title: CEC separation of insect oostatic peptides using a strong-cation-exchange stationary phase.
abstract: The separation of several insect oostatic peptides (IOPs) was achieved by using CEC with a strong-cation-exchange (SCX) stationary phase in the fused-silica capillary column of 75 microm id. The effect of organic modifier, ionic strength, buffer pH, applied voltage, and temperature on peptides' resolution was evaluated. Baseline separation of the studied IOPs was achieved using a mobile phase containing 100 mM pH 2.3 sodium phosphate buffer/water/ACN (10:20:70 v/v/v). In order to reduce the analysis time, experiments were performed in the short side mode where the stationary phase was packed for 7 cm only. The selection of the experimental parameters strongly influenced the retention time, resolution, and retention factor. An acidic pH was selected in order to positively charge the analyzed peptides, the pI's of which are about 3 in water buffer solutions. A good selectivity and resolution was achieved at pH <2.8; at higher pH the three parameters decreased due to reduced or even zero charge of peptides. The increase in the ionic strength of the buffer present in the mobile phase caused a decrease in retention factor for all the studied compounds due to the decreased interaction between analytes and stationary phase. Raising the ACN concentration in the mobile phase in the range 40-80% v/v caused an increase in both retention factor, retention time, and resolution due to the hydrophilic interactions of IOPs with free silanols and sulfonic groups of the stationary phase.
authors.affiliation: Institute of Chemical Methodologies, National Council of Research, Monterotondo Scalo, Rome, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Rocco
authors.forename: Zeineb
authors.initials: Z
authors.lastname: Aturki
authors.forename: Giovanni
authors.initials: G
authors.lastname: D'Orazio
authors.forename: Salvatore
authors.initials: S
authors.lastname: Fanali
authors.forename: Veronika
authors.initials: V
authors.lastname: Solínová
authors.forename: Jan
authors.initials: J
authors.lastname: Hlavácek
authors.forename: Václav
authors.initials: V
authors.lastname: Kasicka
mesh_terms: D000818:Animals; D002021:Buffers; D053801:Capillary Electrochromatography / Q000379:methods*; D002411:Cation Exchange Resins / Q000737:chemistry; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D007301:Insect Hormones / Q000302:isolation & purification*; D009842:Oligopeptides / Q000302:isolation & purification*; D009994:Osmolar Concentration; D013696:Temperature
chemical_list: D002021:Buffers; D002411:Cation Exchange Resins; D007301:Insect Hormones; D009842:Oligopeptides