562 The Immunoassay Handbook
carrier, and identical assay reagents across c-series or i-series
instruments. These design features result in system com-
monality that allows ARCHITECT c-series and i-series
instruments to be connected in speciﬁc combinations to
form integrated systems operated through a single user
interface. An ARCHITECT i2000SR may be integrated
with an ARCHITECT c8000 or c16000 to form a single
instrument, the ARCHITECT ci8200 or ARCHITECT
ci16200, respectively. In addition, two ARCHITECT
i2000SR instruments may be integrated to form an ARCHI-
TECT i4000SR. Similarly, an ARCHITECT i1000SR may
be combined with an ARCHITECT c4000 to form an
ARCHITECT ci4100. Integrated systems (ci-series) retain
the same sample throughput, reagent capacity, and sample
handling capabilities of the stand-alone systems. The ability
to use stand-alone and/or integrated systems provides labo-
ratories with the ﬂexibility to address complex workﬂow
needs, both within a single laboratory, as well as across mul-
tiple laboratories and sites. ARCHITECT family common-
ality ensures equivalent patient results are obtained,
regardless of which instrument conﬁgurations are used.
Across the ARCHITECT family, reagents are available to
perform a wide variety of assays including thyroid, fertility,
routine chemistry panels, speciﬁc proteins, enzymes, elec-
trolytes, oncology, cardiac, metabolic, and infectious dis-
ease analytes. All assays on the ARCHITECT i-series
analyzers use chemiluminescent immunoassay technology.
Multiple immunometric assay technologies are available on
the ARCHITECT c-series analyzers.
Typical Assay Protocols
The ARCHITECT i-series analyzers are capable of
simultaneously performing two-step, one-step, delayed
one-step, STAT, auto-retest, and automated pre-treatment
protocols. The availability of multiple protocols provides
the ﬂexibility required to address analyte-speciﬁc assay
development needs. For illustration purposes, typical
i-series assay protocols are described below using the
i2000SR and its process path (Fig. 4) as an example. On the
ARCHITECT i-series, the majority of assays use a two-
step protocol. In two-step routine assays, specimen and
microparticles are added to a reaction vessel at positions 1
and 2 of the process path, respectively. Reaction compo-
nents are then thoroughly mixed by a pop-up mixer (or,
in-track vortexer, ‘ITV’) at position 3. Incubation contin-
ues until the reaction vessel reaches wash zone 1. In wash
zone 1, magnets attract the microparticles to the inner wall
of the reaction vessel, and unbound material is washed away
in a series of three washes. After wash zone 1, conjugate or
tracer is added to the reaction vessel, and reaction compo-
nents are mixed using a pop-up mixer. Incubation contin-
ues until the reaction vessel reaches wash zone 2, where the
microparticles undergo a second series of three washes to
remove unbound material. After the reaction vessel leaves
the second wash zone, a pre-trigger reagent is added. This
reagent releases the conjugate or tracer into solution, and
prepares the label for the light-generating reaction. Mic-
roparticles are then magnetically attracted to the inner wall
of the reaction vessel, separating them from the label, and
the trigger reagent is added. The trigger reagent initiates
the ﬁnal phase of the light-generating reaction, and the
resulting chemiluminescence is measured using a photo-
multiplier tube. The measured relative light units (RLUs)
are processed by the data management software to yield the
assay result. Finally, the reaction mixture is aspirated, and
the empty reaction vessel is transferred to a waste con-
tainer. In routine one-step assays, specimen is added to the
reaction vessel at position 1. Particles and conjugate or
tracer are added at position 2. Reaction components are
then thoroughly mixed by the pop-up mixer at position 3.
As the reaction vessel approaches wash zone 1, it is diverted
to the outer lane of the process path, allowing the reaction
vessel to by-pass wash zone 1 and continue incubation
without interruption. Incubation continues until
FIGURE 3 ARCHITECT integrated analyzers (ci-series, and i4000). (The color version of this ﬁgure may be viewed at
563CHAPTER 7.9 Abbott ARCHITECT® Family of Analyzers
the reaction vessel reaches wash zone 2. In wash zone 2,
microparticles are magnetically attracted to the inner wall
of the reaction vessel, and unbound material is washed away
in a series of three washes. From this point, reaction vessel
processing is as described for the two-step protocol. For
fully automated pre-treatment protocols, specimen and
pre-treatment reagent are combined in a reaction vessel at
positions 1 and 2 of the process path, respectively. After an
incubation of approximately 7min, an aliquot of the pre-
treated specimen is removed by the sample pipetter and
reintroduced into a new reaction vessel at position 1 of the
process path. From this point, the assay runs in either a
two-step or one-step protocol as described above. STAT
protocols are made possible by the addition of a second
sample pipetter and pop-up mixer to the system hardware.
