Determination of Abused Drugs in Human Plasma by In-Tube SPME-UHPLC-MS/MS

A method of in-tube SPME-UPLC-MS/MS was used to measure abused drugs in plasma. 1 mL of plasma was mixed well with 2 mL of sodium borate buffer,and then centrifuged. The supernatant was taken into a sampler connected with a stainless steel needle fixed with DB-5 capillary column and then injected at a speed of 200 μL·min-1 by a syringe pump. The needle was washed using 1 mL of water and then eluted for 2 min using 50 μL of acetonitrile as eluent. Gradient elution,ESI+ and MRM were adopted in UPLC-MS/MS detection. The detection limits were below 10 μg·L-1 for 16 drugs,and 10-50 μg·L-1 for 18 drugs,and ≥77 μg·L-1 for 3 drugs. 5 drugs were not detected. The recovery rates and RSD′s (n=6) for 37 drugs in plasma were in the range of 4.0%-93.5% and 0.80%-13%,respectively. Drugs were detected in 31 out of the 76 plasma samples by this method.