Field Research Project

1. Field Research Project Anne Powers MT(ASCP), CLS(NCA) COM 545 February 17, 2005

2. What is a Clinical Laboratory Scientist? • Baccalaureate prepared • Strong science education • Anatomy & Physiology • Chemistry • Hematology • Immunohematology • Immunology • Microbiology

3. How is a CLS/MT Credentialed? • National Credentialing Agency for Laboratory Personnel (NCA)(CLS) • American Society for Clinical Pathology (ASCP)(MT) • Some states in the US also require state licensure. At the present time Illinois does not require licensure

4. Where do they work? • Employed in hospital laboratories • Employed in physician’s clinic laboratories • Employed as managers for hospital/physicians office laboratories • Employed as educators • Employed in businesses needing individuals with science background

5. What do they do? • Analyze blood and body fluids for abnormalities in: • Chemical constituents • Hematological constituents • Immunohematological constituents (blood typing, compatibility testing) • Microbiological organisms

6. Vampires? • Some of our patients refer to us as vampires because we draw blood. This procedure is known as phlebotomy

7. Professional Affiliations • American Society for Clinical Pathology • National Credentialing Agency for Laboratory Personnel • American Society for Clinical Laboratory Science • Illinois Society for Clinical Laboratory Science

8. What are all those different colored blood collection tubes used for? • Red or Yellow top tubes • Do not contain any anti-coagulants in the tube so that the blood is allowed to clot • Normally, these tubes are centrifuged to separate the serum (liquid portion) from the cells (RBC, WBC, Platelets) • Chemistry and Immunology are the departments that use this type of specimen most often

9. What are all those different colored blood collection tubes used for? • Purple top tube • Contains an anticoagulant, EDTA • This is allows a whole blood analysis in which we may need to count the cells • If this tube is centrifuged, the liquid portion is referred to as plasma • This tube is used most often in the hematology department

10. What are all those different colored blood collection tubes used for? • Blue top tube • Contains an anticoagulant,citrate • Used most often for coagulation studies such as when a patient is taking “blood thinners” • Coagulation studies are often performed in the hematology department

11. What are all those different colored blood collection tubes used for? • Green top tube • Contains an anticoagulant, heparin • Often used as a substitute for red top in chemistry • Specimen can be centrifuged immediately upon receipt • May decrease the turn-around-time for results

12. Common Laboratory Tests • CBC (Complete Blood Count) • Glucose (Blood Sugar) • Cholesterol • BMP (Basic Metabolic Panel) • Urinalysis • Protime/PTT (coagulation tests) • Cultures (urine, throat, other body fluids)

13. Core Lab Specimen Control

14. Roche Preanalytics

15. Roche Modular

16. Field Research Project • How can the use of multimedia enhance a current lecture on Spectroscopy? • This lecture is currently presented to students as a text document and transparencies of diagrams from reference textbooks.

17. Field Interview • Contact: Shannon Heisler • Company: Levi, Ray, and Shoup • Job Title: Marketing Manager • Educational Background: BA in English Communications from Illinois College

18. Field Interview • Work Experience: • Public Affairs at Illinois College while a student • Public Affairs with US Navy Reserves • Focus on Marketing, Web Development • In 9th year at LRS

19. Suggestions Project • Use PowerPoint hover feature that would describe each component of the spectrophotometer • This would require that each component be separated and graphically redesigned

20. Suggestions for Project • Use HTML for web • Again, hover feature

21. Suggestions for Project • Flash • Lots of possibilities here but requires quite a bit of expertise • Would be more of a visual product • Students may learn more from an interactive product

22. St. John’s HospitalSchool of Clinical Laboratory Science Chemistry Lecture Molecular Absorption Spectroscopy

23. I. Introduction • Most methods based on the measurements of radiant energy transmitted or absorbed under controlled conditions • Spectrophotometer • Device capable of detecting transmitted or absorbed light • Commonly used in the clinical laboratory

24. II. Components of Spectrophotometers • A. Exciter Lamp • Must furnish intense, reasonably cool constant beam of light • Easily aligned • Highly reproducible • Tungsten and halogen work well for near infrared and visible light range • Quartz preferred • Provide more intense beam of light • Better source of white light in the near ultraviolet region

25. B. Collimating Lenses • Inserted between the exciter lamp and the monochromator • Serve to collect light rays emitted from the source lamp and focus them so that the light passing into the monochromator will be an organized beam of parallel light • Sometimes a heat filter is placed in the light beam close to the source lamp to protect the monochromator from radiant heat

26. C. Monochromator • Produces light of a single color from an impure source • Monochromatic light in its true form is of one specific wavelength • Light of one specific wavelength is difficult to isolate and normally, there is a range of wavelengths that are allowed in a monochromator

27. C. Monochromator • For example, light of green color would be about 550 nm but wavelengths of 525-575 nm may also be present • This “range” (525-575nm) is the band pass which is 50nm • The narrower the band pass, the more monochromatic the light

28. Types of Monochromators • A. Single Glass Filter • Simplest monochromator • Band pass is wide and not truly monochromatic • Made by suspending a coloring agent in molten glass • Thickness of glass determines how much light is absorbed • Filters are often identified by (1) peak absorbance, (2) band pass, (3) thickness and/or opacity