These hardware modiﬁcations allow for shorter assay incu-
bation times by providing for STAT sample introduction
and mixing at a point farther along in the system sample
processing path. Reagents for STAT assays are optimized
to allow for the shorter incubation time without compro-
mising assay performance. STAT assay results are available
within 15.6min for the ARCHITECT i-series.
The ARCHITECT c-series analyzers are capable of
performing a variety of different homogeneous assay pro-
tocols, as well as STAT assay protocols (quickest results
within 2.6min and no longer than 10min). A schematic of
the ARCHITECT c-series process path is shown in
Fig. 5. Some assays on the ARCHITECT c-series analyz-
ers are based on immunoturbidimetric methodologies like
particle enhanced turbidimetric inhibition immuno-
assay (PETINIA) and particle enhanced turbidimetric
immunoassay (PETIA). In PETINIA, latex microparti-
cles are coated with small-molecule analytes (antigens).
Unbound microparticles suspended in solution are too
small to block the passage of light through a reaction
cuvette. However, when antibodies to the antigen on the
microparticles are added, the particles aggregate and form
lattices (large complexes) that block the passage of a light
beam. As in many competitive immunoassay methodolo-
gies, free antigen present in a patient sample competes
with the antigen-coated microparticles for antibody. The
greater the concentration of analyte in the patient sample,
the less aggregation and lattice formation and the smaller
the decrease in light transmission through the cuvette.
The smaller the concentration of analyte in the patient
sample, the more aggregation and lattice formation and
the larger the decrease in light transmission. When the
microparticles are coated with antibody instead of anti-
gen, the methodology is known as PETIA. Depending on
whether the assay is designed to use PETINIA or PETIA,
the inhibition of lattice formation or the formation of lat-
tices may be measured as a rate reaction. The rate of
increase or decrease in light transmission is directly pro-
portional to analyte concentration.
Enzyme multiplied immunoassay technique (EMIT®) is
also used on the ARCHITECT c-series to perform homo-
geneous competitive assays. In these assays, analyte (antigen)
in the patient sample competes for antibody binding sites
with an enzyme conjugate labeled with a modiﬁed version
of the analyte. The enzyme conjugate is active unless the
analyte portion of the conjugate is bound by the antibody,
blocking the enzyme’s active site. The enzyme used in
EMIT is glucose-6-phosphate dehydrogenase (G6PDH).
When the concentration of analyte in the patient sample is
high, more antibodies are bound to analyte and less to
enzyme conjugate. Conversely, when the concentration of
analyte in the patient sample is lower, more enzyme conju-
gates is bound by antibody. Free (unbound) enzyme conju-
gate converts substrate to product nicotinamide adenine
dinucleotide phosphate (NAPDH), and the rate of the
FIGURE 4 ARCHITECT i2000SR process path. (The color version of this ﬁgure may be viewed at www.immunoassayhandbook.com).
564 The Immunoassay Handbook
reaction is measured spectrophotometrically at 340nm.
In this format, the rate of increase in product is directly
proportional to the concentration of analyte in the patient
sample. EMIT is routinely used for both drugs of abuse
and therapeutic drugs.
G The Abbott ARCHITECT series is a family of modular,
stand-alone and integrated chemistry and immunoassay
analyzers. Instruments may be combined in speciﬁc
ways to address a variety of workﬂow and testing needs.
G All instruments in the ARCHITECT family use a
robotic sample handler (RSH), identical software, a
universal sample carrier, and identical assay-speciﬁc
reagents and protocols.
G ARCHITECT family commonality ensures that equiv-
alent patient results are obtained across all ARCHI-
TECT chemistry and immunoassay instruments.
G Common software ensures a consistent user experience
across all instruments in the ARCHITECT family.
