Metrohm 889 IC Sample Center - Manual (Page 28)

4.2 Syringe and buffer loop
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889 IC Sample Center
prevents the contamination of the syringe. Washing solution is required in
order to:
￭ remove the sample from the buffer loop and the sample needle.
￭ rinse the buffer loop and the sample needle.
4.2 Syringe and buffer loop
The following range of sample volumes can be covered with the various
injection modes using the 500 µL syringe, in combination with the stand-
ard buffer loop (1000 µL) and the standard sample loop (100 µL):
￭ Full loop: 100 µL
￭ Partial loopfill: 1…50 µL
￭ Pickup: 1…27 µL
The maximum injection volume is calculated in accordance with the fol-
lowing formulas:
￭ Full loop: injection volume = sample loop volume
￭ Partial loopfill: max. injection volume = 0.5 × sample loop volume
￭ Pickup: max. injection volume = (sample loop volume – 3 × needle vol-
ume) / 2
The full loop injection yields the maximum possible reproducibility < 0.3%,
but not the maximum accuracy, because the loop volume is specified as
being with an accuracy of ±10%. The minimum sample loss is 230 µL (2 ×
(sample loop overfilling + rinsing volume) for one 15 µL needle).
The partial loopfill injection yields a maximum accuracy and reproducibility
better than 0.5% relative standard deviation (RSD) for injection volumes
> 10 µL. The minimum sample loss (rinsing volume is equal to 30 µL.
30 µL is the recommended minimum rinsing volume. Smaller rinsing vol-
umes can be programmed, but reproducibility will be reduced as a result.
The pickup injection offers maximum accuracy (the same as with partial
loopfill) and no loss of sample, but somewhat lower reproducibility,
namely a relative standard deviation (RSD) better than 1% for injection
volumes > 10 µL.