微波消解-石墨炉原子吸收光谱法测定大米中铬

建立微波消解-石墨炉原子吸收光谱法测定大米中重金属铬含量的方法。采用微波消解法对样品进行消解,用石墨炉在波长357.9 nm处测定样品中铬的含量。结果表明,该方法线性关系良好,相关系数为0.999 7,检出限为0.006 mg/kg,定量限为0.02 mg/kg,回收率为81.6%～93.1%。该方法具有快速、简便、准确等优点,可用于大米中铬的含量测定。     

火焰原子吸收分光光度法测定水中总铬的不确定度评定

根据国家标准方法测定水中总铬,分析实验过程中不确定度的可能来源,建立不确定度的数学模型,对重要的不确定度分量进行分析评定。结果表明,测定水中总铬的不确定度来源主要是标准曲线拟合过程中产生的不确定度,其次是样品重复测定过程中产生的不确定度。因此,采用定期维护仪器使性能保持在最佳状态、仪器预热、增加标准系列溶液和样品的测量次数等方式可以增加测量结果的可靠性。     

Direct determination of chromium in gelatine by graphite furnace atomic absorption spectrophotometry

A fast and direct method for the determination of Cr in gelatine using graphite furnace atomic absorption spectrophotometry with Zeeman-effect background correction is described. No sample pre-treatment was necessary, minimizing the risk of contamination. The concentration of chromium in gelatine was directly evaluated applying the standard additions method from a metal spiked gelatine (0.5% m/v) dispersed in 1% v/v nitric acid solution. The heating program was implemented in 68 s. The estimated mean characteristic mass is 3.4 pg Cr for a 15 μl sample. The Cr values determined in gelatine with the proposed procedure are in close agreement with those obtained by employing an acid digestion procedure (r = 0.9987).     

Nanoparticles of chromium picolinate enhance chromium digestibility and absorption

BACKGROUND: Trivalent chromium (Cr) is a trace element that is difficult to digest and absorb. The objective of this study was to determine whether reducing organic Cr to nanometre size would increase its digestibility. RESULTS: Forty‐eight 8‐week‐old female Sprague‐Dawley rats were randomly assigned to one of four dietary treatments: (1) basal diet (control); (2) basal diet plus 300 µg kg^?1 Cr as chromium chloride (CrCl₃); (3) basal diet plus 300 µg kg^?1 Cr as chromium picolinate (Crpic); (4) basal diet plus 300 µg kg^?1 Cr as nanoparticulate Crpic (nanoCrpic). NanoCrpic was prepared from Crpic with a particle size of 55–100 nm. The experiment lasted 48 days. Cr digestibility and serum Cr concentration were 1.66 and 1.96 times greater respectively in rats fed nanoCrpic than in rats fed Crpic (P < 0.05). The average daily gain was greater in rats fed nanoCrpic or Crpic than in control rats (P < 0.05). The high‐density lipoprotein content increased while the very‐low‐density plus low‐density lipoprotein content decreased in rats fed nanoCrpic as compared with rats fed Crpic or CrCl₃ (P < 0.05). CONCLUSION: This study indicates that reducing the particle size of Crpic enhances Cr digestibility and absorption in rats and alters some blood metabolite concentrations. Copyright © 2009 Society of Chemical Industry     

原子吸收法快速检测自来水中铅、铬、镉的含量

目的建立一种快速、准确测定自来水中铅、铬、镉含量的石墨炉原子吸收法。方法样品硝酸浓度为1%,基体改进剂为10 g/L磷酸二氢铵,配制铅、铬、镉混合标准溶液,仪器固定体积自动配置曲线,采用外标法定量。结果该检测方法回收率范围:铅95.2%~106.0%,铬95.8%~102.4%,镉94.7%~110.7%;相对标准偏差(relative standard deviation,RSD)范围:铅0.91%~1.33%,铬0.81%~2.07%,镉0.98%~4.45%;检出限:铅0.1μg/L,铬0.1μg/L,镉0.03μg/L;定量限:铅0.3μg/L,铬0.3μg/L,镉0.09μg/L。结论该方法快速、准确、重复性好,可用于自来水中重金属铅、铬、镉的检测。     

Determination of phytic acid in feeds and faeces of pigs and poultry by capillary isotachophoresis

