气相色谱法测定胶粘剂中的游离甲醛

采用超声波萃取胶粘剂中游离甲醛,经2,4-二硝基苯肼衍生后用气相色谱一电子捕获检测器法测定．对提取方法、衍生化条件及色谱条件进行了研究,确定了甲醛检测的最佳条件．研究数据显示,该方法对甲醛的检出限为0．175μLg／g,在0．1～60．0μg／mL浓度范围内,线性相关系数R^2=0．9999;在1、2和8μg／mL3个添加水平下的添加回收率在98．97％-102．24％之间,5个实验室对同一样品中甲醛含量测定值的相对标准偏差为4．0％．结果表明本方法简便、快速、检测限低、回收率高、重现性好．     

高效液相色谱法测定胶粘剂中的游离甲醛

建立了胶粘剂中游离甲醛的高效液相色谱检测方法,对提取方法、衍生化条件及色谱条件进行了研究。结果表明,采用超声波萃取法代替经典的水蒸气蒸馏法能更快速、高效地提取目标物。液相色谱法对甲醛的检出限为0．024μg／mL,在0．1～12μg／mL范围内,线性相关系数R^2=0．9995,在1、2、8μg／mL三个添加水平下,回收率在98．73％～101．68％之间。五个实验室间的相对标准偏差为2．6％。对某白乳胶样品的测定结果表明,本法在定性检测、抗干扰能力及稳定性上都高于常用的乙酰丙酮比色法。     

高效液相色谱法测定卷烟爆珠中的甲醛与乙醛

基于自主设计的一种新型的集萃取、过滤和转移功能为一体的样品萃取管,建立了高效液相色谱(HPLC)测定卷烟爆珠中甲醛和乙醛的分析方法。爆珠用乙腈水溶液萃取,在酸性条件下,经2,4-二硝基苯肼衍生化后,衍生物直接用HPLC法测定。结果表明:采用改进的样品萃取管可大大简化前处理步骤,甲醛和乙醛分别在8~1 500μg/L与10~1 650μg/L范围内呈较好的线性关系,相关系数(r~2)大于0.999,检出限分别为2.5、2.8μg/L,定量下限分别为8.0、9.5μg/L;在2.0、5.0、10.0μg/g 3个加标水平下的平均回收率为96.9%~101.1%,日内精密度和日间精密度均小于4%。该方法具有较好的重复性,适用于卷烟爆珠中甲醛和乙醛的测定。     

催化动力学分光光度法测定痕量甲醛

在稀硫酸溶液中,甲醛对溴酸钾氧亚甲蓝褪色反应有催化作用,研究其动力学条件,建立了测定痕量甲醛的动力学光度分析方法。结果表明,该法线性范围为0.00～0．80μg·L^-,检出限3．315×10^-8g·mL^-1。该法用于食用菌、杏仁和漆料的浸泡液中痕量甲醛的测定,标准加入回收率为96．7％～104．2％     

流动注射分光光度法测定皮革制品中的甲醛

研究了流动注射变色酸分光光度法测定皮革制品中的甲醛。与传统的变色酸光度法相比,该方法具有灵敏度更高,干扰更少的特点。在0.4 mol/L硫酸介质中,甲醛与变色酸在85℃左右形成络合物,该络合物在390 nm有最大吸收峰,且能稳定存在至少96 h。详细考察了各种测试条件如萃取剂、萃取时间、显色时间、反应温度、反应时间等对甲醛测定结果的影响,优化了反应的化学因素和流动注射系统反应条件。该方法的检出限和线性范围分别为0.1μg/L(3σ)和50~1000μg/L,相对标准偏差为0.56%(连续注射500μg/L甲醛标液11次)。该方法成功用于皮革制品或者皮质材料中的甲醛的测定。     

纳米金催化光度法检测食品中的甲醛

采用分光光度法检测以纳米金催化甲醛与菲林试剂反应生成的氧化亚铜微粒在870nm处的吸收值,建立了一种测定食品中甲醛的新方法．研究了纳米金、菲林试剂用量及反应温度、反应时间、共存离子的影响．在最佳实验条件下,甲醛浓度在1．2-600．0μg／mL范围内与吸光值△A线性关系良好,线性回归方程为△A870nm=0．0014C＋0．0627,相关系数为0．9992,检出限为0．45μg／mL．加标回收率为98．0％～100．3％．该法灵敏度高,选择性好,体系干扰少,用于测定腐竹、精制粉丝、红薯粉丝和方便面中甲醛的含量获得满意的结果．     

