Headspace GC FID - peak area repeatability issue
Posted: Mon Apr 11, 2022 12:20 pm
Hello! My first time posting a topic.
I am developing a method on headspace (Shimadzu AOC 6000 Plus) gas chromatography (Shimadzu Nexis 2030) with FID detector. I have to develope, optimize and validate a method that will analyse 16 different analytes (polar and non polar) in sludge.
RSD/% of Areas for Metoxy-2-propanol, Etoxy-2-propanol, Ethyl-benzene, m-,p-Xylene, o-Xylene are big (later eluting analytes with high boiling point).
For example:
I made a solution which consists of:
Analyte ______________V/V volume / volume (%)
Acetone_______________ 3%
Ethyl-acetate___________ 8%
Metoxy-2-propanol______ 10%
Etoxy-2-propanol________ 20%
Ethyl-benzene__________ 20%
Xylene________________ 39%
10 vials ( vial volume =20 mL) with 800 uL of the prepared solution are analyzed.
Conditions
Incubation temp: 80°C
Incubation time: 30 min
Syringe temp:150°C
Fill strokes count: 0
Injection flow rate: 3mL/min
Injection volume: 250 ul
Inlet temp: 200°C
Carrier gas: Nitrogen
Column: SH-I-624Sil MS 60 m x 0,25 mmID x 1,40 um df
Total flow: 154,5 mL/min
Purge flow: 3 mL/min
Column flow: 1,5 mL/min
Linear velocity: 27,6 cm/s
Split ratio: 1:100
Oven temperature program:
----------- 35°C 17,5 min
10°C/min 100°C 3,5 min
40°C/min 240°C 1 min
Total program time: 32,00 min
Detector temp: 240°C
Analyte ______________ RSD (%)
Acetone_______________ 5,80%
Ethyl-acetate___________ 10,32%
Metoxy-2-propanol______ 25,39%
Etoxy-2-propanol________ 23,68%
Ethyl-benzene__________ 23,19%
m-,p-Xylene____________ 23,24%
o-Xylene_______________ 23,65%
Why is RSD so high for later eluting analytes (with high boiling point)? I already excluded a possibilty of leaky vials (used new caps with new septums).
Any suggestions?
I am developing a method on headspace (Shimadzu AOC 6000 Plus) gas chromatography (Shimadzu Nexis 2030) with FID detector. I have to develope, optimize and validate a method that will analyse 16 different analytes (polar and non polar) in sludge.
RSD/% of Areas for Metoxy-2-propanol, Etoxy-2-propanol, Ethyl-benzene, m-,p-Xylene, o-Xylene are big (later eluting analytes with high boiling point).
For example:
I made a solution which consists of:
Analyte ______________V/V volume / volume (%)
Acetone_______________ 3%
Ethyl-acetate___________ 8%
Metoxy-2-propanol______ 10%
Etoxy-2-propanol________ 20%
Ethyl-benzene__________ 20%
Xylene________________ 39%
10 vials ( vial volume =20 mL) with 800 uL of the prepared solution are analyzed.
Conditions
Incubation temp: 80°C
Incubation time: 30 min
Syringe temp:150°C
Fill strokes count: 0
Injection flow rate: 3mL/min
Injection volume: 250 ul
Inlet temp: 200°C
Carrier gas: Nitrogen
Column: SH-I-624Sil MS 60 m x 0,25 mmID x 1,40 um df
Total flow: 154,5 mL/min
Purge flow: 3 mL/min
Column flow: 1,5 mL/min
Linear velocity: 27,6 cm/s
Split ratio: 1:100
Oven temperature program:
----------- 35°C 17,5 min
10°C/min 100°C 3,5 min
40°C/min 240°C 1 min
Total program time: 32,00 min
Detector temp: 240°C
Analyte ______________ RSD (%)
Acetone_______________ 5,80%
Ethyl-acetate___________ 10,32%
Metoxy-2-propanol______ 25,39%
Etoxy-2-propanol________ 23,68%
Ethyl-benzene__________ 23,19%
m-,p-Xylene____________ 23,24%
o-Xylene_______________ 23,65%
Why is RSD so high for later eluting analytes (with high boiling point)? I already excluded a possibilty of leaky vials (used new caps with new septums).
Any suggestions?