National Institute for Occupational Safety and Health

“ MEK and toluene are commonly found in trace amounts in humans working in the paint spray industry. Occasionally, traces of ethanol are also present. This method can be used in screening workers exposed to these central nervous system depressants. INTERFERENCES: Ethanol concentrations in excess of the stated range may interfere with the MEK peaks at low concentration (< 0.2 μg MEK/mL blood) . Ethanol in excess of the stated range also increases blood toluene concentration [1] . ”

“ When substances other than the analytes are suspected to be present in the blood, record their identities to determine possible interferences [2] .
OTHER METHODS: None are known that can determine these constituents simultaneously. Other methods require extraction or distillation for concentration of trace amounts of these chemicals in blood. ”

“ Prepare working standard solutions. Pipet 2 mL from each of the calibration stock solutions into separate 200-mL volumetric flasks. Dilute to the mark with deionized water. The resultant concentrations are 38.1 and 38.6 μg/mL for toluene and MEK, respectively; and 1.58 mg/mL for ethanol. Prepare fresh standards every 92 h. Make blood standards at 5 different concentrations ranging from 0 to 8 μg MEK and toluene/mL blood and from 0 to 500 μg ethanol/mL blood. Add aliquots of the working standards to 2 mL blood with a microliter syringe. ”