CD Spectra Measurements of Organic Compounds and Metal-Complexes using a OneDrop Accessory with Microsampling Disc

Download PDF May 26, 2017

Introduction

While CD measurements are typically obtained to analyze the secondary structure of proteins, CD can also be used to determine the configuration of organic compounds and coordination of metal complexes with optically active ligands.

J-1500 Circular Dichroism Spectrophotometer
JASCO J-1500 CD Spectrometer

This application note will compare CD spectra obtained using the OneDrop microsampling disc with a conventional cell, for organic compounds with an absorption band in the ultraviolet (UV) region and metal complexes with an absorption band in the UV and Visible regions.

Experimental

Measurement conditions for organic compounds (Figure 1)
J-1500 CD spectrometer, MSD, conventional cell
 
Spectral bandwidth1 nm
Accumulation4 times (MSD), 1 time (conventional cell)
Data acquisition interval0.1 nm
Response time2 seconds
Scan speed100 nm/min
Sample volume10 µL (MSD), 400 µL (conventional cell)
Path length1 mm
Measurement conditions for metal complexes (Figure 2)
J-1500 CD spectrometer, MSD, conventional cell
 
Spectral bandwidth1 nm
Accumulation9 times (MSD), 1 time (conventional cell)
Data acquisition interval0.1 nm
Response time2 seconds
Scan speed200 nm/min
Sample volume10 µL (MSD), 400 µL (conventional cell)
Path length1 mm

Keywords

OneDrop measurement, microsampling disc, circular dichroism, organic compounds, metal complexes, J-1500

Results

The CD spectra depicted in Figures 1 and 2 compare the results obtained using the MSD and a conventional cell for organic compounds and metal complexes, respectively. Both the organic compounds and metal complexes’ data show good correlation between spectra measured with the 10 µL volume microsampling disk (blue) and 400 µL volume conventional cell (green), each with a 1 mm path length.

Figure 1. CD spectra of (A) (1S)-(+)-10-Camphorsulfonid acid, ammounium salt and (B) D-Pantolactone using a microsampling disk (blue) and cylindrical cell (green).

Figure 2. CD spectra of (A) 2(+)D-[Coen3]Cl3NaCl-6H2O and (B) 0.25 M NiSO4+, 0.36 M Rochelle salt using a microsampling disk (blue) and cylindrical cell (green).

Conclusion

This application note demonstrates that the OneDrop microsampling disk provides reliable spectra for CD spectroscopy measurements in volume-limited samples

About the Author

Leah Pandiscia received her PhD from Drexel University where she studied Biophysical Chemistry. She is a Spectroscopy Applications Scientist at JASCO.