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combined into a single unit, is used to measure electrolyte concentrations of Naþ,Kþ

and Clsimultaneously with an analytical time of less than 4 min on a sample size of

only 25 mm^3.

The reaction carousel contains 330 cuvettes and before each assay each cuvette is

automatically cleaned and dried using an eight-stage wash mechanism. Supplementary

washes are available to reduce carryover when necessary. Reagents for up to 62 assays

based on different analytical techniques (Table 16.3) may be loaded at the same time

and to maximise throughput, testing is organised in two parallel lines each one of which

is resource and analysis-controlled separately. The analyser uses a fixed cycle time.

Every 4.5 seconds the reaction carousel moves approximately one-quarter turn and

readings are taken each full turn. The total analysis time is dependent upon the assay

being performed and is determined by the assay parameters. All tests are complete in

less than 10 minutes and results are reported immediately whilst complete results for an

individual patient sample are recorded as soon as the final assay is complete. The

theoretical throughput for the analyser is 1800 tests per hour. As with the majority of

analysers, the c1600 is an ‘open system’ in that in addition to the programmed tests, ‘in

house’ tests may also be incorporated into the routine by laboratory personnel. These

may include therapeutic drug monitoring, drugs of abuse tests and specific protein

assays. Each laboratory will have at least two analysers each offering a similar analyt-

ical repertoire so that one can back up the other. The analyser reads the bar code

acquisition number for each sample and on the basis of the reading interrogates the host

computer database to identify the tests to be carried out on the sample. The identified

Reagents

Robotic

sample handler

Sample

pipettor

Local

sample

handler

Reagent pipettors (4)

Ion-selective

electrodes (ISE)

Wash

Mixers (2) station

Fig. 16.1The Abbott ARCHITECT c1600 clinical chemical analyser. (Reproduced by permission of Abbott

Diagnostics UK & Northern Ireland, Maidenhead, UK.)

633 16.2 Clinical measurements and quality control