Single-laboratory validation of a method for the determination of c-phycocyanin and allophycocyanin in Spirulina (Arthrospira) supplements and raw materials by spectrophotometry.

A single-laboratory validation study was conducted for a 2-wavelength spectrophotometric method for the determination of c-phycocyanin (cPC) and allophycocyanin (aPC) in Spirulina supplements and raw materials. The absorption maxima of cPC and aPC are at 620 and 650 nm, respectively. The concentrations of the analytes were calculated from measurement of absorbance at 2 wavelengths. This method provided linear responses for cPC and aPC in the range of 25-250 microg/mL. Duplicate determinations of cPC and aPC in 4 different test materials on 5 different days resulted in relative standard deviations of 0.3-1.0 and 1.0-1.5% for cPC and aPC, respectively. Recoveries were 99.2-102.4 and 100.0-104.0% for cPC and aPC, respectively. The results were satisfactory for the determination of cPC and aPC in Spirulina supplements.