Analytical procedure for detection and quantification of etaqualone in human blood and urine using GC-MS/MS was established and applied to authentic human samples obtained from volunteers. A liquid-liquid extraction method was employed. Each 1.0 mL of blood or urine was alkalized and extracted with diethyl ether. The solvent layer was evaporated to dryness and reconstituted with methanol then analyzed by GC-MS/MS. linear relationships within the concentration range of 1-100 ng/mL were obtained in calibrators for both blood and urine, demonstrating correlation coefficients values being>0.999. For blood and urine samples, the intra-day assay precision and accuracy values are each less than 3.65%, 7.13%, and 6.02%, 9.12%; those values of the inter-day assay are each less than 1.82%, 6.74%, and 3.99%, 7.41%. The extraction recovery rates for etaqualone ranged from 98.7% to 106%. The lower limit of quantifications was 1.0 ng/mL in both blood and urine. Stabilities of etaqualone in blood and urine were satisfactory under various temperatures within 15 days. 8.51 and 2.06 ng/mL of etaqualone in blood and urine were detected at 4 h later oral ingestion; 6.91 and 3.94 ng/mL of etaqualone were also detected 30 min and 2 h later smoking from blood and urine.
Keywords: Etaqualone; Excretion; GC–MS/MS; Human samples; Internal standard method.
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