乙酰丙酮分光光度法测定食糖中甲醛含量的研究

建立了一个检测食糖中甲醛含量的分光光度法。食糖样品溶于水后,加入磷酸,加热蒸馏,经水溶液吸收,馏出液中的甲醛与乙酰丙酮反应,生成黄色的化合物,该化合物在414 nm波长处有最大吸收,可用标准曲线法定量。该方法在1.0~50.0μg线性良好(R~2=0.9999),检出限为0.2 mg/kg,分别在样品中添加甲醛标准品进行3水平加标回收实验(2、5、20 mg/kg),回收率为90.4%~98.2%,相对标准偏差为0.2%~4.3%(n=6)。该方法样品前处理简单、快速,灵敏度、准确度和精密度均满足食糖中甲醛含量的检测要求。     

紫外可见分光光度法测定橄榄油中的叶绿素铜

建立了紫外可见分光光度法测定橄榄油中的叶绿素铜含量的检测方法,样品特征波长为653nm,优化了波长校正方法,校正曲线y=0.032x+0.024,R~2=0.9969,对同一橄榄油添加回收率为81%~97%,精密度0.20%~2.22%。空白值的标准偏差S=0.0066,检出限LOD=3S/K=0.62mg/kg,定量限LOQ=10S/K=2.06mg/kg,K=0.032为线性方程斜率。选择三个671nm吸光度差异较大的三个样品(其中一个最小、一个居中、一个最大),分别在检出限、定量限、两倍定量限做添加回收,检出限加标回收率为48%~90%,定量限加标回收率为77%~93%,两倍定量限加标回收率为89%~96%。     

紫外检测离子色谱法测定酱腌菜中的亚硝酸盐与硝酸盐

建立了紫外检测离子色谱法测定酱腌菜中的亚硝酸盐与硝酸盐的分析方法。样品经超声提取后,以1.8 mmol/L Na2CO3+1.7 mmol/L NaHCO3为流动相,经Metrosep A Supp 4-250阴离子交换色谱柱分离,于210nm处紫外检测。结果表明:此法NO2-、NO3-的检出限分别为1.0 mg/kg和2.0 mg/kg,实际样品的加标回收率分别为80.4%~82.1%和93.1%~96.5%,相对标准偏差≤10%。     

离子色谱法测定香肠中的亚硝酸盐和硝酸盐

建立了离子色谱-电导检测法测定香肠中亚硝酸盐和硝酸盐的分析方法。样品经过亚铁氰化钾溶液和乙酸锌溶液沉淀蛋白质后,离心取其上清液依次过C18柱、Ag柱和Na柱净化后,以氢氧化钾为淋洗液,经DIONEX IonPacTM AS11-HC(4 mm×250 mm)阴离子柱分离,采用DIONEX AERS 500(4mm)阴离子抑制器和电导检测器检测,优化色谱条件后检测样品中亚硝酸盐和硝酸盐的含量。结果表明:亚硝酸盐浓度在0.1~2mg/L、硝酸盐浓度在0.2~8mg/L范围内线性关系良好,相关系数R2均大于0.9998。该方法亚硝酸盐的检出限为0.1mg/kg,硝酸盐的检出限为0.2mg/kg。亚硝酸盐的回收率在96.8%~99.9%,硝酸盐的回收率在98.8%~99.3%。亚硝酸盐的相对标准偏差RSD在0.79%~1.2%,硝酸盐的相对标准偏差RSD在0.26%~2.2%。离子色谱法测定亚硝酸盐和硝酸盐具有方法简便、重现性好、灵敏度高、检测数据准确可靠的特点。     

紫外分光光度法测定蔬菜中硝酸盐的不确定度评定

根据JJF-2005《化学分析测量不确定度评定》和JJF 1059.1-2012《测量不确定度评定与表示》,建立数学模型对紫外分光光度法测定白菜、芦笋和番茄中硝酸盐含量的不确定度分量进行评定和合成。结果表明:当白菜中硝酸盐含量为854.67 mg/kg时,其扩展不确定度为30.77 mg/kg(k=2);当芦笋中硝酸盐含量为136.90 mg/kg时,其扩展不确定度为12.65 mg/kg(k=2);当番茄中硝酸盐含量为103.54 mg/kg时,其扩展不确定度为12.30 mg/kg(k=2)。该评定方法对提高紫外分光光度法测定蔬菜中硝酸盐含量的准确度具有指导意义。     

反相高效液相色谱法同时测定黄豆酱中的苯甲酸、山梨酸、安赛蜜

建立一种用反相高效液相色谱法同时测定黄豆酱中苯甲酸,山梨酸和安赛蜜的新方法。样品经酸化后,用无水乙醚萃取,并浓缩吹干,再加入碳酸氢钠溶液溶解,样品调p H后,采用C18柱(250mm×4.6mm,5μm)分离,以甲醇(5%)+0.02mo L/L乙酸铵溶液(95%)为流动相,流速1.0m L/min,检测波长214nm(安赛蜜)及230nm(苯甲酸和山梨酸),出峰时间定性,外标法定量。结果表明:该方法的检出限为1mg/kg,线性范围为1~50μg/m L,相关系数分别为:安赛蜜R=0.99995;苯甲酸R=1.00000;山梨酸R=0.99993。回收率分别为:安赛蜜89.4%~94.1%;苯甲酸97.6%~101%;山梨酸89.6%~93.2%。相关标准偏差(RSD)分别为:安赛蜜0.38%~2.32%;苯甲酸0.26%~1.04%;山梨酸0.44%~1.82%。该方法准确方便,灵敏度高,可实现黄豆酱中苯甲酸、山梨酸、安赛蜜的测定。     

紫外分光光度法测定食用玫瑰花中类黄酮的含量

建立紫外分光光度法测定食用玫瑰花中类黄酮含量的方法。在420 nm波长处有最大吸收峰,在50 mg/L~600mg/L浓度范围内,吸光度与样品浓度之间呈现良好的线形关系,回归方程为Y=0.051 7+0.000 7x,相关系数r~2=0.999 98,检出限为2.0 mg/kg;回收率在95.43%~104.67%之间,变异系数在0.86%~2.57%。     

加压毛细管电色谱测定乳及乳制品中三聚氰胺

研究建立利用加压毛细管电色谱(p CEC)测定乳及乳制品中三聚氰胺的分析方法。样品采用2%三氯乙酸水溶液超声提取,阳离子固相萃取柱(MCX)净化,提取液经C18反相毛细管电色谱柱分离,流动相乙腈-10 mmol/L辛烷磺酸钠溶液(p H 3.0)=15+85,泵流速0.05 m L/min,分离电压-2 k V,紫外检测器240 nm检测。该方法在1.0 mg/kg~100 mg/kg质量浓度范围内线性关系良好(R2=0.999),在牛奶和酸奶中的定量限为2.5 mg/kg,在奶粉中的定量限为10 mg/kg,加标回收率为78.9%~93.5%,相对标准偏差小于5%。     

果酱和罐头中诱惑红的高效液相色谱测定法

建立果酱和罐头中诱惑红的高效液相色谱测定方法。样品中的诱惑红色素经提取后在酸性条件下被聚酰胺粉吸附,在碱性条件下解吸附,以甲醇和乙酸铵溶液为流动相,等度洗脱,紫外检测器检测,波长254nm,以相对保留时间定性,色谱峰面积定量。浓度与峰面积线性关系良好(r=0.9995),回收率83.0%~105.0%,相对标准偏差小于20%,最低检出浓度为2.5mg/kg;该方法操作简便、灵敏、准确,适用于果酱和罐头中诱惑红的检测。     

多波长紫外吸收光谱法快速测定饮料及糕点中的山梨酸

建立快速、准确测定饮料及糕点中山梨酸的多波长紫外吸收光谱法。在p H 3.25 Tris-盐酸溶液中,碱性紫与山梨酸反应,在紫外区生成具有3个正吸收峰的二元离子缔合物。最大吸收峰位于254 nm,另两个吸收峰分别位于305 nm和223 nm,线性范围为0.03~1.4 mg/L,表观摩尔吸光系数(κ)分别为4.50×10^4L/(mol·cm)(254 nm)、2.09×10^4L/(mol·cm)(305 nm)和2.53×10^4L/(mol·cm)(223 nm),检出限为0.028 mg/L(254nm)、0.030 mg/L(305 nm)和0.025 mg/L(223 nm),当以单波长法(以254 nm为例)测定时,饮料的定量限为4.66 mg/L,糕点的定量限为1.68 mg/kg。当用双波长(254 nm+305 nm)或三波长法(254 nm+305 nm+223nm)测定时,表观摩尔吸光系数(κ)分别为6.59×10^4L/(mol·cm)和9.12×10^4L/(mol·cm),检出限分别为0.014 mg/L和0.0098 mg/L,饮料的定量限分别为2.33 mg/L和1.63 mg/L,糕点的定量限分别为0.843 mg/kg和0.590 mg/kg。以双波长法为例,样品的加标回收率和相对标准偏差RSD(n=5)分别为97.3%~102%和2.0%~2.7%。该法适于糕点及饮料中山梨酸的快速测定。     

高效液相色谱法测定糖汁中没食子酸含量的研究

建立准确测定甘蔗糖汁酚类色素没食子酸含量的高效液相色谱法。采用Hypersil BDSC18柱(4.6mm×250mm,5μm),流动相为乙腈-0.05%磷酸(5:95),检测波长是280nm,流动相流速为1.0mL/min。没食子酸线性范围为20～100mg/L,回归方程Y=15960X-4749,相关系数0.9991,检出限0.22mg/L,平均加标回收率为101.45%(RSD为1.13%)。样品清汁、清糖浆配成浓度15°Bx后,过0.45微滤膜,测定滤液中没食子酸含量,分别是21.70、17.06mg/L。结论:高效液相色谱测定方法准确、可靠,可用于甘蔗糖汁色素中没食子酸的检测。     

Determination of cyanidin-3-glucoside (red kernel food colour) in beverages by high performance liquid chromatography and a study of its degradation by quadruple time-of-flight mass spectrometry

A method for the determination of cyanidin-3-glucoside (red kernel colour, RKC) in various matrices, including carbonated soft drinks, fruit-based soft drinks, sugar confectionery and milk-based drinks, by high performance liquid chromatography (HPLC) based on UV–Vis detection (at 520?nm) have been developed. Pre-treatment procedures for various matrices have been optimised. For soft drinks, the pH values were adjusted to 2.0, and sugar confectionery and milk-based drinks were extracted with 30 and 50% methanol in 0.1% formic acid (pH?～?2.5) aqueous solutions, respectively. The limits of detection for the established methods ranged from 0.2?mg/kg for soft drinks to 2.0?mg/kg for the sugar confectionery and milk-based drinks with the relative standard deviations lower than 7%, which satisfy the method performance requirements for quality control for the beverages. The stability of the colourant RKC under various thermal and pH conditions was investigated by quadruple time-of-flight mass spectrometry (Q-TOF-MS). The main colourant component of RKC, cyanidin-3-glucoside (Cyd-3-Glu), lost the glucose entity under thermal treatment. A new component was identified when RKC degraded under various pH conditions and a degradation pathway is proposed. The results will assist in understanding the degradation mechanism of the colourant Cyd-3-Glu.     

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.

In 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 oral daily intake of these analytes. For this purpose an HPIC/UV method for the determination of nitrate and nitrite in duplicate diets was developed and validated. The sample preparation procedure was derived from the in-house method used for the determination of nitrate and nitrite in human blood plasma. 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 average 103% (N = 21, spiking levels: 1.8-404 mg/kg). Samples of duplicates of 24-h diets were analysed according to the method developed. The median intake of nitrite calculated from the samples collected in spring 1994 was 0.6 mg/person day (range < 0.1-6.1 mg/person/day). For the samples collected in autumn 1994 these figures were < 0.2 mg/person/day (range < 0.1-16 mg/person/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 1-310 mg/person/day) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/person/day. The daily intake for nitrate was higher than that found in the duplicate 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 are discussed in the context of the ADI for nitrate and nitrite as well as the outcome of other recent European intake studies.     