29. Types of Monochromators • B. Double Glass Filter • Two glass filters of different colors are cemented together • Achieves a narrower band pass • Only wavelengths that are passed in common by both filters will be part of the band pass • Are used for transmitting visible and near visible light • Are not precise but are simple, inexpensive, and useful

30. Types of Monochromators • C. Interference Filters • Produce monochromatic light based on the principle of constructive interference of waves • Two pieces of glass each mirrored on one side are separated by a transparent spacer that is precisely one-half the desired wavelength • Light waves enter one side of the filter and are reflected at the second surface

31. Types of Monochromators • Interference filters • Wavelengths that are twice the space between the two glass surfaces will reflect back and forth, reinforcing others of the same wavelength, and finally pass on through • Other wavelengths will cancel out (destructive interference) • These filters produce a very narrow range of wavelengths

32. Types of Monochromators • D. Prisms • A narrow beam of light focused on a prism is refracted as it enters the more dense glass • Short wavelengths are refracted more than long wavelengths, resulting in the dispersion of white light into a continuous spectrum • Prism can be rotated, allowing only the desired wavelength to pass through an exit slit

33. Types of Monochromators • E. Diffraction Gratings • Most common monochromator • Consists of many parallel grooves (15,000 to 30,000 per inch) etched onto a polished surface • Light is diffracted (separated) into component wavelengths as the wavelengths of light are bent when they pass a sharp corner • This results in a complete spectra • Gratings with very fine line ruling produce a widely dispersed spectrum

34. D. Sample Cell • Known as a cuvet • Can be round or square • Light path must be constant and have absorbance proportional to concentration • Must be optically clear • Scratches or buildup can compromise optical integrity • Glass cuvets can be used in the visible range but Quartz is better suited for the ultraviolet range since glass absorbs ultraviolet light

35. E. Photodetectors • Convert transmitted radiant energy into an equivalent amount of electrical energy

36. E. Photodetectors • A. Photocell • Also known as a barrier-layer cell • Composed of film of light-sensitive material such as selenium on a plate of iron • A transparent layer of silver is place over the light-sensitive layer • When exposed to light, electrons in the light-sensitive material are excited and released to flow to the highly conductive silver

37. Photodetectors • A. Photocell • In comparison with the silver, a moderate resistance opposes the electron flow in that direction • This causes the cell to generate its own electromotive force, which can then be measured • The produced current is proportional to the incident radiation

38. Photodetectors • A. Photocell • Do not require external voltage source • Rely on internal electron transfer to produce a current in an external circuit • Electrical energy is not easily amplified • Used mostly in photometers with wide band passes • Is inexpensive and durable • Temperature-sensitive and nonlinear at very low and very high levels of illumination

39. E. Photodetectors • B. Phototube • Similar to a photocell but requires an outside voltage source • Contains a negatively charged cathode and a positively charged anode enclosed in a glass case • Cathode is composed of rubidium or lithium that will act as a resistor in the dark but will emit electrons when exposed to light

40. E. Photodetectors • B. Phototube • Emitted electrons jump over to the positively charge anode, where they are collected and return an external, measurable circuit

41. Photodetectors • C. Photomultiplier Tube • Detects and amplifies radiant energy • Incident light strikes the coated cathode, emitting electrons • The electrons are attracted to a series of anodes (dynodes) • Each dynode has a successively higher positive voltage • Dynodes are made of a material that will give off many secondary electrons when hit by single electrons

42. E. Photodetectors • C. Photomultiplier Tube • Initial electron emission at the cathode triggers a multiple cascade of electrons within the photomultiplier tube • Is 200 times more sensitive than the phototube • Are generally used in instruments designed to detect extremely low levels of light

43. E. Photodetectors • Photodiode • Absorption of radiant energy by a reversed-biased pn-junction diode produces a photocurrent that is proportional to the incident radiant energy • Are not as sensitive as the photomultiplier tube • Have excellent linearity and are quite fast • Each photodiode responds to a specific wavelength

44. F. Readout Device • Historically these devices consisted of ammeters or galvanometers • Newer devices consist of digital displays and printers

45. G. Single Beam Spectrophotometer • Can be useful in certain circumstances • Voltage fluctuations and changes in light source present a problem • When a heavy load is placed on the electric power system, lights dim and later brighten • If measurements are being taken on the spectrophotometer at the same time, the readings will be unreliable

46. G. Single Beam Spectrophotometer • Aging lamp source may momentarily flicker and cause the readings to be unstable and erroneous

47. Fig. 7-6 A Simplified Single Beam Spectrophotometer

48. Use of two photocells • Two photocells are positioned at equal distances from the lamp source and are attached to the same meter so that they oppose each other • This cancels the instability of the lamp source

49. Use of a beam splitter • A device that ‘splits’ the path of light • The device is can be a half-silver mirror (dichroid mirror) • Is placed in the light path between the monochromator and the sample • The light is split and goes to the sample and reference detectors

50. Use of Beam Splitter • Since the light is being split between the sample and a reference cell simultaneously, any fluctuations will affect the sample and the reference cell equally and thus will cancel itself out