On-line thermal lens spectrometric detection of Cr(III) and Cr(VI) after separation by ion chromatography

Šikovec, Mateja; Novič, Milko; Hudnik, V.; Franko, Mladen

doi:10.1016/0021-9673(95)00139-e

Cited by 39 publications

(12 citation statements)

References 7 publications

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“…Equipment. The instrument used in this study was constructed in the laboratory (11). The dual beam TLS spectrometer consisted of an intensity-modulated continuous-wave Arion laser (60 mW at 476 nm) used as a pump beam, and the He-Ne laser (20 mW at 632.8 nm) acted as a probe beam.…”

Section: Methodsmentioning

confidence: 99%

Fast quality screening of vegetable oils by HPLC‐thermal lens spectrometric detection

Luterotti

Franko

Bićanić

2002

J Americ Oil Chem Soc

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Isocratic reversed-phase HPLC with thermal lens spectrometric (TLS) detection enabled identification of linseed, olive, sesame, and wheat germ vegetable oils to control the authenticity of the oils based on characteristic carotenoid/carotene profiles. Four characteristic regions of carotenoids (i.e., lutein, xanthophyll, carotene, and lycopene) have been identified in each type of oil. The concentrations of total β-carotene (BC) and α-carotene (AC), together with trans-to cis-isomers of β-carotene (TBC/CBC) and BC/AC ratios were shown to be reliable and useful indices for fast screening of oils for nutritional quality. The oil TBC/CBC ratio and the BC concentration (in µg/mL) should meet the following numerical criteria: linseed (≥2:1, ≥1.7), olive (≥3:1, ≥0.4), sesame (≥1:1, ≥0.1), and wheat germ oil (≥1:1, ≥1.7). Based on the above criteria, unsatisfactory olive oils differed significantly from the consumable ones. Likewise, the concentration of AC in consumable wheat germ and sesame oil should not be lower than 0.6 and 0.02 µg/mL, respectively. The AC level in safflower oil should not be higher than 0.04 µg/mL. The BC/AC ratios exceeding 3:1, 6:1, and 8:1 should be used as an additional quality requirement for consumable wheat germ, sesame, and safflower oil, respectively.Profiling of carotenoids in vegetable oils is of great nutritional and epidemiological interest. The separation, identification, and quantitation of trans/cis-isomers of β-carotene (TBC, CBC) in edible oils is important to measure antioxidant activity and for quality control. The cis-isomer(s) are either naturally present or formed during the processing of oils. In fruits and vegetables all-trans-β-carotene has been shown to undergo cis-isomerization (1), with the 9-cis-and 13-cis-stereoisomers being the predominant isomerization products.Various studies on the distribution of pigments in olives and olive oils have shown that the characteristics of olive oil depend on genetic, agronomic, environmental, and processing factors (2-7). The content of pigments differs greatly among single-variety virgin olive oils. Arbequina variety olives have chlorophyllides, esterified xanthophylls, α-carotene (AC), ξ-carotene, and phytofluene that are exclusive to this variety (2).The carotenoid (17-19%) and total chlorophyll (81-83%) fractions dominate in fresh olives, whereas lutein (10-11%) and β-carotene (4-5%) are the most abundant among the carotenoids (3). In virgin olive oils the concentration of total xanthophylls (including neoxanthin, mutatoxanthin, antheraxanthin, luteoxanthin, and violaxanthin) varies between 0.3 and 1.6 µg/g, whereas those of pheophytins, lutein, and β-carotene range from 3.3 to 51.4, 0.2 to 9.3, and 0.3 to 7.7 µg/g, respectively (3-7). However, the chlorophyll and carotenoid contents gradually decrease during olive fruit ripening (2). Separation, identification, and quantification of carotenoids and chlorophylls in olive fruit and in olive oils based on normal-phase HPLC (5,6), reversed-phase ion-pair HPLC (2,4), and TLC (3) hav...

