Determination of streptomycin and dihydrostreptomycin in milk and honey by liquid chromatography with tandem mass spectrometry.
Two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed for the determination of streptomycin (STR) and its derivative dihydrostreptomycin (DHSTR) in milk and honey. These aminoglycoside antibiotics are used as veterinary drugs. In the EU, the presence of dihydro- and streptomycin residues in honey is forbidden, the maximum residue level (MRL) in milk is 200 microg/kg. The methods were optimised with regard to sensitivity and chromatographic efficiency, and validated by a procedure consistent with EU directive 2002/657. Average recoveries and accompanying standard deviations were satisfactory. The limit of quantification of STR was 2 microg/kg in honey and 10 microg/kg in milk, of DHSTR it was a factor two lower. The precision of the milk analysis was improved by using STR as the internal standard for DHSTR and vice versa. In a survey of 186 honeys available on the Dutch market, 26% of the honeys of foreign origin were positive for (DH)STR. This occurence rate was consistent with previous surveys, but lower concentrations were found.
van Bruijnsvoort
Michel
M
Dutch Food and Non-Food Authority/lnspectorate for Health Protection and Veterinary Public Health, 7200 AE Zutphen, The Netherlands. michel.van.bruijnsvoort@vwa.nl
Ottink
Stef J M
SJ
Jonker
Klaas M
KM
de Boer
Enne
E
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D004096:Dihydrostreptomycin Sulfate / Q000032:analysis*; D006722:Honey / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013307:Streptomycin / Q000032:analysis*
D000900:Anti-Bacterial Agents; D004096:Dihydrostreptomycin Sulfate; D013307:Streptomycin