The sample after reaction waswashed out with deionized water (DI
water), then centrifuged at relative centrifugal force (RCF) of 4070 g for
5 min. Clear liquid at the upper layer was collected, and pH value was
adjusted to around 3 using 0.025 M H2SO4 in order to convert the
unconverted calcium lactate to LA. Then the sample was fed through
an ion-exchange column packed with DOWEX 50WX8-400 resin
(Sigma Aldrich) to remove metal ions. The samples after ion-exchange
were analyzed on an HPLC equipped with a Shodex SH 1011 column
(300 × 8 mm), a refractive index (RI) detector (waters 410), and an
Ultraviolet (UV) detector. The column temperature was set at 60 °C,
and the mobile phase used was 0.5 mmol H2SO4 in DI water with a
flow rate of 0.6 mL/min. The LA, glycerol, and PG were well identified
by the RI detector, and the methyl/ethyl lactate was well identified by the UV detector at 210 nm. External calibration was used to quantity
each component in the products.
Glycerol conversion, LA, methyl/ethyl lactate yield, and PG yield
were calculated according to the following equations:
The sample after reaction waswashed out with deionized water (DIwater), then centrifuged at relative centrifugal force (RCF) of 4070 g for5 min. Clear liquid at the upper layer was collected, and pH value wasadjusted to around 3 using 0.025 M H2SO4 in order to convert theunconverted calcium lactate to LA. Then the sample was fed throughan ion-exchange column packed with DOWEX 50WX8-400 resin(Sigma Aldrich) to remove metal ions. The samples after ion-exchangewere analyzed on an HPLC equipped with a Shodex SH 1011 column(300 × 8 mm), a refractive index (RI) detector (waters 410), and anUltraviolet (UV) detector. The column temperature was set at 60 °C,and the mobile phase used was 0.5 mmol H2SO4 in DI water with aflow rate of 0.6 mL/min. The LA, glycerol, and PG were well identifiedby the RI detector, and the methyl/ethyl lactate was well identified by the UV detector at 210 nm. External calibration was used to quantityeach component in the products.Glycerol conversion, LA, methyl/ethyl lactate yield, and PG yieldwere calculated according to the following equations:
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