A Fast and Efficient Ultrasound-Assisted Extraction of Tocopherols in Cow Milk Followed by HPLC Determination.

A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and allowing a fast quantification of α-tocopherol, δ-tocopherol and γ tocopherol. The optimized ultrasonic extraction combines an efficient and simple saponification at room temperature and a rapid HPLC quantification of TOCs in milk. The precision of the full analytical procedure was satisfactory and the recoveries at three spiked levels were between 95.3% and 87.8%. The linear correlations were evaluated (R2 > 0.99) and the relative standard deviation (RSD) values for intra-day and inter-day tests at three spiked levels were below 1% for the retention time and below 5.20% for the area at low level spiking. The proposed procedure, reducing the experimental complexity, allowed accurate extraction and detection of three TOCs in milk samples from Modicana cattle breed.

UPLC-MS/MS method for determination of retinol and α-tocopherol in serum using a simple sample pretreatment and UniSpray as ionization technique to reduce matrix effects.

Background Our goal was to develop a simple, rapid and precise ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of retinol and α-tocopherol in serum. Currently published LC-MS/MS methods either require complex extraction procedures (liquid-liquid or solid-phase) or do not meet desirable specifications for imprecision in serum (coefficient of variation [CV] <6.8% and 6.9%, respectively). Methods Sample preparation consisted of a simple protein precipitation with ethanol and acetonitrile. Stable isotope-labeled internal standards (IS) and a homemade calibration curve were used for quantification. The analysis was performed using an Acquity I-class Xevo TQ XS LC-MS/MS. Chromatographic runtime was 6.0 min using a reversed phase gradient elution. UniSpray (US) as an ionization technique was compared to electrospray ionization (ESI). Analytical validation included matrix effect, recovery and trueness compared to National Institute of Standards and Technology (NIST) standards and United Kingdom National External Quality Assessment Service (UK NEQAS) samples. Results Intra- and inter-run CVs were <4.9% for retinol and <1.7% for α-tocopherol, both complying with desirable specifications for imprecision. Bias compared to NIST standards was <3.1% for both compounds. The method was linear over the entire tested range. The lower limit of quantification (LLOQ) with US was lower than with ESI for both retinol (0.022 vs. 0.043 mg/L) and α-tocopherol (0.22 vs. 0.87 mg/L). Matrix effects were not significant (<15%) for retinol. However, for α-tocopherol matrix effects of on average 54.0% were noted using ESI, but not with US. Conclusions We developed a fast, precise and accurate UPLC-MS/MS method for the determination of retinol and α-tocopherol in human serum using a single-step sample pretreatment. Ionization using US eliminated the matrix effects for α-tocopherol.

Thermoprotective properties of Opuntia ficus-indica f. inermis cladodes and mesocarps on sheep lymphocytes.

This study aims to investigate the thermoprotective properties of Opuntia ficus-indica f. inermis. Extracts were prepared from cladodes (CE) and mesocarps (ME), then subjected to a spectrophotometric and LC-MS analyses. Lymphocytes were isolated from peripheral blood of non-stressed sheep, supplemented with CE, ME, betanin or α-tocopherol, and subjected to two thermal treatments: 40 and 41 °C, for 6 h. Viable lymphocytes and H2O2 production were evaluated. The antioxidant activity of ME was 3.43 folds higher than CE. The LC-MS analysis of CE and ME allowed identifying 11 phenolic acids, 2 flavanones, 6 flavones, 3 flavonols and 1 betanin type betacyanin. Lymphocytes mortality increased linearly as function of the severity and the duration of heat stress. This mortality was correlated with H2O2 production. At 41 °C, only ME allowed maintaining lymphocytes viability. Moreover, ME was more efficient than CE in reducing H2O2 production. This thermoprotection was ensured by betaxanthin and betacyanin pigments. Interestingly, betanin was more efficient than α-tocopherol in preventing hyperthermia-induced lymphocytes' mortality. We report here for the first time the thermoprotective properties of cladodes and mesocarps of Opuntia ficus-indica f. inermis. Betanin was able to maintain lymphocyte viability through reducing H2O2 production, and therefore the oxidative-induced heat stress.

Extraction of Carotenoids and Fat-Soluble Vitamins from Tetradesmus Obliquus Microalgae: An Optimized Approach by Using Supercritical CO2.

