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Common Problem
Q：Why the calibration of new projects always fails in some cases?
A. The parameters are problem, so you can modify the parameters and re-calibrate.
B. There is no problem with the parameters, but so is the calibrator position or reagent, including
b1: Poor repeatability, problem with water quality or reagent; in this case, you can replace with a new container or re-calibrate the new lot of reagent.
b2. Fitting fails. In this case, you can modify the fitting method or reduce the number of calibrators or change the calibrators, finally replace the reagent, you'd better to get the calibration data.
B. There is no problem with the parameters, but so is the calibrator position or reagent, including
b1: Poor repeatability, problem with water quality or reagent; in this case, you can replace with a new container or re-calibrate the new lot of reagent.
b2. Fitting fails. In this case, you can modify the fitting method or reduce the number of calibrators or change the calibrators, finally replace the reagent, you'd better to get the calibration data.
Q：Failure reason analysis by the clinical laboratory.
A: There are only two reasons for QC failure: detection system and controls. The detection system is divided into human, machine (instrument), material (reagent, calibrator), method (SOP) and environment.
A. Human factors:
a1. There was change in QC, and the reagent was mispositioned
a2. QC set wrong calibration value and set too long time limit for the calibrator
a3. QC did not place the thawed (redissolved) control at room temperature for enough time, used the water bath and body temperature to accelerate the dissolution of the control
a4. The loading volume added by the tester is inaccurate (the tip or pipette is not calibrated regularly, or the sample is not added vertically)
a5. The tester used a wrong unit
B. Machine (instrument) factor:
b1. The instrument was no serviced recently
b2. The voltage was unstable or no UPS was used
b3. The temperature of the incubator or the reaction heating block was not constant
b4. The optical colorimetric light source was aged to cause weak light intensity
b5. The filter screen needed to be cleaned, the syringe leaked, the instrument pipeline leaked, and the syringe piston fell off
b6. Cross contamination caused by sample adding probe carryover, or partial clogging of the sample adding probe
C. Reagent factor:
C1. Long opening time of the reagent bottle led to volatilization, and the reagent was concentrated and exceeded the shelf life
C2. Different lots of reagent were mixed
c3. There were bubbles in the reagent bottle or tube
c4. There was cross contamination between the reagents, or no reagent blank test was conducted
D. Calibrator factor:
d1. The calibrator was not well mixed
d2. The calibrator was beyond the shelf life or the reagent went bad due to long exposure in the air
d3. Contamination was caused by repeated use of calibrator
d4. The calibrator was not completely redissolved or frozen and thawed repeatedly after redissolution
d5. The calibrator was not matched with the reagent
d6. The calibrator was mispositioned, or the calibration value was to reset after changing the lot
E. Operating method (SOP):
e1. SOP did not set forth the operation contents (e.g. the cycle of instrument maintenance and service, calibration time limit, and so on)
e2. SOP records were wrong (e.g. the records were inconsistent with the instructions of instrument, reagent, calibrator and control)
e3. Although SOP described related operation contents, these descriptions were not specific and could not ensure operation consistency (e.g., no mixing duration or times were specified for the control)
F. Control factor:
f1. The opening time of the control bottle was beyond the opening time limit specified by the instructions
f2. The storage temperature of the control did not meet the instructions
f3. The control was not completely dissolved or was frozen and thawed repeatedly after redissolution
A. Human factors:
a1. There was change in QC, and the reagent was mispositioned
a2. QC set wrong calibration value and set too long time limit for the calibrator
a3. QC did not place the thawed (redissolved) control at room temperature for enough time, used the water bath and body temperature to accelerate the dissolution of the control
a4. The loading volume added by the tester is inaccurate (the tip or pipette is not calibrated regularly, or the sample is not added vertically)
a5. The tester used a wrong unit
B. Machine (instrument) factor:
b1. The instrument was no serviced recently
b2. The voltage was unstable or no UPS was used
b3. The temperature of the incubator or the reaction heating block was not constant
b4. The optical colorimetric light source was aged to cause weak light intensity
b5. The filter screen needed to be cleaned, the syringe leaked, the instrument pipeline leaked, and the syringe piston fell off
b6. Cross contamination caused by sample adding probe carryover, or partial clogging of the sample adding probe
C. Reagent factor:
C1. Long opening time of the reagent bottle led to volatilization, and the reagent was concentrated and exceeded the shelf life
C2. Different lots of reagent were mixed
c3. There were bubbles in the reagent bottle or tube
c4. There was cross contamination between the reagents, or no reagent blank test was conducted
D. Calibrator factor:
d1. The calibrator was not well mixed
d2. The calibrator was beyond the shelf life or the reagent went bad due to long exposure in the air
d3. Contamination was caused by repeated use of calibrator
d4. The calibrator was not completely redissolved or frozen and thawed repeatedly after redissolution
d5. The calibrator was not matched with the reagent
d6. The calibrator was mispositioned, or the calibration value was to reset after changing the lot
E. Operating method (SOP):
e1. SOP did not set forth the operation contents (e.g. the cycle of instrument maintenance and service, calibration time limit, and so on)
e2. SOP records were wrong (e.g. the records were inconsistent with the instructions of instrument, reagent, calibrator and control)
e3. Although SOP described related operation contents, these descriptions were not specific and could not ensure operation consistency (e.g., no mixing duration or times were specified for the control)
F. Control factor:
f1. The opening time of the control bottle was beyond the opening time limit specified by the instructions
f2. The storage temperature of the control did not meet the instructions
f3. The control was not completely dissolved or was frozen and thawed repeatedly after redissolution
Q：Why the ALT result is unstable?
A：(1) The reagent went bad due to storage or other reasons, which caused such problems. It is suggested to change a new box of reagents and calibrate it before testing.
(2) The components of control might have deteriorated during transportation or storage (a tertiary hospital once encountered the same problem and the control was normal after changing to another lot of control)
(2) The components of control might have deteriorated during transportation or storage (a tertiary hospital once encountered the same problem and the control was normal after changing to another lot of control)
Q：Why should the retained sample be tested in time during brood glucose testing?
A： After blood sampling, if it is not centrifuged, the blood glucose concentration will gradually decrease due to the glycolysis of red blood cells and the action of bacterial decomposition of glucose and leukocyte esterase. Some studies have shown that after blood sampling, it will be injected into a test tube and placed at room temperature for coagulation. If the serum is not centrifuged in time, the blood glucose will be reduced by 7% (0.28-0.56 mmol/L) per hour due to glycolysis of blood cells. When it is injected into the sterilized vacuum test tube, it will decrease by 1.9% (0.033--0.066mmol/L/L) per hour at lower temperature. Therefore, if the blood sample is injected into a vacuum test tube without glycolysis prevention additives, it should be sent to separate the serum and tested in time, so as to prevent improper injection into the container and too long storage time from affecting the test results, and provide correct blood glucose test values for clinic, which is of great significance to the diagnosis and treatment of diabetes.
Q：Cause analysis of the mismatch between R1 and R2 volume in the double reagent item of automatic biochemical analyzer.
A：After the double reagent item is completed for a period of time, R1 and R2 can't be matched in the kit, because the reagent needle has additional allowance when adding reagents, and the additional allowance is different with the reagent volume added. Taking Hitachi instrument as an example: in the operation manual of Hitachi biochemical instrument, there is a table about "To prevent the reagent from being diluted, a certain amount of allowance is added to the set volume every time the reagent is aspirated" as follows: