Principles of Chemistry Instrumentation Flashcards
Benefits of Instrumentation
- shortened analysis time
- shortened turnaround time
- higher productivity
shortened turnaround time(TAT)
the time elapsed between ordering a lab test and the physician receiving the result
When Choosing an instrument it is important to consider…
- quality of test results
- test volume
- cost per test
- ease of operation
- maintenance costs
- preventative measurements
- comparison of methods
- integration into LIS
Types of hazards in the lab
biological hazards, physical hazards, chemical hazards
Quality assessment programs used on instruments
- document personnel training
- maintenance and repair logs
- calibrators and controls
- use manufacturer’s protocol
- instrument checks
Instrumentation Principles
- Photometry/spectrophotometry
- reflectance photometry
- nephelometry/turbidity
- ion-selective electrodes
- electrochemical technology
photometer
an instrument that measures the light reflected from a colored reaction product. Use filter. measures the intensity of light.
spectrophotometer
an instrument that measures intensities of light at selected wavelengths. use prism
monochromator
a device that isolates a narrow portion of the light
Light Transmitted (%T)
the percentage of light that passes through a solution reflectance
Light absorbed (%A)
a logarithmic expression of the amount of light absorbed by a substance containing colored molecule; optical density (O.D.)
note* the more concentrated the solution, more is absorbed and less is transmitted
Beer’s law
a mathematical relationship that demonstrates the linear relationship of concentration to absorbance and that forms the basis for spectrophotometric analysis
main difference between photometers and spectrophotometers?
photometers use filters and spectrophotometers uses prism.
note- spectrophotometer is more accurate than the use of filters
Reflectance photometry
measure reflected light; light reflected by colored product.
note* used for hemoglobin
solid-phase chemistry
an analytical method in which the sample is added to a strip or slide containing all reagents for the procedure in dried form
nephelometry/turbidity
- light scatter
- particles in suspension
ion-selective electrodes
an electrode manufactured to detect a specify ion and measure its concentration
- analyzers use two electrodes
- measure electrical potential across membrane
- two electrodes used one known and one unknown
note*- sodium chloride, potassium, bicarbonate
amperometry
the technology that uses electrodes and electrode potential to measure electron generation
- measure generation of electrons
- electrochemical technology
- Accu-chek can be used for sugar, HBAIC, HDL, total cholesterol
Point-of-care testing
- bring test to patient
- small, portable analyzers
- home glucose meters first POC tests
- over-the-counter pregnancy tests
- used everywhere
Where do we use POCT?
in the hospital, bedside in patient room, emergency department, critical care units, surgery
nonhospital sites, screening programs, health fairs, nursing homes, POLs
Components of POCT program
- compliance with regulations
- safety program
- quality assessment
- personnel training and assessment
- technical support
- data management
Advantages of POCT
- rapid results
- patient participation
- less trauma
- reduced errors
- multiskilled personnel
- improved communication
disadvantages of POCT
- increased costs
- risk of:
- personnel training deficiencies
- inadequate quality assessment procedures
- inadequate supervision
Glucose
major carbohydrate in blood, also the major source of energy for the body’s cells
-blood glucose is the most frequently performed clinical test
diabetes mellitus
a disease in which the blood glucose is elevated because of lack of insulin regulation
hyperglycemia
elevated blood glucose
4 major organs that are affected by diabetes?
retinal (eyes), heart, kidneys and the nerve system
our body regulates glucose by?
hormonal control. insulin helps reduce the sugar consumed
insulin
the pancreatic hormone essential for proper metabolism of blood glucose and maintenance of blood glucose levels
-insulin allows uptake of glucose by cells
glycogen
the storage form of glucose found in high concentration the the liver
Diabetes type I
can not secrete or produce insulin, therefore sugar can not be used by cells, and increases in the blood streams
treatment-inject artificial insulin
glycogenesis
conversion of glucose to glycogen
glycogenolysis
the conversion of glycogen to glucose
glycolysis
energy production as a result of the metabolic breakdown of glucose; the breakdown of glucose to pyruvic acid or lactic acid accompanied by the release of energy in the form of ATP
glucagon and insulin
glucagon increases blood sugar, inulin decreases blood sugar to help maintain homeostasis
Which physician treats diabetes patients?
endocrinologists
diagnostic tests for diabetes
- fasting plasma glucose(8 hr fast)
- oral glucose tolerance test (OGTT) (3 hr fast
- 2 hour plasma (postprandial)
- random plasma glucose greater than 200 mg/dL
- Hemoglobin A1C
note* all tests collected using gray tube except for hemoglobin A1C which is collected using the lavender tube
3 hour oral glucose tolerance test (OGTT)
-patient fasts, then blood and urine collected, patient consumes 50-75 g of sugar, then blood and urine collected after 30 min, 1 hour, 2 hours and 3 hours.
Hemoglobin A1C
hemoglobin modified by the binding of glucose to the beta globin chains of hemoglobin
aka glycated or glycosylated hemoglobin
What are the best diagnostic test for diabetes?
fasting plasma glucose and hemoglobin A1C
