A new highly specific and sensitive CE method (electrokinetic chromatography with sodium dodecyl sulfate) for the determination of the total alginic acid content in pharmaceutical formulations is described by means of CE at 230 nm after treatment with alginate lyase [18.104.22.168] and separation of unsaturated products, Δ-oligomers (∆HexA-[HexA]n), in particular DP3 (∆HexA-HexA-HexA) and DP4 (∆HexA-HexA-HexA-HexA). Using a buffer constituted with 10 mM sodium borate and 50 mM SDS at pH 9.0, MECC was able to determine with very high resolution the alginic acid Δ-oligomers produced by the action of the lyase (mainly DP3 and DP4) as one single species. The intra- and inter-day variations (CV%) were between 6.3 and 9.1 for migration time and between 2.5 and 5.7 for peak area, respectively. The calibration curve showed good linearity for the examined concentration range (60 - 360 ng) with an average correlation coefficient greater than 0.980. The LOD and the LOQ of the method were 15 (0.25 mg/mL) and 40 ng (0.67 mg/mL), respectively. The intra- and inter-day variations in terms of CV% were 5.5% and 8.6%, respectively, and the intra- and inter-day accuracy was estimated to range from 4.1% to 8.9%, while the percent recoveries of alginic acid were calculated to be 102%, 97% and 93% for different AA amounts. Variations in temperatures, voltage, and buffer composition in comparison with adopted conditions within a 10% limit do not modify the electrophoresis results. The evaluation of alginic acid was performed in both solid and liquid pharmaceutical formulations also in the presence of other ingredients, in particular aluminium, sodium and potassium bicarbonate, and emulsifying and flavouring agents. The quantitative results obtained were 101.2 ± 3.4% of alginic acid content in tablets and 98.4 ± 2.8% in liquid formulation, in total conformity with the label claims.
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|Anno di pubblicazione:||2008|
|Titolo:||Micellar electrokinetic capillary chromatography (MECC) determination of alginic acid in pharmaceutical formulations after treatment with alginate lyase and UV detection|
|Appare nelle tipologie:||Articolo su rivista|
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