SLOVENIAN VETERINARY RESEARCH

86Z. Bajc, D. Z. Doganoc, K. Šinigoj Gačnik(A)(B)Figure 4: Selectivity for the determination of MG and LMG in carp muscle tissue. (A) LMG: standard mixture 16 ng/mL,blank and blank with standard addition of 4 µg/kg. (B) MG: standard mixture 16 ng/mL, blank and blank with standardaddition of 4 µg/kg.The average recoveries and precision of repeatabilityand within-laboratory reproducibility at 2,3 and 4 µg/kg are summarised in Table 2 for troutsamples and in Table 3 for carp samples. For MGthe average recovery was in the range between 47%and 62%. The recovery for LMG was higher than forMG and ranged between 67% and 78%. In Table 2and 3 we can see that there were almost no differencesbetween trout and carp samples in recoveryand standard deviation of measurements. Accuracyof the method was checked by participating in theproficiency testing programme organized by FAPAS ®(Series 2 Round 59, 2004). The z-score lied between-2 and 2, hence the result was considered as satisfactory.Table 2: Accuracy and precision of MG and LMG determined in fortified trout muscle at three concentration levels(n = 18 at each level)MGLMGParameterRepeatabilityMean concentration (µg/kg)s (µg/kg) aRSD (%) bRecoveryWithin-lab reproducibilityMean concentration (µg/kg)s (µg/kg)RSD (%)RecoveryFortification level (µg/kg)2 3 41.230.1511.9621.100.1614.5551.830.179.2611.690.2112.8572.320.303.0582.210.2611.655RepeatabilityMean concentration (µg/kg) 1.44 2.02 2.94s (µg/kg) 0.17 0.10 0.16RSD (%)Recovery12.0724.6675.574Within-lab reproducibilityMean concentration (µg/kg) 1.54 2.10 2.94s (µg/kg) 0.19 0.23 0.18RSD (%)Recovery12.17710.7726.274as = Standard deviationbRSD = Relative standard deviation