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.

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.

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.

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 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%).

Highlights:

• DryLab employs to find the optimum time of a simple (or segmented) gradient, yielding best resolution of a particular sample.
• Short silica-based monolithic columns can be used with fast 1 min- gradients up to 5 mL/min.
• Isocratic retention parameters were used for prediction and modeling gradient chromatograms.
• The gradient range was optimized for maximum peak capacities within a fixed gradient time.