Xylem YSI 2500, User Manual

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16-2
Calibration Shift by Detergents
The sensitivity of the platinum anode of the sensor is affected somewhat by absorption or desorption of material from the
buffer which bathes it. In normal operation, such changes are quite gradual and are corrected in the periodic recalibration
of the instrument. However, concentrated detergent solutions may have a much more sudden effect. Concentrated
anionic detergents can cause readings to be abruptly elevated or depressed; concentrated nonionic detergents generally
depress readings. For this reason, concentrated detergent solutions should not be sampled. No problem has been
observed from the naturally occurring detergency of specimens.
Endogenous and Exogenous Substances
YSI has tested hundreds of substances to determine whether they have any effect on the sensor system used in the YSI
2500.
The endogenous substances listed were found to be noninterfering at the highest naturally occurring levels. The column
headed "Interfering Level" indicates the concentration at which each substance might be expected to cause an error of 1
mmol/l in the lactate reading, or 5 mg/dl in the glucose reading. Certain exogenous substances can interfere with
measurements.
The YSI 2500 should not be used to analyze specimens containing any of these substances at or above the listed
Interfering Level.
Physical Damage
Never inject concentrated mineral acids, concentrated bases, or strong organic solvents into the YSI 2500 as these may
permanently damage the enzyme membranes or the plastic parts of the probe and sample chamber. Do not inject water-
insoluble oils or greases, because it may be difficult to clear them from the sample chamber. Blood specimens with
excessive content of fats are not a problem.
NOTE: Chlorpromazine, Iodoacetamide, Phloridzin and various mercurials have been reported to inhibit the transport of
glucose through erthrocyte membranes in vitro, which could conceivably lead to erroneously low whole blood glucose
readings by YSI methods. We have been unable to produce any error in our laboratory with reasonable levels of these
materials, but it may nevertheless be prudent to determine glucose in plasma, rather than whole blood, for specimens in
which these substances (or any other reported glucose transport inhibitors) are believed to be present.