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A simple LC method with UV detection for the analysis of creatine and creatinine and its application to several creatine formulations

2002; Elsevier BV; Volume: 29; Issue: 5 Linguagem: Inglês

10.1016/s0731-7085(02)00167-x

1873-264X

Alekha K. Dash, Angeli Sawhney,

Metabolomics and Mass Spectrometry Studies

The objective of this study was to develop a simple and sensitive LC method for the determination of creatine and creatinine in various creatine supplement formulations. The chromatographic system comprised of a LC-600 pump, SCL-6B system controller, and SPD-6AV detector (Shimadzu, Japan). The mobile phase consisted of 0.045 M ammonium sulfate in water. The chromatographic separation was achieved at ambient temperature on a Betabasic C-18 column (250×4.6 mm, Keystone Sci.). The flow rate was maintained at 0.75 ml/min and effluents are monitored at 205 nm. 4-(2-Aminoethyl)benzene sulfonamide was used as an internal standard (IS). This method required less than 7 min of chromatographic time. The standard curves were linear over the concentration range of 1–100 μg/ml for creatine and 2–100 μg/ml for creatinine, respectively. The relative standard deviations (RSD) for the within-day and day-to-day precision for creatine were within 1.0–4.6 and 2.2–4.7%, respectively. The RSD for the accuracy of creatine assay was in the range of 2.4–4.7%. The RSD values for the within-day precision, day-to-day precision and accuracy for creatinine validation were 1.7–4.4, 2.3–5.4 and 2.4–4.8%, respectively. This method was used to determine: (i) the creatine concentration in various marketed products; (ii) saturated solubility of various creatine salts; and (iii) stability of creatine in aqueous solution. In conclusion, a simple and sensitive LC method with UV detection was developed for the simultaneous determination of creatine and creatinine in formulations. Di-creatine citrate salt showed a higher aqueous solubility (at 25 °C) as compared to creatine and creatine monohydrate. Some of the over-the-counter (OTC) products tested contained a very low level of creatine in contrast to their label claim. Substantial conversion of creatine into creatinine was noticed in liquid formulation.