Integrated systems are operated through a single soft-
ware user interface.
G The RSH allows prioritization of STAT tests to ensure
they are processed ﬁrst. All ARCHITECT family
instruments provide STAT assay results between 2.6
and 10min for c-series tests, and less than 15.6min for
i-series tests. STAT assay timing is the same for both
stand-alone and integrated systems.
G Pressure differential monitoring technology reduces
analytical error by detecting clots, bubbles, foam, and
insufﬁcient sample volume. SmartWash technology
effectively controls sample-to-sample carryover for the
integrated systems (<0.1ppm) and reaction vessel-to-
reaction vessel carryover for the iSystems (<0.35ppm).
G All ARCHITECT i-series assays utilize CHEMIFLEX
technology, a combination of ﬂexible assay protocols
and Abbott-developed chemiluminescent detection
G ARCHITECT i2000SR. Stand-alone immunoassay
analyzer with a maximum throughput of 200 tests per
hour. Continuous sample access with 25 refrigerated
reagent storage positions and sample load-up capacity
of 135 via priority (35) and routine (100) areas. Reagent
kit sizes of 100 or 500 tests provide high reagent test
capacity to maximize walk-away time. May be inte-
grated with another ARCHITECT i2000SR, c8000 or
c16000 to form an ARCHITECT i4000SR, ci8200, or
G ARCHITECT i1000SR. Stand-alone immunoassay
analyzer with maximum throughput of 100 tests per
hour. “Load on the ﬂy” access to reagents and samples.
May be integrated with an ARCHITECT c4000 chem-
istry analyzer to form an ARCHITECT ci4100.
G ARCHITECT i4000SR. Integrated immunoassay ana-
lyzer with maximum throughput of 400 tests per hour.
Continuous sample access with 50 refrigerated reagent
positions and sample load-up capacity of 285 samples
via priority (35) and routine (250) areas. Flexible
reagent kit sizes of 100 or 500 tests allow optimization
of system capacity for maximum “walk-away” time.
Single user interface.
G ARCHITECT c8000 and c16000. Stand-alone chemistry
analyzers with maximum throughputs of 1200 tests per
hour for the c8000 and 1800 tests per hour for the c16000.
Load capacity of 215 samples (including 35 priority posi-
tions) and 65 refrigerated reagent positions plus inte-
grated chip technology (ICT) modules for Na+, K−, and
Cl−. May be integrated with an ARCHITECT i2000SR
analyzer to form a ci8200 or ci16200, respectively.
G ARCHITECT c4000. Stand-alone chemistry platform
with maximum throughput of 800 chemistry tests per
hour. Load capacity of 100 samples with up to 35 sam-
ple priority positions. May be integrated with an
FIGURE 5 ARCHITECT c-series process path. (The color version of
this ﬁgure may be viewed at www.immunoassayhandbook.com).
1 Sample pipettor dispenses sample.
2 Reaction carousel rotates approximately 1/4 turns.
Reagent pipettor 1 dispenses reagent 1 in the cuvette
4 The reaction carousel rotates one cycle to the ﬁrst
mixing position where the mixer unit (mixer 1) mixes
the sample and reagent 1.
4 and 5
As the reaction carousel rotates from position 4 to
position 5, the cuvette passes the photometric position
where the lamp is located and the photometer
measures the absorbance.
5 Reaction carousel has completed 4 cycles. If onboard
dilution is required, the sample pipettor aspirates the
diluted sample and dispenses the sample into the new
cuvette that is currently at position 1.
31 For an ICT sample, the ICT probe aspirates the
diluted sample into the ICT unit.
67 If the reaction requires a second reagent, reagent
pipettor 2 dispenses reagent 2 into the cuvette.
68 The mixer unit (mixer 2) mixes the second reagent
with the sample and reagent mixture.
Note: The reaction carousel continues to rotate and the reaction mixture incubates.
The photometer takes absorbance readings every time the cuvette passes the
photometric position for a total of up to 33 read times. The cuvette washer removes
the reaction mixture to waste and cleans the cuvette with Alkaline Wash, Acid Wash,
and DI water. Then the cuvette washer dispenses DI water into the cuvette for a water
blank measurement to ensure cuvette integrity. Finally, the cuvette washer aspirates
the water and dries the cuvette.
