26 February / March 2019
Figure 4: Blending organic solvents to achieve a gradient separation of seven basic analytes. 20 mM KH2
PO4 pH 2.7
(aq) was used as the aqueous mobile phase component (line A) and various aqueous/organic mixes were used on line B (see fi gure captions). Column: ACE 3 C18, 150 x 4.6 mm, fl ow rate: 1.0 mL/min, temperature: 35°C, gradient: 5-70% B in 11 mins, detection: 205 nm. Sample: 1. Benzylamine, 2. Procainamide, 3. Terbutaline, 4. Salbutamol, 5. Amiloride, 6. Trimethylbenzylamine, 7. Pindolol.
Conclusions
Acetonitrile and methanol both offer advantages and disadvantages for use as the organic modifi er in reversed-phase liquid chromatography, with the optimum choice being application driven. Perhaps the most important aspect of these two solvents is that they offer substantially different selectivity to one another. Investigating both methanol and acetonitrile is therefore highly recommended as a valuable approach when developing a new reversed-phase method.
To view past issues or the latest news online please visit
www.chromatographytoday.com
If you would like to be included please email your details to
marcus@intlabmate.com or call us on +44 (0)1727 855574
Oligonucleotide Separations with RP Phases
Online Gas Analyzer Experts
ODORS & AIR MONITORING EXPERTISE IN ONLINE GC
Monitoring up to 123 compounds with accuracy in industrial areas
BTEX VOCs Halogenated PCB Solvents Aromatics Dioxins Precursors PAH Hydro- carbons
Permanent gases
OVOCs
Industrial or urban atmospheres Suitable for each type of environment
Low levels of quantification (ppm/ppb/ppt) Reliable and stable results with data double check FID & Mass spectrometry (MS) No saturation of detectors with MS technology Reliable measurement of a large spectrum of compounds in air
airmoSCAN Xpert
Turnkey Stand-alone Solution
ARABLAB
12 - 14 March 2019 Booth # 1133
PEFTEC
22 -23 May 2019 Booth #106
www.chromatotec.com -
info@chromatotec.com
Therapeutic oligos represent an important area of research in the pharmaceutical industry today. These drug candidates are typically 8-50 nucleotides long and contain single-stranded DNA or RNA. Oligonucleotides are typically analysed using ion-pairing chromatography. Oligonucleotides are easily degraded via phosphodiester-cleaving enzymes. However, with a thiophosphate modified phosphate group, the stability significantly increases. Phosphorothioate modified oligos will have a stereocenter at each modified phosphate group, leading to 2n-1 diastereomers, all with an individual retention time in the chromatography. For a 20-nucleotide long oligo, that’s 524 288 species present. The partial resolution of these species results in peak broadening, further complicating chromatographic separation. To resolve the problem, ion-pairing agents with longer alkyl chains can be used.
In a study of the influence of stationary phase and ion-pairing agent on the separation of oligos, Kromasil Phenyl showed to be a very good choice when separating oligonucleotides in general, exhibiting very sharp peaks, and good selectivity.
More information online:
ilmt.co/PL/XvKy
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
