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QUALITY CONTROL

This document presents a comprehensive guide on the quality control (QC) procedures for volumetric devices, specifically pipettes and samplers. Key accuracy metrics such as precision (CV less than 0.3%) and bias (less than 0.6%) are emphasized. Methods for QC include gravimetry and colorimetry, with detailed procedures for calibrating devices and calculating standard deviations, coefficient of variation, and bias. It also outlines acceptable limits for these metrics and the importance of regular assessments for reliable laboratory results.

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QUALITY CONTROL

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  1. QUALITY CONTROL of volumetric devices M.Jabari 2005

  2. PIPETTES I Line To deliver (EX) II Line Volumetric To contain (IN) (Wash with solution ) Pipette Graduated (Measuring )

  3. PRCISION AND ACCURACY % CV must be less than 0.3 % % Bias must be less than 0.6% Ideal % Bias 0 – 0.6% is acceptable

  4. QC OF PIPETTE S(x-M)2 SD = n - 1 SD % CV = X 100 Mean Expected value Observed value _ % Bias = X 100 Expected value

  5. QC OF PIPETTE GRAVIMETRY METHOD COLORIMETRY METHOD

  6. GRAVIMETRY METHOD • First weight a dish . • Then with a pipette that you want caliber it transfer DW into the dish and weight that . • Repeat 10 time this action and record weight . • Caculate each time pure weight of DW that transfer with pipette. • Caculate SD , %CV and % Biass .

  7. (X –mean)2 S(x-M)2 = 0.119 Mean = 10.06 S(x-M)2 SD = = 0.16 = 0.4 n - 1 SD % CV = X 100 = 0.04 Mean Acceptable 0.04 < 0. 3 10.06 1.07 0.119

  8. (X –mean)2 Mean of Expected weight Mean ofObserved weight _ % Bias = X 100 Mean of Expected weight _ 10 10.06 _ % Bias = = 0.006 X 100 10 Acceptable 0.006 < 0. 6 10.06 1.07 0.119

  9. COLORIMETRY METHOD Methyl orange 492 nm Phenol red 405 nm

  10. For 1 ml pipette : • In a ballon class A . • Prepare 0.1 gr /100 ml (stock ) . • Dilute 1 : 11 and measure absorbance . • Select 10 tube and add 10 ml DW in each tube . (for 2 ml add 20 ml DW ) • Add 1 ml stock reagent into each tube . • Measur absorbance and record it .

  11. Absorbance of 1:11 in class A ballone is 442 (X –mean)2 Mean of Expected OD Mean ofObserved OD _ % Bias = X 100 Mean of Expected OD _ 442 435 _ % Bias = = 1.58 X 100 442 435 0 358 No acceptable 1.58 > 0.6

  12. (X –mean)2 S(x-M)2 = 358 Mean = 435 S(x-M)2 SD = = 39 = 6.2 n - 1 SD % CV = X 100 = 1.4 Mean No acceptable 1.4 > 0.3 435 0 358

  13. QC OF SAMPLER GRAVIMETRY METHOD COLORIMETRY METHOD

  14. GRAVIMETRY METHOD • Each sampler shoud assese 3 – 4 time annually . • Acceptable % CV up to 3% • Acceptable % Biass up to 5%

  15. First weight a dish . • Then with a sampler that you want caliber it transfer DW into the dish and weight that . • Repeat 10 time this action and record weight . • Caculate each time pure weight of DW that transfer with sampler . • Caculate SD , %CV and % Biass .

  16. (X –mean)2 S(x-M)2 = 16.1 Mean = 100.7 S(x-M)2 SD = = 1.78 = 1.33 n - 1 SD % CV = X 100 = 1.3 Mean Acceptable 1.3 < 3 100.7 16.1

  17. (X –mean)2 Mean of Expected weight Mean ofObserved weight _ % Bias = X 100 Mean of Expected weight 100 100.7 _ % Bias = = 0.7 X 100 100 Acceptable 0.7 < 5 100.7 16.1

  18. COLORIMETRY METHOD Methyl orange 492 nm Phenol red 405 nm

  19. ml 10-100 sampler • For 10-100 ml sampler : • In a ballon class A . • Prepare 0.1 gr /100 ml (stock ) . • Dilute 1 : 101 and measure absorbance . • Select 10 tube and add 1 ml DW in each tube . ( for 20 ml ,50ml ,100ml add 2 , 5 , 10 ml DW ) • Add 10 ml stock reagent into each tube . • Measur absorbance and record it .

  20. Absorbance of 1:101 in class A ballone is 455 (X –mean)2 Mean of Expected OD Mean ofObserved OD _ % Bias = X 100 Mean of Expected weight _ 455 458.4 _ % Bias = = 0.74 X 100 455 458.4 0 36.4 Acceptable 0.74 < 5

  21. (X –mean)2 S(x-M)2 = 36.4 Mean = 458.4 S(x-M)2 SD = = 4.04 = 2.01 n - 1 SD % CV = X 100 = 0.43 Mean 458.4 0 36.4 Acceptable 0.43 < 3

  22. ml MORE THAN 100 SAMPLER • For more than 100 ml sampler : • In a ballon class A . • Dilute 1 : 11 from stock reagent .

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