高效液相色谱法定量测定果蔬中甲醛含量

通过五氟苯肼与甲醛进行衍生,建立高效液相色谱法定量测定果蔬中甲醛含量的分析方法。样品在温度为60 ℃超声波条件下直接提取衍生30 min,离心纯化后高效液相色谱检测,外标法定量。优化的色谱条件为：XDB-C18色谱柱（4.6 mm×250 mm,5 μm）,流动相：乙腈-水（70∶30,V/V）,流速1.0 mL/min,柱温40 ℃,检测波长258 nm。结果表明,该方法的定量检测限可达到0.114 mg/kg,在0.114～57 mg/L范围内呈良好的线性关系,当甲醛添加量分别为1.14、8.55、17.10 mg/kg时,平均回收率为81.4%～101.8%,相对标准偏差为2.6%～5.0%（n=6）。该方法样品前处理简便、稳定性好、检测限低,适合果蔬中甲醛含量的快速检测。     

乙酰丙酮衍生化高效液相色谱-荧光检测法测定食品中的甲醛

建立基于乙酰丙酮衍生化利用配有荧光检测器高效液相色谱测定食品中甲醛含量的方法。色谱柱为EclipseXDB-C18（250 mm×4.6 mm,5 μm）,流动相为V（乙腈）∶V（水）=20∶80,激发波长为416 nm,发射波长为505 nm,采用外标法定量,甲醛质量浓度在0.001～20.0 mg/L范围内呈良好线性,相关系数为0.999 9。甲醛质量浓度为0.005、0.05、0.5、5.0 mg/L时相对标准偏差分别为4.2%、1.9%、1.4%和0.81%。固体及粉末样品的检出限为0.025 mg/kg,液体样品的检出限为0.025 mg/L。本方法用于干香菇、面粉及啤酒样品中甲醛含量的测定,加标回收率为92.0%～97.7%,相对标准偏差不大于5.6%。结果表明,本方法灵敏度高,方便快捷,结果可靠。     

乙酰丙酮分光光度法测定白菜中甲醛含量的方法优化及其在快检结果验证中的应用

目的建立乙酰丙酮分光光度法测定白菜中甲醛含量的方法,并用此方法验证甲醛速测盒的检测结果。方法以甲醛含量为指标,研究样品浸泡时间、加蒸馏水量、加磷酸量、蒸馏时间等前处理条件和显色时间、水浴时间、加乙酰丙酮量等测定条件对白菜中甲醛测定结果的影响。以大白菜为试样,对比乙酰丙酮分光光度法和甲醛速测盒的检测结果。结果白菜中甲醛含量测定的最佳的条件为样品浸泡时间35 min,加水量160 m L,磷酸添加量5 m L,蒸馏时间80 min,乙酰丙酮添加量1 m L,水浴时间5 min,显色时间15 min。在此条件下,白菜中甲醛回收率为95.2%～99.7%。甲醛速测盒的结果与之比对,结果一致。结论乙酰丙酮分光光度法结果准确,适合用于大白菜中甲醛的测定,实验中所用甲醛速测盒与之结果一致,可以快速有效测定白菜中甲醛含量。     

氯化钙对花生中黄曲霉毒素B1提取及其快速检测结果的影响

以氯化钙为蛋白沉淀剂、黄曲霉毒素B1为靶标,探究了70％甲醇水（V/V）提取液中不同含量氯化钙对花生中黄曲霉毒素提取及其免疫检测结果的影响;采用样品加标回收的方法,研究比较了五种不同含量氯化钙对胶体金免疫层析试纸条和ELISA检测结果的影响。研究结果表明,样品经含1％CaCl2（m／V）的甲醇水处理后,用胶体金免疫层析试纸条检测时,试纸条T线颜色梯度变化,不同浓度加标回收率等参数均得到明显改善,前处理效果显著;选取20份花生实际样品,经过这种前处理之后,进行胶体金免疫层析试纸条和ELISA检测,同时将其检测结果与免疫亲和层析高效液相色谱法（IAC-HPLC）进行比对,胶体金免疫层析试纸条与IAC-HPLC检测结果符合率为90％,间接竞争ELISA与IAC-HPLC检测结果相关系数达0．996,表明本研究所改进的样品前处理方法能提高免疫检测准确度,具有很好的应用性。     

A rapid liquid chromatography determination of free formaldehyde in cod

A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25–200 mg kg^?1 (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure – a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.     

