Fourier transformation liquid chromatography: increasing sensitivity by a factor of 50.

Markus Matz,Manfred Wilhelm,Timo Beskers,Carlo Botha

doi:10.1039/d1an02298a

Markus Matz, Manfred Wilhelm + Show 2 more

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https://doi.org/10.1039/d1an02298a

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Abstract

Methods that increase sensitivity are a constant topic in research. To increase the sensitivity for high-performance liquid chromatography (HPLC) a continuous injection method with a sinusoidal analyte concentration profile was developed. The sinusoidal analyte concentration profile is obtained by a sinusoidal variation of the relative volume contents between two solvent reservoirs, one containing a pure solvent and the other an analyte stock solution prepared with the same solvent. Discrete Fourier transformation enables the analyte-specific phase angle shift to be calculated from the chromatograms. The proposed method is established and evaluated for size exclusion chromatography (SEC). Accordingly, the phase angle shift is used for molecular weight determination by establishing a molecular weight calibration using different narrowly distributed polystyrene (PS) calibration standards. In a comparison with conventional SEC, the Signal-to-Noise ratio (S/N), normalized to the square root of the time of the evaluated data set, increases by a factor of approximately 50.

Highlights

One of the most widely used analytical separation techniques is high-performance liquid chromatography (HPLC).[1]
Comparing the noise levels of both spectra reveals that VWD-1 has a Signal-to-Noise ratio (S/N) ≈ 10−6 and VWD-2 a S/N ≈ 10−5, which might be attributed to another signal amplification factor of the detectors
Two solvent reservoirs have been used, one containing the pure solvent and the other an analyte stock solution prepared with the same solvent

Summary

Introduction

One of the most widely used analytical separation techniques is high-performance liquid chromatography (HPLC).[1]. Both methods have been further investigated.[8,9,10,11,12,13,14,15,16,17,18,19] Methods with multiple random injections have been applied to liquid and gas chromatography where the chromatogram is evaluated using cross-correlation or Hadamard transformation to increase the S/N and for process control.[8,9,10,14,15,16,17,18] continuous sinusoidal “injections” have only been established in rare cases for gas chromatography for process control purposes.[11,12,13] To date, none of these modified injection methods have been used extensively or fully developed This is probably mostly attributed to the more complex data processing compared to the conventional injection method (i.e. single injections) and to the fact that current chromatographic issues can already be answered using the conventional injection method.[9]

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