Analytical method based on room-temperature phosphorimetry for the determination of rescinamine in pharmaceutical tablets

Simultaneous determination of reserpine, rescinnamine, and yohimbine in human plasma by ultraperformance liquid chromatography tandem mass spectrometry

A sensitive and selective UPLC-MS/MS method was developed and validated for the determination of three indolic alkaloids (reserpine, rescinnamine, and yohimbine) in human plasma using papaverine as internal standard (IS). After a one step protein precipitation with acetonitrile, separation was carried out using C18 column (50 × 2.1 mm, i.d. 1.7  μ m) and mobile phase consisting of acetonitrile : water : formic acid (60 : 40 : 0.1%, v/v/v) pumped at a flow rate of 0.2 mL/min. The mass spectrometric determination was carried out using an electrospray interface operated in the positive mode with multiple reaction monitoring (MRM) mode. The precursor to product ion transitions of m/z 609.32 > 195.01, m/z 635.34 > 221.03, m/z 355.19 > 144, and m/z 340.15 > 202.02 were selected for the quantification of reserpine, rescinnamine, yohimbine, and IS, respectively. The analytical response was found to be linear in the range of 0.36-400, 0.27-300, and 0.23-250 ng/mL with lower limit of quantification of 0.36, 0.27, and 0.23 ng/mL for reserpine, rescinnamine, and yohimbine, respectively. Validation was made following official guidelines. The proposed method enabled reproducible results and hence could be reliable for pharmacokinetic and toxicological analysis.

Sequential determination of norfloxaxin and levofloxacin in the presence of other fluorquinolones using synchronous scanning room-temperature phosphorimetry and Th (IV) as the selective signal inducer

The selective determination of norfloxacin in mixtures with other fluorquinolones was achieved by synchronous scanning solid surface room-temperature phosphorimetry (SSRTP) and Th(NO(3))(4) as selective phosphorescence inducer. The method also allowed the determination of levofloxacin in a sequential way. The optimization of experimental conditions was made through an univariate approach, in order to find the best conditions for norfloxacin phosphorescence, followed by a 2(3) factorial design in order to verify interaction among relevant variables, to check robustness for each variable and to perform final adjustment of parameters. Absolute limit of detection (ALOD) for norfloxacin was 12ng with a linear signal response extending up to 400ng. Under the same experimental conditions set for norfloxacin, the ALOD for levofloxacin was 13ng with linear signal response up to 450ng. Accuracy of the method, using Th (IV) as selective phosphorescence inducer, was evaluated through the analysis of commercial and simulated pharmaceutical formulations with recoveries between 94.4 and 101% for norfloxacin and 95.9 and 103.8% for levofloxacin. The use of Cd (II), a traditional phosphorescence inducer for fluorquinolones, did not allow selective determination of norfloxacin. Further studies indicated the potential application of the method in urine samples.