565CHAPTER 7.9 Abbott ARCHITECT® Family of Analyzers
ARCHITECT i1000SR analyzer to form an ARCHI-
G ARCHITECT ci4100. Consolidated clinical chemistry
and immunoassay testing on a single platform with
maximum throughput of up to 800 chemistry and 100
immunoassay tests per hour. On-board reagent capac-
ity of approximately 55 chemistry kits and 25 immuno-
assay kits. Load capacity of up to 180 samples with 35
sample priority positions. Single user interface.
G ARCHITECT ci8200 and ci16200. Consolidated
chemistry and immunoassay testing platform with
maximum throughput of 1200 chemistry and 200
immunoassay tests per hour, and 1800 chemistry and
200 immunoassay tests per hour, respectively. Load-up
capacity of 365 samples (including 35 priority posi-
tions) and up to 90 refrigerated reagent positions plus
ICT for Na+, K−, and Cl−. Single user interface.
On the ARCHITECT i-series instruments, all assays
use chemiluminescent magnetic microparticle immuno-
assay (CMIA) technology. The majority of assays are
two-step, immunometric assays with antibody attached
to paramagnetic microparticles, and an Abbott-devel-
oped acridinium-derivative-labeled antibody/small
molecule as conjugate or tracer. Some assays have anti-
gens or other proteins coated on the microparticles.
Using two-step formats wherever appropriate reduces
assay non-speciﬁc binding (NSB), eliminates exposure
of the conjugate/tracer to potential interferents in the
specimen (e.g., human anti-mouse antibodies, ‘HAMA’),
and minimizes the potential for high-dose hook effects.
Low molecular weight analytes are predominantly mea-
sured using a two-step ‘competitive’ protocol. In this
format, analyte is ﬁrst extracted from specimen on to
the paramagnetic microparticles. In step 2, tracer binds
to unoccupied binding sites on the particles. A small
number of assays use a one-step or delayed-one step
protocol. Pre-treatment assays utilize the same capture
and signal-generating principles as one- or two-step
assays, except that the specimen is incubated with pre-
treatment reagent prior to the capture and detection
phases of the assay. STAT assay protocols operate under
the same assay principles described above, but have a
shorter ﬁrst incubation time.
ARCHITECT c-series instruments use several different
homogeneous immunoassay methodologies. These include
immunoturbidimetry (e.g., PETIA and PETINIA), and
EMIT®. The principles of these assay formats are
Assay calibration is dependent on the particular assay and
instrument system. For the ARCHITECT i-series instru-
ments, some assays utilize a six-point calibration, while oth-
ers utilize two-point adjustment of a master calibration curve.
For the latter method, the master calibration curve is
established during reagent manufacturing using six calibra-
tors, and is stored within the two-dimensional barcode asso-
ciated with each reagent lot. The two-dimensional barcode
associated with reagent and calibrator lots also contains expi-
ration date and reagent inventory information. For the
ARCHITECT c-series instruments, the assays are calibrated
by the user following assay-speciﬁc methods utilizing a mini-
mum of two calibrators. The statistical methodology for
establishing calibration curves, as well as the process for cali-
bration curve adjustment (if applicable), depends on the assay
and instrument system. Where available, assays are standard-
ized versus accepted international reference preparations
(e.g., World Health Organization International Reference
Preparations, National Institute of Standards and Technology
(NIST) or Institute for Reference Materials and Measurements
(IRMM) standard reference materials (SRMs), or certiﬁed ref-
erence materials (CRMs), highly puriﬁed commercially avail-
able material (e.g., US Pharmacopeia grade)), or internationally
recognized reference measurement procedures. The Joint
Committee for Traceability in Laboratory Medicine (JCTLM)
maintains a database of internationally recognized reference
materials and methods but immunoassays pose a special chal-
lenge because in many cases neither a material nor a method
may be available. In these cases, a manufacturer’s in-house stan-
dard and/or the best available method is the basis for calibrator
traceability and assay standardization.
Immunoassays on the ARCHITECT family of analyzers,
both c-series and i-series, may utilize monoclonal or poly-
clonal antibodies, or antibody fragments. The choice of
antibody is assay speciﬁc, and is based on analytical and
clinical performance requirements established during assay
development. Where applicable, reagent storage buffers
contain blocking agents to minimize potential interfer-
ences caused by heterophilic antibodies and HAMA.