A method for phytic acid determination in the feeds and faeces of pigs and poultry has been developed on the basis of capillary isotachophoresis. Phytic acid was extracted by 0.95 M HCl and separated from interfering compounds by iron precipitation. Complete formation of ferric phytate required 7 mol FeCl₃ mol⁻¹ phytic acid. Residual Fe³⁺ was estimated colorimetrically by the tiron reagent, and ferric phytate was dissolved in 1.5 M NaOH at 9 mol NaOH mol⁻¹ Fe precipitated. Analyses were carried out using an electrolyte system with Cl⁻ as the leading anion, bis‐tris‐propane, and 2‐morpholinoethanesulphonic acid as the terminating anion. The recovery of phytic acid (added to hen faeces) using this procedure was 962 ± 24 g kg⁻¹. The limit of determination of phytic acid was 0.3 µmol ml⁻¹ extract. The amount of phytic acid in feeds ranged from 8.3 to 10.8 g kg⁻¹ on a dry matter basis. Phytic acid P represented 112 g kg⁻¹ total P in faeces of young pigs (40–60 kg) fed a feed with supplemental phytase (490 U kg⁻¹), 153 g kg⁻¹ total P in faeces of finishing pigs and 185 g kg⁻¹ total P in faeces of non‐lactating sows. Excreta of laying hens contained 23.7 g phytic acid kg⁻¹ dry matter (362 g kg⁻¹ total P). The isotachophoretic method is sufficiently simple and reproducible to be used for routine analyses of feeds and faeces. © 2000 Society of Chemical Industry     

Differences in fatty acid composition of fish faeces as determined by two extraction methods

Chloroform-methanol, a supposedly efficient solvent system for lipid extraction, was applied to heterogeneous samples, respectively fish diets and fish faeces. Comparisons were made of the compositions of the fatty acids prepared from solvent-recovered lipids with those obtained by total saponification. These show that solvent extraction, followed by saponification prior to fatty acid methyl ester preparation, gives differences attributable to incomplete extraction. Direct sample saponification in ethanolic alkali is recommended if all fatty acids in the diet are of interest.     

石墨炉法测量矿泉水中总铬不确定度的评估

目的 评估石墨炉法测量矿泉水中总铬过程的不确定度。方法 根据GB 8538-2016测量矿泉水中石墨炉法测定水中总铬的测定方法, 建立不确定度分析数学模型, 找出可能引入不确定度的来源的所有分量, 并对找出的所有分量进行分析计算和评定, 计算出合成不确定的大小和扩展不确定度的大小。结果 矿泉水样中总铬的含量为(0.37±0.08) ng/mL, k=2。本文讨论的不确定度来源于总铬标准溶液、溶液稀释配制过程引入、仪器测量性能引入、和标准曲线的线性回归方程引入的, 其中标准曲线方程引入的相对标准不确定度μrel(X)=0.106, 合成相对标准不确定度μrel(C)=0.107。结论 本研究中不确定度的主要来源是标准曲线的线性回归方程引入的不确定度。     

悬浮液进样石墨炉原子吸收光谱法测定乳粉中 痕量铬

目的建立了乳粉加水和曲拉通溶解,利用石墨炉原子吸收光谱法直接测定铬的检测方法。方法采用NH4H2PO4作基体改进剂,降低原子化温度,解决拖尾现象;在石墨炉升温过程中采用分步干燥和分步灰化优化升温程序,降低灰化损失。结果铬浓度在0~30μg/L范围内具有良好的线性关系,相关系数为0.9995;方法检出限为4μg/kg;利用该法测定乳粉考核样品中铬的含量,回收率为98.9%,相对标准偏差(n=6)为3.0%;利用本法对10批奶粉进行测定,结果均低于0.1mg/kg,与国标方法无显著差异。结论该法简便快速、灵敏度高、污染少,适用于乳粉以及液体乳中痕量铬的快速准确测定。     

液相色谱-电感耦合等离子体质谱法测定饲料中的六价铬

目的建立液相色谱-电感耦合等离子体质谱法(liquid chromatography-inductively coupled plasma mass spectrometry,LC-ICP-MS)测定饲料中六价铬含量的分析方法。方法以碱性溶液和磷酸缓冲液为提取溶剂,100 mmol/L硝酸铵溶液(pH值7.5)为流动相,采用Dionex IonPac AG19(4 mm×50 mm,4μm)+Dionex IonPac AS19阴离子柱(4 mm×250 mm,4μm)对样品提取液进行分离,电感耦合等离子体质谱进行测定。结果该方法检出限为0.30 mg/kg,线性相关系数大于0.999,精密度RSD5%,回收率在80%～110%之间。结论该方法科学准确、操作简单快速,可满足各种饲料中六价铬含量的测定。     

原子吸收分光光度法测定食品中微量元素

用原子吸收法测定营养食品莲子，麦片，黑芝麻糊，豆奶粉中的Fe,Zn,Ca,Mn,Cu,K,Na等7种微量元素的含量。采用标准加入法进行回收率测定，测得回收率在95.0%-108.0%。相对标准偏差在0.3%-3.3%。     

Faecal recovery and diurnal variation in excretion of dietary chromium by mature swine

