The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994
Hamg. Vaessen et Rc. Schothorst, The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994, FOOD ADDIT, 16(5), 1999, pp. 181-188
lit spring and autumn of 1994 duplicates of 24-h diets were collected from
123 respondents. One of the goals of this study was to determine the amount
of nitrite and nitrate in the duplicates of 24-h diets to establish the or
al daily intake of these analytes. For this purpose an HPIC/UV method for t
he determination of nitrate and nitrite in duplicate diets was developed an
d validated. The sample preparation procedure was derived from the in-house
method used for the determination of nitrate and nitrite in human blood pl
asma. The sample is diluted with water, deproteinized with Carrez reagent,
followed by chromatographic clean-up on an SPE C18-column. Both the nitrate
and the nitrite results are quantitative. The recovery for nitrite was on
average 104% (n = 21, spiking levels. 0.84-95 mg/kg) and for nitrate on ave
rage 103% (N = 21, spiking levels. 1.8-404 mg/kg). Samples of duplicates of
24-h diets were analysed according to rite method developed. The median in
take of nitrite calculated from the samples collected in spying 1994 I vas
0.6 mg/person/day (range < 0.1-6.1 mg/person/day). For the samples collecte
d in autumn 1994 these figures were <0.2 mg/person/day (range < 0.1-16 mg/p
erson/day). The mean intake of nitrate was 73 mg/person/day (range 7-322 mg
/person/day) in spring 1994 and 87 mg/person/day (range 4-310 mg/person/day
) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/pers
on/day. The daily intake for nitrate was higher than that found in the dupl
icate diet study carried out in 1984/1985, when an average daily intake of
52 mg/person was measured. The intake of nitrite was also higher than found
in the duplicate diets collected in 1984/1985. The findings of the study a
re discussed in the context of the ADI for nitrate and nitrite as well as t
he outcome of other recent European intake studies.