[Detection and determination of protein-bound formaldehyde. II. Improved recovery of formaldehyde by reduction with sodium cyanoborohydride (NaCNBH3)].

When using NaCNBH3 as a reductant, it is possible to recover 70% of added formaldehyde in foods--in this skim milk powder. Formaldehyde is attached to the epsilon-Aminogroups of lysine and is detected after reduction in form of N epsilon-methyllysine in an automated amino acid analyzer system. After addition of N alpha-acetyllysine the reduction is carried out by incubating the skim milk powder at 70 degrees C for 1 h. The best combination of pH, concentration of reductant, time and temperature of incubation is described.