Immunochromatographic lateral-flow test strip for the rapid detection of added bovine rennet whey in milk and milk powder

An immunochromatographic lateral-flow test dipstick test was developed for the fast detection of bovine rennet whey in liquid milk and milk powder. The test is based on the binding of casein glycomacropeptide (cGMP) by two specific anti-bovine κ-casein monoclonal antibodies and has a visual detection limit of around 15 ng mL^?1 for cGMP and 1% (v/v) for rennet whey in milk using standards and spiked samples. The dipstick performance was evaluated in a collaborative trial using skim milk powder and raw, pasteurized and UHT milk. The suitability of the dipstick was demonstrated in comparison with gel permeation-high performance liquid chromotography and a colorimetric method, by analysing 60 raw milk samples collected from farms in Brazil. The dipstick results correlated well with the HPLC results and were more reliable than those obtained with the colorimetric method. The dipstick test correctly identified all raw milk samples with a rennet whey content above 4%.     

Rapid and sensitive determination of formaldehyde in some beverages and foods by flow-injection fluorimetric analysis

A simple and sensitive flow-injection (FI) method for rapid determination of formaldehyde in beverage and food products has been developed. Adopting stop-flow technique, the proposed method distinctly improved the sensitivity of FI fluorimetric method for the determination of formaldehyde based on Hantzsch reaction with cyclohexane-1,3-dione. The fluorescent intensity was proportional to formaldehyde concentrations ranging 0.1 ng mL⁻¹ to 1.000 μg mL⁻¹, and the detection limit ( S / N  = 3) was 0.04 ng mL⁻¹ of formaldehyde. The relative standard deviations ( n  = 11) for determination of 0.100 and 0.005 μg mL⁻¹ of formaldehyde were 1.3% and 2.1%, respectively. The analytical frequency was 18 samples per hour. This method was applied directly for the determination of formaldehyde in diluted beverages and extraction solutions of foods, and the results obtained correlated well with those obtained by the standard method in which a sample pretreatment of steam distillation was required.     

荷叶中荷叶碱的高效液相色谱检测方法及其提取工艺研究

通过正交试验探讨用乙醇回流提取荷叶中荷叶碱的最佳工艺,并建立荷叶碱含量测定的高效液相色谱测定方法。结果表明,用75%的乙醇在90℃温度下按固液比为1∶20(m∶V)回流提取3.5h,荷叶碱回收率高于95%;高效液色谱检测其含量在43.16～258.96μg/mL有很好的线性关系,相关系数达0.999 3,最低检出量为0.103 4μg/mL。说明用该方法提取荷叶碱可行,测定结果稳定、精确。     

高效液相色谱法测定鸭血制品中甲醛含量

建立鸭血制品中甲醛的高效液相色谱测定法。以衍生液2,4-二硝基苯肼乙腈溶液-水（1∶1,v/v）的混合溶液为提取剂对样品进行提取,Waters SunFireC18（4.6 mm×250 mm,5 μm）色谱柱进行分离,流动相为甲醇-水（65∶35,v/v）,流速1.0 mL/min,在波长365 nm处以紫外检测器检测,外标法定量。结果表明,甲醛在线性范围0.4～6.0 μg/mL内,相关系数为0.999 7,最低检出限为0.2 mg/kg,精密度（相对标准偏差）小于5%,加标回收率为85.1%～92.7%。本方法操作简便、灵敏度高、分离度好,适用于鸭血中甲醛含量的测定。     

食品中甲醛分析方法研究进展

食品中的甲醛问题引起了人们的高度重视,检测食品中的甲醛至关重要。食品中的甲醛主要来源于食品自身代谢合成、人为添加和环境污染。甲醛的分析方法包括样品前处理方法和甲醛检测方法。根据不同的食品种类,需要选择合适的样品前处理方法,具体方法包括:浸泡法、蒸馏法、超声法和蛋白沉淀法。甲醛检测方法分为常规检测方法和快速检测方法。常规检测方法主要有分光光度法和色谱法。分光光度法包括乙酰丙酮法、变色酸法、AHMT法、间苯三酚法和盐酸苯肼法。目前甲醛快速检测方法成为了研究热点,示波极谱法、试纸法、生物传感器法等快速检测方法得到快速发展。     

啤酒中微量甲醛测定方法的比较与选择

研究对HPLC法和酶催化光度法测定啤酒中甲醛含量的实验条件进行优化,对乙酰丙酮法、AHMT法、HPLC法和酶催化光度法测定啤酒中的甲醛含量进行比较和分析,实验结果表明,从实验重复率、甲醛回收率及检测限考察,酶法为最佳测定方法,HPLC法也能够满足实际检测的需要,但与酶法相比,其对实验设备的要求较高,不经济且不方便。AHMT法由于采用直接火加热导致甲醛提取率降低,从而降低了实验结果的可信度。乙酰丙酮法由于检测限偏高,较难满足实际检测的需要。     

