Restek
Resource Hub / ChromaBLOGraphy / New EZGC library Residual solvents on the Rtx-225

New EZGC library: Residual solvents on the Rtx-225

25 May 2022

The Rtx-225 is a versatile column with unique selectivity for low-boiling-point compounds.  The cyano-phenyl composition of this phase limits the maximum operating temperature to <240°C.

To help figure out if this column will work for your analytes of interest, a new residual solvents library has been added to EZGC, containing compounds from all three solvent classes designated by the USP and ICH 1,2 (Table 1).

Chemical:

CAS (#)

Class (#)

Benzene

71-43-2

1

Chloroform

67-66-3

1

Trichloroethene

79-01-6

1

1,4-Dioxane

123-91-1

2

Chlorobenzene

108-90-7

2

cis-1,2-Dichloroethene (Z)

156-59-2

2

Cyclohexane

110-82-7

2

Ethylbenzene

100-41-4

2

m/p-Xylene

108-38-3

2

Methylcyclohexane

108-87-2

2

o-Xylene

95-47-6

2

Tetrahydrofuran

109-99-9

2

Toluene

108-88-3

2

trans-1,2-Dichloroethene (E)

156-60-5

2

1-Butanol

71-36-3

3

1-Pentanol

71-41-0

3

1-Propanol

71-23-8

3

2-Butanol (sec-butyl alcohol)

78-92-2

3

2-Butanone (MEK)

78-93-3

3

2-Propanol (isopropanol)

67-63-0

3

3-Methyl-1-butanol (isoamyl alcohol)

123-51-3

3

4-Methyl-2-pentanone (MIBK)

108-10-1

3

Butyl acetate

123-86-4

3

Diethyl ether (ethyl ether)

60-29-7

3

Ethanol

64-17-5

3

Ethyl acetate

141-78-6

3

Ethyl formate

109-94-4

3

Isobutanol (2-methyl-1-propanol)

78-83-1

3

Isobutyl acetate (acetic acid 2-methylpropyl ester)

108-21-4

3

Isopropyl acetate (acetic acid, 1-methylethyl ester)

108-21-4

3

Methyl acetate

79-20-9

3

Methyl-tert-butyl ether (MTBE)

1634-04-4

3

Propyl acetate

109-60-4

3

Table 1: Residual solvents included in the Rtx-225 EZGC library.

Using EZGC, we were able to build a method that could separate 25 of the 33 compounds in under 5 minutes (Figure 1).

blog-new-EZGC-library-residual-solvents-on-the-rtx-225-01-with-table.png

Figure 1: EZGC method predictions for separation of class 1-3 residual solvents.

Our column was measured to be 29.09m. We used an inlet temperature of 250oC, Topaz straight inlet liner with wool (cat#23300), and a 400:1 split injection. The standards used were cat# 36004 (class 1), 36217 (class 2), 36013 (class 3).

Even though we had quite a few coelutions, the use of a mass-spectrometers helped to identify individual peaks for all 33 compounds. If you are also using a mass-spectrometer, the EZGC chromatogram modeler can help you to select unique ions differentiating co-eluting peaks, saving valuable trial-and-error time.

For further reading:

  1. Impurities: Guideline for Residual Solvents Q3C(R8). International council for harmonisation of technical requirements for pharmaceuticals for human use April 22, 2021.
  2. <467> RESIDUAL SOLVENTS. United States Pharmacopia March 23, 2007.