The stability of retinol, α-tocopherol, trans-lycopene, and trans--carotene in liquid-frozen and lyophilized serum (original) (raw)
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Clinica Chimica Acta, 1998
The concentrations of retinol, a-tocopherol, and trans-b-carotene in lyophilized serum stored at 2 258C and 2 808C have been monitored for 10 years. There was no evidence of degradation of any of these compounds over the 10-year period. Retinol, a-tocopherol, and trans-b-carotene were less stable at 2 258C in liquid-frozen serum than they were in lyophilized serum. At 2 808C, trans-b-carotene levels were stable for up to 3 years of storage in liquid-frozen serum. Both retinol and a-tocopherol appeared stable in liquid-frozen serum for at least 5 years at 2 808C. The effect of repeated freeze / thaw cycles on retinol, a-tocopherol, trans-lycopene, and trans-bcarotene in liquid-frozen and reconstituted lyophilized serum both stored at 2 208C was also studied. Retinol, a-tocopherol, trans-lycopene, and trans-b-carotene in reconstituted lyophilized serum stored at 2 208C were stable for at least 3 days with minimal ( , 5) freeze / thaw cycles.
Clinical chemistry, 1988
We investigated the effects of storage and handling on measured values for carotenoids, retinol, and tocopherol in plasma. We found no significant differences in the concentrations of these analytes measured in plasma samples that were frozen immediately after separation as compared with replicate samples maintained at room temperature in the dark for 24 h. Analytes were stable in solvents for at least 18 h at 23 degrees C after extraction. Purging samples with nitrogen gas before freezing had no detectable beneficial effects. All analytes were stable in plasma stored at -70 degrees C for at least 28 months or at -20 degrees C for five months. By 15 months the concentrations of carotenoids were significantly less (P less than 0.05) in plasma stored at -20 degrees C than in plasma stored at -70 degrees C, while retinol and tocopherol concentrations were not significantly different. Concomitant with the decrease in carotenoids was the appearance of unidentified peaks in the ultraviole...
Biomedical Chromatography, 1998
In this report we describe a modified reverse phase HPLC method that avoids the solvent evaporation step and allows simple and rapid determination of retinol, ␣-tocopherol, ␣-carotene and -carotene and achieves complete separation of ␣and -carotene. Retinyl acetate, ␣-tocopheryl acetate and retinyl palmitate in ethanol were added to serum as internal standards. Serum was then deproteinized with an equal volume of ethanol, and the lipid was extracted with ethyl acetate-butanol (1:1 v/v). A portion of this solution was injected into a C18 reverse phase chromatographic column and absorbencies of the vitamins and internal standards were measured at 292 nm for tocopherols, 325 nm for retinoids and 450 nm for carotenoids; peak-height ratios were used to quantify each vitamin. The analytical recoveries for retinol, ␣-tocopherol ␣and -carotene at various concentrations tested were 95-103, 90-98, 92-99 and 94-96%, respectively. The intra-and interassay variations for low and high concentrations of retinol, ␣-tocopherol, ␣and -carotene ranged from 2.4 to 6.7 for intraassay and from 4.3 to 8.5 for interassay replication. The detection limits were 1.25 (0.04), 19 (0.44), 0.35 (0.006) and 0.94 (0.017) g/dL (␦mol/L) for retinol, ␣-tocopherol, ␣and -carotene, respectively.
Journal of the Brazilian …, 2012
A method for the simultaneous quantification of lycopene, β-carotene, retinol and α-tocopherol by high-performance liquid chromatography (HPLC) with Vis/fluorescence detection with isocratic elution was optimized and validated. The method consists of a rapid and simple liquid-liquid extraction procedure and a posterior quantification of extracted supernatants by HPLC. Aliquots of plasma were stored at –20°C for three months for stability study. The methodology was applied to samples from painters and individuals not exposed to paints (n = 75). The assay was linear for all vitamins (r > 0.99). Intra- and inter-run precisions were obtained with coefficient of variation smaller than 5%. The accuracies ranged from 0.29 to –5.80% and recoveries between 92.73 and 101.97%. Plasma samples and extracted supernatants were stable for 60 days at –20°C. A significant decrease of lycopene, β-carotene and retinol concentrations in plasma from exposed individuals compared to non-exposed individuals (p < 0.05) was observed. The method is simple, reproducible, precise, accurate and sensitive, and can be routinely utilized in clinical laboratories.
