Subcritical fluid chromatography of water soluble nucleobases on various polar stationary phases facilitated with alcohol‐modified CO₂ and water as the polar additive

Abstract

The separation of four water soluble nucleobases (thymine, uracil, adenine, and cytosine) via supercritical fluid chromatography with a CO(2)-based mobile phase containing an alcohol modifier and additive is described. Methanol, ethanol, 1-propanol, and 1-butanol were examined in conjunction with water as a neutral additive. Packed column stationary phases included silica bonded diol, cyanopropyl, and 2-ethyl pyridine. Thymine and uracil eluted with good peak shapes without additive, while adenine and cytosine yielded late eluting, severely tailing peaks. The addition of up to 5% water to each of the five alcohols gave rise to much sharper peaks that eluted under gradient conditions in less than 10 min with no baseline noise. Results with water under identical chromatographic conditions were compared with formic acid and ammonium acetate as additives. Water proved to be much superior to formic acid, and it was comparable to ammonium acetate. The role of water was speculated to not only enhance the solvating power of the binary mobile phase for water soluble analytes, but the common elution pattern exhibited by each of the three stationary phases suggested that water had altered the surface chemistry of the packed phase.

Fast separation of triterpenoid saponins using supercritical fluid chromatography coupled with single quadrupole mass spectrometry

“…Organic modifiers, such as MeOH, EtOH, ACN and IPA [28], are often added to scCO 2 in order to avoid the precipitation of the analytes within the column [29], reduce retention times and improve separation efficiency. Due to the low solubility of the polar kudinosides in the non-polar scCO 2 , a relatively polar solvent had to be added to the mobile phase and the influence of this modifier on the SFC separation performance was studied using these four typical organic solvents.…”

“…Water is an interesting additive in SFC, due to its positive effect on peak shape and reproducibility of retention times [29]. The benefit of the addition of water to the mobile phase on the separation of the highly polar kudinosides was investigated by varying its proportion in mobile phase component B from 0 to 12% (v/v).…”

Theory and Practice of UHPLC and UHPLC–MS

“…In this context, UHPLC coupled with tandem MS or TOF/MS remains the gold standard. Multiresidue screening methods with UHPLC technology have been applied to a wide variety of analytes and matrices, including: (1) doping agents (Thorngren et al, 2008;Badoud et al, 2009Badoud et al, , 2010 and veterinary drugs (Kaufmann et al, 2007) in biological matrices; (2) drugs (Kasprzyk-Hordern et al, 2008a,b), pesticides (Gervais et al, 2008), and herbicides (Pastor Montoro et al, 2007) in environmental matrices; and (3) veterinary drugs (Stolker et al, 2008), drugs , and pesticides (Romero-Gonzalez et al, 2008;Taylor et al, 2008;Garrido Frenich et al, 2008) in food samples. Because of the high number of investigated compounds, conventional HPLC runs can be relatively long, particularly to avoid peak coelution leading to matrix effects.…”

“…Volatile additives, such as ammonium acetate, ammonium formate, and ammonia were generally also recommended in other studies Hamman et al, 2011). In most studies, a positive effect of an additive on MS sensitivity has been noted (Nováková et al, ,b, 2016Pilarová et al, 2016;Wolrab et al, 2016;Bamba et al, 2008). A comparison of ESI-MS response when using methanol alone as a pure organic modifier and methanol with different additives including 2% water, 10 mM ammonium acetate, 10 mM ammonium formate, and 10 mM ammonium formate with 2% water is shown in Fig.…”

“…Lipid extracts can be separated into their respective classes, and subsequently individual lipid species can be identified using high-resolution MS (HRMS) or MS/MS spectra. SFCeMS offers higher throughput than LCeMS (Laboureur et al, 2015;Bamba et al, 2008). …”