Instrumental Blank Samples Assessed Through Short Run Control Charts

Matos, Andreia; Rego, Andreia; Castanheira, Isabel; Matos, Ana Sofia

http://hdl.handle.net/10400.18/4363

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Abstract(s)

This research work presents a study where Statistical Process Control (SPC) is used as an internal quality control tool. SPC was used to monitor and assess the stability of instrumental blank samples for inorganic arsenic analysis through instrumental blank samples used to determine by inductively coupled plasma mass spectrometry (ICP-MS). Control charts allows a simple way to check the accuracy of the analytical methods in a daily routine [1]. Particularly, the Short Run control charts, based on the Quesenberry Q statistics, are very useful when there are not enough data to estimate process parameters or when the sample size is variable in time [2][3]. The use of Short Run control charts joint with process capability analysis revealed to be a suitable tool allowing to detect possible reagent or instrumental contaminations in a daily base. The main purpose of this paper is to develop a joint application using the main SPC concepts, such as control charts and process capability analysis. An intra- and inter-day instrumental blank samples control scheme, using control charts based on Quesenberry Q statistics, was applied to inorganic arsenic to monitor and assess statistical consistence of blank data analysed by ICP-MS [2]. Control charts joint with process capability analysis will constitute a novelty study that will allows to evaluate the in used instrumental LOQ values for inorganic arsenic and establish a new limit.