delay time 300 ns; laser intensity
2500; 40 random sample points for each laser shot; 50 shots; m/
z acquisition range 300–2000 D. Sample: TLS (1 mg) was dissolved
in 2 ml of distiled water for testing; supernatant sample (0.5 ll)
was dropped onto the MALDI-TOF board, dried at room temperature,
and covered by 0.5 ll of matrix solution.
The purity of TLS was tested by an HPLC apparatus consisting of
a UV detector, a rheodyne manual injector fitted with a 20 ll loop,
and a C18 column (Lunan Ruihong Chemical Instrument Co.,
Tengzhou, China). The mobile phase consisted of methanol (20%)
and cushion fluid (80%) at a flow rate of 0.6 ml/min, with detection
at a wavelength of 285 nm. The cushion fluid was composed of
0.067 M potassium dihydrogen phosphate solution and 0.067 M
disodium hydrogen phosphate solution (9:1, v/v). The TLS sample
(10 mg) was diluted with mobile phase in a 25 ml volumetric flask
for analysis.