建筑材料中甲醛含量的柱内衍生HPLC法测定

选用偏二甲肼作柱内衍生剂,利用甲醛与偏二甲肼能在适当的pH值条件下生成有较强紫外吸收的偏二甲腙的实验原理,建立了内墙涂料和胶牯剂中甲醛的柱内衍生高效液相色谱测定方法。实验讨论了甲醛与偏二甲肼反应的机理、pH值对亲核加成反应的影响,估算了流动相的pH值范围为2相似文献   

高分子复合材料中残余甲醛的萃取及高效液相色谱分析

 依据顶空 /气 液平衡原理 ,较为系统地研究了高分子复合材料中残余甲醛的萃取及高效液相色谱定量分析方法 ,探讨了影响萃取率的主要因素 ,进行了萃取及色谱分离条件的优化 ,并实现了复合材料中微量残余甲醛的准确定量测定。方法检测限为 0 1mg/kg ;相对标准偏差小于 5 % ,加标回收率为 96 %～ 10 3%。     

整体柱高效液相色谱法测定草甘膦原药中甲醛含量

建立了衍生化-高效液相色谱法对草甘膦原药中痕量甲醛含量进行测定的方法。样品中残留甲醛经超声波水浴提取，与2，4-二硝基苯肼衍生反应，生成的2，4-二硝基苯腙用反相整体柱色谱进行快速分离，在360nm紫外波长下检测，外标法定量。该分析方法在2．0～200mg/L浓度范围呈良好线性，添加回收率在88％～105％之间，相对标准偏差小于5％。样品中甲醛的最小检测浓度为0．5mg/kg。比较了整体色谱柱和常规C18反相柱分离效果，表明整体色谱柱可在1．5min内实现衍生化产物的快速分离并进行定性定量，同时发现相对于常规柱，采用整体柱提高了检测灵敏度约10倍。     

MBTH法测定织物中的微量甲醛

研究了MBTH法测定织物中微量甲醛的原理及条件．甲醛与MBTH反应形成嗪，嗪与MBTH的氧化产物反应生成青蓝色化合物，该青蓝色化合物在635nm处有最大吸收，在最佳条件下甲醛的检出限为0．00l8μg／mL.利用此法测定织物中甲醛的含量，相对标准偏差为0％-2.5％，回收率为96％-105％，结果满意．     

可视化测定痕量甲醛的研究

摘 要：共振光散射(RLS)法是近年发展起来的新的分析测试技术,它具有简便快速,灵敏度高的特点,已用于痕量元素或物质的分析。本文基于一定条件下,在碱性溶液中甲醛能还原Ag+ 得到黄色银胶,使体系的RLS增强,从而建立起测量环境中痕量甲醛的RLS新方法。结果表明,新建方法测定甲醛的浓度线性范围为1.0?10-6?2.0?10-5 mol/L,检出限为1.0?10-7 mol/L,样品加标测定的回收率为96.26%? 103.32%。并且不同浓度的甲醛还原Ag+ 得到黄色银纳米粒子的颜色明显不同,基于此建立了一种可视化半定量测定痕量甲醛的新方法,新建方法简便快速,灵敏度高。用于环境水样、室内空气中甲醛的测定,结果满意。     

Microwave-assisted on-line derivatization for sensitive flow injection fluorometric determination of formaldehyde in some foods

A rapid and sensitive flow injection fluorometry has been developed for the determination of formaldehyde based on the microwave on-line accelerating its Hantzsch reaction with cyclohexane-1,3-dione. Under the optimized conditions, the fluorescent intensity is proportional to formaldehyde content in the range from 0.05 ng/mL to 2.000 μg/mL. The detection limit (S/N = 3) is 0.02 ng/mL and the analytical frequency is 28 injections per hour. The relative standard deviations are 2.2% and 3.1% for eleven injections of 0.100 and 0.001 μg/mL of formaldehyde, respectively. With the assistance of microwave irradiation, a best sensitive fluorometry was established for the determination of formaldehyde at a high analytical frequency. This method was successfully applied to food analysis without requiring any sample pretreatment, and the determination results were correlated well with those obtained by the standard method with a sample pretreatment of steam distillation.     

