Separation, pre‐concentration, and HPLC analysis of methylxanthines in urine samples

Abstract

An SPE method, using RP18 phases, for the simultaneous extraction of caffeine, theobromine, theophylline, paraxanthine, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1-methyluric acid, 1,3-dimethyluric acid, 1,7-dimethyluric acid, and 1,3,7-trimethyluric acid from urine has been developed. Besides a gradient HPLC system for the analysis of the compounds of interest on a LiChrosorb RP-18 (7 microm) column with mobile phase containing 0.05% aq. solution of trifluoroacetic acid and acetonitrile has been elaborated. The procedure has been successfully applied to the analysis of methylxanthines and methyluric acids in urine of patients with chronic asthma treated with theophylline and in urine of healthy subjects.

Analysis of Supramolecular Complexes of 3-Methylxanthine with Field Asymmetric Waveform Ion Mobility Spectrometry Combined with Mass Spectrometry

“…The CF for maximum transmission of [(3-MX) 8 (Figure 4b), whilst having a symmetrical profile, is much more affected by the electric fields with the CF for maximum transmission increasing from 0.65 Td (DF 194 Td) to 2.85 Td (DF 323 Td), an increase of 2.20 Td, and the intensity starts to decrease significantly at DF 260 Td and above. The intensities of [(3-MX) 8 + Na] + and [(3-MX) 16 + 3Na -H] 2+ at DF values in the range 180-300 Td at the lowest fragmentor voltage of 50 V (Supplementary Figure 4), show the expected decrease in the intensity for the doubly charged [(3-MX) 16 + 3Na -H] 2+ ion at higher DFs as seen from Figure 4h. However, the intensity of [(3-MX) 8 + Na] + ion shows an unexpected overall increase as the DF increases.…”

“…However, the intensity of [(3-MX) 8 + Na] + ion shows an unexpected overall increase as the DF increases. We believe that this increase in intensity of the singly charged 3-MX octameric complex is evidence that the higher ordered and more highly charged species, such as the doubly charged [(3-MX) 16 …”

“…3-MX is a purine derivative and a metabolite of caffeine and theophylline [14,15], and has been monitored biologically in urine and plasma by liquid chromatographic methods [16][17][18][19]. Guanine is a related purine base structure that self-assembles into tetrad structures in biological systems (G-quadruplexes) to form complexes that have been well characterized, theoretically and experimentally [2,[20][21][22][23][24].…”

Simultaneous Determination of Biogenic Amines and Methylxanthines in Foodstuff—Sample Preparation with HPLC-DAD-FL Analysis

“…For methylxanthines, diode array detector (DAD) (Baranowska and Zydroń 2002;Baranowska et al 2006;Hicks et al 1996;Matissek 1997;Zydroń et al 2004) is widely used. Interest in application of ultra high-performance liquid chromatography has increased in the last few years (Tzanavarasa et al 2010;Dadáková et al 2009;Mayer et al 2010;Latorre-Moratalla et al 2009).…”

Cafeína: revisão sobre métodos de análise

“…A cafeína e seus metabólitos foram dessorvidos da pré-coluna com a própria fase móvel do sistema cromatográfico composta de metanol e tampão fosfato 0,01 M, pH = 5 (30:70, v/v). Zydron et al 42 usaram uma coluna de extração em fase sólida de octadesilsilano, de composição idêntica à da coluna analítica, para isolar cafeína e teofilina da urina de pacientes com asma crônica ou saudáveis. Os compostos foram separados por cromatografia de fase reversa com fase móvel, modo gradiente, composta de solução aquosa de ácido trifluoracético 0,05% e acetonitrila.…”