A spectrophotometric procedure for sialic acid determination in milk employing a flow-batch analysis system with direct heating

Publication date: June 2019Source: Microchemical Journal, Volume 147Author(s): Joicy B. S. Costa, Nattany T.G. de Paula, Paulo A.B. da Silva, Gustavo C.S. de Souza, Ana Paula S. Paim, André F. LavoranteAbstractThe quantitative determination of sialic acid can indicate the addition of cheese whey to milk. This work describes an automated procedure to determine sialic acid in milk samples using a flow-batch system analysis with direct heating. The sialic acid quantification was based on a reaction between the sialic acid and acid ninhydrin producing a stable compound with maximum absorption at 470 nm. The flow-batch system was designed using heating and spectrophotometric detection in the reaction chamber. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg L−1 sialic acid (R = 0.99 and n = 7), a detection (3σ criterion) and quantification (10σ criterion) limit estimated at 0.239 and 0.726 mg L−1, respectively, a relative standard deviation of 1.90% (n = 10) for a reference solution of 4.0 mg L−1 sialic acid and a sampling rate of 7 determinations per hour were achieved. Analysis of eleven milk samples, application of the t-test to the results found, and comparison with the official method provided no significant differences at a 95% confidence level. Compared to the official method, the proposed system reduced reaction time by 50%, temperature of the reaction by 30%, and diminished the consumption of reage...
Source: Microchemical Journal - Category: Chemistry Source Type: research