Quantitative Analysis of PAH in Pitch by HPLC with Fluorescence Detector

Rapid and Sensitive Detection of Polycyclic Aromatic Hydrocarbons in Tea Leaves Using Magnetic Approach

A rapid and efficient method using an alkyl-functionalized magnetic nanoparticles-based extraction technique combined with Ultra-High Performance Liquid Chromatography was developed for the detection of trace amounts of polycyclic aromatic hydrocarbons in tea leaves. As a popular coating for chromatographic column packing materials, C₁₈-alkyl has been demonstrated to be effective in separating polycyclic aromatic hydrocarbons. Additionally, the magnetism of the nanomaterials accelerates the extraction process while their high surface ratio enables desirable dispersity in the sample matrix. Meanwhile, the adsorbents can be washed and reused 30 times without compromising recovery, which greatly reduces the budget. The effects of various parameters were investigated and optimized, and the recoveries for five analytes were in the range of 84.8-105.4%. The RSD of intra-day and inter-day were below 11.9% and 6.8%, respectively. The limits of detection and limits of quantification ranged from 1.69-9.97 ng g^-1 and 5.12-30.21 ng g^-1, indicating satisfactory sensitivity. Thus, the proposed methodology is rapid, highly efficient, and economical, and it expands the application of magnetic cleanup approaches in complex food matrices.

Determination of organic matter in grinding sludges by UV spectrophotometry

The aim of this paper is to determinate the total organic matter content of grinding sludges by a simple and fast methodology based on a solvent extraction followed by a UV spectrophotometry analysis. Several UV spectra exploitation methods are used. The multiwavelength deconvolution procedure provides quantitative results in good accordance with those obtained by a gravimetric method, possibly underestimated and enables a separate quantification of the cuttings fluids and the lubricants in the sludges. The normalisation procedure and the search of isobestic points provide important qualitative information on the evolution and on the composition of the oils used in metal processing. Therefore, this study is a first step for the development of a tool for the characterisation of organic matter in grinding sludges.

High-sensitivity chromatographic detector incorporating three-dimensional charge coupled device fluorimetry

This article describes a detector for liquid chromatography that provides three-dimensional, excitation-emission-intensity data of fluorescent compounds. The instrument achieves multi-wavelength excitation by employing a polychromator that disperses radiation along the vertical portion of a quartz capillary flow cell. The ensuing sample fluorescence is collected in the horizontal plane and dispersed using an emission polychromator to form a focused two-dimensional excitation-emission image at a charge coupled device (CCD) pixel array. Each vertical pixel equates to a narrowly defined excitation wavelength band, whilst horizontal pixels equate to corresponding emission wavelengths, with the intensity of light encroaching onto the CCD pixel elements providing the third-dimensional variable in the measurement. It is shown that the extreme sensitivity of CCD detection coupled to the dual polychromator arrangement makes possible the collection of fluorescence excitation-emission-intensity data of polycyclic aromatic hydrocarbons in a flow stream in less than 0.05 s with nanogram per millilitre limits of detection.