Correlation ion chromatography with indirect UV detection

Improvement of Signal-to-Noise Ratio of Electropherograms and Analysis Reproducibility with Digital Signal Processing and Multiple Injections

“…Averaging of the measured spectra, however, is time-consuming and as an attractive alternative, introduction of the sample a hundred times during one analysis with (at short time intervals compared to the duration of analysis) has been considered by many researchers as a possible means of decreasing the detection limits in separation science. Such a technique in separation science is known as correlation chromatography (CC) (the alternative term multiplex chromatography has been used in the USA) and has been applied in gas chromatography (GC) [4 -7], high performance liquid chromatography (HPLC) [8], and ion chromatography [9]. The detector signal resulting from multiple injections performed at random times is incomprehensible for the human operator, so it must be transformed to chromatograms in a common form by a special decorrelation procedure.…”

Direct Hadamard Transform Capillary Zone Electrophoresis without Instrumental Modifications

“…Another approach to improve sensitivity in separation science is by use of multiplexing techniques. , Those include mathematical strategies like Fourier (FT) or Hadamard transform (HT) which are already well-established in the literature for various kinds of analytical tools, e.g. gas chromatography (GC), − LC, − ion mobility, , and mass spectrometry (MS). − In separation applications, the modulation of the input information–the analyte signal–is achieved by means of pseudorandom binary sequences (PRBS) that consist of defined consecutions of “1” and “0” coding for the injection of sample and blank, respectively. − Their number of elements m is denoted by the exponent n (-bit) according to m = 2 n – 1. Cross-correlation of the overlapped detector signal with the input sequence allows, subsequently, for the deconvolution of the conventional chromatographic information resulting in an increased SNR. − The principles of Hadamard transform and cross-correlation techniques have been described in detail in the literature. ,,,, …”

Applications of Hadamard Transform to Gas Chromatography/Mass Spectrometry and Liquid Chromatography/Mass Spectrometry

“…Correlation chromatography is a powerful method for reduction of the LOD. Therefore, correlation chromatography has been applied to not only GC – but also to LC – and to CE. , The Hadamard transform (HT) technique is a technique that is analogous to the correlation method. The HT technique has been applied in many fields, including time-of-flight mass spectrometry, – Raman, , fluorescence imaging, – ion mobility spectrometry, , and NMR. , In our previous studies, – Hadamard transformation has been successfully applied to capillary electrophoretic separations where the signal-to-noise (S/N) ratios were substantially improved by sample injections according to the PRBS.…”

“…Multiple injection devices for GC have also been developed for correlation GC, in which the solenoid valve, , cylindrical slide valve, and fluidic logic gate were used. Conversely, in correlation LC, the input signals modulated by PRBS were generated by valve systems – , and by an electrochemical concentration modulator . In this study, we developed novel injection devices for HT-GC/MS and HT-LC/MS, respectively.…”

“…1 Correlation chromatography is a powerful method for reduction of the LOD. Therefore, correlation chromatography has been applied to not only GC [2][3][4][5] but also to LC [6][7][8][9][10][11] and to CE. 12,13 The Hadamard transform (HT) technique is a technique that is analogous to the correlation method.…”