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Section: Methodsmentioning

confidence: 99%

Fast quality screening of vegetable oils by HPLC‐thermal lens spectrometric detection

Luterotti

Franko

Bićanić

2002

J Americ Oil Chem Soc

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“…8-Hydroxyquinoline (or oxine) and its derivatives have been well studied for the solvent extraction of metal ions. 7,8,[15][16][17][18][19][20] Other examples involve bis-2-ethylhexyl succinamic acid for lanthanides, 21 1,5-diphenylcarbazide for Cr(VI) and/or Cr(III) after its oxidation to Cr(VI), 22,23 1,10-phenanthroline (abbreviated as Phen in the complex) for Fe(II) and/or Fe(III) after its reduction to Fe(II), 1,23,24 precipitation of salicylic acid (abbreviated as SA in the complex) by Fe(III), 25 and dimethylglyoxime for Ni(II). 1 In this paper, Fe(III) and Fe(II) were separated and determined via in-column and post-column reaction with salicylic acid and 1,10-phenanthroline as eluent and complexing reagent.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Determination of Fe(III) and Fe(II) Ions via Complexation with Salicylic Acid and 1,10-Phenanthroline in Microcolumn Ion Chromatography

2008

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Fe(III) and Fe(II) ions were separated and determined via in-column and post-column reactions with salicylic acid and 1,10-phenanthroline by microcolumn ion chromatography with UV-Vis detection. The separation could be achieved on a silica microcolumn using an aqueous ethanol solution of salicylic acid as eluent. The effluent from the column was then mixed with aqueous ethanol solution of 1,10-phenanthroline and detected at 518 nm. Fe(III) ion was detected as the complex with salicylic acid, whereas Fe(II) ion was detected as the complex with 1,10-phenanthroline. The detection limits with 0.25 mL injection volume at S/N = 3 were 0.21 and 0.10 mg L -1 for Fe(III) and Fe(II), respectively. Increasing the injection volume of sample, e.g., 5.1 mL, improved the sensitivity; the detection limits at S/N = 3 were 12 and 9.2 mg L -1 for Fe(III) and Fe(II), respectively. The present system was applied to the determination of iron in a local well water sample.

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“…For detection of Cr(VI), a postcolumn derivatization with DPC is needed (51). Comparative analysis of drinking water samples has revealed another advantage of TLS detection, which was found much less affected by light scattering, resulting from CO 2 released in acidified samples containing higher levels of carbonate.…”

Section: Ic-tls and Ce-tlsmentioning

confidence: 99%

Thermal Lens Spectrometric Detection in Flow Injection Analysis and Separation Techniques

Franko

2008

Applied Spectroscopy Reviews

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Recent applications of thermal lens spectrometry in liquid chromatography (HPLC, ion chromatography), capillary electrophoresis, and flow injection analysis are reviewed. Possible effects of performing TLS measurements in flows are discussed initially for different TLS configurations. The emphasis is given to the analysis of real samples, and the performances of various detection schemes in combination with chromatographic techniques and FIA are discussed particularly in terms of sensitivity, sample throughput, and eventual interferences from complex matrices. Coaxial TLS detection with continuous wave excitation is most suitable for detection in HPLC, ion chromatography, and FIA using long-path length cells, when large volume samples are available. On the other hand, transverse or crossed beam TLS was found most suitable for detection in CE where it provides low absolute LODs, which are lowered even further by thermal lens microscopy on microchips, where the capability of detecting a single molecule in the detection volume was demonstrated.

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On-line thermal lens spectrometric detection of Cr(III) and Cr(VI) after separation by ion chromatography

Cited by 39 publications

References 7 publications

Fast quality screening of vegetable oils by HPLC‐thermal lens spectrometric detection

Fast quality screening of vegetable oils by HPLC‐thermal lens spectrometric detection

Simultaneous Determination of Fe(III) and Fe(II) Ions via Complexation with Salicylic Acid and 1,10-Phenanthroline in Microcolumn Ion Chromatography

Thermal Lens Spectrometric Detection in Flow Injection Analysis and Separation Techniques

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