Judy Berry

Grapefruit juice was analysed by gradient UHPLC for naringin - a major flavanoid in grapefruit juice that gives it its bitter taste. A ZORBAX Rapid resolution HD (RRHD) StableBond-C18 2.1 ? 150 mm, 1.8 ?m column was able to resolve over 60 peaks, including naringin in 7 minutes, and was re-equilibrated in just three minutes by operating at a high flow rate (0.8 mL/min). The high pressure generated (965 bar) is well within the 1200 bar operating range of the RRHD column and 1290 Infinity LC.

The flexibility to use short sub-2 micron columns on UHPLC instruments at high flow-rates permits fast analysis with high resolution of complex samples. An Agilent ZORBAX Rapid Resolution High Definition (RRHD) Eclipse Plus C18 1.8 µm column separated seven different biocides in less than 1 minute with high resolution. A flow-rate of 1.7 mL/min was used on 2.1 × 50 mm column to achieve the rapid separation. The Agilent 1290 Infinity LC system was used as the column pressure just exceeded 1000 bar at this high flow-rate. A sample of hand sanitizer was found to contain 2-phenoxyethanol and methylparaben using the method.

The FDA has no objection to Rebaudioside A having a generally recognized as safe (GRAS) status as a sweetener for food and drink.1 Stevia sweeteners may contain other steviol glycosides as well, mainly Stevioside, Rebaudioside C and Dulcoside A. Because the FDA GRAS confirmation is only for the use of Rebaudioside A at 95% purity or above in food and beverages, stevia extracts must be highly purified and characterized prior to use.

An Agilent ZORBAX Rapid Resolution HT Eclipse Plus Phenyl-Hexyl column resolved many compounds from Stevia rebaudiana Bertoni plant extracts using an isocratic reversed phase method with UV and MS detection instead of a typical approach employing an amino column with a refractive index or other special detector. The Eclipse Plus Phenyl-Hexyl method's advantages include high peak capacity, isocratic mobile phase, low acetonitrile consumption, and MS compatibility.