Temperature-Dependent Behavior of C<sub>30</sub> Interphases. A Solid-State NMR and LC−NMR Study

Pursch, Matthias; Strohschein, Sabine; Händel, and Heidrun; Albert, Klaus

doi:10.1021/ac950761y

Cited by 140 publications

(130 citation statements)

References 27 publications

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“…It is well known that lutein and zeaxanthin are difficult to separate on monomeric C 18 columns, and high resolution can be achieved only by use of polymeric C 18 or C 30 columns with gradient elution (19,28,29 ). Unfortunately, the retention of ␣-and ␤-carotene tends to increase with polymeric C 18 or C 30 with a column temperature Ͼ35°C (17 ). Furthermore, lycopene is usually retained on the column and eluted after ␤-carotene, thus decreasing sensitivity.…”

Section: Discussion Analysis Of Vitamin a And Carotenoidsmentioning

confidence: 99%

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

2003

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Background: Epidemiologic evidence suggests that the concentrations of antioxidant vitamins in human plasma may play an important role in numerous chronic diseases, such as cancer and cardiovascular disease. However, methods for simultaneous measurement of these antioxidants are scarce. We developed and validated a new HPLC method for simultaneous determination of these vitamers in human plasma that uses a novel column-switching approach. Methods:The new method uses liquid-liquid extraction and isocratic separation with two monomeric C 18 columns maintained at 35 and 4°C coupled with ultraviolet-visible and fluorometric detection. This method could separate 14 vitamers and 3 internal standards within 27 min. No additional modifier was required; the mobile phase was acetonitrile-methanol (65:35 by volume), and the flow rate was 1 mL/min. Results: For photodiode array detection, the detection limits (signal-to-noise ratio >3) were 0.02 mg/L for ␤-carotene, lutein, zeaxanthin, and canthaxanthin; 0.01 mg/L for all-trans-retinol, ␤-cryptoxanthin, ␣-carotene, and lycopene; and 0.1 mg/L for all tocopherols and tocotrienols. The detection limit was at least 25-fold lower (0.004 mg/L) when fluorometry was used for measurement of ␦-, ␥-, and ␣-tocotrienol and ␦-tocopherol compared with ultraviolet detection. The recovery and imprecision of the assay were generally >90% and <10%, respectively. Conclusions: This new method separates a wide range of fat-soluble antioxidant vitamins in human plasma, including six carotenoids, three isoforms of tocotrienols and tocopherols (␦-, ␥-, and ␣-), and all-trans-retinol. The overall findings suggest that our method is faster,

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Section: Discussion Analysis Of Vitamin a And Carotenoidsmentioning

confidence: 99%

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

2003

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“…The HPLC separation of carotinoids (Figure 3 a) was performed on a C3D-RP phase according to the conditions described in reference [24].…”

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confidence: 99%

Coordination-Ionspray-MS (CIS-MS), a Universal Detection and Characterization Method for Direct Coupling with Separation Techniques

Bayer

Gfrörer

Rentel

1999

Angew. Chem. Int. Ed.

115

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By on-line addition of a central atom (for example, Ag , B , Pd , Li ) positively or negatively charged complexes of analytes can be formed for CIS-MS. This technique is applicable to both polar and nonpolar compounds-for example, for alcohols, ethers, and a large number of olefins, polyolefins, and arenes as well as steroids, vitamins of the D and E families, carotinoids, polystyrols, terpenes, and unsaturated fatty acids-and can be readily coupled with separation techniques.

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“…In the previous reports on C 30 bonded phases, two resonances of 13 C signal for the (CH 2 ) n carbon atoms were observed [27,28]. One resonance is due to the trans-conformations (32.6 ppm), indicating rigid and ordered chains; another peak at 30.1 ppm characterizes the mobile and amorphous regions, indicating the presence of a high proportion of gauche-conformations.…”

Section: Solid-state Nmr Analysismentioning

confidence: 81%

Preparation, characterization and application of octadecyl modified magnesium oxide microspheres

Jin

Zhang

et al. 2011

Analytica Chimica Acta

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Temperature-Dependent Behavior of C₃₀ Interphases. A Solid-State NMR and LC−NMR Study

Abstract: Figure 10. Model for the shape recognition of the C30 phase at high (left) and subambient (right) temperatures.

Cited by 140 publications

References 27 publications

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

Coordination-Ionspray-MS (CIS-MS), a Universal Detection and Characterization Method for Direct Coupling with Separation Techniques

Preparation, characterization and application of octadecyl modified magnesium oxide microspheres

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Temperature-Dependent Behavior of C30 Interphases. A Solid-State NMR and LC−NMR Study

Abstract: Figure 10. Model for the shape recognition of the C30 phase at high (left) and subambient (right) temperatures.

Cited by 140 publications

References 27 publications

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

Simultaneous Determination of Tocotrienols, Tocopherols, Retinol, and Major Carotenoids in Human Plasma

Coordination-Ionspray-MS (CIS-MS), a Universal Detection and Characterization Method for Direct Coupling with Separation Techniques

Preparation, characterization and application of octadecyl modified magnesium oxide microspheres

Contact Info

Product

Resources

About

Temperature-Dependent Behavior of C₃₀ Interphases. A Solid-State NMR and LC−NMR Study