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1.
Modification of the ion exchange HPLC procedure for the detection of nitrate and nitrite in dairy products 总被引:1,自引:0,他引:1
Existing ion exchange HPLC methodology for nitrate and nitrite analysis in cured meat products suffers from high analyte variability at low concentrations and also chromatographic interference by artifacts in some other foods, such as dairy products. An investigation into the sources of variability has shown that both the cyclohexyl solid phase extraction cartridge and the glass fibre filter used in the original method can introduce artifacts which interfere with the determination of the nitrate in foodstuffs. We have also found that the use of a graphitized solid phase extraction cartridge used in tandem with the cyclohexyl solid phase extraction cartridge removed the artifacts from the chromatograph of dairy products that co-eluted with nitrite and nitrate. Values for the nitrite and nitrate content of dairy products were obtained by the HPLC procedure using these two solid phase extraction cartridges and the values obtained were in close agreement with those obtained by cadmium column reduction and colorimetry. 相似文献
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离子色谱法检测硝酸盐亚硝酸盐前处理方法的研究 总被引:1,自引:0,他引:1
目的 利用离子色谱法检测乳及乳制品中亚硝酸盐、硝酸盐,在实际检测中用该国标方法在前处理样品时,存在沉淀样品不完全进而影响检测准确性、重复性不理想的弊端,为提高检测的准确性,缩小检测偏差,需对国标方法中样品的前处理改进。方法 样品经乙腈沉淀脂肪蛋白质后,采用相应的方法提取和净化,以氢氧化钾溶液为淋洗液,阴离子交换柱分离,电导检测器检测。以保留时间定性,外标法定量。结果 该方法克服了乳及乳制品GB5009.33-2010第三法检测检出限高及检测用时长,精密度低的的弊端。结论本方法适合于乳及乳制品定量测定。 相似文献
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Determination of nitrite in food samples by anodic voltammetry using a modified electrode 总被引:1,自引:0,他引:1
Wilney J.R. Santos Phabyanno R. Lima Auro A. Tanaka Sônia M.C.N. Tanaka Lauro T. Kubota 《Food chemistry》2009
A glassy carbon (GC) electrode modified with alternated layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeT4MPyP) and copper tetrasulfonated phthalocyanine (CuTSPc) was employed for nitrite determination by differential pulse voltammetry (DPV). This modified electrode showed excellent catalytic activity for the nitrite oxidation. After optimizing the operational conditions, a linear response range from 0.5 to 7.5 μmol l−1 with a low detection limit of 0.1 μmol l−1 was obtained. The proposed sensor was stable with a sensitivity of 20.0 μA, 1 μmol−1 and good repeatability, evaluated in terms of relative standard deviation (R.S.D. = 1.3%) for n = 10. Possible interferences from several common ions were evaluated. This sensor was applied for the voltammetric determination of nitrite in some food samples. The results were consistent with those obtained with the standard spectrophotometric procedure. 相似文献
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Effect of nitrate and nitrite curing salts on the generation and oxidation of fatty acids in non-fermented sausages 总被引:1,自引:0,他引:1
J. L. Navarro M. I. Nadal P. Nieto J. Flores 《European Food Research and Technology》2001,212(4):421-425
The purpose of this work was to study the effect of nitrate and nitrite curing salts on FFA generation and oxidation during
an industrial process of country-style dry sausages (35/40 mm casing diameter) to determine their role in flavour development.
The pH values of the sausages are around 6.0 during the dry processing. FFA liberation is two or three times greater in the
samples with nitrite than in those with nitrate. However, the intensity of the oxidative phenomena during the drying process
does not depend on the quantity of FFA. In the samples with nitrate more intense oxidative phenomena take place, which lead
to a stronger typical dry-cured flavour than in samples with nitrite.
