Application of capillary electrophoresis for organic acid analysis in herbal studies

Abstract

A capillary electrophoresis (CE) procedure has been developed for the separation of 25 inorganic and organic acid anions using a buffer system consisting of 15 mM tris(hydroxymethyl)aminomethane, 3 mM 1,2,4-benzenetricarboxylic acid, 1.5 mM tetraethylenepentaamine (TEPA) and 20% methanol with pH adjusted to 8.4. A good separation of organic acids extracted from a mixture of Chinese traditional medicine (TCM) containing three herbs, Flos chrysthemi, Spica prunellae, and Folium mori was obtained using the procedure developed with satisfactory working range (0.20-77 mg/g), low detection limit (90-190 microg/g), and good repeatability (relative standard deviation 4.47-6.99%, n = 4). A satisfactory extraction of organic acids was achieved within 20 min using 0.1 M NaOH. The addition of TEPA to provide a reduced electroosmotic flow (EOF) environment was shown to remove interfering organic compounds extracted from TCM. The applicability of using organic acids as markers for determining the mixing ratio of constituent herbs for a TCM mixture was investigated using a three-component mixture with a 1:1:1 mixing ratio. A satisfactory mixing ratio of 1.04:1.09:0.98 was obtained using the methodology developed based on organic acids as markers. The application of our method for determining more complicated TCM mixtures has been discussed.

Profiling preparations of recombinant birch pollen allergen Bet v 1a with capillary zone electrophoresis in pentamine modified fused-silica capillaries

“…5. The decrease in the µ EOF was only 27% when adding 1.0 mmol L −1 TEPA and is less pronounced when compared to the data reported for Tris buffers [43]. However, one has to take into account the unique properties of phosphate in shielding silica surfaces [65,66] as well as the different sepa- ration pH.…”

“…A recent survey of dynamic coating agents revealed oligoamines, particularly spermine and tetraethylenepentamine (tetren, TEPA; Fig. 1), to be highly efficient in wall shielding, especially when compared to frequently applied monoand diamines [41][42][43][44], additionally ensuring a smooth baseline [42]. However, beside adsorption to the capillary wall TEPA is known to act in multiple ways when included in the BGE: by (i) attachment to the protein surface and by (ii) ion-pairing with the buffer anions.…”

Optimization of capillary zone electrophoresis separation and on-line preconcentration of 16 phenolic compounds from wines produced in South America

“…Recent advances in CE have made it a rapid and economical method with high separation efficiency that may solve problems with interfering substances present in the matrix that are commonly found in the HPLC analysis. Moreover, CE presents low consumption of reagents and generates less volume of toxic wastes as compared to other techniques (Frazier, 2001;Fung & Tung, 2001). Capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) have already been used to separate and quantify phenolic compounds (Jáč et al, 2006).…”

The evaluation and comparison of trigonal and linear tricationic ion-pairing reagents for the detection of anions in positive mode ESI-MS

“…Low levels of organic acids have been determined in a variety of samples such as food, environmental, and biological matrices [1][2][3][4][5][6][7][8][9]. Some dicarboxylic acids, such as glutaric, fumaric, and adipic acids are marker compounds for certain metabolic disorders and have been determined in urine samples [10].…”

“…Common separation methods include ion chromatography [1,[12][13][14][15], ion pair chromatography [3,11,16], reverse-phase mode chromatography [17][18][19], and capillary electrophoresis (CE) [4,5,20]. To enhance the spectroscopic detection of anions that do not contain a UV chromophore, some CE and high-performance liquid chromatography (HPLC) methods utilize sample derivatization [21,22] or indirect UV or fluorescence detection methods [23][24][25].…”