Determination of ethylenethiourea (ETU) and propylenethiourea (PTU) in foods by high performance liquid chromatography-atmospheric pressure chemical ionisation-medium-resolution mass spectrometry.
A robust and sensitive method for the determination of ethylenethiourea (ETU) and iso-propylenethiourea (i-PTU) in foods is reported. ETU and i-PTU were extracted by blending with dichloromethane (DCM) in the presence of sodium sulphate, sodium carbonate, thiourea and ascorbic acid. 2H4-ETU and n-PTU were used as internal standards. After filtration the DCM was removed by rotary evaporation and the extract re-dissolved in water before analysis by reversed-phase liquid chromatography with detection by atmospheric pressure chemical ionization-mass spectrometry using a double focusing mass spectrometer at a resolution of 5000. Mean recoveries of ETU and i-PTU from fruit-based, cereal-based and meat-based infant foods, potato chips and tinned potatos at 0.01 mg kg(-1) and from pizza and yoghurt at 0.02-0.1 mg kg(-1) were 95% and 97% respectively. Precision, including both repeatability and internal reproducibility, was in the range of 3.1-13.1%.
Startin
James R
JR
Central Science Laboratory, Sand Hutton, York, UK. j.startin@csl.gov.uk
Hird
Simon J
SJ
Sykes
Mark D
MD
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005031:Ethylenethiourea / Q000032:analysis*; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling; D005659:Fungicides, Industrial / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D013890:Thiourea / Q000031:analogs & derivatives* / Q000032:analysis
D005659:Fungicides, Industrial; C035039:propylenethiourea; D005031:Ethylenethiourea; D013890:Thiourea