Ultrasensitive assays of trans- and cis-β-carotenes in vegetable oils by high-performance liquid chromatography–thermal lens detection

Luterotti, Svjetlana; Franko, Mladen; Šikovec, Mateja; Bićanić, D.

doi:10.1016/s0003-2670(02)00228-3

Cited by 24 publications

(14 citation statements)

References 40 publications

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“…For experimental details see the study reported by Gómez Guzman et al [8], Luterotti et al [9], and Franko [10]. The transient photothermal signals were captured and fitted to the model proposed by Shen et al [11] and Baesso et al [12].…”

Section: Methodologiesmentioning

confidence: 99%

Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

Tiburcio-Moreno¹,

Marcelín-Jiménez

Leanos-Castaneda³

et al. 2012

Int J Thermophys

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The stability of vitamin E acetate exposed to ultraviolet (UV) light was studied using three spectroscopic methods. An ethanol solution of vitamin E acetate was treated with either UVC light (254 nm) or UVA light (366 nm) during a period of 10 min followed by a study of UV-Vis optical absorption, then by fluorescence spectroscopy excitation by UV radiation at either 290 nm or 368 nm and, finally the solution was studied by thermal lens spectroscopy. Immediately, the same solution of vitamin E acetate was subjected to the UV irradiation process until completion of six periods of irradiation and measurements. UVC light treatment induced the appearance of a broad absorption band in the range of 310 nm to 440 nm with maximum absorbance at 368 nm, which progressively grew as the time of the exposure to UVC light increases. In contrast, UVA light treatment did not affect the absorption spectra of vitamin E acetate. Fluorescence spectra of the vitamin E acetate (without UV light treatment) showed no fluorescence when excited with 368 nm while exciting with 290 nm, an intense and broad emission band (300 nm to 440 nm) with a maximum at 340 nm appeared. When vitamin E acetate was treated with UVC light, this emission band progressively decreased as the time of the UVC light irradiation grew. No signal from UV-untreated vitamin E acetate could be detected by the thermal lens method. Interestingly, as the time of the UVC light treatment increased, the thermal lens signal progressively grew. Additional experiments performed to monitor the time evolution of the process during continuous UVC treatment of the vitamin E acetate using thermal lens spectroscopy exhibited a progressive increase of the thermal lens signal reaching a plateau at about 8000 s. This study shows that the vitamin E acetate is stable when it is irradiated with UVA light, while the irradiation with UVC light induces the formation of photodegradation products. Interestingly, this photodegradation process using the study of the thermal lens effect could be followed closely even though poor absorption of the photodegraded product of the vitamin E acetate was observed at the laser wavelength used. As the thermal lens method allowed for accurate monitoring of the extent of photodegradation of the vitamin E acetate, this study opens the photodegradation process as a new application to be added to the recent applications of thermal lens spectroscopy in chemical analysis.

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Section: Methodologiesmentioning

confidence: 99%

Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

Tiburcio-Moreno¹,

Marcelín-Jiménez

Leanos-Castaneda³

et al. 2012

Int J Thermophys

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“…16 In the current research as little as 0.3 and 1.1 ng ml Ϫ1 lycopene and ␤-carotene has been measured in the samples. The sensitivity is so high that some extracts needed to be diluted prior to HPLC-TLS analysis.…”

Section: Resultsmentioning

confidence: 83%

Ultratraces of carotenes in tomato purées: HPLC-TLS study

Luterotti

Marković

Franko

et al. 2003

Review of Scientific Instruments

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The present study was designed to provide information about ͑i͒ the profile of carotene pigments and ͑ii͒ trace quantities of lycopene and ␤-carotene left in tomato purées. The ultrasensitive method comprising HPLC and thermal lens spectrometric ͑TLS͒ detection enabled us to detect as low as 0.3 and 1.1 ng ml Ϫ1 lycopene and ␤-carotene in purée extracts, respectively. Total concentration of ␤-carotene and lycopene ͑varying from 3 to 170 ng g Ϫ1 ) in the examined tomato purées may serve as an indicator of the carotene-specific antioxidative capacity of these products. Although conventional spectrophotometry can be used to rapidly assess the quality of products derived from tomatoes, a highly sensitive and selective method such as HPLC-TLS is needed for reliable analyses of samples such as, for example, those subjected to inappropriate storage and/or handling.

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“…It is extremely sensitive and can detect as low as 30 fg of carotenoids per ml in organic solvents, but less in the seawater (0.6 ng per ml) [20,25]. In this experiment, the TLS real-time method enabled detection of 6⋅10 3 lysed S. costatum cells ml -1 .…”

Section: Resultsmentioning

confidence: 93%

New approach in studies of microalgal cell lysis

et al. 2009

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Abstract:A new approach to the studies of the microalgal cell lysis by utilizing a combination of two complementary methods is presented.Delayed fluorescence (DF) is a measure of the living algal biomass, detecting only cells with active photosynthesis. Thermal lens spectrometry (TLS) detects the total pigment amount released from lysed cells. Both methods select for photosynthetic organisms, reducing possible background from other sources (e.g. heterotrophic bacteria, zooplankton, and abiotic substances). The DF/TLS method was tested with a laboratory Skeletonema costatum culture exposed to a geometric dilution series of the lysing factor poly-APS. The exposure resulted in similar EC 50 values for DF intensity, TLS and dissolved esterase activity of 0.8±0.2, 1.77±0.35, and 1.25±0.1 mg poly-APS l -1 , respectively. The combined DF/TLS method enabled a rapid evaluation of the living vs. dead cells without any sample pretreatment or manipulation.

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Ultrasensitive assays of trans- and cis-β-carotenes in vegetable oils by high-performance liquid chromatography–thermal lens detection

Cited by 24 publications

References 40 publications

Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

Ultratraces of carotenes in tomato purées: HPLC-TLS study

New approach in studies of microalgal cell lysis

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