Determination of formaldehyde in beer based on cloud point extraction using 2,4-dinitrophenylhydrazine as derivative reagent

A cloud point extraction method was developed for extraction of formaldehyde in beer prior to high performance liquid chromatography analysis. The formaldehyde was taken into complex with 2,4-dinitrophenylhydrazine in aqueous nonionic surfactant Triton X-114 medium and concentrated in the surfactant-rich phase by bringing the solution to the temperature of 60 °C. Under optimal conditions, the limit of detection of formaldehyde is 0.7 ng mL⁻¹. The intra- and inter-day precisions expressed as relative standard deviations are 4.2% and 5.5%, respectively. The proposed method was successfully applied for determination of formaldehyde in various beer samples. The contents of formaldehyde in these samples are in the range of 172-385 ng mL⁻¹. The results were in agreement with those obtained by the state standard method (steam-distillation and spectrophotometry analysis) used in China. The developed method was demonstrated to be rapid and sensitive for extraction and determination of formaldehyde in beer.     

食品人工合成色素检测方法改进

本研究在国标法基础上改进检测食品人工合成色素方法,采用丙酮―水(体积比为90∶10)混合溶液提取,经聚酰胺小柱净化后进高效液相色谱仪分析;通过改变检测波长,大大提高色素响应度与检出限,同时也增大色素间分离度,得到较为满意结果。该法定量限为0.5 mg/kg,线性范围0.5 mg/kg~50 mg/kg,加标回收率86.0%~102.8%,相对标准偏差为0.73%~4.66%(n=6)。     

A photochemically induced fluorescence based flow-through optosensor for screening of nitenpyram residues in cruciferous vegetables

One of the most used agrochemicals in agricultural production, nitenpyram (NTP), has been determined by using a flow-through optosensing device based on Photochemically Induced Fluorescence detection. The combination of both methodologies allows, on one hand, a quick on-line photodegradation of NTP and, on the other hand, the preconcentration, quantification and desorption of the fluorescent photoproduct generated when retained on Sephadex QAE-A25 as solid support, which was monitored at 295 and 362 nm for excitation and emission, respectively. The proposed analytical method presents a detection limit of 500 pg mL^?1 by using Multicommutated Flow Injection Analysis. Recovery experiments were carried out in different kinds of cruciferous vegetables at or below the MRL established in Japan, demonstrating that this method combines advantages of simplicity, high sensibility and high selectivity, fulfilling the requirements for its application in quality control. Results obtained in the analysis of real samples were in good agreement with those provided by a reference HPLC method.     

A simplified method for the determination of several fish drugs in edible fish and shrimp by high-performance liquid chromatography

A simplified HPLC method was used to recover antibiotic and antibacterial agents from 11 cultured fish and one shrimp. The average recoveries of oxytetracycline, oxolinic acid, miloxacin, and sulfamonomethoxine were 77, 92, 89 and 80%, respectively. The detection limit was 0.02–0.04 μg/g. We also examined the recovery of oxytetracycline and oxolinic acid used for cultured black tiger shrimp, which is a popular imported shrimp in Japan. To demonstrate the usefulness of this technique for detecting drug residues in cultured fish, the method was used to examine the muscle tissues of 12 commercial fish and shrimp obtained from several fish shops. No agents were found in any of the fish tested.     

The determination of the coccidiostat nicarbazin in animal tissue and eggs. I. Determination by pulse polarography and high pressure fluid chromatography with electrochemical detection

The determination of nicarbazin residues in foodstuffs of animal origin by two different methods, polarography, HPLC with electrochemical detection, is described. By applying pulse polarography at the dropping mercury electrode to acetonitrile extracts of animal tissues and eggs, a detection limit of 50 micrograms/kg and mean recoveries of 79% were obtained. The same extracts were used for the HPLC determination with electrochemical detection. This led to a detection limit of 1 microgram/kg. Additional rapid confirmation can be obtained from HPLC using an internal standard (nifursol) and comparing peak area proportions of both substances at varied polarization voltages. The quantitative determination of nicarbazin in chicken eggs by both polarography and HPLC was found to be in good agreement.     

