Chemistry Instrumentation Test 1

total laboratory automation

comprehensive, automated system encompassing the preanalytic, analytic, and post analytic phases of testing

Automation advantages

assists techs in test performance (process large workloads without increasing staff), assesses results of the tests performed, it reduces or eliminated monotonous and repetitive tasks

single-channel analysis

each specimen is subjected to a single process so that only results for a single analyte are produced

single-channel analysis example

osmo

mutliple-channel analysis

each specimen is subjected to multiple analytical processes so that a set of tests results is obtained on a single specimen

Multiple-channel analysis examples

complete metabolic panel (CMP), basic metabolic panel (BMP)

parallel analysis

all specimens are subjected to a series of analytical processes at the same time and in a parallel fashion

sequential analysis

each specimen enters the analytical process one after another, each result or set of results emerges in the same order as the specimens are entered

batch analysis

many specimens are grouped (batched) in the same analytical session, one one analyte ran at a time, different assays may be ran on a analyzer by switching the reagents

random access analysis

most common configuration of analyzers, any specimen by command is analyzed by any process or out of sequence, may be analyzed for different tests

the process whereby an analytical instrument performs many tests with only minimal involvement of an analyst is referred to as

automation

most critical unit operation

patient identification

error rate of human entry/misreading of specimen numbers?

1 in 300

what is the error rate of barcode misreading specimen labels?

1 in 1 million

splatter should be minimized with the use of

liquid level sensors (LLS)

continuous flow

each sample passes through the same sample probe into a stream of flowing liquid to transport to analytical stations, peristatic pumps trap fluid between two rollers that move through the tubing

discrete analysis

sample is aspirated by a sample probe and delivered, often with reagent, through the same orifice into a reaction cup

fixed volume pipettes

used in samples and reagents in analyzers that perform a single assay or a small variety of tests

selectable-volume pipettes

allow the selection of a limited number of predetermined volumes, uses in systems that allow many different applications

carry over

transport of a quantity of analyte or reagent from one specimen reaction into a subsequent one (4:1 ratio of flush may be needed to limit carryover to less then 1%)

closed analyzer

systems can only use reagents from a particular manufacturer

open analyzer

systems are able to use in-house reagents or reagents purchased from suppliers different from the analyzers manufacturer

5 factors that affect the chemical reaction include

1. the vessel in which the reaction occurs (reaction vessel)

2. the curvet in which the reaction is monitored

3. the time of the reaction

4. mixing and transport of reactants

5. thermal conditioning of fluids

Most automated instruments report results to the LIS using

bidirectional interface, can receive data from the patient sample barcode and transmit results to the LIS in electronic formats

autoverification

automatically releasing results that have no associated problems

code 128

encode uppercase and lowercase letters, numbers and symbols. used for shipping labels and packaging

ISBT 128

a specific implementation of code 128 used for labeling medical products of human origin, including blood products

code 39

older, alphanumeric symbology used in various industries like automotive, electronics and warehousing

Interleaved 2 of 5

a numeric-only symbology that encodes pairs of digits using the width of both bars and spaces

a tray of clear samples cups sits on a laboratory bench top for an extended period of time. what analyte might be affected?

bilirubin

instrument operator follows a manufactuer-recommmended sequendce of events

preventative maintenance, reagent loading, calibration, quality control, operating instrument, evaluating diagnostic messages

Immunoassay generally involves the use of antibody as a reagent

IgG

most immunoassays use a

label, substance with a measurable property attached to an antigen, antibody, or binding substances

what enzyme is used for its ability to amplify a weak signal and increase detectability of a target molecule

horseradish peroxidase (HRP)

enzymes used as labels must have

a high amount of stability, extreme specificity, absence from the antigen or antibody, no alteration by inhibitor with the system

the difference between the excitation wavelength and emission wavelength is known as

stokes shift

examples of luminescent labels

luminol emits light energy under alkaline conditions in the presence of peroxide and peroxidase, acrindinium ester is a triple ringed organic molecule linked by an ester bond to an organic chain h

homogenous assays

does not require a physical separation of the free and bound labeled analyte; the activity or expression of the label depends on whether the labeled reactant is free or bound, it does not require a physical separation step such as washing

heterogenous assays

uses a physical separations step to separate free and bound labeled analyte. The labeled, unbound analyte is separated or washed away, and the remaining labeled, bound analyte is measured

in heterogenous assays, physical separation is necessary and is achieved by interaction with a

solid phase, solid particles, beads, trays, or tubes onto which antibody or antigen is absorbed

the most common separation technique is the use of

paramagnetic particles, that can quickly by immobilized to a solid phase by application of a magnetic field

solid phase

is used to immobilize reagent antibody or antigen in order to separate free from bound labeled reactant after washing