Apl. Wang et al., LIQUID-CHROMATOGRAPHY TIME-OF-FLIGHT MASS-SPECTROMETRY WITH A PULSED SAMPLE INTRODUCTION INTERFACE, Analytical chemistry, 66(21), 1994, pp. 3664-3675
Conventional high-performance liquid chromatography (LC) has been comb
ined with time-of-flight mass spectrometry (TOFMS) with the use of a p
ulsed sample introduction (PSI) interface. The ion chromatogram obtain
ed by using LC/TOFMS is similar to that obtained with a UV detector. N
o significant peak distortion is introduced by the PSI interface. Vari
ous experimental parameters affecting the performance of the LC/TOFMS
system are investigated. It is shown that the PSI LC/TOFMS system can
handle liquid now rates ranging from 0.5 to 1.6 mL/min. Water and vari
ous organic solvents can be used as the mobile phase. Volatile buffers
and solvent modifiers can also be used. Several other parameters affe
cting the system performance, including the temperature of the sample
vaporizer and the capillary tube in the interface as well as the flow
rate of the makeup gas, are also investigated. In addition, the effect
ive sample transfer efficiency of the PSI interface is studied. It is
shown that, by pulsing only 0.31%-0.61% LC effluent into the mass spec
trometer with the interface, a chromatogram can be obtained with its p
eak area equivalent to that obtained by introducing 37%-72% sample int
o the system continuously. This represents an increase of sampling dut
y cycle by a factor of 118 using the pulsed technique, although the ov
erall detection duty cycle of the present LC/TOFMS system is still low
. Finally, several examples of separation and detection by the PSI LC/
TOFMS system are given to illustrate its analytical capability. The ad
vantages and limitations of the PSI interface in comparison with other
interfacing techniques are briefly discussed.