Objective To improve the desorption efficiency in the determination of isophorone in workplace air by gas chromatography using mixed solvent.
Methods Air samples collected with charcoal tubes were desorbed with 10% isopropanol and carbon disulfide mixture, separated with capillary column INNOWAX (30.0 m×0.53 mm×1.0 μm), and detected with flame io n detector using retention time for qualification and external standard curve for quantitation of isopropanol.
Results The 10% isopropanol and carbon disulfide mixture was applied for isophorone desorption, and the average desorption efficiency was 92.6%. The relative standard deviation of three isophorone spiked levels (10, 60, and 150 mg/L) was below 5% for intra assay or below 10% for inter assay. A good linearity was observed in the range of 0.28-400mg/L with the regression equation & #375;=1.947x-0.904 and correlation coefficient r=1.000 0. The limit of detection of the method was 0.084 mg/L. The minimum detectable concentration and the limit of quantitation of isophorone in solvent and air were 0.034 mg/m3 and 0.11 mg/m3 respectively based on sampling volume (2.5 L).
Conclusion The method using 10% isopropanol and carbon disulfide mixture as desorption solvent for determination of isophorone in workplace air is of great precision and accuracy. Its desorption efficiency is higher than the method using carbon disulfide only (<70%) and meets the requirements of relative standards.
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