On-line Determination of Nitrite in Water-Miscible Cooling Lubricants

摘要

Cooling lubricants (coolants) nowadays are essential auxiliary components in the metal-working industry. Besides for cooling and lubricating they are also used for the transport of metal splinters and to protect plants from corrosion. Effective cooling at increasing performance rates is only guaranteed with high water shares. Thus, o/w emulsions with water shares up to 97% are used and most coolants are water-miscible. To meet all requirements, water-miscible coolants consist of a great variety of substances and, thus, endanger employees in contact with them. Among the risks the formation of carcinogenic nitrosamines from nitrite and secondary amines [1,2] is particularly important. In this context the control of the nitrite content once a week and a maximum working place concentration of 20 mg/mL is prescribed [3].