The most popular method for quantifying citric acid concentrations in juices is reverse-phase high-performance liquid chromatography (HPLC).7,8 With all organic acids, including citric acid, phase collapse may be an issue because these polar compounds separate best in purely aqueous mobile phases.9 If the surfaces of the alkyl chains dewet it becomes harder for the polar compounds to adsorb onto the stationary phase, when this happens the phase is said to have collapsed. Indicators of this phenomenon are erratic chromatograms with ultimate retention loss.9 To overcome this issue, the column can be regenerated by rinsing with high concentrations of organic solvent, but collapse will likely reoccur. Another solution is to obtain an Ultra-Aqueous or Water-Compatible Allure™ column.10 These columns are manufactured to preserve retention in up to 100% aqueous