Correction for protein content in the determination of the glucosinolate content of rapeseed by the X‐RF method

Thirty six rapeseed samples from a factorial designed nitrogen and sulphur trial were analysed for total glucosinolate content by the X‐ray fluorescence (X‐RF) and HPLC methods and for protein content by the Kjeldahl method. Protein content varied from 16.0 to 22.6%. Correction for seed protein content in the calculation of glucosinolate content by X‐RF significantly improved the agreement between the two methods of glucosinolate analysis. The following equation was used in the correction: Y = 14.99 [ S (mg g −1 )‐protein %/7.5].