Uncertainty evaluation on the reference method of leukocyte counts for fresh blood

doi:10.3969/j.issn.1673-8640.2015.05.023

Abstract

Abstract: Objective To study the evaluation method and procedure on the uncertainty of leukocyte counts by reference method for fresh blood. Methods The reference method recommended by the International Committee for Standardization in Hematology(ICSH) was used for leukocyte counts. The components of uncertainty were validated. The International Organization for Standardization(ISO) Guide to the Expression of Uncertainty of Measurement (GUM), type A and type B methods were used to evaluate each component. Combined standard uncertainty and expanded uncertainty were calculated according to 95% confidence interval. Results The leukocyte counts from fresh blood had the average value of 6.71×10⁹/L. The combined standard uncertainty was 0.097×10⁹/L(95% confidence interval, coverage factor k=2), and the expanded uncertainty was 0.19×10⁹/L. Conclusions The main sources of uncertainty are from the overlapped calculation correction and pipetting volume. Therefore, there should be strictly control on pipetting volume in order to make lower uncertainty. The evaluation model of uncertainty is established, which can be applied to the leukocyte counts and standardization, providing effective methods for traceability.

Key words: Leukocyte count, Fresh blood, Reference method, Uncertainty

CLC Number:

R446.1

GUO Xiaojun, WANG Qing, SONG Ying, MAIO Yingbo, XU Lei. Uncertainty evaluation on the reference method of leukocyte counts for fresh blood[J]. Laboratory Medicine, 2015, 30(5): 512-516.

Figures/Tables 5

稀释浓度	细胞计数¹	细胞计数²
25.07%	6.733 9	6.736 1
50.10%	6.722 4	6.725 8
75.07%	6.718 4	6.718 6
100%	6.713 0	6.715 2

浓度(x)	计数值(y_i)	理论值( $y ˙$ )	计数值(y_i)	理论值( $y ˙$ )
25.07%	6.733 9	6.733 2	6.736 1	6.733 2
50.10%	6.726 4	6.726 5	6.725 8	6.726 5
75.07%	6.718 4	6.719 7	6.718 6	6.719 7
100%	6.713 0	6.713 0	6.715 2	6.713 0

浓度(x)	计数值(y_i)	理论值( $y ˙$ )	计数值(y_i)	理论值( $y ˙$ )
25.07%	6.733 9	6.733 2	6.736 1	6.733 2
50.10%	6.726 4	6.726 5	6.725 8	6.726 5
75.07%	6.718 4	6.719 7	6.718 6	6.719 7
100%	6.713 0	6.713 0	6.715 2	6.713 0

符号	不确定度分量	量值	单位	标准不确定度	相对标准不确定度
f_rep	测量的重复性	6.714×10⁹	/L	0.018 5	0.002 752
V_sample	加样体积	80	μL	0.244 9	0.003 062
V_dilution+V_lytic	稀释体积	20.5	mL	0.000 818 9	0.000 399 5
V_reaction	计数体积	0.5	mL	0.020 4	0.004 08
f_c	重叠计数校正	6.713×10⁹	/L	0.089 22	0.013 29
u_c	合成标准不确定度	6.714×10⁹	/L	0.097 4	/
U	扩展不确定度	6.714×10⁹	/L	0.19	/

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