乳粉中钙的火焰原子吸收测定方法改进

钙作为人体所必需的微量元素常被添加到食品中去 ,市售乳粉中钙含量较高 ,常见的测定食品中钙的方法有火焰原子吸收法和ＥＤＴＡ滴定法 (ＧＢ12 398- 90 [1] )笔者在省站发放的乳粉盲样质控中发现用上述两种方法测定乳粉中的钙 ,实验的重现性差 ,无法获得满意的结果。本文主要通过改变样品前处理及盐酸的镧盐试剂用量 ,调整工作曲线线性范围 ,使实验结果大大改善 ,方法的精密度为ＲＳＤ0 .5 % ,回收率在 83.8%- 86 .6 %之间。1　材料与方法1 1　仪器与试剂1 1 1　仪器　日本岛津ＡＡ - 6 80 0型原子吸收分光光度计 ,钙空心阴极灯 (北京市朝…     

血清总钙的火焰原子吸收分光光度测定法

测定血清总钙的方法有邻-甲酚酞络合酮比色法、甲基麝香草酚蓝比色法、乙二胺四乙酸二钠滴定法等。本文探讨了血清经稀释,用火焰原子吸收法直接进行测定。 1 实验部分 1.1 仪器 ①AAS 9542 C原子吸收分光光度计;②钙元素空心阴极灯。 1.2 工作条件 波长422.7 nm,灯电流3 mA,狭缝0.4 nm,空气     

头发中钙的沸水浴消解火焰原子吸收测定法

目的建立一种简便的火焰原子吸收法测定头发中钙的方法。方法采用沸水浴法将头发消解后用硝酸镧溶液定容,用火焰原子吸收法测定。结果火焰原子吸收法测定头发中钙相对标准偏差为1.27%～1.72%,回收率为95.24%～103.52%,检出限为0.012μg/L。结论火焰原子吸收法测定头发中钙简便,检出限低,精密度和准确度高,可作为测定头发中钙的方法。     

火焰原子吸收法测定补钙制品中的钙及其干扰抑制

近年来保健食品在我国发展很快,其中以补充钙剂为目的的保健食品占有相当大的比例.据报道我国居民摄入钙量严重不足,尤其是儿童青少年和老年人缺钙比例很高.因此补钙类保健食品在我国有很大的市场.过去,食品中钙的测定多用化学法,但化学法操作繁琐,且灵敏度不够.目前,原子吸收法广泛应用于钙的测定中,但对其中的干扰现象说法不一.食品卫生标准方法中有关钙的测定方法是针对普通食品而制定的,由于保健食品的特殊性,标准方法并不完全适合于保健食品的测定.因此我们针对保健食品的特殊性,对补钙产品中钙含量的测定方法及其干扰抑制从以下3个方面进行了研究.分析报告如下.     

火焰原子吸收法测定血小板中钙的研究

本文建立了一种火焰原子吸收法测定血小板中钙的实验方法。该方法操作简便，用血量少，灵敏度高。变异系数为６．３３％和３．４８％，回收率在９６．０～１０６．０％之间。钙离子浓度与吸光度呈良好的线性关系。本法已应用于临床检验。     

火焰原子吸收法测定奶粉中高浓度钙

为达到补钙目的,目前市场上钙强化食品日益增多。为提高对食品中高浓度钙的检测能力,对火焰原子吸收法测定奶粉中高浓度钙的测定条件进行了探索,并与传统EDTA—2Na滴定法进行了比较,现报告如下。1实验部分1.1仪器与试剂岛津AA—6800原子吸收分光光度计;钙元素空心阴极灯(北京市     

火焰原子吸收光度法测定尿中钙

目的火焰原子吸收法,直接测定尿中钙的含量。方法尿样稀释后加入氯化镧,原子吸收仪火焰法直接测定尿中钙的含量。结果钙的含量在2.0~10.0μg/m L范围内呈良好的线性关系,日内和日间精密度RSD均﹤2%,平均回收率为95.7%。结论此方法简单、准确、灵敏度高,精密度及准确度均符合要求,结果令人满意。     

火焰原子吸收法测定血清中结合钙和非结合钙

血清样品用硫酸铵固体盐析后,过滤,滤液即为非结合钙(游离钙)溶液,采用基体匹配的方法分别测定非结合钙和总钙含量,基差值便为蛋白结合钙。该法精密度为2.6％～3.4％,回收率为95.4％～104.5％。     

混合酸消解-EDTA滴定法测定头发中钙

目的建立EDTA滴定法测定头发中钙的方法。方法采用混合酸将头发消解后用去离子水定容,用EDTA标准滴定溶液滴定。结果滴定法测定头发中钙相对标准偏差为1.32%～2.61%,回收率为88.80%～110.40%。结论 EDTA滴定法测定头发中钙简便,精密度和准确度高,可作为测定头发中钙的方法。     

EDTA滴定法测定保健食品中钙元素的改进研究

目的:使用改进的EDTA滴定法测定保健食品中的钙元素。方法:采用干法消化样品,以硫化钠做掩蔽剂,进行EDTA滴定测定。结果:方法相对标准偏差为0.024%～0.29%,加标回收率为94.7%～98.8%,经t检验,与ICP-AES法测定结果无显著性差异。结论:改进的EDTA滴定法结果准确,操作简单安全,能够用来测定保健食品中的钙元素。     

全自动蒸馏-电位滴定法测定山药中二氧化硫残留

目的 建立全自动蒸馏-电位滴定法测定山药饮片中二氧化硫残留的方法.方法 联合应用全自动蒸馏仪,电位滴定仪联合使用,来测定山药饮片中的二氧化硫残留.结果 山药饮片中加样回收率为97.62％,RSD为1.41％,精密度RSD为1.07％,该方法所测得的结果与药典规定方法所测得结果基本一致.结论 采用全自动蒸馏-电位滴定法测...     