In recent years, great attention has been focused on rapid, selective, and environmentally friendly extraction methods to recover pigments and antioxidants from microalgae. Among these, supercritical fluid extraction (SFE) represents one of the most important alternatives to traditional extraction methods carried out with the use of organic solvents. In this study, the influence of parameters such as pressure, temperature, and the addition of a polar co-solvent in the SFE yields of carotenoids and fat-soluble vitamins from T. obliquus biomass were evaluated. The highest extraction of alpha-tocopherol, gamma-tocopherol, and retinol was achieved at a pressure of 30 MPa and a temperature of 40 °C. It was observed that overall, the extraction yield increased considerably when a preliminary step of sample pre-treatment, based on a matrix solid phase dispersion, was applied using diatomaceous earth as a dispersing agent. The use of ethanol as a co-solvent, under certain conditions of pressure and temperature, resulted in selectively increasing the yields of only some compounds. In particular, a remarkable selectivity was observed if the extraction was carried out in the presence of ethanol at 10 MPa and 40 °C: under these conditions, it was possible to isolate menaquinone-7, a homologous of vitamin K2, which, otherwise, cannot not recovered by using traditional extraction procedures.

Identification of α-tocopherol as a bioactive component of Dicranopteris linearis with disrupting property against preformed biofilm of Staphylococcus aureus.

AIMS: The potential of Dicranopteris linearis leaves' extract and its bioactive components were investigated for the first time for its disrupting ability against Staphylococcus aureus biofilms. METHODS AND RESULTS: The leaves of D. linearis were subjected to sonication-assisted extraction using hexane (HEX), dichloromethane, ethyl acetate and methanol (MeOH). It was found that only the MeOH fraction exhibited antimicrobial activity using broth microdilution assay; while all four fractions do not exhibit biofilm inhibition activity against S. aureusATCC 6538P, S. aureusATCC 43300, S. aureusATCC 33591 and S. aureusATCC 29213 using crystal violet assay. Among the four fractions tested, only the HEX fraction showed biofilm disrupting ability, with 60-90% disruption activity at 5 mg ml-1 against all four S. aureus strains tested. Bioassay-guided purification of the active fraction has led to the isolation of α-tocopherol. α-Tocopherol does not affect the cells within the biofilms but instead affects the biofilm matrix in order to disrupt S. aureus biofilms. CONCLUSIONS: α-Tocopherol was identified to be the bioactive component of D. linearis with disruption activity against S. aureus biofilm matrix. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of α-tocopherol as a biofilm disruptive agent might potentially be useful to treat biofilm-associated infections in the future.

The Effect of Pressure and Solvent on the Supercritical Fluid Chromatography Separation of Tocol Analogs in Palm Oil.

There are six tocol analogs present in palm oil, namely α-tocopherol (α-T), α-tocomonoenol (α-T1), α-tocotrienol (α-T3), γ-tocotrienol (γ-T3), ß-tocotrioenol (ß-T3) and δ-tocotrienol (δ-T3). These analogs were difficult to separate chromatographically due to their similar structures, physical and chemical properties. This paper reports on the effect of pressure and injection solvent on the separation of the tocol analogs in palm oil. Supercritical CO2 modified with ethanol was used as the mobile phase. Both total elution time and resolution of the tocol analogs decreased with increased pressure. Ethanol as an injection solvent resulted in peak broadening of the analogs within the entire pressure range studied. Solvents with an eluent strength of 3.4 or less were more suitable for use as injecting solvents.

Identification and evaluation of antioxidants in Japanese parsley.

Two cultivars of Japanese parsley were harvested in different seasons; their antioxidant capacities were evaluated by oxygen radical absorbance capacity (ORAC) methods, and the contents of hydrophilic and lipophilic antioxidants were compared. Japanese parsley possessed potent antioxidant capacities both in hydrophilic and lipophilic extracts when evaluated by ORAC methods. LC/MS/MS analyses revealed that chlorogenic acid and four kinds of quercetin glycosides were major antioxidants in the hydrophilic extract. Lutein was the main contributor to the antioxidant capacity of the lipophilic extract. Antioxidant capacities of the hydrophilic extracts of both cultivars tended to be higher in winter because of the increase in the contents of chlorogenic acid and quercetin glycosides. An obvious trend in the lipophilic antioxidant capacities or lutein contents was not observed irrespective of the cultivar.

