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Determination of Byproducts

Determination of traces of solvents: (pdf)

The content of solvents in solid and liquid samples is an important parameter in numerous fields. Toxic solvents are forbidden in certain products and control of their content is thus necessary.

Analysis:

The peptide is dissolved in water or dimethylsulfoxide free of traces of solvent. The solvents are separated by capillary gas chromatography. The procedure is follows closely the method of European Pharmacopoeia.

Advantage:

• Almost any solvent can be determined quantitatively.
• Only about 0.5mg of the sample is required for this analysis. 

Determination of water: (pdf)

In contrast to the indirect methods of determination of water whereby products of reaction with water are quantified, our analytical method measures water directly. After thermal desorbtion, water is separated from other volatile components and detected quantitatively.

Analysis:

The sample is transfered directly into the injection block. After thermal desorption at 140°C, water is separated from other volatile components and detected quantitatively. Quantitation is done by the external standard method.

Advantage

• The determination of water is not interfered with by other hydroxyl-containing components.
• Other volatile components do not falsify results.
• The amount of sample re-quired is approx. 0,5 mg
• The relative standard deviation of the analysis is approx. 5 % for an absolute water content of 2 %.
• The limit of quantitation is approx. 0,05 %.

Determination of counter ions: (pdf)

 Determination of the counter ions of the peptide is essential if the peptide is take used in in-vivo or in-vitro tests. Especially tfa must be determined on account of its considerable toxic potential.

Analysis:

0,05ml methyl alcohol/BF3 containing 25nl pentafluoroacetic acid as internal standard are added to the sample. The mixture is heated to 110°C for 10 minutes. After cooling the solution is carefully extracted by n-hexane. The separation of the esters is performed by gas chromatography.

Advantage

• The determination of counter ion can be determined from strongly polar peptides.
• The amount of sample required is approx. 0,5 mg
• The relative standard deviation of the analysis is approx. 5 %.
• The limit of quantitation is 0,1 %.