Chromatographie Abhängigkeit der Trennleistung eines chromatographischen Systems von Geschwindigkeit der mobilen Phase Van Deemter

Eddy-Diffusion A Peakform kurz nach der Injektion Peakform nach Passieren des Säulenbettes

Diffusion B Peakform kurz nach der Injektion Peakform nach Passieren der Säule

Stoffaustausch C Veränderung der Peakform durch den Stoffaustausch-Prozess

Open Tubular Columns At a constant pressure Flow rate is proportional to cross sectional area Flow rate is inversely proportional to the column length For open tubular column this means that we can get Increased linear flow rate and/or a longer column Decreased Plate height, which means improved better resolution

Gas Chromatography

Van Deemter Kurve in Abhängigkeit des Kristallgitters

C-Term

Mass Transport Band Spreading

Asymmetric Bands

Comparison of open tubular and packed columns. Open tube columns Higher resolution Shorter Analysis time Increased sensitivity Lower sample capacity

2D - GC

Modulators Thermal modulator Cryogenic modulator

Comprehensive GC Auch GC x GC oder multidimensional GC. 1. Trennung auf „normaler“ Säule. 2. Trennung auf kurzer microbore Säule. Gesamtes Effluenz der 1. Säule wird in sehr viele Fraktionen aufgeteilt und auf die 2. Säule gegeben. Resultierendes Chromatogramm hat zwei Zeitachsen (die Retentionszeiten der beiden Säulen) trapping und Reinjektion durch „Modulator“ bewirken Fraktionsfokussierung.

Gas Chromatography

Gas Chromatography

Gas Chromatography

Residual Solvents - ICH Topic Q3C OC, because of thermally labile in first line Formamide Anhydrid Meth- and ethoxyethane High boiler Roughly spoken: Low boiler dmf hs Alternatively high boiler + some others Direct OC DMA Drawback: crack products

HPLC - Gas Chromatography

She’s a reversed-phase gradient HPLC This is Ursula She’s a reversed-phase gradient HPLC

HPLC guard column Injector port LOAD / INJECT

Alltech 450 UV Detector (254nm fixed)

This is Pat It is a GC-MS Multistage temperature program Time needed for one cycle: 55 min GC HP 6890 SAMPLER HS / OC Multistage temperature program HP 5973 - MSD It is a GC-MS

Plate THEORY

In distillation, Plate theory Actual plates exist whhere vapour passes through a liquid phase During this mixing, equilibrium between the phases is assumed The height of a plate can often be directly measured In a packed column or a capillary the plates can´t be observed – called theoretical plates HETP = h

Typical Plate Heights GC ~ 0.1 to 1 mm [30 m] HPLC ~ 0.01 mm [0,25 m] CZE ~ 0.001 mm [0,1 m]

The Peak Ideal chromatographic peaks are Gaussian in peak shape. This comes directly from the Craig Model. We know certain facts about Gaussian peaks.

k`= t´R / tR Parameter aus Chromatogramm Gaussform angenommen

Partition coefficient k´ Plate theory K is assumed to be independent of concentration. It can be altered by such factors as temperature. ß = rc/2df Solute fractions: mobile phase: 1 / (1+ k´) stationary phase: k´/ (1+ k´) 1 = 1 / (1+ k´) + k´/ (1+ k´)

Alltech’s Heliflex® AT™-1ht GC capillary column is designed for the analysis of samples containing high boiling compounds and high molecular weight samples. The phase ratio of a column () is equal to the radius of the column divided by twice the film thickness. A higher  allows for the elution of high molecular weight samples in a reasonable time; or the elution of medium molecular weight samples at low temperatures. By keeping the temperatures low, the column bleed is also kept to a minimum. Phase Ratio: =r/2df ID df  0.25 0.25 250 0.32 0.25 320 0.53 1.20 110 0.25 0.10 625 0.32 0.10 800 K = k` x ß k`= K / ß

Heat as a separations tool.

We could potentially measure the width at half height and knowing it is a Gaussian peak derive the following.

Resolution = Dtr / wave = 0.589Dtr/w1/2 ave

Factors Affecting Resolution k`= K / ß

Oberflächenchemie

Cross section of a Fused Silica Column Open Tubular

HTS

PHASEN

Choosing the Bonded Phase

Choosing the Bonded Phase PG = polar amide group Polar amide group embedded in a long alkyl chain reduces interactiions between basic analytes and silica support R = C14 alkyl R1 = isopropyl shielding Diisopropyl side groups provide steric protection against low pH Triple endcapping, shielding