title: Determination of radiostrontium in milk samples by ultra-low-level liquid scintillation counting: a validated approach.
abstract: Strontium-90 is a hazardous radionuclide derived from nuclear fission processes, and it decays emitting high-energy beta-particles forming yttrium-90. It may be easily absorbed in humans through several food supply chains, since it is chemically similar to some important biological elements such as potassium and calcium. In this work an analytical method for the determination of radiostrontium in milk by liquid scintillation counting was developed in order to obtain a precise quantification at low activity concentration levels. Moreover, a full validative approach was applied to confirm method reliability. Good analytical performance was obtained by developing an in-house validation model according to Regulation 882/2004/EC and Decision 657/2002/EC with a good selectivity, a decision threshold and detection limit corresponding to 0.003 and 0.006 Bq l⁻¹ (α = β = 0.05) respectively, a repeatability value, expressed as CV%, equal to 13%, a mean recovery value equal to 102.5% and a measurement uncertainty equal to 11.5%. Strontium and yttrium chemical yields were determined by a reliable analytical method by inductively coupled mass spectrometry, assuring a suitable correction of final result. The results of the method validation, combined with a quality control assurance, performed on a reference material, demonstrated that the procedure represents a substantial improvement in the determination of ⁹⁰Sr relating to accurate confirmation analyses.
authors.affiliation: a National Reference Center for the Detection of Radioactivity in Feed and Foodstuff , Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata , Foggia , Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: dell'Oro
authors.forename: Marco
authors.initials: M
authors.lastname: Iammarino
authors.forename: Nicola
authors.initials: N
authors.lastname: Bortone
authors.forename: Michele
authors.initials: M
authors.lastname: Mangiacotti
authors.forename: Antonio Eugenio
authors.initials: AE
authors.lastname: Chiaravalle
mesh_terms: D053000:Analytic Sample Preparation Methods; D000818:Animals; D005062:European Union; D005507:Food Contamination, Radioactive; D005513:Food Inspection / Q000379:methods*; D017408:Guidelines as Topic; D007558:Italy; D057230:Limit of Detection; D008892:Milk / Q000737:chemistry* / Q000592:standards; D011848:Radioactive Pollutants / Q000032:analysis*; D015203:Reproducibility of Results; D012588:Scintillation Counting; D013324:Strontium / Q000032:analysis*; D013326:Strontium Radioisotopes / Q000032:analysis; D035501:Uncertainty; D015019:Yttrium / Q000032:analysis; D015021:Yttrium Radioisotopes / Q000032:analysis
chemical_list: D011848:Radioactive Pollutants; D013326:Strontium Radioisotopes; D015021:Yttrium Radioisotopes; D015019:Yttrium; D013324:Strontium
keywords: beta-emitters; liquid scintillation; milk; radioactivity; radiostrontium; validation