Simultaneous determination of sugars, uric and orotic acids in infant formulae by HPLC-UV/RI

In a simple, rapid isocratic HPLC method sugars (glucose, galactose, saccarose, maltose, lactose), uric and erotic acids were separated on a Spherisorb NH2, 5 mu m Chromatographic column and detected using refractive index and ultraviolet (lambda = 280 nm) detectors in series. The identification was made by comparison of the retention times with those of the corresponding standards xilose and melizitose were used as internal standards. The determinations were performed in the linear range of 0.5-30.0 g/L for sugars, 1.0-18.0 mg/L and 0.5-20.0 mg/L for uric acid and erotic acid, respectively. The detection limits were 0.20 g/L for xilose, glucose, galactose, and lactose and 0.10 g/L, 0.35, g/L, 0.40 g/L for saccarose, maltose, and melizitose, respectively. For uric and erotic acids the detection limits were 0.5 mg/L and 0.1 mg/L, respectively. The validity of the method was verified. For recovery studies of internal standards several determinations were conducted, using the standard addition method at three specific concentrations (1.0, 5.0, and 10.0 g/l). The recoveries ranged from 95 to 101%. The precision of the method was also evaluated, the %CV being 1.01, 0.51, 0.45, 0.73, 0.82, 0.82, and 0.74 for xilose, saccarose, maltose, lactose, melizitose, uric acid, and erotic acid, respectively. The sample pre-treatment was simple with a single er;traction. The good precision and accuracy obtained proved that this method is suitable for routine analysis.