RADIOMETER ABL800 FLEX User manual

Contents
1. Potentiometric measuring principles
2. Amperometric measuring principles
3. Optical measuring principles
4. User-defined corrections
5. Performance specifications
6. Parameters
7. Solutions and gas mixtures
Index
Date of Issue
Reference
manual
ABL800 FLEX

SYSTEM PERFORMANCE AND WARRANTY DISCLAIM
Radiometer cannot provide or verify instrument performance characteristics and accept
warranty claims or product liability claims if the recommended procedures are not carried out,
if accessories other than those recommended by Radiometer are used, or if instrument
repairs are not carried out by authorized service representatives.
The instructions given in the Operator’s Manual for the ABL800 FLEX must be observed in
order to ensure proper instrument performance, and to avoid electrical hazards.
TRADEMARKS
ABL™, Deep Picture™, QUALICHECK™and Radiometer™are trademarks of Radiometer
Medical ApS, Denmark.
ABL is registered in the USA.
QUALICHECK is registered in the USA and in some other countries.
COPYRIGHT
The contents of this document may not be reproduced in any form or communicated to any
third party without the prior written consent of Radiometer Medical ApS.
While every effort is made to ensure the correctness of the information provided in this
document Radiometer Medical ApS assumes no responsibility for errors or omissions which
nevertheless may occur.
This document is subjected to change without notice.
©Radiometer Medical ApS, DK-2700 Brønshøj, Denmark, 2004. All Rights Reserved.

Contents
1. Potentiometric measuring principles........................................................... 1-1
Overview......................................................................................................... 1-1
General information ........................................................................................ 1-2
Reference electrode......................................................................................... 1-8
pH electrode .................................................................................................... 1-9
pCO2electrode .............................................................................................. 1-14
Electrolyte electrodes.................................................................................... 1-22
References..................................................................................................... 1-34
2. Amperometric measuring principles ........................................................... 2-1
Overview......................................................................................................... 2-1
General information ........................................................................................ 2-2
pO2electrode................................................................................................... 2-4
Metabolite electrodes .................................................................................... 2-12
3. Optical measuring principles........................................................................ 3-1
Overview......................................................................................................... 3-1
Optical system................................................................................................. 3-2
Correcting for interferences............................................................................. 3-7
Measurement and corrections.......................................................................... 3-9
References..................................................................................................... 3-14
4. User-defined corrections............................................................................... 4-1
Overview......................................................................................................... 4-1
General information ........................................................................................ 4-2
Correction factors for oximetry parameters and bilirubin............................... 4-4
Electrolyte and metabolite parameters ............................................................ 4-7
5. Performance characteristics......................................................................... 5-1
Overview......................................................................................................... 5-1
Definition of terms and test conditions ........................................................... 5-2
Performance test results – chart description.................................................... 5-5
Performance test results - pH .......................................................................... 5-8
Performance test results – pCO2.................................................................... 5-10
Performance test results – pO2...................................................................... 5-13
Performance test results – cK+....................................................................... 5-16
Performance test results – cNa+..................................................................... 5-18
Performance test results – cCl–...................................................................... 5-20
Performance test results – cCa2+.................................................................... 5-22
Performance test results – cGlu..................................................................... 5-24
Performance test results – cLac..................................................................... 5-26
Performance test results – ctHb..................................................................... 5-28
Performance test results - oximetry............................................................... 5-30
Performance test results - bilirubin................................................................ 5-40
Additional information about FLEXMODE ................................................. 5-46
Interference tests............................................................................................ 5-47
References..................................................................................................... 5-55
6. Parameters..................................................................................................... 6-1

Contents ABL800 FLEX Operator's Manual
Overview......................................................................................................... 6-1
General information ........................................................................................ 6-2
Measured parameters....................................................................................... 6-5
Input parameters............................................................................................ 6-14
Derived parameters........................................................................................ 6-17
Units and numerical format of derived parameters ....................................... 6-22
List of equations............................................................................................ 6-27
Oxyhemoglobin dissociation curve (ODC)................................................... 6-43
Conversion of units ....................................................................................... 6-48
Default values................................................................................................ 6-50
Altitude correction......................................................................................... 6-51
References..................................................................................................... 6-52
Index
Date of Issue