First chemical evaluation and toxicity of Casinga-cheirosa to Balb-c male mice.

Laetia suaveolens, known as "casinga-cheirosa", crude extract EB719 has previously shown cytotoxic activity against prostate cancer and squamous cell carcinoma. For the first time, seven molecules were isolated from its apolar-α-tocopherol (1) and sitosterol (2)-and polar-3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-feruloylquinic acid (5), hyperoside (6), and isoquercitrin (7)-fractions. Acute toxicity was determined in a two-stage experiment: (1) a reduced number of Balb-c male mice received 5000 mg/kg of EB719 to allow evaluation of general activity and other 27 parameters, plus death, up to the establishment of non-lethal dose (NLD), as well as lethal dose 50% (LD50); (2) NLD was administered and diazepam introduced as reference drug. EB719 showed LD50=178.0 mg/kg, and NLD 156.3 mg/kg. In stage one EB719 did not influence general activity, but provoked impairment in grasp reflexes, tail squeeze and breathing; piloerection and cyanosis were increased. In stage two, alterations occurred in auricular reflex, piloerection and breathing after diazepam administration, but not in response to EB719. Intestinal hemorrhage caused by local bleeding was observed after necropsy, and may be the main cause of animals' death other than a systemic effect of the extract. Although the isolated compounds are biologically and pharmacologically active in both men and animal systems, it is premature to relate their occurrence in EB719 to the observed intestine hemorrhage in mice.

Rapid determination of α-tocopherol in cereal grains using dispersive liquid-liquid microextraction followed by HPLC.

The traditional for the determination of α-tocopherol in cereal grains includes saponification of a sample followed by liquid-liquid extraction, and it is time- and solvent consuming. In this study, a dispersive liquid-liquid microextraction (DLLME) method was developed to extract α-tocopherol in situ from the saponified grain sample solution. The DLLME experimental parameters including the type and volume of extractants, the volume of dispersers, the addition of salt and the extraction/centrifuging time were examined and optimized. The recommended analytical procedure showed excellent precision (relative SDs of the α-tocopherol amount of 3.1% over intraday and 7.2% over interday), high sensitivity (the detection limit of 1.9 ng/mL), and strong recovery values (88.9-102.5%). In addition, statistical analyses showed no significant difference between the detected amounts of α-tocopherol found by the standardized method and this new procedure. The method was successfully applied to determining the amounts and distribution of α-tocopherol in 14 cereal grain samples.

Inhibitory effect of PMC, a potent hydrophilic α-tocopherol derivative, on vascular smooth muscle cell proliferation: the pivotal role of PKC-α translocation.

CONTENT: Vascular smooth muscle cells (VSMCs) play a major role in the pathogenesis of atherosclerosis and restenosis, and thus the excessive proliferation of VSMCs contributes to neointimal thickening during atherosclerosis and restenosis. PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane) is the most potent hydrophilic derivative of the alpha-tocopherols; it acts as a potent anti-inflammatory and free-radical scavenger. OBJECTIVE: The present study was designed to examine the inhibitory mechanisms of PMC in VSMC proliferation. MATERIALS AND METHODS: VSMC proliferation and cytotoxicity were measured by MTT and LDH assays, respectively. The cell cycle and translocation of PKC-alpha in VSMCs were used by flow cytometry and confocal microscope, respectively. To detect PKC-alpha translocation and activation in VSMCs, immunoblotting was performed in the present study. RESULTS: In this study, we demonstrate an anti-proliferative effect of PMC in VSMCs. Concentration-dependent inhibition of serum-induced VSMC proliferation was observed in PMC (20 and 50 muM)-treated cells. PMC pretreatment also arrested VSMC cell cycle progression at the G2/M phase. Furthermore, PMC exhibited obvious inhibitory effects on phorbol 12-myristate 13-acetate (PMA)-induced protein kinase C (PKC)-alpha translocation and phospho-(Ser/Thr) substrate phosphorylation. DISCUSSION AND CONCLUSION: The inhibitory mechanisms of PMC on VSMC proliferation is mediated, at least in part, by inhibition of PKC-alpha translocation and causes cell cycle arrest in the G2/M phase. PMC treatment may represent a novel approach for lowering the risk of or improving function in abnormal VSMC proliferation-related vascular diseases.

