Horwitz formula

The concept of HORRAT values was introduced by Horwitz etal. (1989). The HORRAT value is the ratio of RSDr obtained from the actual experimental data from intcriab-oratory data to the PRSDr calculated from the Horwitz formula ... 

In some cases it may be useful to make a rough estimation of the measurement uncertainty of a method at the target concentration, for example, at the MRL of a veterinary drug, to help to determine whether the method will be tit for purpose before undertaking a full validation and measurement uncertainty estimation exercise. This can be done by applying the Horwitz formula to obtain an estimate applicable to inter-laboratory reproducibility data, or a suitably adjusted version for intra-laboratory data. " The Horwitz formula, as initially applied to interlaboratory (between-laboratory) reproducibility data R) in percentage, and with the concentration C expressed as a mass fraction, is ... 

The relative uncertainties UIX(%) obtained at the four fortified concentrations are apparently the same since the uncertainty of constant bias is not included in the budget. For comparison, the between-laboratory relative standard deviations (RSDR, %) according to the Horwitz formula are also calculated, and the within-laboratory relative standard deviations (RSDr, %) should be RSDR (%).2 ... 

Apply one of the formulas derived by Horwitz relating the relative standard deviation to concentration expressed as a mass fraction. 

Hoffmann etal. [26] suggested the structural formula (la) for tetrazene, i.e. l-guanyl-4-nitrosoaminoguanyltetrazene. The correctness of this formula was later questioned by Patinkin, Horwitz and Lieber [27]. The synthesis of tetrazene by the action of tetrazolediazonium hydroxide (II) on aminoguanidine salts (III) at 0°C, suggested that tetrazene has the structure of l-(5-tetrazolyl)-4-guanyltetrazene hydrate (I) ... 

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