ABL800 FLEX Operator's Manual Contents
Warnings/Cautions
Throughout the manual, the descriptions may contain operational precautions and
warnings.
Definitions
Notice Definition
WARNING Warning alerts users to potential serious outcomes to
themselves or the patient (such as death, injury, or serious
adverse events).
PRECAUTION Precaution alerts users to exercise special care necessary for
the safe and effective use of the device. Precaution may
include actions to be taken to avoid effects on patients or
users that may not be potentially life threatening or result in
serious injury, but about which the user should be aware.
Precaution may also alert users to adverse effects on the
device by use or misuse, and the care necessary to avoid such
effects.
NOTE Notes give practical information.
WARNING/
CAUTION In this manual a distinction between a warning and a caution is not made. Any
notice that alerts the user to possible dangers of any kind is given the title
WARNING/CAUTION.
All WARNING/CAUTION notices that appear in this manual are listed here in
alphabetical order.
List of
WARNING/
CAUTION
Notices (NOTES are not presented in list form.)
• S5370 Cleaning Additive:
Very toxic by inhalation, in contact with skin and if swallowed. Danger of
cumulative effects. May cause sensitisation by inhalation and skin contact.
Toxic to aquatic organisms, may cause long term adverse effects in the
aquatic environment. After contact with skin, wash immediately with plenty
of water. Wear suitable protective clothing. In case of accident or if you feel
unwell seek medical advice immediately (show the label if possible). The
material and its container must be disposed of as hazardous waste.
• Electrolyte for E1001 Reference Electrode:
Irritating to eyes, respiratory system and skin. In case of contact with eyes,
rinse immediately with plenty of water and seek medical advice
• Gas cylinders:
Pressurized container. Non-flammable compressed gas. Do not breathe gas.
Gas mixtures containing less than 19.5 % oxygen may cause suffocation.
Protect from sunlight and do not expose to temperatures exceeding 50 C
(122 F). Store and use with adequate ventilation. Keep away from oil and
grease. Do not refill.
o
o

1. Potentiometric measuring principles
Overview
This chapter describes the potentiometric measuring principles and the pH, pCO2
and electrolyte electrodes that are based on this principle.
Introduction
Contents This chapter contains the following topics.
General information......................................................................................... 1-2
Reference electrode.......................................................................................... 1-8
pH electrode..................................................................................................... 1-9
pCO2electrode................................................................................................. 1-14
Electrolyte electrodes....................................................................................... 1-22
References........................................................................................................ 1-34

1. Potentiometric measuring principles ABL800 FLEX Reference Manual
General information
Potentiometric
method The potential of an electrode chain is recorded using a voltmeter, and related to the
concentration of the sample (the Nernst equation).
An electrode chain describes an electrical circuit consisting of a sample, electrode,
reference electrode, voltmeter, membranes, and electrolyte solutions.
Sample
Electrolyte
solution Electrolyte solution
Reference
electrode Electrode
V
Membrane Membrane
Voltmeter
Every element in the electrode chain contributes a voltage to the total potential
drop through the chain. Thus:
• When immersed in the appropriate electrolyte solution, both electrodes have
separate potentials.
• The membrane junctions between the sample and electrolyte solutions also have
separate potentials.
The potentiometric measuring principle is applied to pH, pCO2, and electrolyte
electrodes.
Nernst equation The complete electrode chain potential therefore, is the sum of these separate
potentials and is the quantity measured by the voltmeter.
E= E + E
total 0sample
where the final unknown potential (Esample) can be calculated knowing the total
electrode chain potential (Etotal) and the standard potential (E0).
Having measured the unknown potential (Esample), the Nernst equation is then
applied to determine the activity (ax) of the species under study:
EE T
na
sample =+ 023R
Flog
.x
where:
E0= standard electrode potential
R =
gas constant (8.3143 Joule ×K−1 ×mol−1)
T= absolute temperature (310 K (37 oC ))
Continued on next page
1-2