Efficient solid phase extraction of α-tocopherol and ß-sitosterol from sunflower oil waste by improving the mesoporosity of the zeolitic adsorbent.

The recovery of α-tocopherol and ß-sitosterol from the deodorizer distillate of sunflower oil using solid phase extraction is reported. Performance of the silicon-rich and inexpensive zeolite, ZSM-5, and its modified versions were compared as adsorbents. Modifications of the zeolite frame were performed under both acidic and basic conditions to desilicate and dealuminate the parent ZSM-5. Base treatment resulted in hierarchical porosity and increased mesoporosity in the structure, which made the desilicated material as the best adsorbent of the study. Optimization of the solid phase extraction conditions was also studied and high recoveries of α-tocopherol and ß-sitosterol, up to 99.20% and 97.32%, respectively, were achieved. The preparation and characterisation of the reported sorbents, as high-performance adsorbents, were not only proved to be economically promising, due to recycling of nutritious products, but also improves the ecological credentials of the process through reduction in waste.

Whey protein isolate-gelatin nanoparticles enable the water-dispersibility and potentialize the antioxidant activity of quinoa oil (Chenopodium quinoa).

The quinoa oil presents benefits to health, but its low water dispersibility in the aqueous matrix and instability of bioactive compounds is challenging for food application. This study performed the physicochemical and chemical characterization of quinoa oil and evaluated its water dispersibility and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity after nanoencapsulation in porcine gelatin and combination with whey protein isolate by emulsification O/W technique. Thus, three formulations were obtained: 1) OG-containing quinoa oil and porcine gelatin in aqueous phase 2; 2) OWG1-containing quinoa oil, whey protein isolate, and porcine gelatin in aqueous phase 2; and 3) OWG2-containing quinoa oil and whey protein isolate in aqueous phase 1, and porcine gelatin in aqueous phase 2. The oil characterization showed that quinoa oil presented the predominance of linoleic acid (53.4%), and concentration of alpha and gamma-tocopherol, respectively, of 8.56 and 6.28 mg.100g-1. All formulations presented a smooth surface without depression or cracking, an average diameter between 165.77 and 529.70 nm. Fourier transform infrared spectroscopy indicated chemical interaction between the encapsulating agents and the oil in all formulations, being more intensified in OWG1 and OWG2. Based on this, these formulations showed higher dispersibility in aqueous solution [68% (3.48) and 71% (2.97)]. This resulted in higher antioxidant activity for OWG1 and OWG2, showing the amounts that reduces antioxidant activity by 50% equal to 5.30 (0.19) mg/mL and 5.54 (0.27) mg/mL, respectively, compared to quinoa oil [13.36 (0.28) mg/mL] (p < 0.05). Thus, quinoa oil nanoencapsulation proved to be an efficient alternative to enable water-dispersibility and enhance antioxidant activity, increasing its potential for application in the food industry.

[Studies on the chemical constituents of the fruit of Xylocarpus granatum].

OBJECTIVE: To study the chemical constituents of the fruit of Xylocarpus granatum. METHODS: The chemical constituents were isolated by chromatographic methods and their structures were elucidated by NMR spectra and physicochemical properties. RESULTS: Ten compounds were isolated from the fruit of Xylocarpus granatum and the structures of them were identified as spicatin (1), xyloccensin K(2), 6-acetoxycedrodorin (3), aurantiamide acetate (4), (+)-catechin (5), alpha-tocopherol (6), abscisic acid (7), daucosterol (8), 4-hydroxybenzoic acid (9) and ethyl 3,4-dihydroxybenzoate (10). CONCLUSION: Compound 4 -10 are isolated from this plant for the first time.

Antioxidant pectin enriched fractions obtained from discarded carrots (Daucus carota L.) by ultrasound-enzyme assisted extraction.

