An inter-laboratory comparison of urinary 3-hydroxypropylmercapturic acid measurement demonstrates good reproducibility between laboratories

Table 5 Repeatability, reproducibility, and intra, inter-laboratory coefficient of variation for 3-HPMA between the four participating laboratories

Samples	Mean 3-HPMA (ng/ml) ^a	r ^b	R ^c	CoV within (%) ^d	CoV between (%) ^e
1	34	5.8	13.9	6.1	NA^f
2	428	50	100.8	4.2	8.4
3	1201	142.7	261.8	4.2	7.8
4	3528	268.4	460.3	2.7	4.7
5	45	7.6	24.2	5.9	NA^f
6	330	54.9	138	6	15
7	755	143.3	363.4	6.8	17.2
8	1021	89.1	346.4	3.1	12.1
9	1235	223.1	710.1	6.5	20.5

^aMean of individual 3-HPMA values for all participating laboratories and for the corresponding sample set
^bReproducibility
^cRepeatability
^dcomposite intralaboratory coefficient of variation
^einter-laboratory coefficient of variation for the four participating laboratories
^fNA: not applicable due to data < LOQ

ISSN: 1756-0500