Diurnal variation in faecal excretion of dietary chromium (Cr) was studied in this experiment in mature swine. Five gestating sows weighing between 225 and 250 kg were fed a corn/soya bean meal diet containing 14% crude protein, NRC recommended amounts of vitamins and minerals with a Ca: P ratio of 1.3:1. Chromic oxide was added (0.1% w/w) to the test diet, and ferric oxide was added (0.5% w/w) to the pre-test and post-test diets as dietary markers. Sows received 0.9 kg of the diet twice daily for 8 days. Total faeces from the test diet were collected and a sample of approximately 150 g of morning samples for days 6 to 9 of the experiment was separated. Faecal recovery of dietary Cr was calculated from the total collection and the samples of the 4-day period. It was found that faecal concentration of the Cr varied between days (P < 0.05) and between times of the day (P < 0.05); true equilibrium of Cr excretion was never reached. Diurnal variation in faecal excretion of dietary Cr was shown to exist; Cr concentration was higher in the late morning samples than in the morning samples (P < 0.05). Total faecal recovery of dietary Cr was 93.27%, whereas a greater (P < 0.05) value was obtained by morning sampling (118.76%). A portion of the dietary Cr (6.73%) was retained in the gastrointestinal tract even after 2 days of Cr withdrawal from the diet.     

Routine determination of calcium and magnesium in soil extracts by atomic absorption spectrophotometry

Experiments using a commercial atomic absorption spectrophotometer show that accurate routine determinations of calcium and magnesium in extracts of soil in N/2 acetic acid or neutral N ammonium acetate can be made, employing 1600 ppm Sr (as SrCl₂.6H₂O) as an additive to suppress interferences due to phosphate and other ions. The technique may be applied also to determinations of cation exchange capacity which require measurement of magnesium in solution.     

关于火焰原子吸收法检测食品中钾元素的讨论

火焰原子吸收法因其具有灵敏度高、精密度高、选择性好、仪器相对简单、操作方便、检测耗时短等优点,已广泛应用于食品中金属元素的检测,但是火焰原子吸收法在检测过程中存在很多干扰因素。采用火焰吸收法检测2种食品中钾元素含量,并分析基体干扰、浓度干扰、离子化干扰对钾元素测量结果的影响,结果表明,对不同样品进行不同处理以排除干扰,使测量结果更准确。     

石墨炉原子吸收光谱法测定乳制品中铬的含量

本文主要开展了石墨炉原子吸收光谱法测定乳品中铬含量优化条件的研究.通过采用样品处理技术、基体改进剂、平台式横向加热石墨管、交流纵向塞曼效应背景校正技术相结合的技术及通过对仪器测定条件的优化可基本消除样品干扰问题,其测定灵敏度、检出限及精密度大幅提高.     

原子吸收分光光度法测定葡萄酒中铜的不确定度评定

对原子吸收分光光度法测定葡萄酒中铜含量的测量不确定度进行评定。根据GB/T 15038-2006《葡萄酒、果酒通用分析方法》的检测原理和方法,结合JJF 1059-1999《测量不确定度评定与表示》和CNAS-GL06《化学分析中不确定度的评估指南》规定的基本程序,考察分析了火焰原子吸收分光光度法测定葡萄酒中铜含量测量不确定度的来源,利用实际测量获得的实验数据和其他相关资料,计算并评定测量结果的合成不确定度。结果表明,以原子吸收分光光度法测定葡萄酒中的铜含量,其不确定度的主要来源为溶液浓度,其次为测量重复性。     

石墨炉-原子吸收法测定饮用纯净水中 铅含量的不确定度

目的评定石墨炉-原子吸收法测定饮用纯净水中铅含量的不确定度。方法分析影响饮用纯净水中铅含量测定的各种影响要素,包括标准溶液、标准溶液稀释过程、原水样的体积、待测水样的体积、标准曲线拟合和测量结果重复性等,并进行定量评定。结果本方法测量的合成不确定度为3.01%,扩展不确定度为6.02%。本方法测量饮用纯净水中铅含量的结果为(5.347±0.322)ng/mL(k=2,置信区间95%)。结论通过对本方法的不确定度评定,掌握引入不确定度的主要因素,降低可控不确定度对实验结果的影响,提高实验结果的准确性。     

Determination of copper in fish feed by graphite furnace atomic absorption spectrometry using slurry sampling

The present work develops and optimizes a method to determine copper in samples of feces and fish feed by graphite furnace atomic absorption spectrometry (GFAAS) through the direct introduction of slurries of the samples into the spectrometer’s graphite tube coated internally with metallic rhodium and tungsten carbide that acts as chemical modifiers. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (0.50% m/v of feces or feed devoid of copper) were 0.24 and 0.79 μg L⁻¹ for the standard feces slurries and 0.26 and 0.87 μg L⁻¹ for the standard feed slurries. The proposed method was applied in studies of absorption of copper in different fish feeds and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven.