3-5
The Sipper Pump Piston retracts and draws in 25 microliters of sample. The Sipper moves back
to the Sample Chamber, the Sipper Pump Piston extends and the sample is dispensed. In less
than a minute, the analyte values for the sample are displayed and printed. An example of the
display format is shown below. Notice that the results are shown in line 2, while the
“Ready to
sample....”
message for the next analysis is in line 1.
Ready to sample at Station #2
B:LAC 0.00 g/L W:GLU 8.98 g/L
The printer format can be configured to express sample ID, date, time, temperature, sample
size, instrument serial number, probe currents and more. See Appendix D for example print-
outs.
For the purposes of learning basic operation, compare the instrument value with the labeled
value of the YSI standard. The 'linearity' standard should be within ±5% of the label value. For
example, if you calibrated the 2700 SELECT at 2.50 g/L dextrose using YSI 2776 as the
calibrator solution, YSI 1531 (9.00 g/L) should read between 8.55 g/L and 9.45 g/L dextrose. If
the reading falls outside these limits, recalibrate the instrument by pressing [CALIBRATE].
After recalibrating, repeat the analysis as directed above. If your reading is still outside this
range, proceed for now. Later in this section, specific actions for nonlinearity will be addressed.
Operation at the Manual Station (#3)
Remove the tube from the Test Tube Holder. Rotate the Tube Holder back into place. Next press
[3] on the keypad. Note the change in Station # on the LC display. Alternatively, rotate the Test
Tube Holder out to trigger the switch that senses a test tube. The Sipper will automatically go to
Station #3 (Manual).
With the door fully closed, press [SAMPLE]. The display reads:
Manual sample pause moving MS
Wait for the Sipper to come to a stop at the Manual Station, then bring the sample up to the
Sipper so the tip is
just
immersed, about 3 millimeters (1/8 inch) below the fluid surface (See
Figure 3.4).
If the Sipper dips too deeply into the sample, future measurements may be
contaminated by carry-over of excess sample on the outside of the Sipper.
Be very careful not to jar or push on the Sipper during manual operation. You could disturb its
critical alignment.
The display now reads:
Present sample to needle and hit
[SAMPLE] to aspirate
Press [SAMPLE].
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