Kinetic determination of formaldehyde and hexamethylenetetramine with a cyanide-selective electrode

An automatic potentiometric reaction-rate method is described for the determination of formaldehyde and hexamethylenetetramine. The formaldehyde reacts with cyanide, and the reaction rate is followed with a cyanide-selective electrode. The time required for the reaction to consume a fixed amount of cyanide, and therefore for the potential to increase by a preselected amount (8.0 mV), is measured automatically and related directly to the formaldehyde concentration. The average error for the determination of 60–300 μg of formaldehyde in a sample volume of 1.00 ml was about 1.3%. Amounts of hexamethyl-enetetramine in the range 50–250 μg in a sample volume of 0–050 ml were determined after acid hydrolysis to formaldehyde with an average error of about 1.6%. Measurement times were in the range 18–80 s for both determinations. The method has been applied to the determination of hexamethylenetetramine in pharmaceutical preparations.     

衍生液提取-高效液相色谱法快速测定香菇中的游离甲醛

以2,4-二硝基苯肼乙腈溶液-pH 5磷酸盐缓冲液(体积比为1:1)为提取溶液,提取香菇中游离的甲醛,采用高效液相色谱法测定。结果表明,乙腈-pH 5磷酸盐缓冲液(体积比为1:1)能够有效地抑制香菇中酶反应释放甲醛,达到提取香菇中游离甲醛的目的。在提取液中加入衍生化试剂2,4-二硝基苯肼,将甲醛的提取和衍生化反应相结合,此衍生液提取方法有效地提高了检测效率。鲜香菇样品中分别添加5.0、10.0、20.0 mg/kg的甲醛,平均回收率分别为89.2%、91.7%和90.4%,相对标准偏差(n=6)＜5.0%。方法的定量限（S/N＞10）为5.0 mg/kg。该方法适用于香菇中游离甲醛的检测,且快速简便、重现性好,是确定香菇中甲醛天然本底值的有效方法。     

Determination of formaldehyde by its catalytic effect on the oxidation of pyrogallol red by bromate using flow-injection spectrophotometric detection

This paper reports a simple and sensitive flow-injection method for the spectrophotometric determination of formaldehyde based on the catalytic effect of formaldehyde on the oxidation of pyrogallol red with bromate in acidic media. The decrease in absorbance of the reaction mixture was measured at 470 nm. The calibration graph was linear in the range of 0.47 to 40.0 μ/mL formaldehyde for a sample rate of 30±5 samples per hour. The limit of detection is 0.36 μ/mL. The relative standard deviations for ten replicate measurements of 2.5, 5.0, and 20.0 μ/mL formaldehyde were 3.9, 2.1, and 0.7%, respectively. The method was applied to the determination of formaldehyde in river water, shampoo, and melamine-formaldehyde resin. The text was submitted by the authors in English.     

Fluorimetric flow injection analysis of trace amount of formaldehyde in environmental atmosphere with 5,5-dimethylcyclohexane-1,3-dione

A simple and sensitive flow injection method with fluorimetry and 5,5-dimethylcyclohexane-1,3-dione (dimedone) was developed for the determination of formaldehyde. Formaldehyde reacted with dimedone in the presence of ammonium acetate to form a fluorescence compound, which has an excitation wavelength at 395 nm and an emission wavelength at 463 nm. A two-channel flow system was assembled. Distilled water and 0.3% dimedone buffered at pH 5.5 were delivered at 0.7 ml min⁻¹ and 100 μl of sample was injected into the carrier stream. The reaction was done in the reaction system designed newly, which consists of heating and cooling devices. The chemical reactivity with formaldehyde was excellent in the reaction system and selective. The calibration graphs were linear in the range of 25–100 and 5–10 ppb. RSDs (n=10) for 50 and 10 ppb formaldehyde were 0.6 and 3.4% and the LOD (S/N=3) was 0.9 ppb. The sample throughput was 20 h⁻¹. The method was applied to the determination of formaldehyde in gas sample evolved from adhesive agents and in living environmental indoor. The sensitive and selective method is useful for monitoring trace of formaldehyde in the environmental atmosphere.     