Carrot residues were upgraded as pectin-enriched fractions (PEFs) useful for functional food formulation due to co-extracted antioxidants (α- and ß-carotenes, lutein, α-tocopherol), and gelling effect. High power ultrasound (US)-enzyme assisted extraction was applied for efficiency and sustainability. Carrot powder (CP) in citrate-buffer (pH 5.20) was submitted to US-pretreatment (12.27 W/cm2: 20 kHz, 80% amplitude, 20 min) and a subsequent digestion (5 h-40 °C) without or with hemicellulase or cellulase. US-hemicellulase led to the highest PEF yield (27.1%), and extracted almost the whole pectin content of CP. US-pretreatment increased the extraction yield of all PEFs, but the existence of an additional positive effect of the following step depended on the enzyme used. PEFs contained 40-47% of UA with low DM (24-49.9%), and co-extracted antioxidants. US decreased the antioxidant contents, DM, and molecular weight, but allowed obtaining calcium crosslinked true gels, also with higher elastic modulus than non-US-extracted PEFs, being promising as food additives.

Lipid Characteristics of Camellia Seed Oil.

Camellia oleifera, C. japonica and C. sinensis are three representative crops of the genus Camellia. In this work, we systematically investigated the lipid characteristics of these seed oils collected from different regions. The results indicated significant differences in acid value (AV), peroxide value (PV), iodine value (IV), saponification value (SV) and relative density of the above-mentioned camellia seed oils (p < 0.05). The C. japonica seed oils showed the highest AV (1.7 mg/g), and the C. sinensis seed oils showed the highest PV (17.4 meq/kg). The C. japonica seed oils showed the lowest IV (79.9 g/100 g), SV (192.7 mg/g) and refractive index (1.4633) of all the oils, while the C. sinensis seed oils showed the lowest relative density (0.911 g/cm3). The major fatty acids in the camellia seed oils were palmitic acid (16:0), oleic acid (18:1) and linoleic acid (18:2); the oleic acid in C. oleifera and C. japonica seed oils accounted for more than 80% of the total fatty acids. The oleic acid levels in the C. oleifera and C. japonica oils were higher than those in the C. sinensis seed oils, while the linoleic acid levels in the former were lower than those in the latter one. Differences also exist in the triacylglycerol (TAG) composition, although the most abundant TAG molecular species in the camellia seed oils was trioleoylglycerol (OOO). Seven sterol species, squalene and α-tocopherol were detected in the camellia seed oils, however, the contents of tocopherol and unsaponifiable molecules in the C. oleifera and C. japonica seed oils were significantly lower than those in the C. sinensis seed oil. These results demonstrated that the varieties of Camellia affected the seed oil lipid characteristics.

Determination of antioxidant components in rice bran oil extracted by microwave-assisted method.

Rice bran oil was extracted by microwave-assisted extraction with isopropanol and hexane using a solvent-to-rice bran ratio of 3:1 (w/w). The experiments were done in triplicate at 40, 60, 80, 100, and 120 degrees C with a total extraction time of 15 min/sample. The oil components were separated by normal-phase HPLC and quantified with a fluorescence detector. The radical scavenging capability of the oil was tested with DPPH and was expressed as mumol Trolox Equivalent Antioxidant Activity. The increase in total vitamin E with temperature from 40 to 120 degrees C was 59.63% for isopropanol and 342.01% for hexane. Isopropanol was the best solvent for the extraction of gamma-tocopherol and gamma-tocotrienol as compared with hexane for both microwave-assisted and conventional solvent extraction. Isopropanol was better for oil yield extraction at high temperatures. Samples extracted with isopropanol at 120 degrees C had higher antioxidant activity. No differences in oil yield, total vitamin E, and antioxidant activity of oil was noticed between the two methods (microwave-assisted and solvent extractions), at 40 degrees C. No degradation of alpha-tocopherol was noticed during the process.

Comparison of extraction methods for quantifying vitamin E from animal tissues.

