SOLUTIONS

Dual Flow RI Detector

Dual Flow RI Detector

The EcoSEC GPC system features dual flow RI detection, which results in superb RI baseline stability and reduced RI baseline drift.

In a conventional RI detector, over time, the refractive index of the stagnant pure solvent in the reference side will slowly change and the two photodiodes will no longer produce equal signals, thus the contents of the reference and sample sides have different refractive indices and will produce a voltage difference similar to that of an analyte in solution. For example, the refractive index of THF slowly alters over time, due to the buildup of peroxide-related compounds, resulting in baseline drift. The dual flow design of the RI detector in the EcoSEC GPC System compensates for the changes in refractive index of the solvent over time by continuously flowing pure solvent through the reference side of the flow cell.

The EcoSEC GPC System displays an extremely stable baseline with low baseline drift when analyzing polymers in neat, mixed, and complex solvent systems. See the tabs below with figures showing five consecutive injections of polystyrene standards in chloroform, DMAc with 0.02 mol/L LiBr, and 95:5 Dichloromethane:HFIP with 5 mmol/L tetraethylammonium bromide on semi-micro TSKgel GPC columns. The run times were deliberately extended to one hour without auto zeroing the detector between injections for a total of five hours at a flow rate of 0.35 mL/min.

Baseline Stability of the EcoSEC GPC System in Chloroform 

RI_Detector_tab1.png 
Column:           TSKgel SuperHZM-M, 3 µm, 4.6 mm ID × 15 cm × 2
Mobile phase:  chloroform
Flow rate:         0.35 mL/min
Detection:         
RI (EcoSEC GPC System)
Temperature:   
40 °C
Injection vol.:   
10 µL
Sample:            polystyrene standards, PStQuick MP-M series 




Baseline Stability of the EcoSEC GPC System in DMAc with 0.02 mol/L LiBr

RI_Detector_tab2.png
Column:          TSKgel SuperHZM-M, 3 µm, 4.6 mm ID × 15 cm × 2
Mobile phase: DMAc with 0.02 mol/L LiBr
Flow rate:        0.35 mL/min
Detection:        
RI (EcoSEC GPC System)
Temperature:  
40 °C
Injection vol.: 
10 µL
Sample:           polystyrene standards, PStQuick MP-M series



Baseline Stability of the EcoSEC GPC System in 95:5 Dichloromethane:HFIP with 5 mmol/L tetraethylammonium bromide

RI_Detector_tab3.png

Column:          TSKgel SuperHZM-M, 3 µm, 4.6 mm ID × 15 cm × 2
Mobile phase: 95:5 dichloromethane:HFIP with 5 mmol/L tetraethylammonium bromide
Flow rate:        0.35 mL/min
Detection:        
RI (EcoSEC GPC System)
Temperature:  
40 °C
Injection vol.: 
10 µL
Sample:           polystyrene standards, PStQuick MP-M series