Acquityapc xt

Two-dimensional LC
× LC–HRMS experiments were performed using an Agilent
1290 Infinity 2D- LC system (Agilent Technologies, Waldbronn, Germany)
coupled with a Waters Synapt-G2 high-resolution mass spectrometer.
The system comprised two binary pumps (G4220A) for solvent delivery,
an autosampler (G4226A), column thermostat (G1316C) equipped with
a 2D-LC 8-port 2-postion modulation valve (G4236A) with 40 μL
loops, and a diode-array detector (G4212A) equipped with an Agilent
Max-Light cartridge flow cell (G4212–6008, 10 mm, V_det = 1.0 μL). The ¹D column was a Phenomenex
Luna HILIC (150 × 2.0 mm i.d., 3.0 μm particles, 200 Å
pore size) column used for gradient-NPLC, while two Waters Acquity
APC XT columns (75 × 4.6 mm i.d., 1.7 μm particles, 45
Å pore size and 75 × 4.6 mm i.d., 2.5 μm particles,
125 Å pore size, respectively) were coupled in series for SEC
experiments.
For parallel UV/HRMS detection, the analytical
effluent was split after the second-dimension SEC column set using
a tee piece and in-house-made restriction capillaries (450 ×
0.075 mm i.d. and 900 × 0.050 mm i.d. capillaries), ensuring
a split ratio of 9:1 to the diode array and mass spectrometer, respectively.
Using the diverter valve of the Synapt-G2 system, the smallest split
flow was combined with a make-up flow (1:1 ratio) consisting of 1
mM NaI with 0.5% (v/v) 3-nitrobenzyl alcohol in deionized water.

Molar masses of acetylated
lignin–TOFA and starting lignin acetylated in the presence
of TOFA (roughly 50 wt %) were analyzed using SEC. The Waters Acquity
APC system was used for the analysis (Waters Corporation, Milford,
MA, USA), equipped with Acquity APC XT columns 45, 200, and 450 Å,
and using 30 °C as the column oven temperature. Sample concentration
was 1 mg mL^–1 in tetrahydrofuran (THF). Samples
were filtered through a 0.2 μm syringe filter (GHP Acrodisc
13 mm, Pall Corp., Ann Arbor, MI, USA) before injection (50 μL).
Total run time was 12 min, with a flow rate of 0.8 mL min^–1. Molar masses were evaluated using data from the UV range (254 nm),
and the following polystyrene standards were used for calibration:
474, 840, 2500, 5010, 13,300, 32,300, 43,400, 76,000, and 139,400
Da (Polystyrene Calibration Kit, Scientific Polymer Products, Inc.)
along with 321,000 and 526,000 Da (Fluka).