Four extraction methods: (1) solvent (SOL), (2) ultrasound assisted solvent (UA), (3) saponification and solvent (SP), and (4) saponification and ultrasound assisted solvent (SP-UA), were used in sample preparation for quantifying vitamin E (tocopherols) in chicken liver and plasma samples. The extraction yields of SOL, UA, SP, and SP-UA methods obtained by adding delta-tocopherol as internal reference were 95%, 104%, 65%, and 62% for liver and 98%, 103%, 97%, and 94% for plasma, respectively. The methods with saponification significantly affected the stabilities of tocopherols in liver samples. The measured values of alpha- and gamma-tocopherols using the solvent only extraction (SOL) method were much lower than that using any of the other extraction methods. This indicated that less of the tocopherols in those samples were in a form that could be extracted directly by solvent. The measured value of alpha-tocopherol in the liver sample using the ultrasound assisted solvent (UA) method was 1.5-2.5 times of that obtained from the saponification and solvent (SP) method. The differences in measured values of tocopherols in the plasma samples by using the two methods were not significant. However, the measured value of the saponification and ultrasound assisted solvent (SP-UA) method was lower than either the saponification and solvent (SP) or the ultrasound assisted solvent (UA) method. Also, the reproducibility of the ultrasound assisted solvent (UA) method was greater than any of the saponification methods. Compared with the traditional saponification method, the ultrasound assisted solvent method could effectively extract tocopherols from sample matrix without any chemical degradation reactions, especially for complex animal tissue such as liver.

Phytochemical analysis of non-polar solvent extracts of the Wisteria sinensis leaves.

A comparative study on the phytochemical composition of the n-hexane and chloroform extracts from Wisteria sinensis leaves collected in June and October is described. Continuous extraction in Soxhlet apparatus, as well as ultrasound-assisted technique, was used for the preparation of the extracts. All the extracts were analysed by GC/MS method. As a result, α-tocopherol was identified as the main component (56%) of the extracts from October leaves, whereas, ß-sitosterol was identified as the main compound (47%) in the extracts from the June leaves. Additionally, pure α-tocopherol was isolated from n-hexane extract of the October leaves using column chromatography. A total of 6.25 mg of α-tocopherol was isolated from 1 g of dried leaves. The presence of the vitamin E in extracts from W. sinensis leaves is described here for the first time.

Biological Active Ecuadorian Mango 'Tommy Atkins' Ingredients-An Opportunity to Reduce Agrowaste.

Mango is a commercially important tropical fruit. During its processing, peel and seed kernel are discarded as waste but they could be recovered as an excellent and cost-effective source of health-promoting ingredients. This study aimed to characterize some of them, including carotenoids like the provitamin A ß-carotene and lutein, with an interest beyond its role in eye health. Other health-promoting compounds like tocopherols and polyphenols were also evaluated, as well as the in vitro antioxidant capacity of mango by-products. Regarding isoprenoids, α-tocopherol was mainly found in the peels and carotenoids concentration was higher in the pulps. ß-carotene was the most abundant carotene in pulp and seed kernel, whereas peel was the only source of lutein, with violaxanthin the most abundant xanthophyll in the different mango organs tested. With regard to polyphenols, peels exhibited greater variability in its phenolic composition, being the total content up to 85 and 10 times higher than the pulp and seed kernels, respectively. On the other hand, peels also stood out for being a very rich source of mangiferin. Seed kernels and peels showed higher antioxidant capacity values than the pulps. These results contribute to the valorization of mango by-products as new natural ingredients for the pharma and food industries.

Microemulsion electrokinetic chromatography for the separation of retinol, cholecalciferol, delta-tocopherol and alpha-tocopherol.

A microemulsion electrokinetic chromatographic method was used to separate fat-soluble vitamins. The separation of retinol, cholecalciferol, and delta- and alpha-tocopherol was performed using a microemulsion containing 0.75% (v/v) n-heptane, 30 mM bis(2-ethylhexyl)sodium sulfosuccinate (AOT), 5% (v/v) 1-butanol, 15% (v/v) 1-propanol and 15% (v/v) methanol in 20mM boric acid-sodium borate buffer. The effect of the different microemulsion constituents was studied, including the type and concentration of surfactant, buffer, oil and co-surfactants. The presence of methanol in the microemulsion was found to be necessary to achieve the separation of the tocopherols. Detection was carried out at 200, 265 and 325 nm for the tocopherols, cholecalciferol and retinol, respectively. Calibration curves and precision data were obtained for each analyte. Good linear relationships were found between the analytical signal and the analytes concentration in the 25-500 mg L(-1) for retinol and cholecalciferol, and 25-300 mg L(-1) for tocopherols ranges. The precision of the method afforded relative standard deviations in the 4.0-10% range.