Authors: Lake ST, Altman PM, Vaisman J, Addison RS
A sensitive high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) assay has been developed for the quantitative analysis of vardenafil in human plasma. Vardenafil and the internal standard, alprazolam, were extracted from 0.2 mL aliquots of alkalinized plasma by a single solvent extractio n into hexane : dichloromethane. Reversed-phase chromatographic separation was affected by gradient elution with mobile phases consisting of 10 mM ammonium formate pH 7.0 (solvent A) and methanol (100%, solvent B), delivered at a flow rat e of 0.4 mL/min. The analytes were detected by using an electrospray ion source on a 4000 QTrap triple quadrupole mass spectrometer operating in positive ionization mode. The mass transitions we…



Viagra    Viagra
Our price - $1.15
per pill
Viagra is an oral drug for male impotence, also known as erectile dysfunction. Having been around for a ... more »

buy Viagra now
Cialis    Cialis
Our price - $2.18
per pill
Cialis is used for treating erectile dysfunction in men (e.g., impotence). Comparing with Viagra, Cialis ... more »

buy Cialis now
Levitra    Levitra
Our price - $3.42
per pill
Levitra is a reformulated advanced prescription formulation with the highest degree of effectiveness in ... more »

buy Levitra now