A specific and sensitive method for the determination of linamarin in urine

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Abstract
A method is described for the quantitative determination of the cyanogenic glycoside linamarin. A preseparation procedure for urine samples was necessary to remove interfering substances. This was done by solid‐phase extraction on a silica column containing cyclohexyl functional groups, which retained linamarin but allowed thiocyanate to pass unrestricted through the column. After elution of linamarin from the column by 35% (v/v) aqueous methanol, the glycoside was quantified following enzymatic hydrolysis, using the specific enzyme linamarase, and the free cyanide thus liberated was estimated spectrophotometrically. This method allowed quantification of linamarin in urine down to 10 μmol/l, with an estimated recovery of 91%. In 75 Tanzanian subjects consuming insufficiently processed cassava, the mean (± SD) urinary linamarin concentration was 104 (± 104) μmol/l (range 0‐644 n,mol/L), while that for thiocyanate was 486 (μ 451) μmol/l (range 10‐2,940 μmol/l), giving an approximate 15 molar concentration ratio between urinary linamarin and thiocyanate.