... J. Agric ... A very small amount of 2,2-dimethyl-2-silapentane-5-sulfonate sodium salt (DSS; Wako Pure Chemical Industries, Ltd., Osaka, Japan) was added to the ... mL) was transferred into a 15 mL centrifuge tube, and the pH value was adjusted to ∼4.2 using 6 M HCl or 4 M NaOH ...