Literature

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Literature

So far, more than 260 peer reviewed papers have been published on the application of DryLab – a complete list of which you can find here.

DryLab draws on the philosophy described in the three most famous Solvophobic Theory papers I, II, III of Csaba Horváth, which were developed in the years 1975-1977 at Yale University (see also literature by Dr. Imre Molnár).

Read more about the Fundamentals of DryLab and its History.

Method development for the separation of monoclonal antibody charge variants in cation exchange chromatography, Part II: pH gradient approach

Sz.Fekete, A.Beck, J.Fekete, D.Guillarme
J Pharm Biomed Anal., 102, 282-289 (2015)

Keywords: Ion exchange, Monoclonal antibody, pH gradient, Method development, Cetuximab

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http://doi.org/10.1016/j.jpba.2014.09.032

The cation exhange pH gradient approach was evaluated for the characterization of 10 model monoclonal antibodies including panitumumab, natalizumab, cetuximab, bevacizumab, trastuzumab, rituximab, palivizumab, adalimumab, denosumab and ofatumumab.

This work shows that retention and resolution can be modelled in cation exchange pH gradient mode, based on only four initial runs (i.e. two gradient times and two mobile phase temperature). Only 6 h were required for a complete method optimization when using a 100 mm × 4.6 mm strong cation exchange column. Optimization was performed by computer simulation using DryLab modeling software. The accuracy of predictions was excellent, with an average difference between predicted and experimental retention times of about 1%.

The 10 model antibodies were successfully eluted in both pH and salt gradient modes, proving that both modes of elution can be considered as multi-product charge sensitive separation methods. For most of the compounds, the variants were better resolved in the salt gradient mode and the peak capacities were also higher in the salt gradient approach. These observations confirm that pH gradient approach may be of lower interest than salt gradient cation exchange chromatography for antibody characterization.

Effect of temperature on acid–base equilibria in separation techniques. A review.

L. G. Gagliardi, M. Tascon, C. B. Castells
Analytica Chimica Acta, 889, 19 August, 35-57 (2015)

Keywords: Acid–base equilibria, Temperature, Buffer properties, Selectivity, Separation techniques

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http://doi.org/10.1016/j.aca.2015.05.053

Highlights:

The study of theoretical principles of acid–base equilibrium has been reviewed.
The proton transfer process is often present in the analytical separation practice.
The influence of temperature on secondary chemical equilibria is examined.
The focus is laid on liquid chromatography and capillary electrophoresis.
Temperature can be a useful variable to modify selectivity under predictable basis.

Establishing column batch repeatability according to Quality by Design (QbD) principles using modeling software

N. Rácz, R. Kormány, J. Fekete, I. Molnár
J Pharm Biomed Anal., 108, 10 April, 1–10 (2015)

Keywords: DOE, DryLab, QbD, Robustness, UPLC-column comparison

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http://doi.org/10.1016/j.jpba.2015.01.037

Twelve columns of same brand name but different batches were compared. 3D design of experiment modeled by DryLab was used to compare column selectivity and performance. 3D resolution space allows establishing better method robustness before validation. A multivariable design space (MODR) allows flexible routine work with columns. This procedure allows easy column replacement to retain method robustness.

Protocols for finding the most orthogonal dimensions for two-dimensional high performance liquid chromatography.

D. N. Bassanese et. al
Talanta, 134, 1 March, 402-408 (2015)

Keywords: Two-dimensional high performance liquid chromatography, Orthogonality, Stationary phase optimisation, HPLC simulation, Potassium permanganate chemiluminescence, Bins method

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http://doi.org/10.1016/j.talanta.2014.11.037

Highlights:

Columns for two-dimensional chromatography were compared to maximise orthogonality.
Simulation software was employed to rapidly optimise 2D-HPLC operating conditions.
2 Optimisation protocols were compared to find the best 2D-HPLC column combination.
Both protocols were proven to be effective at predicting the final orthogonality.
The operating conditions were adjusted with DryLab and the simulated chromatograms were compared to the real runs.

Development of a purity control strategy for pemetrexed disodium and validation of associated analytical methodology.

A. Warner, I. Piraner, H. Weimer, K. White
Journal of Pharmaceutical and Biomedical Analysis, 105, 25 February, 46-54 (2015)

Keywords: Pemetrexed disodium, Impurity control, System suitability, Relative response factor determination, Method validation

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http://doi.org/10.1016/j.jpba.2014.11.032

Highlights:

Pemetrexed sodium purity methods were developed and validated.
Information and structure of 13 main impurities for pemetrexed sodium are provided.
Conditions for the system suitability solutions in situ preparation are described.
DryLab software tool was used to provide efficiency.
The system suitability assures the main impurities resolution and identification.
Relative response factors were determined using HPLC-UV in tandem with CAD or in combination with NMR.

Gas phase carbonyl compounds in ship emissions: Differences between diesel fuel and heavy fuel oil operation.

A. A. Reda et. al
Atmospheric Environment, 112, July, 370-380 (2015)

Keywords: Carbonyl compounds, DNPH, Ship emission, Heavy fuel oil, GC–SIM–MS

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http://doi.org/10.1016/j.atmosenv.2015.03.057

Gas phase emission samples of carbonyl compounds (CCs) were collected from a research ship diesel engine at Rostock University, Germany. The ship engine was operated using two different types of fuels, heavy fuel oil (HFO) and diesel fuel (DF). Sampling of CCs was performed from diluted exhaust using cartridges and impingers. Both sampling methods involved the derivatization of CCs with 2,4-Dinitrophenylhydrazine (DNPH). The CCs-hydrazone derivatives were analyzed by two analytical techniques: High Performance Liquid Chromatography–Diode Array Detector (HPLC–DAD) and Gas Chromatography–Selective Ion Monitoring–Mass Spectrometry (GC–SIM–MS). Analysis of DNPH cartridges by GC–SIM–MS method has resulted in the identification of 19 CCs in both fuel operations. These CCs include ten aliphatic aldehydes (formaldehyde, acetaldehyde, propanal, isobutanal, butanal, isopentanal, pentanal, hexanal, octanal, nonanal), three unsaturated aldehydes (acrolein, methacrolein, crotonaldehyde), three aromatic aldehyde (benzaldehyde, p-tolualdehyde, m,o-molualdehyde), two ketones (acetone, butanone) and one heterocyclic aldehyde (furfural). In general, all CCs under investigation were detected with higher emission factors in HFO than DF. The total carbonyl emission factor was determined and found to be 6700 and 2300 μg kWh−1 for the operation with HFO and DF respectively. Formaldehyde and acetaldehyde were found to be the dominant carbonyls in the gas phase of ship engine emission. Formaldehyde emissions factor varied from 3870 μg kWh−1 in HFO operation to 1540 μg kWh−1 in DF operation, which is 4–30 times higher than those of other carbonyls. Emission profile contribution of CCs showed also a different pattern between HFO and DF operation. The contribution of formaldehyde was found to be 58% of the emission profile of HFO and about 67% of the emission profile of DF. Acetaldehyde showed opposite behavior with higher contribution of 16% in HFO compared to 11% for DF. Heavier carbonyls (more than two carbon atoms) showed also more contribution in the emission profile of the HFO fuel (26%) than in DF (22%).

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