Prior to synthesizing
the monolithic packing, the polyimide-coated fused-silica capillaries
(100 μm i.d., 375 μm o.d.) from Polymicro Technologies
(Phoenix, AZ, USA) were first treated by an adapted etching protocol28 (link) at room temperature comprising a rinse with
methanol followed by deionized water, then etching with aqueous 1
M NaOH for 2 h followed by a rinse with deionized water until neutral.
This was followed by flushing with 1 M aqueous HCl for 20 min, deionized
water until neutral, methanol for 1 h, and drying by a flow of nitrogen
at room temperature for 12 h. These etched capillaries were subsequently
modified to produce three different activated capillaries (Figure S1 ; prefix “S” refers to
the Supporting Information), first by 10% (v/v) (3-aminopropyl)triethoxysilane
(APTES) in toluene at 60 °C overnight, followed by washing with
water and methanol and drying as in the final step of the above etching
procedure, yielding capillariesC1 . Dried C1 capillaries
were subsequently reacted according to two different schemes; capillariesC2 were prepared by filling C1 with 10% (v/v) aqueous formaldehyde
and reacting at 80 °C for 4 h, followed by washing and drying
as above; capillariesC3 were filled with the MF precondensate
(see below) diluted 1 + 9 (v/v) with water and reacted at 80 °C
for 4 h, followed by washing and drying as above. Activated capillaries
were stored in a desiccator for use in the polymerization of MF monolithic
columns.
the monolithic packing, the polyimide-coated fused-silica capillaries
(100 μm i.d., 375 μm o.d.) from Polymicro Technologies
(Phoenix, AZ, USA) were first treated by an adapted etching protocol28 (link) at room temperature comprising a rinse with
methanol followed by deionized water, then etching with aqueous 1
M NaOH for 2 h followed by a rinse with deionized water until neutral.
This was followed by flushing with 1 M aqueous HCl for 20 min, deionized
water until neutral, methanol for 1 h, and drying by a flow of nitrogen
at room temperature for 12 h. These etched capillaries were subsequently
modified to produce three different activated capillaries (
the Supporting Information), first by 10% (v/v) (3-aminopropyl)triethoxysilane
(APTES) in toluene at 60 °C overnight, followed by washing with
water and methanol and drying as in the final step of the above etching
procedure, yielding capillaries
were subsequently reacted according to two different schemes; capillaries
and reacting at 80 °C for 4 h, followed by washing and drying
as above; capillaries
(see below) diluted 1 + 9 (v/v) with water and reacted at 80 °C
for 4 h, followed by washing and drying as above. Activated capillaries
were stored in a desiccator for use in the polymerization of MF monolithic
columns.
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