Interferences naturally present or added additives in cured
meat products may account for differences in nitrate and nitrite
recovery. For example, Butt, Riaz, and Iqbal (2001) demonstrated
that the presence of 50-fold sulphate and chloride did not affect
the resolution and percent recovery of nitrite, but did reduce the
resolution and recovery of nitrate. In addition, the presence of
magnesium, iron and calcium significantly reduced the percentage
recovery of both anions, which should be removed to ensure accurate
determination of nitrate and nitrite. Furthermore, Butt et al.
(2001) also demonstrated that under optimized HPLC conditions,
both nitrate and nitrite peaks began to merge when the concentration
of nitrite was above six-fold of nitrate concentration, hence nitrite
used in calibration curve and for recovery were half the
concentration of nitrate to minimize the merging of nitrite and nitrate
peaks.
Using similar detection method as Reinik et al. (2005), they
found the mean sodium nitrite and nitrate concentrations in ham
were 20.8 and 68 mg/kg, respectively. However in this study, the
nitrite concentration in ham averaged at 34.2 ± 5.6 mg/kg and
nitrate concentration was lower at 19.0 mg/kg (Table 2). Some
manufacturers add less nitrite but more nitrate as a nitrite reserve.
This may also explain the differences in the findings by Öztekin
et al. (2002), where the nitrite and nitrate contents in ham were
4.0 and 35.6 mg/kg, respectively.