2012
Um método para quantificação simultânea de licopeno, β-caroteno, retinol e α-tocoferol por cromatografia líquida de alta eficiência (HPLC) com detecção no visível/fluorescente e eluição isocrática foi otimizado e validado. O método consiste de extração líquido-líquido rápida e simples e posterior quantificação do sobrenadante extraído por HPLC. Alíquotas de plasma foram estocadas a-20°C por três meses para estudo da estabilidade. Aplicação metodológica foi realizada em amostras fornecidas por pintores e indivíduos não expostos a tintas (n = 75). O ensaio foi linear para todas as vitaminas analisadas (r > 0,99). Precisões intradia e interdia apresentaram coeficiente de variação (CV) menor que 5%. Exatidões variaram de 0,29 a-5,80% e recuperações entre 92,73 e 101,97%. Amostras de plasma e sobrenadante extraído foram estáveis por até 60 dias a-20°C. Foi demonstrada uma diminuição significativa nas concentrações de licopeno, β-caroteno e retinol em indivíduos expostos quando comparados com os não-expostos (p < 0,05). O método é simples, reprodutível, preciso, exato e sensível, e pode ser utilizado na rotina de laboratórios clínicos. A method for the simultaneous quantification of lycopene, β-carotene, retinol and α-tocopherol by high-performance liquid chromatography (HPLC) with Vis/fluorescence detection with isocratic elution was optimized and validated. The method consists of a rapid and simple liquid-liquid extraction procedure and a posterior quantification of extracted supernatants by HPLC. Aliquots of plasma were stored at-20°C for three months for stability study. The methodology was applied to samples from painters and individuals not exposed to paints (n = 75). The assay was linear for all vitamins (r > 0.99). Intra-and inter-run precisions were obtained with coefficient of variation smaller than 5%. The accuracies ranged from 0.29 to-5.80% and recoveries between 92.73 and 101.97%. Plasma samples and extracted supernatants were stable for 60 days at-20°C. A significant decrease of lycopene, β-carotene and retinol concentrations in plasma from exposed individuals compared to non-exposed individuals (p < 0.05) was observed. The method is simple, reproducible, precise, accurate and sensitive, and can be routinely utilized in clinical laboratories.
Journal of Chemistry, 2013
A method is described here for the simultaneous determination of retinol,α-tocopherol, lycopene, andβ-carotene in human plasma. The effectiveness of various protein precipitants and extraction solvents was tested. After adequate sample preparation, the samples were injected directly into the HPLC system. The separation was realized on an analytical reversed-phase column with a UV-Vis detection. The analytical performance of this method was satisfactory. The intraassay and interassay coefficients of variation were below 10%. The recoveries were as follows: 97.0% (CV 2.4%) for retinol, 94.6% (CV 1.7%) forα-tocopherol, 91.9% (CV 3.6%) for lycopene, and 93.9% (CV 4.2%) forβ-carotene. The levels of selected fat-soluble vitamins in plasma of patients with cardiovascular disease were measured and discussed.
Journal of Chromatographic Science, 2011
We describe a simplified isocratic HPLC method for the simultaneous determination of all-trans-retinol, 3 tocopherols (α-, δ-, and γtocopherol), and 8 carotenoids (lutein, zeaxanthin, canthaxanthin, β-cryptoxanthin, all-trans-lycopene, 5-cis-lycopne, α-carotene, and β-carotene) in human plasma, which uses a single C18 reversed-phase column (4.6 × 250 mm, 3 µm). A photodiode array detector was used to measure the UV-vis wavelength absorbance of retinol and the eight carotenoids, and fluorescence detection was used for the tocopherols. The linear ranges of the calibration curves for the calibration solutions injected into the HPLC column are 0.02-6.0 µg/mL for all-trans-retinol, β-cryptoxanthin and α-carotene; 0.01-3.0 µg/mL for δ-tocopherol, lutein, and lycopene; 0.08-24.0 µg/mL for γ-tocopherol; 0.3-90.0 µg/mL for α-tocopherol; 0.005-1.5 µg/mL for zeaxanthin and canthaxanthin; and 0.04-12.0 µg/mL for β-carotene.
Malaysian journal of nutrition, 1995
The determination of serum vitamins having antioxidant properties has gained in importance in recent years. This is mainly due to the observation that an inverse correlation exists between blood levels of these vitamins, including retinol, carotenoids and tocopherol, and diet-related chronic diseases such as coronary heart disease and cancers. This laboratory has been carrying out a series of studies into the nutritional and analytical aspects of retinol and carotenoids. A simple reversed-phase HPLC method has been developed in an effort to improve methodologies for the separation and quantitation of carotenoids and retinol in foods and biological specimens, especially blood serum. As an extension to these studies, trials were carried out to determine the feasibility of analysing tocopherols using the same chromatographic procedure. With the addition of another detector wavelength, the same procedure detected and quantitated 3 major tocopherols simultaneously with retinol and five c...
Journal of Chromatography B, 2009
An improved isocratic and rapid HPLC method was developed for the measurement of carotenoids, retinol and tocopherols in human serum. Vitamins were extracted with hexane. Mobile phase consisted of a mixture acetonitrile:methylene chloride:methanol with 20 mM ammonium acetate. This method used a small bead size (3 m) Spherisorb ODS2 column with titane frits. Diode array and fluorescence detectors were used respectively for the detection of carotenoids and retinol/tocopherols. Chromatographic separation was complete in 13 min for -cryptoxanthin, cis-trans-lycopene, ␣-carotene, -carotene, cis--carotene, retinol, ␦-tocopherol, ␥-tocopherol and ␣-tocopherol. Echinenone and tocol were employed as internal standards for diode array and fluorescence detection. Accuracy was validated using standard reference material (SRM) 968C. Intra-assay and inter-assay precision were respectively 0.2-7.3% and 3.6-12.6%. Sensitivity was verified using the ICH recommendations and the limit of detection (LOD) obtained was sufficient for routine clinical application.