Determination of Nitrite and Nitrate in Fruit Juices by UV Detection
硝酸盐、亚硝酸盐的测定紫外检测果汁
S. Marten, J. Harms, Wissenschaftliche Gerätebau Dr. Ing. H. Knauer GmbH
Introduction:
引言:
A method for the determination of nitrite and nitrate
in parallel by UV detection is described. 法测定硝酸盐、硝酸盐紫外检测平行叙述.
Simultaneous determination of nitrite and nitrate is
proposed for monitoring threshold levels of these
additives in foods. 同时测定亚硝酸盐和硝酸盐监测门槛水平提出这些食品添加剂.
The acute toxicity of nitrate is in
this instance of only peripheral importance. 急性毒性是在这种情况下,只有硝酸盐周边重要性.
The primary health hazard lies rather in the rapid
reduction of nitrate to nitrite which leads to the
production of carcinogenic nitrosamine when nitrite
reacts with secondary amines in the stomach. 初级卫生谎言而在迅速减少硝酸盐向亚硝酸盐导致生产致癌亚硝胺当亚硝酸胺在反应中胃部.
In addition, nitrite is also known to cause
methemoglobinemia (oxygen deficiency) to occur in 另外,亚硝酸盐也是已知造成血红蛋白血症(氧气不足)发生婴儿.
infants.
In order to provide a way to monitor the
legal recommended limits of these additives in
foods, a rapid and cost-effective HPLC method is
presented here. 为了提供一个合法途径监督限额推荐这些食品添加剂、 快速而具成本效益的方法是高效
液相这里.
With an isocratic Smartline HPLC system from
Knauer, one can carry out an uncomplicated and
fast analysis.
静压系统与智能线从knauer含量,可以进行简单、快速的分析.The analysis of nitrite and nitrate in
fruit juices can be carried by ion pair
chromatography on Knauer RP C18 phases using
various counter ions (n-octylammonium or
tetrabutylammonium). 亚硝酸盐、硝酸盐分析果汁能够通过离子对高效
液相色谱knauerC18为分阶段运用各种反离子(氮octylammonium或四丁基).
The detection takes place by UV at 210 nm. 侦破发生在210纳米的紫外线.
The Smartline system used
consists of the Pump 1000, the UV Detector 2500,
the Autosampler 3800, the Manager 5000 with
degasser unit and the Column Oven 4000. 该系统采用智能线分为泵1000、2500紫外线探测器,3800自动进、 5000经理与精炼炉栏和4000股.
HPLC method parameters: 含量参数:
Column: Eurosil Bioselect 300-5 C18, 120 x 4 mm (I7Y413) [or Eurospher 100-5 C18, 250 x 4.6 mm (I115Y535)]
Eluent: 0.01 M n-octylamine, set to pH 4 / 5 mM
[or tetrabutylammonium hydrogen sulfate set to pH 6.5]
Flow: 1 ml/min
Temperature: 30 °C [40 °C]
Injektion volume: 5 μl
Detection: UV (Smartline 2500) at 210 nm
专栏:300-5eurosilbioselectC18为120×4毫米(i7y413)[或用C18eurospher100-5、 250×460毫米(i115y535)]洗液:0.01米氮辛、 pH值定为4/5毫米[或四丁基硫酸氢定pH值6.5〕流:1毫升/分钟温度: 30℃[40℃]injektion量:5μ检测:紫外(智能线2500)210纳米
Sample preparation:
Carrez solution I: Solution of potassium hexacyanoferrate (II) in water, p.A.
c = 150 g/L
样品制备:我carrez解:解钾氰化(二)在水中,左右 丙=150微克/公升
Carrez solution II: Solution of zinc sulfate in water, p.A., c = 300 g/L
SPE method: condition SAX cartridges with 2 ml MeOH and 4 ml water,
load 1 ml sample, wash with 3 x 1 ml water, elute with 2 ml
0.5 M NaCl solution
carrez解二:解决水硫酸锌、左右,三=300微克/公升萃取方法: 全程状况及子弹200毫升甲醇4毫升的水,1毫升样品负荷、 3×1毫升水冲洗、洗脱与NaCl溶液2毫升0.5米
Calibration solutions were prepared from nitrite and nitrate standards in the
range of 0.1 ppm to 25 ppm. 校准溶液制备硝酸盐标准幅度为0.1分之二十五分之.
For nitrate, the concentration range was extended to 200 ppm. Commercially available fruit and
vegetable juices were investigated after treatment with the Carrez I and II solutions in a ratio of 50:1. 对于硝酸盐,浓度范围扩大到200ppm之间. 商用果蔬汁carrez调查与处理后,在第一和第二解比例50.
Once precipitated, the
sample was centrifuged and the supernatant was removed. In order to remove potentially interfering substances, the sample
can be further cleaned on an SPE anion exchange cartridge. The filtrate can then be used directly for HPLC analysis.
一旦沉淀,上清、样品离心去掉. 为了消除潜在的干扰物质,样品可以再进行清洗萃取阴离子交换枪弹. 滤液可直接用于高效
液相色谱分析.
Results:
Since both ions are typically present in markedly
different concentrations, their simultaneous
determination using a conductivity detector under a
set sensitivity range is not always possible. 结果:自离子通常存在着两种不同浓度、 他们同时测定电导率用一套灵敏度探测器在距离不能事事.
Herein
lies the strength of this method with ion pair
chromatography and UV detection. With this
technique, both ions can be detected down to a
concentration of 0.1 ppm. 这种方法的力量所在一双
离子色谱和紫外检测. 这种技术,可以发现两者离子浓度降至0.1ppm之间.
This value represents the
limit of quantitation for both ions. 这代表了价值为限定量离子.
The use of two
different ion pair compounds as eluents allows for
adjustment of coeluting peaks and ensures reliable
results. Linear calibration curves for the standards run
with both eluents showed regression coefficients (r2)
of 0.9998 or better. 使用两种不同的离子对化合物作为洗脱液允许调整重叠高峰和可靠保证. 直线与曲线的标准来说都洗脱液显示回归系数(R2上)0.9998或更好.
The recovery rate of both ions is not influenced by the Carrez precipitation procedure: 95 –
98 %, without the SPE step. 离子回收率均没有受到carrez降水过程:95-98%, 未经萃取的步骤.
Inclusion of the SPE step only reduces the recovery rate slightly, however the
sensitivity is reduced by a factor of 2 through dilution in the elution step (1 ml loaded sample / 2 ml extraction
volume). 列入该萃取回收率逐步降低,只有轻微 但是敏感性降低的因素,通过二步稀释的洗脱(1毫升装样品/2毫升开采量).
As had been expected, nitrite ion concentrations below the 0.1 ppm limit of quantitation were found in
the fruit and vegetable juices examined. 像人们预料, 亚硝酸盐离子浓度低于0.1分之极限发现的定量果蔬汁审查.
Manufacturers of such juices must not allow nitrite concentrations to
exceed 0.1 ppm in their products. 厂家不要让这种果汁硝酸盐含量超过百万分之零点一的产品.
Nitrate values varied widely among the vegetable juices tested. While the
nitrate value for one brand of carrot juice was 140 ppm, another brand of red beet juice gave a nitrate value of
approximately 850 ppm, well outside of the calibration range. 硝酸价值观之间相差甚远蔬菜汁考验. 而硝酸盐价值品牌胡萝卜汁是1401分之 另一品牌红甜菜汁作了硝酸盐价值约850分之 校正好射程之外.