Analysis of commercial anti-itch medication by using YMC-Triart C18 under alkaline mobile phase condition

In liquid chromatography, pH value of mobile phase is one of the important parameters affecting the retention behavior and peak shape of analytes. YMC-Triart C18 with the innovative surface modification on organic/inorganic hybrid silica allows the use of various mobile phases over a wide pH range due to its great chemical durability, and provides the robust analysis under alkaline mobile phase conditions as impractical for conventional C18 columns.
In this report, we introduce the analytical method development of a commercial anti-itch medication by using YMC-Triart C18.

Mobile phase pH screening under gradient analysis condition

In the analysis of the anti-itch medication consisting of main compounds as shown in the right figure, the chromatograms were compared at different mobile phase conditions. Under the acidic (pH 2.9) or neutral (pH 6.1) conditions, the separation and shape of the chromatographic peaks were not satisfied due to the presence of pharmaceutical additives. On the other hand, under the alkaline (pH 9.6) condition, the efficient separation and good shape of the all chromatographic peaks were achieved. .

Sample
50% acetonitrile extract of a commercially available anti-itch medication

Column YMC-Triart C18 (3 µm, 120 Å)
150 X 4.6 mmI.D.
Eluent A) 10 mM HCOOH for pH 2.9
10 mM HCOONH4 for pH 6.1
10 mM HCOONH4-NH3 for pH 9.6
B) acetonitrile35-100%B (0-10 min)
Flow rate 1.0 mL/min
Temperature 37°C
Detection UV at 254 nm
Injection 10 µL

Rapid analysis under isocratic condition optimized from gradient elution

By even isocratic elution, the good peak shapes were obtained, and the rapid analysis with the efficient separation of each compound was achieved.

Column YMC-Triart C18 (3 µm, 120 Å)
150 X 4.6 mmI.D.
Eluent 10 mM HCOONH4-NH3 (pH 9.6)/acetonitrile (35/65)
Flow rate 1.0 mL/min
Temperature 37°C
Detection UV at 254 nm
Injection 10 µL