Determination of plasma tenofovir concentrations using a conventional LC-MS method.

The quantification of tenofovir, a nucleoside reverse transcriptase inhibitor prescribed once daily, in human plasma is important due to a recent increase in its use. HPLC, however, can not easily detect and quantify tenofovir because of interfering peaks. Therefore, we developed a rapid and conventional LC-MS method, validated by estimating the precision and accuracy for inter- and intraday analysis in the concentration range of 0.019-1.567 microg/ml. The calibration curve was linear in the described concentration range. Average accuracy ranged from 95.9 to 100.7%. Relative standard deviations of both inter- and intraday assays were less than 11.6%. Recovery of tenofovir was more than 80.2%. This novel method provides a conventional, accurate and precise way to determine tenofovir in human plasma samples.