Received: 14 July 2000 / Revised version: 15 September 2000 相似文献
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采用在线镉柱还原流动注射分析法测定食品中的硝酸盐氮和亚硝酸盐氮。其中硝酸盐氮方法的线性范围为20.0~2000.0μg/L,相关系数r≥0.999,检出限为1.1μg/L,相对标准偏差为0.97%,样品测定频率为22样/h,实际水样的加标回收率为94%~106%。亚硝酸盐氮方法的线性范围为2.0~200.0μg/L,相关系数r≥0.999,检出限为0.4μg/L,相对标准偏差分别为0.35%,样品测定频率为27样/h,实际水样的加标回收率为91%~109%。此方法简单快捷,对于食品样品的测定结果令人满意。 相似文献
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用硝酸根电极同时测定肉制品中硝酸盐和亚硝酸盐含量。以0.1mol/l硫酸钠作为总离子强度调节剂,在pH3.4±0.1,硝酸根电极在硝酸钠4.0—30μg/ml浓度范围内呈良好的能斯特应答。一次标准加入法定量。在酸性条件下,用过氧化氢氧化提取液中NO_2~-,测得NO_3~-总量,然后用差减法求得NO_2~-含量。用本法测定了13种市售肉制品中硝酸盐和亚硝酸盐含量。变异系数2.31%—9.83%,回收率95.0%—108.4%。用NO_3~-和镉柱还原法,NO_2~-和萘乙二胺比色法进行了对照,结果无显著性差异(α0.05)。 相似文献
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Nitrate and nitrite concentrations were determined for sweet basil and scallions over 24 h to determine if time of sampling or harvest impacts concentrations in raw vegetables. Also, nitrate and nitrite concentrations were determined separately for various edible parts of these plants. Basil had significant changes in nitrate and nitrite concentrations over a 24 h period. Nitrate was correlated to changes in light intensity with a 3 h lag time. The highest nitrate concentrations in basil (2777 ppm) occurred around 3 h after the light intensity peaked and had low values (165–574 ppm) during the dark period. The scallion nitrate and nitrite concentrations were always low but nitrate showed a peak a few hours before sunrise. Nitrate and nitrite concentrations in some raw vegetables may be reduced by harvesting at the best time of day for each type of plant. Nitrate concentrations were different in the edible plant parts tested. 相似文献
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Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl(2), and MgCl(2)). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations. 相似文献
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Michael Wootton Siu H. Kok Ken A. Buckle 《Journal of the science of food and agriculture》1985,36(4):297-304
A range of fresh and processed meat and vegetable products was analysed by h.p.l.c. for nitrite and nitrate contents. Satisfactory results were obtained for vegetable products and most meats, but some meat products were subject to matrix interference. Sucrose, sulphate and phosphate did not affect results. Added sodium chloride decreased retention time of nitrite and increased apparent levels of both nitrite and nitrate. Ascorbic and erythorbic acids decreased apparent nitrite levels and correspondingly increased apparent nitrate levels. 相似文献
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The influence of nitrite and nitrate on microbial, chemical and sensory parameters of slow dry fermented sausage 总被引:1,自引:0,他引:1
Nitrate and/or nitrite are used in the manufacture of dry-fermented sausages. However, research has mainly been focusing on nitrite and its effect on flavour development whereas little attention has been paid to nitrate. The aim of the present work was to study the effect of nitrate and nitrite as curing salts on the quality of a slow fermentation process. Two different batches containing nitrate or nitrite were manufactured. Microbial and chemical parameters were monitored during ripening and after vacuum packed storage, as well as their fatty acid composition and their profile of volatile compounds. The oxidation, measured as TBARS (Thiobarbituric acid reactive substances), was greater in the samples with added nitrite than in the samples with added nitrate. FFA (free fatty acids) release was higher in the samples containing nitrite throughout the process. Volatile compounds arising from amino acid degradation and carbohydrate fermentation were generated at higher levels in the samples with added nitrate, probably due to the higher population of microorganisms in these samples and the effect of nitrate on their metabolism. 相似文献
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Chemiluminescence microflow injection analysis system on a chip for the determination of nitrite in food 总被引:1,自引:0,他引:1
A new microflow injection analysis (μFIA) system on a chip for the determination of nitrite is described. The chip is produced by using two transparent poly(methylmethacrylate) (PMMA) slices measured 50 × 40 × 5 mm, and the microchannels etched by CO2 laser are 200 μm wide and 100 μm deep with the volume of reaction area about 1.8 μL. Nitrite is sensed by the chemiluminescence (CL) reaction of luminol with ferricyanide that is the product of the reaction of ferrocyanide with nitrite in acidic medium. The syringe pump with an accurate timer controls all reagents, including the sample. The linear range of the nitrite concentration is 8–100 μg L−1 and the detection limit is 4 μg L−1 (S/N = 3). The proposed method has good reproducibility with the relative standard deviation 4.1% for 50 μg L−1 of nitrite (n = 9) and is very sensitive and simple. It has been successfully applied to the determination of nitrite in food. 相似文献
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目的建立动物源样品中敌敌畏的简易凝胶色谱净化-气相色谱检测方法。方法采用凝胶净化粉湿法装填于玻璃层析柱,制成长约15 cm、直径1 cm的简易凝胶净化柱,对样品的净化洗脱液进行分段收集,分析其中敌敌畏回收率的规律。结果最终确定4.6~25 m L体积段的洗脱液为敌敌畏的最佳洗脱体积段,乙酸乙酯-环己烷(6:4,V:V)为最优配比的洗脱溶液,凝胶柱装填3.00 g凝胶粉时净化效果最佳。选取猪肉、牛肉、鸡肉、鱼肉样品,进行确证试验,回收率和变异系数均满足精确度要求,方法检出限为0.003μg/m L,加标回收率为88.2%~100.7%,相对标准偏差为0.4%~1.2%。结论该方法快速、灵敏、准确,适合动物源性食品中敌敌畏的测定。 相似文献