Validated Method for Determination of α‐Lipoic Acid in Dietary Supplement Tablets by Reversed Phase Liquid Chromatography

Abstract

A rapid high performance liquid chromatographic method was developed and validated for the determination of a-lipoic acid in pharmaceutical dosage forms. The analysis was performed using a reversed phase Supelcosil LC-18 (150 Â 4 mm, 3 mm) column. The mobile phase consisted of acetonitrile : 0.05 M potassium mono-phosphate, pH 2.5 (45 : 55 v/v) at a flow rate of 0.8 mL/min. The UV-detector was set at 332 nm. The developed method showed a good linear relationship in the concentration range from 10 -500 mg/mL with a correlation coefficient from 0.9999. The limit of detection and limit of quantification were 4.4 and 16.8 mg/ mL, respectively. These values are high due to the low absorption coefficient of pure lipoic acid (1 ¼ 150) at 332 nm. Statistical analysis proves that the method is reproducible.

Simultaneous determination of lipoic acid (LA) and dihydrolipoic acid (DHLA) in human plasma using high-performance liquid chromatography coupled with electrochemical detection

“…HPLC with fluorescence detection, offers a good method for the determination of ␣-lipoic acid in biological fluids but its lengthy and time consuming derivitization and sample preparation steps are laborious [5,24]. HPLC with electrochemical detection method is therefore seems to be an ultimate choice in terms of sensitivity, shorter analysis time and lower cost for most of the standard research laboratories to quantify ␣-lipoic acid in biological fluids in comparison with other literature reported methods [3,5,15,[18][19][20][21]23,24]. To our knowledge only a few HPLC methods with fluorescence detection have been reported for the simultaneous determination of LA and DHLA in biological fluids and pharmaceuticals samples [5,13], and no HPLC-ECD method for the simultaneous determination of LA and DHLA in biological fluids has been reported so for.…”

“…HPLC is one of the most suitable and proper method for quantification of lipoic acid in biological fluids owing to its high accuracy, sensitivity, and simplicity regarding sample preparation and treatment procedures in routine laboratory practice [22]. HPLC linked with ultraviolet [23], fluorescence [5,24,25] and electrochemical detectors [16,22,26,27] has been used for the evaluation of lipoic acid in food supplements and biological samples. The major demerits associated with HPLC-UV method are the absence of strong chromophore in lipoic acid and its comparatively lower sensitivity [15].…”

Use of fluorine-doped tin oxide electrodes for lipoic acid determination in dietary supplements

“…These include high performance liquid chromatography (HPLC) coupled to UVvisible detector [4][5][6], to a coulometric electrode array detector (CEAD) and to an electrospray ionization mass spectrometer (ESI-MS) [7] .Spectrophotometric methods have been reported as well [8][9][10]. However, the available techniques present some drawbacks such as high cost, complexity and time-consuming sample preparation, and presence of interferents.…”

Determination of lipoic acid in human plasma by HPLC-ECD using liquid–liquid and solid-phase extraction: Method development, validation and optimization of experimental parameters

“…HPLC with fluorescence detection, proved to offer a good method for the determination of ␣-lipoic acid in biological fluids but require lengthy derivatization and laborious sample preparation steps [2,17]. HPLC with electrochemical detection seems to be a method of choice in terms of sensitivity, short run time and low cost for most of the standard laboratories to quantify ␣-lipoic acid in biological fluids as compared with other reported analytical methods [1,2,9,[11][12][13][14]16,17].…”

“…HPLC is the more suitable and appropriate method for the evaluation of lipoic acid due to its high sensitivity, specificity, inexpensive sample preparation and ease of samples handling procedures in clinical practice [15]. HPLC with different detection modes including ultraviolet [16], fluorescence [2,17] and electrochemical [10,15,18,19] have been reported for the quantification of lipoic acid in dietary supplements and biological fluids. HPLC-UV method has limitations due to the lack of strong chromophore in lipoic acid and its high detection limits [9].…”