Development and validation of a method for the determination of EDTA in non-alcoholic drinks by HPLC

A method for quantification of ethylenediaminetetraacetic acid (EDTA) in commercially available non-alcoholic drinks was developed and validated. The chromatographic separation was performed on an RP C18 column, and the mobile phase consisted in a mixture of 0.01 m ammonium phosphate monobasic: acetonitrile: 40% tetrabutylammonium hydroxide (90:10:0.2) pH 2.42 and a UV detector operated at 257 nm. The validation of the method demonstrated that it is able to determine EDTA in non-alcoholic drinks in an efficient and accurate manner, with a detection limit of 0.6 mg/L, quantification limit of 2.0 mg/L, precision (relative standard deviation (RSD)) 4.4, accuracy (as percentage of recovery) of 92.5%, and a linear response between 1 and 20 mg/L. As an application of the proposed method, the level of EDTA in 18 samples was determined. The samples consisted in carbonated and non-carbonated non-alcoholic drinks, either ready-to-drink or in powdered form.     

GFAAS测定血中铅的方法改进

目的:建立一种快速、有效的GFAAS测定血铅的方法。方法:用0.1%曲拉通X100+0.1%Pd+0.1%Mg(NO3)2的混合化学改进剂稀释血样后直接上GFAAS测定,通过标准加入-校准曲线法计算出结果。结果:铅浓度在0μg/L～100μg/L范围内的标准曲线相关系数为0.999,检测限为1.7μg/L,精密度范围为1.80%～2.93%,回收率96.2%～104.2%,质控样品的测定结果符合要求。结论:本法操作简便、灵敏、精密度好、准确度高,适合日常大批量样品的检测。     

涉水产品中丙烯腈单体测定的新方法探讨

目的建立气相色谱法测定各类涉水材料中丙烯腈单体新方法。方法以二硫化碳作溶剂提取涉水材料中的丙烯腈,直接取提取液,采用气相色谱法进行测定。结果丙烯腈在0.5～100.0mg/L质量浓度范围内相关系数为0.999 6,相对标准偏差为0.90%～5.46%(n=6),加标回收率91.3%～101.1%(n=6),方法检出限为0.15mg/kg。结论建立的方法简便、快捷、准确性和重现性好,适用于各类涉水材料中丙烯腈单体的测定。     

A simplified method for cholesterol determination in meat and meat products

The objectives of this study were to develop an accurate and precise method for cholesterol quantification in meat samples based on modifications made to an existing procedure (AOAC Official Method 994.10), and to apply this modified method to evaluate cholesterol levels in longissimus muscles (LM) from Angus (AN, n=5), Brahman (BR, n=4), and Romosinuano (RM, n=9) breeds. Validation of this method was performed using a meat homogenate (Standard Reference Material 1546) from National Institute of Standards and Technology (NIST), and LM samples from the three breeds with fat contents ranging from 2.4% to 9.3%. The results indicated that the modified method was accurate with cholesterol recovery exceeding 95%. The method was also found to be precise with an average coefficient of variation of 3.12%. The modification reduced 90% of chemicals used and eliminated time-consuming steps that hindered high throughput application of the traditional method. The application of this method to quantify cholesterol contents of LM samples revealed differences among the three breeds evaluated. The Angus LM with a higher fat content (50% higher) was associated with a significantly higher cholesterol concentration (70.25 mg/100 g) as compared to LM from Brahman and Romosinuano purebreds (64.77 and 65.76 mg/100 g; P=0.005 and 0.006, respectively). Cholesterol concentration was found to be correlated with the i.m. fat content of LM muscle from the three breeds (r=0.90, P<0.001). Cholesterol concentrations of LM determined in this study were comparable to those reported in the USDA National Nutrient Database for Standard Reference for separable lean from Choice rib-eye steaks. This modified method was reliable and should be evaluated for adoption as an appropriate method for cholesterol quantification in meat samples.     

Free formaldehyde determination in cosmetic products by the HPLC method

In order to standardize the analytical methods and procedures with the ones used in the EU, a method of free formaldehyde determination in cosmetic products preserved with formaldehyde donors, recommended by Commission Directive (90/207/EEC of 4th April, 1990), has been tested. The free formaldehyde level is determined by HPLC using post column derivatisation with acetylacetone. Formaldehyde content was determined in 44 fortified samples of cosmetic emulsions and shampoos. Recoveries ranged from 94.8-97.5%. Relative Standard Deviation 1-2.3%.     

Gliadin determination in gluten-free products by the ELISA method]

Immunoenzymatic method with rabbit antibodies against gliadin and antibodies conjugates with peroxidase for gliadin determination in gluten-free food using polypropylene and polystyrene was successfully used. Results of gliadin determination indicate that content of gliadin in investigated samples was low--about 0.1%.