Determination of thiocyanate in milk
Partanen, L.; Valkonen, K.; Alatossava, T.
Milchwissenschaft 53(3): 132-135
We developed both a modified colorimetric method and a high performance liquid chromatography (HPLC) method to measure thiocyanate concentration in milk samples. When measuring thiocyanate concentration in milk by colorimetric methods, it is important to take into account the yellow color of milk sample supernatants following protein precipitation with trichloroacetic acid. Previously published colorimetric methods have ignored this background color of milk samples, whereas in our modified colorimetric method we separately investigated color forming components when assessing thiocyanate concentration in milk. Based on our colorimetric method, the pooled bovine milk thiocyanate concentration was 2.5 +- 0.8 mg/l (n=3) and the pooled goat milk thiocyanate concentration was 1.6 +- 0.9 mg/l (n=6). By using the HPLC method the pooled bovine milk thiocyanate concentration was 1.6 +- 0.4 mg/l (n=3) while no thiocyanate could be detected in pooled goat milk samples (detection limit of thiocyanate 0.4 mg/l). The HPLC method appears more accurate than the colorimetric method, particularly when measuring thiocyanate concentrations in milk samples below 2 mg/l.