Enzymatic determination of vitamin A in pharmaceutical formulations with spectrophotometric detection

Rishi, Lubna; Asgher, Mohammad; Yaqoob, Mohammad; Waseem, Amir; Nabi, Abdul

doi:10.1016/j.saa.2008.12.024

Cited by 20 publications

(13 citation statements)

References 27 publications

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“…Pharmaceutical samples containing vitamin E existing as dl ‐ α ‐tocopheryl acetate did not show any significant CL response, and it was converted into tocopherol by transesterification (9,11). The end product of transesterification was dissolved in 5.0 mL of methanol and diluted appropriately with carrier solution, methanol, 5% v/v containing Brij‐35, 0.2% for retinol and 0.05% for α ‐tocopherol and CL was measured as per the procedure given below.…”

Section: Methodsmentioning

confidence: 99%

“…Several analytical methods have been developed for determining retinol and a-tocopherol in diverse samples such as colorimetry/spectrophotometry (9)(10)(11)(12), fluorimetry (13), voltammetry (14), capillary zone electrophoresis (15) and liquid chromatography based on ultraviolet, fluorimetric, photodiode/diode array and amperometric detectors (16)(17)(18)(19). Some of these methods have many advantages such as high sensitivity and accuracy; however, disadvantages e.g., high costs, high volumes of toxic solvents and time-consuming separation procedure, obstruct their applications in many cases.…”

Section: Introductionmentioning

confidence: 99%

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Flow injection methods for the determination of retinol and α‐tocopherol using lucigenin‐enhanced chemiluminescence

et al. 2010

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Flow injection (FI) methods are reported to determine retinol and α-tocopherol based on its enhancement affect of lucigenin chemiluminescence (CL) in alkaline medium. Surfactants including Brij-35, Triton X-100, cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate have been reported for the first time to enhance lucigenin CL intensity in the presence of retinol and α-tocopherol. With Brij-35, the CL intensity was enhanced by 67% for retinol and 58% for α-tocopherol. CTAB was found to enhance the CL intensity by 16% for retinol whereas for α-tocopherol, the CL intensity was quenched up to 95%. Retinol could be determined specifically in the presence of α-tocopherol using CTAB. The calibration graphs were found to be linear up to 1.43 mg/L (R(2) = 0.9985, n = 8) with a detection limit (3s) of 1.43 × 10(-3) mg/L for retinol and 2.15 mg/L (R(2) = 0.9989; n = 8) with a detection limit (3s) of 4.31 × 10(-4) mg/L for α-tocopherol. An injection throughput of 120/h, and relative standard deviations of 0.9-2.8% (n = 4) were achieved in the concentration range studied. The influence of common ions, excipients in pharmaceutical formulations and related organic compounds on the determination of retinol and α-tocopherol individually was studied. The proposed methods were applied to determine retinol and α-tocopherol in pharmaceutical formulations and human blood serum. The results did not differ significantly from the CL method and HPLC reference method at 95% confidence level.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow injection methods for the determination of retinol and α‐tocopherol using lucigenin‐enhanced chemiluminescence

et al. 2010

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“…Several analytical methodologies such as spectrophotometry [4,5], fluorimetry [6] and chemiluminescence [7,8] as well as other optical methods (Raman [9] and IRspectroscopy [10]) have been applied for determination of retinol in food, pharmaceutical supplements and biological fluids. These samples have usually complex composition and matrix effect takes place.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Voltammetry of Retinol in Surfactant Media and Its Application for the Analysis of Real Samples

2010

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Retinol is irreversibly oxidized at 790 mV in water 0.1 M LiClO 4 that corresponds to formation of retinal. Effect of surfactant on voltammetric characteristics of retinol oxidation has been evaluated. The calibration graph was linear in the range 29.4-980 mM of retinol with detection limit of 15 mM in presence of 1.1 10 À4 M of sodium dodecyl sulfate. Application of surfactant media leads to decrease of detection limit, enlargement of analytical range for retinol determination and permits analyze retinol in water media. Simple, express and reliable voltammetric approach for determination of retinol in real samples using surfactant media have been developed.

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“…Different types of chromatography [6][7][8][9], spectrophotometry [10,11], and chemiluminescence [12,13] have been used to determine retinol and α-tocopherol in different samples, particularly wild plants [14]. Electrochemical methods, in particular voltammetry, represent a suitable technique, due to the relatively low cost of the instrumentation required, the possibility of miniaturization, and their fast and sensitive analytical performance.…”

Section: Introductionmentioning

confidence: 99%

MWNT-modified electrodes for voltammetric determination of lipophilic vitamins

Ziyatdinova

Morozov

Budnikov

2011

J Solid State Electrochem

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Multi-walled carbon nanotube modified graphite electrodes (MWNT-GEs) have been created for the voltammetric determination of α-tocopherol and retinol. The electrode surface was characterized by atomic force microscopy. The MWNT-GEs presented structured surfaces and a significant (26-fold) increase in roughness over unmodified graphite electrodes (8.2 vs. 0.32 nm for MWNT-GEs and GEs, respectively). Their surfaces consisted of aggregates with a highly regular "thorn-like" structure. α-Tocopherol and retinol were oxidized on the bare GEs and the MWNT-GEs in 0.1 M HClO 4 in acetonitrile. Decreases in the overpotential of 0.2 and 0.04 V for α-tocopherol and retinol, respectively, and increased oxidation currents were observed on the MWNT-GEs in comparison with the unmodified electrodes. The calibration graphs were linear in the range 0.065-2.00 mM for α-tocopherol and 0.05-1.50 mM for retinol. The detection limits were found to be 0.05 and 0.04 mM for α-tocopherol and retinol, respectively. The developed electrodes were applied to determine α-tocopherol and retinol in pharmaceuticals. The results obtained agreed well with coulometric titration data.

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Enzymatic determination of vitamin A in pharmaceutical formulations with spectrophotometric detection

Cited by 20 publications

References 27 publications

Flow injection methods for the determination of retinol and α‐tocopherol using lucigenin‐enhanced chemiluminescence

Flow injection methods for the determination of retinol and α‐tocopherol using lucigenin‐enhanced chemiluminescence

Cyclic Voltammetry of Retinol in Surfactant Media and Its Application for the Analysis of Real Samples

MWNT-modified electrodes for voltammetric determination of lipophilic vitamins

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