For the ARCHITECT i-series instruments, all assays use
paramagnetic microparticles. Magnetic separation of the
solid phase from unbound materials occurs in the wash
zones. An optimized saline/surfactant buffer is used to per-
form the washing. Within each wash zone, the washing
event is composed of three distinct dispense/aspirate cycles
of this system wash buffer. For the ARCHITECT c-series
instruments, immunoassays are homogeneous, and may
involve either one or two reagent additions. Immunoassay
reactions take place in standard spectrophotometer glass
cuvettes and a separation mechanism is not available, so
assay methodologies that do not require a separation of
bound and unbound reaction components are used.
For ARCHITECT i-series instruments, signal generation
is based on an Abbott-developed acridinium derivative with
566 The Immunoassay Handbook
chemical properties optimized for use in immunoassays.
This class of compounds (sulfopropyl acridinium carbox-
amides) has better aqueous solubility and stability than tra-
ditional N10-methylacridinium-9-carboxylic acid phenyl
esters. The light-generating reaction is initiated by the
addition of a pre-trigger reagent containing acid and hydro-
gen peroxide. This pre-trigger reagent causes the label to
be released from the solid phase and into solution. The
microparticles are then magnetically attracted to the inner
wall of the reaction vessel, separating them from the label,
which remains in solution. In the ﬁnal phase of the reac-
tion, a trigger reagent-containing base is added. The resul-
tant chemiluminescence is measured by a photomultiplier
tube (as relative light units, “RLU”) and translated by the
data management software into the assay result. The light
generating reaction is shown in Fig. 6.
On the ARCHITECT c-series instruments, all immuno-
assay formats utilize spectrophotometric detection. In some
cases, for example EMIT assays, analytical signal is gener-
ated by an enzymatic reaction and the rate of the reaction is
measured by monitoring absorbance changes over time.
For the immunoturbidimetric assays, absorbance change is
monitored, either as an increase in absorbance through an
antibody-mediated formation of microparticle lattices or
the inhibition of formation of microparticle lattices.
Processing, and Laboratory
Information Systems (LIS)
The ARCHITECT clinical chemistry and immunoassay
analyzers have on-board software that performs many
functions. The RSH is controlled by the software, which
ensures that STAT samples are assigned the highest test-
ing priority, being moved to the front of the queue over
routine samples already loaded in the sample bays. For
the integrated systems, the software shuttles the STAT
samples to whichever module, clinical chemistry or
immunoassay, will produce a test result in the least
amount of time. The system software also tracks routine
operational information such as reagent usage and
reagent volume, displays the current and a limited num-
ber of calibration curves, and can provide graphical dis-
plays of long-term historical quality control data. The
analyzer software also recognizes typical analytical prob-
lems such as the prozone (pre-zone) effect for immunoas-
says and rejects results generated under prozone
conditions and automatically orders a dilution and retest
of the sample.
Middleware is available to provide more sophisticated
data manipulation. Available capabilities include auto-
veriﬁcation of patient test results, estimation of Six
Sigma metrics for all assays (an objective, quantitative
measure of analytical quality), formulation of quality
control rules based on Sigma metrics (high quality assays
can employ simple QC algorithms such as accepting test
results if two controls fall within three standard devia-
tions with a 90% probability of error detection), the abil-
ity to automatically enable or disable individual assays
and analyzers based on QC results, and the capability of
holding patient results from release to the LIS or hospi-
tal information system (HIS) until QC is approved (thus
assuring patient safety), sample tracking and delta checks
for individual patients, moving averages calculation, and
continuous monitoring of test turnaround time. Labora-
tory operations “dashboard” displays can also be pro-
vided to display the key performance indicators desired
by a laboratory. Middleware also offers constant reagent
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Hubl, W., Zogbaum, M., Boyd, J.C., Savory, J., Schubert, M., Meyer, D. and
Demant, T. Evaluation of analytical methods and workflow performance of the
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Acta 357, 5–54 (2005).
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turbidimetric and immunonephelometric assays for specific proteins. Clin.
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FIGURE 6 ARCHITECT i-series light-generating reaction.