MilliporeSigma
  • Prediction of the chromatographic retention of acid-base compounds in pH buffered methanol-water mobile phases in gradient mode by a simplified model.

Prediction of the chromatographic retention of acid-base compounds in pH buffered methanol-water mobile phases in gradient mode by a simplified model.

Journal of chromatography. A (2015-02-11)
Axel Andrés, Martí Rosés, Elisabeth Bosch
ABSTRACT

Retention of ionizable analytes under gradient elution depends on the pH of the mobile phase, the pKa of the analyte and their evolution along the programmed gradient. In previous work, a model depending on two fitting parameters was recommended because of its very favorable relationship between accuracy and required experimental work. It was developed using acetonitrile as the organic modifier and involves pKa modeling by means of equations that take into account the acidic functional group of the compound (carboxylic acid, protonated amine, etc.). In this work, the two-parameter predicting model is tested and validated using methanol as the organic modifier of the mobile phase and several compounds of higher pharmaceutical relevance and structural complexity as testing analytes. The results have been quite good overall, showing that the predicting model is applicable to a wide variety of acid-base compounds using mobile phases prepared with acetonitrile or methanol.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Potassium phosphate dibasic, reagent grade, ≥98.0%
Sigma-Aldrich
Potassium phosphate dibasic, meets USP testing specifications
Sigma-Aldrich
Hydrochloric acid, 36.5-38.0%, BioReagent, for molecular biology
Sigma-Aldrich
Sodium acetate, anhydrous, for molecular biology, ≥99%
Sigma-Aldrich
Sodium acetate, powder, BioReagent, suitable for electrophoresis, suitable for cell culture, suitable for insect cell culture, ≥99%
Sigma-Aldrich
Sodium acetate, BioXtra, ≥99.0%
Sigma-Aldrich
Sodium acetate, meets USP testing specifications, anhydrous
Sigma-Aldrich
Pyrrolidine, ≥99.0%
Sigma-Aldrich
Sodium acetate solution, BioUltra, for molecular biology, ~3 M in H2O
Sigma-Aldrich
Potassium phosphate dibasic, anhydrous, for luminescence, for molecular biology, BioUltra, ≥99.0% (T)
Sigma-Aldrich
Phosphoric acid, crystalline, ≥99.999% trace metals basis
Sigma-Aldrich
3-Ethyl-2,4-pentanedione, mixture of tautomers, 98%
Sigma-Aldrich
Sodium hydroxide, BioUltra, for luminescence, ≥98.0% (T), pellets
Sigma-Aldrich
Sodium acetate, 99.995% trace metals basis
Sigma-Aldrich
Hydrogen chloride, ReagentPlus®, ≥99%
Sigma-Aldrich
Pyrrolidine, ≥99.5%, purified by redistillation
Sigma-Aldrich
Potassium phosphate dibasic, 99.95% trace metals basis
Supelco
Methanol solution, contains 0.10 % (v/v) formic acid, UHPLC, suitable for mass spectrometry (MS), ≥99.5%
Sigma-Aldrich
Methanol solution, NMR reference standard, 4% in methanol-d4 (99.8 atom % D), NMR tube size 3 mm × 8 in.
USP
Sodium acetate, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Sodium hydroxide, ultra dry, powder or crystals, 99.99% trace metals basis
Supelco
Ammonium chloride, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Sodium hydroxide, puriss. p.a., ACS reagent, K ≤0.02%, ≥98.0% (T), pellets
Sigma-Aldrich
Sodium hydroxide, BioXtra, ≥98% (acidimetric), pellets (anhydrous)
Sigma-Aldrich
Sodium hydroxide, puriss., meets analytical specification of Ph. Eur., BP, NF, E524, 98-100.5%, pellets
Sigma-Aldrich
Hydrochloric acid, meets analytical specification of Ph. Eur., BP, NF, fuming, 36.5-38%
Sigma-Aldrich
Potassium phosphate dibasic, puriss. p.a., ACS reagent, anhydrous, ≥99.0% (T)
Sigma-Aldrich
Sodium hydroxide, reagent grade, ≥98%, pellets (anhydrous)
Sigma-Aldrich
Sodium hydroxide, reagent grade, 97%, powder
Sigma-Aldrich
Potassium phosphate dibasic, ACS reagent, ≥98%