Determination of airborne carbonyls: comparison of a thermal desorption/GC method with the standard DNPH/HPLC method

The standard method for the determination of gaseous carbonyls is to collect carbonyls onto 2,4-dinitrophenyl hydrazine (DNPH) coated solid sorbent followed by solvent extraction of the solid sorbent and analysis of the derivatives using high-pressure liquid chromatography (HPLC). This paper describes a newly developed approach that involves collection of the carbonyls onto pentafluorophenyl hydrazine (PFPH) coated solid sorbents followed by thermal desorption and gas chromatographic (GC) analysis of the PFPH derivatives with mass spectrometric (MS) detection. Sampling tubes loaded with 510 nmol of PFPH on Tenax sorbent effectively collect gaseous carbonyls, including formaldehyde, acetaldehyde, propanal, butanal, heptanal, octanal, acrolein, 2-furfural, benzaldehyde, p-tolualdehyde, glyoxal, and methylglyoxal, at a flow rate of at least up to 100 mL/min. All of the tested carbonyls are shown to have method detection limits (MDLs) of subnanomoles per sampling tube, corresponding to air concentrations of <0.3 ppbv for a sampled volume of 24 L. These limits are 2-12 times lower than those that can be obtained using the DNPH/HPLC method. The improvement of MDLs is especially pronounced for carbonyls larger than formaldehyde and acetaldehyde. The PFPH/GC method also offers better peak separation and more sensitive and specific detection through the use of MS detection. Comparison studies on ambient samples and kitchen exhaust samples have demonstrated that the two methods do not yield systematic differences in concentrations of the carbonyls that are above their respective MDLs in both methods, including formaldehyde, acetaldehyde, acrolein, and butanal. The lower MDLs afforded by the PFPH/ GC method also enable the determination of a few more carbonyls in both applications.     

HPLC法同时测定食品接触橡胶密封垫圈中3种醛类化合物迁移量

目的:建立一种利用HPLC同时测定食品接触橡胶密封垫圈中甲醛、乙醛和丙烯醛迁移量的分析方法。方法:以4%乙酸水溶液、10%乙醇水溶液、20%乙醇水溶液、50%乙醇水溶液及橄榄油作为食品模拟物,按GB 5009.156—2016进行迁移试验,经衍生化反应后,采用Accucore RP-MS色谱柱分离,以乙腈—水溶液为流动相等度洗脱,紫外检测器检测。结果:3种醛类化合物在0.05~5.00 mg/L内呈良好的线性关系,相关系数R²≥0.9983。甲醛、乙醛和丙烯醛检出限分别为0.58,0.62,1.68 mg/kg;定量限分别为0.98,0.99,2.93 mg/kg,在1.0~15.0 mg/kg添加水平范围内,3种醛类化合物回收率为81.0%~103.3%;相对标准偏差为0.78%~7.05%。结论:该方法适用于食品接触橡胶密封垫圈中醛类化合物迁移量的检测。     

HPLC测定乳制品中的甲醛含量

针对奶糖及奶制品的甲醛残留问题,建立了一种灵敏、快速和有效的HPLC-UV检测乳制品中甲醛的方法。牛奶和奶粉样品中甲醛经三氯乙酸(TCA)提取,奶糖另添加乙酸锌和亚铁氰化钾进行辅助沉淀,用1mg/mL2,4-二硝基苯肼(DNPH),在60℃条件下衍生30min后,用HPLC-UV分离测定,外标法定量。该方法对3种奶制品平均加标回收率在95%以上,日内精密度和日间精密度在5%以下,甲醛含量在0.03～4.00μg/mL范围内呈良好的线性关系,检出限和定量限分别为0.03μg/mL和0.10μg/mL,对常见醛类和醇类有较好的抗干扰性。该方法具有操作简单,准确性高,稳定性好,抗干扰性强的特点,是一种测定乳制品中甲醛的有效分析技术。     

催化动力学光度法测定腐竹中的痕量甲醛

基于在硫酸介质中,甲醛对高碘酸钾氧化甲基红有较强的催化作用,建立测定腐竹中痕量甲醛的新方法。研究影响催化褪色反应速度的条件。在最优化条件下,甲醛浓度在2.25 × 10-4～1.35 × 10-2μg/ml 范围内与吸光度呈良好的线性关系,方法的检出限为4 × 10-5μg/ml。对浓度为0.0041μg/ml 的甲醛标准溶液进行11 次平行测定,得相对标准偏差(RSD)为0.1%。该法具有灵敏度高、选择性好等特点。用于腐竹中痕量甲醛的测定,回收率为93%～106%,结果令人满意。