resolved with a significant base line separation, making it possible to overload the column and still achieve
Reliable analysis of synthetic polymers
The polymer industry is actively engaged in developing new materials with key performance attributes. Priorities include the introduction
of renewable polymers to replace those derived from fossil fuels, formulating materials with improved performance to volume gearings for packaging applications, and enhancing polymer recyclability or biodegradability. Polymer scientists require absolute
molecular weight, size and structural information in order to manipulate polymer properties to meet these goals. Designed specifically analysis of
synthetic polymers is Omnisec, Malvern
Instruments’ new gel permeation chromatography/size exclusion chromatography (GPC/SEC) system. The Omnisec platform brings
together highly efficient and precise sample separation in the Omnisec Resolve module with a fully integrated, high sensitivity multi-detector array in the Omnisec Reveal module. A complete Omnisec system
delivers the accurate molecular weight and molecular size measurements and detailed structural information needed to drive synthetic polymer research. Malvern Instruments has also
released a series of application notes to
highlight the sensitivity of the system in synthetic polymer analysis. The new application notes include
‘Measurements of absolute molecular weight of synthetic polymers using Omnisec’, which demonstrates the ability of the system to accurately measure the molecular weight of polystyrene, polyvinyl chloride (PVC) and polymethyl methyacrylate (PMMA) with no need for relevant calibration standards. ‘The Mark-Houwink plot –
Differentiation of Branching and Composition’ demonstrates how this plot may be used to determine and compare polymer structure. The data presented
shows that Omnisec is able to detect differences in branching with excellent levels of sensitivity, through its powerful light scattering detector and viscometer. Meanwhile, Malvern
The Omnisec from Malvern Instruments offers sensitivity in the analysis of synthetic polymers.
Instruments is launching a reliable optimised solution for lignin characterisation. Lignin is a vital industrial polymer but presents challenges when it comes to measurement of the properties that define its performance. Through experimental
study Malvern has identified
the best strategy to apply when using gel permeation/size exclusion chromatography (GPC/SEC) to secure reliable information. Lignin is a natural polymer, derived
from wood and other vascular plants, that finds application as, for example, a biofuel, a dispersant in high performance cement, and oilfield additive. GPC/SEC is used to measure
the molecular weight (MW), MW distribution, viscosity and structural properties that control its performance. However, lignin has an unusual molecular structure in solution which compromises data accuracy when conventional, single detector, calibration-based GPC/SEC is applied. Malvern’s solution exploits the capabilities of multi-detector GPC/SEC. This involves the use of a light scattering detector to directly measure MW without any requirement for calibration. Here though, the tendency for lignin to fluoresce in solution, thereby distorting light scattering data, can be problematic The data from Malvern shows how
careful choice of experimental conditions and methods can overcome challenges in the measurement of lignins and provide reliable results.
For more information, visit
www.malvern.com
www.scientistlive.com
maximum performance within one run. For this particular sample, it would be possible to increase loading onto the column even further and accelerate the amount produced per unit time. Tese results indicate that working with EterntyXT at high pH in the purification of amines should benefit the performance of preparative chromatography. As EternityXT is available from 1.8 µm to 10 µm, it is possible to use the same stationary phase across the entire drug development and production cycle.
For more information ✔ at
www.scientistlive.com/eurolab
Fredrik Lime & Cecilia Mazza are with AkzoNobel.
www.kromasil.com
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