[Determination of unbound formaldehyde in protein coverings using the colorimetric method with chromotropic acid].

In the period 1989-1991 in a control of health quality of packing material and utility objects in contact with food 1964 samples of protein coverings for processed food were analysed, determining the content of formaldehyde, lead, arsenic and copper according to the requirements of Production Standard ZN-76/MPSS-M-19-149. It was found that in about 40% of covering samples formaldehyde level exceeded the acceptable level of 1000 mg/kg. In about 90% of the samples the level of formaldehyde was below 1800 mg/kg. In 14% of the samples the lead level was increased. Arsenic and copper were within normal range in most analysed coverings.