DETERMINATION OF CYANIDE IN WHOLE-BLOOD BY CAPILLARY GAS-CHROMATOGRAPHY WITH CRYOGENIC OVEN TRAPPING

Cyanide, one of the most important toxic substances, has been found me asurable with high sensitivity by capillary gas chromatography (GC) wi th cryogenic oven trapping upon injection of headspace (HS) vapor samp les. The entire amount of cyanide in the HS sample could be cryogenica lly trapped prior to on-line GC analysis, A 0.5mL volume of blood in t he presence or absence of cyanide and propionitrile (internal standard , IS) was added to a vial containing 0.25 mt of distilled water, 0.3 g of Na2SO4, 0.2 mt of 50% H3PO4, and 0.1 g of ascorbic acid (when need ed), and the mixture was heated at 70 degrees C for 15 min. A 5-mL vol ume of the HS vapor was introduced into a GC capillary column:in the s plitless mode at -30 degrees C oven temperature that was programmed up to 160 degrees C for GC analysis with nitrogen-phosphorus detection. A sharp peak was obtained for cyanide under the present conditions, an d backgrounds were very clean. The extraction efficiencies of cyanide and IS were 2.89-3.22 (100 or 500 ng/mL) and 2.42%, respectively. The calibration curve showed good linearity in the range of 25-1000 ng/mL and the detection limit was similar to 2 ng/mL, The coefficients of in traday and interday variations were 2.9 and 11.8%, respectively, The m ean blood cyanide level measured for actual fire victims was 687 +/- 5 97 ng/mL,(mean +/- SD, n = 9). Endogenous blood cyanide concentration for healthy subjects was 8.41 +/- 3.09 ng/mt (mean +/- SD, n = 6).