ABL800 FLEX Reference Manual 1. Potentiometric measuring principles
General information, Continued
Nernst equation
(continued)
n = charge on the ion
F =
Faraday constant (96487 coulomb ×mol−1)
x
a= activity of
x
The Nernst equation is rearranged to express the activity as a function of the
potential Esample. Having measured Esample the activity can be calculated since all
other quantities are already known. Finally the analyzer converts activity to
concentration.
Strictly speaking, the potential of an electrode chain or the magnitude of current
flowing through an electrical chain is related to the activity of a substance, and not
its concentration.
Activity expresses the ‘effective concentration’ of a species, taking non-ideality of
the medium into account.
Activity and concentration are related by the following equation:
ax= γcx
where:
ax= the activity of the species x
γ= the activity coefficient of species x under the measurement conditions
(for ideal systems γ= 1)
cx= the concentration of species (mmol/L)
NOTE: To be exact, activity is related to the molality of species x, i.e., the number
of mmoles per kg of solvent. However molality is converted to concentration
(molarity).
The analyzer automatically converts activities into concentrations [1]. The term
concentration is therefore used in explanations of the measuring principles for each
of the electrodes further on in this chapter.
The potentiometric measuring principle is applied in the pH, pCO2, and electrolyte
electrodes. It is slightly different for the pCO2electrode, however, since the Nernst
equation is not directly applied.
Calibration is an analytical process defining the functional relationship between the
obtained readings or analytical responses and the concentration or other quantities
present in the calibration material (liquid or gas). Thus, a calibrating solution or a
gas mixture (for pCO2calibrations) is drawn into the measuring chamber and the
analyzer adjusts itself to measure the known value of the liquid or gas.
Calibration
Continued on next page
1-3

1. Potentiometric measuring principles ABL800 FLEX Reference Manual
General information, Continued
The electrodes are active elements and must be calibrated regularly. Signals from
the electrodes change because of, e.g., protein build-up, worn-out membranes,
aging electrodes, etc.
Calibration
(continued)
The responses from the electrodes when measuring on the calibrating solutions are
checked to ensure that the amplified signals from the electrodes are converted to
accurate values for an unknown sample. The relationship between the electrode
amplifiers’ output and the pH/pCO2/electrolyte electrodes are simple mathematical
functions. Calibration data can therefore be determined by relating the electrode
signals during the calibration process to the values of the calibrating solutions.
Calibration line The calibration line expresses the relationship between the potential measured at
an electrode, and the concentration of the species specific to the electrode. The
calibration line forms the basis of the scale used by the analyzer to convert
electrode chain potentials to concentrations. Each electrode has a different
calibration line.
The pH electrode is used as an example to illustrate how the calibration line is
derived from two calibration solutions with known pH.
The calibration solutions give the following two points: −64 mV at pH 6.802 (Cal
2) and −100 mV at pH 7.398 (Cal 1)
Within the coverage range 6.300 to 8.000 the pH electrode is linear, and the
relationship between potential and pH is linear, so a line can be drawn between the
two points, as shown below:
Calibration line
pH
Measured
potential
(mV)
−
100
−
64
6.802
pH of Cal 2 sol. 7.398
pH of Cal 1 sol.
−
97
7.346
pH of sample
This is a two-point
calibration. In one-point
calibration, only the position
of the calibration line is
determined. The slope of the
calibration line is maintained
from the last 2-point
calibration.
The calibration line is stored in the computer and is used during measurement to
convert the potential measured at the pH electrode during sample analysis to an
actual pH value.
Continued on next page
1-4

ABL800 FLEX Reference Manual 1. Potentiometric measuring principles
General information, Continued
Calibration line
(continued) To describe the actual condition of the electrode, its calibration line is compared to
the calibration line of the theoretical electrode.
Theoretical calibration line
pH
Measured
potential
(mV)
−112.4
−75.5
6.8 7.4
The theoretical electrode is
defined to measure the
following:
−112.4 mV at pH 7.400,
−75.5 mV at pH 6.800.
The position and slope of the calibration line compared to the theoretical
calibration line are described by the status and sensitivity.
Sensitivity The electrode sensitivity illustrates the slope of the calibration line compared to the
slope of the theoretical electrode.
The sensitivity of the theoretical electrode is 100 % or 1.00.
Theoretical calibration line
Slope= −61.5 mV/pH
Sensitivity = 100 %
pH
Measured
potential
(mV)
−112.4
−75.5
6.8 7.4
2-point calibration line
Slope = −58.4 mV/pH
Sensitivity = 95 %
If an electrode
has a sensitivity
of 95 % or 0.95,
its sensitivity is
5 % lower than
the theoretical
electrode.
The sensitivity of an electrode is calculated as:
(%)
)802.6398.7(5.61 398.7802.6 −×
−
=atPotentialatPotential ySensitivit
where 61.5 = sensitivity of theoretical electrode.
Each electrode has its own sensitivity limits.
Continued on next page
1-5