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This paper develops an instrumental analytical approach for detection of fourteen polycyclic aromatic hydrocarbons (PAHs) in edible oil samples using gel permeation chromatography (GPC) and ultra-high performance liquid chromatography (UHPLC) coupled with diode array detector (DAD), and fluorescence detector (FLD). The GPC was used to remove triglycerides from edible oil samples. The extracted samples were then detected using UHPLC—DAD—FLD. In order to obtain good separation and high reproducibility, the UHPLC—DAD—FLD experimental condition was optimized. The PAHs including three groups of isomeric PAHs can be separated completely in 12 min using BEH Shield RP 18 column with a suitable gradient elution program. The mean recoveries were in the range of 73–110% with an acceptable reproducibility (RSD < 10%, n = 3). During real sample analysis, the method can decrease the chance of false positives with both DAD and FLD being used simultaneously. The results indicate that the approach is simple, easy, and acceptably reproducible, thereby showing great potential as a method for detection of fourteen PAHs contained in edible oil samples.

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We will present the first example of a two-dimensional scanned TLC-plate, measured by use of a diode-array scanner. A spatial resolution of 250 μm was achieved on plate. The system provides real 2D fluorescence and absorption spectra in the wavelength-range from 190 to 1000 nm with a spectral resolution of greater than 1 nm. A mixture of 12 sulphonamides was separated by using a cyanopropyl-coated silica gel plate (Merck, 1.16464) with the solvent mix of methyl tert-butyl ether-methanol-dichloromethane-cyclohexane-NH3 (25%) (48:2:2:1:1, v/v) in the first and with a mixture of water-acetonitrile-dioxane-ethanol (8:2:1:1, v/v) in the second direction. Both developments were carried out over a distance of 70 mm. A separation number (spot capacity) of 259 was calculated. We discussed a new formula for its calculation in 2D-TLC separations. The drawback of this method is that measuring a 2D-TLC plate needs more than 3 h measurement time.

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High performance thin layer chromatography (HPTLC) is a frequently used separation technique which works well for quantification of caffeine and quinine in beverages. Competing separation techniques, e.g. high-performance liquid chromatography (HPLC) or gas chromatography (GC), are not suitable for sugar-containing samples, because these methods need special pretreatment by the analyst. In HPTLC, however, it is possible to separate ‘dirty’ samples without time-consuming pretreatment, because disposable HPTLC plates are used. A convenient method for quantification of caffeine and quinine in beverages, without sample pretreatment, is presented below. The basic theory of in-situ quantification in HPTLC by use of remitted light is introduced and discussed. Several linearization models are discussed.A home-made diode-array scanner has been used for quantification; this, for the first time, enables simultaneous measurements at different wavelengths. The new scanner also enables fluorescence evaluation without further equipment. Simultaneous recording at different wavelengths improves the accuracy and reliability of HPTLC analysis. These aspects result in substantial improvement of in-situ quantitative densitometric analysis and enable quantification of compounds in beverages.

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mass spectrometry (LC–QqQ-MS) [ 26 ]. High-performance liquid chromatography (HPLC) is a widely used method in terms of simplicity, rapidity, and high efficiency. Diode array detector (DAD) has many advantages, such as high selectivity, high sensitivity

Open access
Acta Chromatographica
Authors: Yun Wang, Jianhong Chen, Yutian Li, Puling Li, Javed Iqbal, Ying Chen, Yinlian Ma, and Cun Zhang

different concentration for linear validation. Apparatus and HPLC Analysis HPLC was performed on a Shimadzu HPLC system (Shimadzu Corporation, Japan) equipped with an LC-20AT binary pump, an SPD-M20A diode array detector

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employed CE system consisted of an Agilent CE instrument (Agilent Technologies Deutschland, Waldbronn, Germany) equipped with a diode array detector (DAD) and a data handling system comprised of an IBM personal computer and Agilent ChemStation software

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A new formula is presented for transforming fluorescence measurements in accordance with Kubelka-Munk theory. The fluorescence signals, the absorption signals, and data from a selected reference are combined in one expression. Only diode-array techniques can measure all the required data simultaneously to linearize fluorescence data correctly. To prove the new theory HPTLC quantification of the analgesic flupirtine was performed over the mass range 300 to 5000 ng per spot. The fluorescence calibration curve was linear over the whole range. The transformation of fluorescence measurements into linear mass-dependent data extends the technique of in-situ fluorescence analysis to the high concentration range. It also extends Kubelka-Munk theory from absorption to fluorescence analysis. The results presented also emphasize the importance of Kubelka-Munk theory for in-situ measurements in scattering media, especially in planar chromatography.

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consisting of a quatpump, an online degasser, an auto plate-sampler, a column oven, and a diode array detector (DAD). All separation steps were carried out on an Agilent Eclipse plus C 18 column (4.6 mm × 250 mm, 5 μm). The mobile phase was composed of 1

Open access

chromatography-diode array detector-hyphenated with tandem mass spectrometry (HPLC–DAD–ESI-MS/MS) was performed to investigate the dynamic changes of trifoliate oranges during the different fermentation statues. Multivariate statistical analyses, including

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chromatography-diode array detector-hyphenated with tandem mass spectrometry (HPLC–DAD–ESI-MS/MS) was performed to investigate the dynamic changes of trifoliate oranges during the different fermentation statues. Multivariate statistical analyses, including

Open access