On-Line Fourier Transform Infrared Spectrometric Detection in Gradient Capillary Liquid Chromatography Using Nanoliter-Flow Cells

Abstract

A capillary liquid chromatographic system has been successfully interfaced with a mid-IR Fourier transform infrared (FT-IR) spectrometer. Spectra were recorded on-line using a micromachined transmission CaF(2) cell (internal volume of 7.5 nL) that was placed on a dedicated beam condenser attached to the spectrometer. Linear gradients were run from (50:50) to (35:65) water (0.05% TFA)/acetonitrile in 15 min for the separation of standard solutions of four nitrophenols (4-nitrophenol, 3-methyl-4-nitrophenol, 2,4-dinitrophenol, and 2-nitrophenol) in a reversed phase system, providing limits of detection between 35 and 94 ng on-column. The changing background absorption due to gradient elution was successfully corrected by using a dedicated algorithm implemented in Matlab. When this chemometric data treatment was used, highly characteristic analyte spectra could be recorded as indicated by correlation coefficients between 89 and 95.8%, obtained when comparing mid-IR spectra of standard solutions and the spectra extracted from the chromatogram.

An electrochemical sensor based on polyelectrolyte-functionalized graphene for detection of 4-nitrophenol

“…Based its serious harm to the environment and human beings, to develop an effective determination method of 4-NP in the environmental protection is very important. Literature reveals that there are various methods have been used to detect 4-NP and applied in real samples, such as liquid chromatography [29,30], chemiluminescence [31], UV-vis spectrophotometry [32] as well as other combined use [33,34]. Despite these methods have the characteristics of high efficiency and resolution, however, the expensive instrument cost, time consuming, quite harsh requirements for part of the instruments of the testing environment and some other factors, such as field, real-time online detection due to restricting by various environment and conditions, limited the development of these approaches.…”

Current challenges in second‐order calibration of hyphenated chromatographic data for analysis of highly complex samples

“…During the last few years, some protocols have been suitably proposed for correcting or modeling background drift in two‐way chromatographic data, such as using MCR‐ALS for modeling background signal of GC × GC‐TOFMS data of complex mixture of polycyclic aromatic hydrocarbons (PAHs), using ATLD for modeling background contribution of LC × LC‐DAD signals, developing 2 straightforward methods based on simple‐to‐use interactive self‐modeling mixture analysis and principal component analysis to remove background signal and facilitate the performance of MCR‐ALS modeling, using orthogonal spectral signal projection to simultaneously treat various types of background drift . Also, the other methods, which were suitably proposed for correcting background drift in two‐way chromatographic data, can be found in the literature …”

Avanced Total Lab Automation System (ATLAS)

“…However, the time resolution of the chromatogram will decrease and two peaks, which are eluted shortly after each other, might be not detected separately. The strong absorption of the solvent can be easily subtracted in an isocratic eluation whereas background correction algorithms have to be used in gradient elution (Quintás et al, 2009a;. The second possible method is based on physically eliminating the solvent from the sample and the IR spectra are measured afterwards as traces on an IR transparent substrate.…”