Control Materials (Control Sera) PDF

Control Materials (Control Sera) Dr. Mohamed.A.Mahdi  Control Materials Required for QC program. Defined as same sample, to be tested every day when testing is done. This type of sample is called control sera.  There are some methods used in quality control and accor...

Control Materials (Control Sera) Dr. Mohamed.A.Mahdi  Control Materials Required for QC program. Defined as same sample, to be tested every day when testing is done. This type of sample is called control sera.  There are some methods used in quality control and according to these it divides in to:- i. Internal quality control. ii. External quality control.  Internal quality control Achieved by the lab it self. This can be achieved by 2 ways:- 1. Control sera (pool sera \specimen). 2. Commercially prepared control sera.  Pooled sera - Is necessary to check errors of bias – (inaccuracy)in tests.  Preparation of Pooled sera 1. At the end of the day work; collect all the specimens that analyzed in the lab which give normal result to a screw cap container and exclude the following specimen: icteric (Jaundiced)-cloudy (lipemic)- pink color (hemolyzed)- abnormal color (dyes). (Perform HB antigen test for all specimens). 2. Freeze the pooled sera (collection performed daily and freeze volume up to 1 liter or amount enough for 4 to 6 months). 3. After collection of volume; leave it to dissolve completely at room temperature and transported into large bottle and must be mixed well. 4. Send sample of pooled sera for hepatitis antigen test. (if +ve; the sera should be discarded and if - ve continue to prepare). 5. Add preservative to the pooled sera as: 1. 100 mg sodium fluoride/dl of serum. Or 2. 1ml sodium borate merthiolate/dl of serum. 6. Mix well; but gently. 7. Centrifuge the pooled sera to precipitate any fibrin or debris for 30 minutes and take the supernatant carefully (if any fats appeared at the surface of supernatant; clear the serum by using cotton or glass wool. 8. Divides the pooled sera into small container (about 1 ml), closed directly, labeled and freeze at -20°C or less.  Commercially prepared control sera Are available in two forms:- 1. freeze –dried (lyophilized)sera. 2. liquid synthetically manufactured sera.  Freeze-dried control sera Preserved at 2-8°C. Before the use; read the instructions. Open slowly to avoid loss of some substances (you have to use good quality glass ware and special diluents). Mix well.  Leave it at room temperature for 5-10 minutes distributed into small sterile containers (0.5 – 1ml). Don not use manual pipettes to avoid contamination. Label. Freeze. Store at -20°C or below until required.  Comparison Pooled Sera Commercially Sera Advantage 1. v.cheap 1. Safe to use. Dis advantage 1.Biological 1.Expensive hazard 2.In some analysis (infection) animals sera can not act exactly as human sera.  This control (pooled +commercially)will detect errors in reagent and STD but not individual pipetting or calculating errors.  Comparison between Quality Assurance and Quality Control QA QC Focus on On preventing errors. On identifying errors Goal To improve development To identify errors and test processes so that after a laboratory errors do not arise when test is being the laboratory test is performed and being performed. before it’s released.  External quality control Such a system of checking using an organization outside the lab.must never be a substitute for internal quality control because it can only assess past performance when test results have already been reported and acted on.  What is an Error It is the failure of planned action to achieve their desired goal. Which this occur without unforeseeable or chance intervention. Errors either to be:  1. Unintended errors a. Lapse: memory failure or recognition failure. b. Slip: omission, misordering, misterming or reversal.  2. Intended errors a. Violation: routine violation, situational violation or sabotage. b. Mistake: assumption, bad habit or failure problems solving. Analytical Errors  1/ Errors of bias (Inaccuracy - Systematic - Regular). Checked by control sera. Are include :- a. Un satisfactory reagent or STD (preparation – storage –impure –expired ). b. In correct calibration. c. In correct wave length. d. Poorly written procedure.  2/ Errors of scatter (Imprecision – Random -Irregular) a. Faulty technique (pipetting – mixing – incubation). b. Dirty tubes, pipettes, glass ware. c. Heavy work load. d. Low work load. e. Fluctuating of electricity and temperature. f. Finger spot on cuvette and air bubbles. g. Incomplete removal of interfering substances.(such as RBCs).