高效液相色谱法同时测定植物油中角鲨烯、生育酚和甾醇烯

建立高效液相色谱法同时测定植物油中角鲨烯、4 种生育酚和4 种甾醇烯类化合物的方法。样品经正己烷提取、硅胶柱净化,首次采用C30柱（250 mm×4.6 mm i.d.,5 μm）同时分离9 种组分,流动相为乙腈-叔丁基甲醚（70∶30,V/V）溶液和水,梯度洗脱,流速1.0 mL/min。紫外检测器和荧光检测器串联使用,角鲨烯和甾醇烯的紫外检测波长分别为210 nm和235 nm,生育酚的荧光检测激发波长为290 nm,发射波长为340 nm。结果表明：9 种化合物在其线性范围（生育酚为0.05～100 mg/L、角鲨烯为5～500 mg/L、甾醇烯为0.02～1.0 mg/L）内的相关系数均大于0.999,在3 种添加水平（生育酚为1、100、500 mg/kg,角鲨烯为10、100、500 mg/kg,甾醇烯为0.075、0.15、0.50 mg/kg）时其平均回收率为85.5%～103.8%,相对标准偏差小于10%。方法的检出限分别为：生育酚0.03 mg/kg、角鲨烯3 mg/kg、甾醇烯0.012 mg/kg;定量限分别为：生育酚0.1 mg/kg、角鲨烯10 mg/kg、甾醇烯0.04 mg/kg。本方法灵敏、准确、可靠,已用于植物油中9 种脂溶性化合物的同时检测。     

液相色谱二极管阵列荧光法测定羊绒制品中的3种酚类激素

建立了羊绒制品中双酚A、4-n-壬基酚和辛基酚3种酚类环境激素的高效液相色谱二极管阵列荧光检测方法.样品经索氏提取后,在Shim-pack XR-ODSⅡ快速色谱柱上分离,采用甲醇/乙腈/水(体积比为30∶50∶20)为流动相,紫外检测波长为225 nm,荧光检测激发波长为228 nm,发射波长为305 nm,外标法定...     

高效液相色谱法测定月饼中纳他霉素残留

建立了测定月饼中防霉剂纳他霉素的高效液相色谱分析方法。采用ODS分离柱,V(甲醇):V(水)=70∶30流动相,在303 nm波长下检测纳他霉素含量,测定结果的相对标准偏差为1.8%~7.3%,检出限为0.5mg/kg,平均回收率为77.8%~97.9%%。     

高效液相色谱法同时测定食品中18种食品添加剂

建立高效液相色谱同时测定食品中18种食品添加剂的高通量分析方法。对于不含油脂或油脂含量低的样品采用含抗坏血酸棕榈酸酯的正己烷饱和乙腈-6mol/L HCl溶液-饱和氯化钠混合溶液一次提取净化,对于油脂样品采用含抗坏血酸棕榈酸酯的正己烷饱和乙腈-乙腈饱和正己烷液液萃取。采用Ecosil C18色谱柱(250mm×4.6mm,5μm),乙腈-0.6%乙酸溶液作为流动相,梯度洗脱,用紫外检测器检测,检测波长280nm,外标法峰面积定量。18种食品添加剂在1.0～25mg/L范围内线性良好,相关系数r均大于0.99,样品在10、25mg/kg和50mg/kg三个添加水平的平均回收率为88.9%～99.9%之间,相对标准偏差为2.43%～11.7%(n=6),方法的定量限为10mg/kg。方法简便、准确,适用于食品中18种食品添加剂高通量的检测。     

高效液相色谱紫外荧光双检测器测定蔬菜中的克百威

建立一种测定农产品中克百威含量的高效液相色谱法。样品经乙腈萃取后,提取液采用固相萃取技术分离、净化,经浓缩后,采用Symmetry C18色谱柱分离,流动相为甲醇∶水=35∶65(体积比),紫外检测220 nm,标准曲线R=0.999 9,最低检出限为0.033 mg/kg;荧光检测激发波长279 nm,发射波长307 nm,标准曲线R=0.999 8,最低检出限为1.6×10-3mg/kg。平均回收率分别为95.5%。