Application of Hadamard transform to gas chromatography/nonresonant multiphoton ionization/time‐of‐flight mass spectrometry

Abstract

The technique of Hadamard transform was successfully coupled with GC/nonresonant multiphoton ionization/TOFMS, for the first time. 1,4-Dichlorobenzene and the fourth harmonic generation (266 nm) of a Nd:YAG laser were employed as a model sample and an ionization laser, respectively. A Hadamard-injector coupled with a capillary-based supersonic jet nozzle (capillary-injector) was also developed in this study. The Hadamard-injector was used to obtain the chromatogram, which was encoded by successive sample introduction based on Hadamard codes, and the capillary-injector was used for injection of GC-elutes into TOFMS. Compared with a conventional single injection method, the S/N ratios were substantially improved after inverse Hadamard transformation of the encoded chromatogram. Under optimized conditions, when Hadamard matrices of 103 and 255 were used, the S/N ratios of the signals for 1,4-dichlorobenzene (concentration level, 4 microg/1 mL ACN) were substantially improved to 4.1- and 6.6-fold, respectively, and those improvements are in good agreement with those obtained by theory (5.1- and 8.0-fold).

Rapid identification of false peaks in the spectrum of Hadamard transform ion mobility spectrometry with inverse gating technique

“…In order to enhance the signal to noise ratio (SNR), the Hadamard multiplexing technique was proposed and achieved the increase of the duty cycle (DC) from nearly 1% to 50%. Aer application in spectrometry, 1,2 Hadamard multiplexing has been adopted in many other elds, such as time-of-ight mass spectrometry, [3][4][5][6] uorescence imaging, 7 nuclear magnetic resonance (NMR), 8,9 capillary electrophoretic separations, [10][11][12][13][14][15][16][17] gas chromatography/mass spectrometry (GC/MS), [18][19][20][21][22][23][24] and ion mobility spectrometry, [25][26][27][28][29] etc.…”

Implementation of Hadamard encoding for rapid multisample analysis in liquid chromatography

“…The first realization of this principle in chromatography was demonstrated in correlation chromatography . Multiplexing utilizing Hadamard encoding has been applied to increase S/N in many fields, including TOF–MS , CE , and GC–MS . We reported on the use of structured modulation sequences and Hadamard transform in high‐throughput multiplexing gas chromatography (htMPGC) .…”

Online High Throughput Measurements for Fast Catalytic Reactions Using Time-Division Multiplexing Gas Chromatography

“…Therefore, a superimposed (convoluted) chromatogram is recorded. As suggested by Smith, mpGC has been used for many applications to enhance the signal-to-noise ratio (SNR) by making use of the multiplex advantage. − However, the original idea was to use mpGC as a tool for process analytics . For this application, a process stream is continuously sampled according to an endlessly repeated PRBS and a deconvoluted chromatogram containing the averaged information on the components, which elute within the time duration of the last PRBS, is calculated after every time interval Δ t .…”