Integrated Retention/Spectrophotometric Detection Method for the Determination of Formaldehyde

Abstract

An integrated-sensor method for the determination of formaldehyde based on retention of the reaction product of the analyte with p-rosaniline and sulfite in a flow-cell packed with Dowex 1-X-8 anion exchange resin was developed. The method has a good selectivity with a detection limit of 0.3 μg ml^?1 (1 ml sample) or 75 ng ml^?1 (2 ml sample), and a linear range between 1–30 μg ml^?1. The relative standard deviations (n = 11) were 2.8 and 1.3% for 2 and 20 μg ml^?1 formaldehyde, respectively. Depending on the working conditions, the sampling frenquency ranged between 10 and 18 h^?1. The method was applied to the determination of formaldehyde in well water.     

Determination of formaldehyde in foodstuffs by flow injection spectrophotometry using phloroglucinol as chromogenic agent

A spectrophotometric method for the determination of formaldehyde in foodstuffs was described by using phloroglucinol as the chromogenic agent. The reaction between formaldehyde and phloroglucinol could occur rapidly at room temperature under mild conditions. The spectrophotometric measurements were conducted at 474nm of an unstable intermediate orange product of the reaction, which greatly increased the sample throughput. Flow injection technique was used to control the merging and reaction timing of the reagents and sample. A detection limit (3sigma) of 0.023microg ml(-1) was achieved. The relative standard deviation was 0.29% for the determination of 7microg ml(-1) formaldehyde (n=11). The proposed method was applied to the analyses of formaldehyde in several preserved foodstuffs and the results were in good agreement with those obtained by a standard method.     

On-line collection/concentration of trace amounts of formaldehyde in air with chromatomembrane cell and its sensitive determination by flow injection technique coupled with spectrophotometric and fluorometric detection

A simple, rapid and highly sensitive method for the determination of trace amounts of formaldehyde in air by using flow injection analysis (FIA) system coupled with a three-hole chromatomembrane cell (CMC) was investigated by using a spectrophotometer and a fluorometer. The CMC was applied to on-line collection/concentration of trace amounts of formaldehyde in air into water as an absorbing solution; formaldehyde in the air was found to be quantitatively transferred into the absorbing solution in CMC. The solution, containing absorbed formaldehyde, was introduced into the carrier stream of the FIA system. The amount of formaldehyde in an absorbing solution was measured spectrophotometrically and fluorometrically after the reaction with a mixed reagent of acetylacetone and ammonium acetate at pH 5.6–5.8. The amount of formaldehyde in the absorbing solution, measured by the proposed system, could be converted to the concentration of formaldehyde in the air sample. A calibration graph prepared by a series of standard formaldehyde aqueous solutions was adopted. The formaldehyde in indoor air, determined as exampled by the proposed spectrophotometric FIA, was found to be 5.14 ± 0.08 ppbv for 20 ml of the air sample at the air flow rate of 6 ml min⁻¹, and the relative standard deviation (R.S.D.) was 1.56%. The limit of detections (LODs) of HCHO in an absorbing solution was 2 × 10⁻⁸ M (0.6 ppb) and 8 × 10⁻⁹ M (0.2 ppb), respectively, by the spectrophotometric and the fluorometric FIA, and the LODs of HCHO in air sample of 40 ml were 0.05 and 0.03 ppbv, respectively. The interferences from foreign species were examined; tolerable concentrations of other aldehydes were more than 50-fold of formaldehyde (1 × 10⁻⁶ M).     

水发食品中甲醛现场测定的样品快速前处理新方法研究

提出了一种用于现场测定水发食品中甲醛含量的样品快速前处理新方法,采用乙酸锌和亚铁氰化钾沉淀样品中的蛋白质和脂肪,在弱酸性介质和沸水浴条件下提取了样品中的甲醛,并与乙酰丙酮立即发生显色反应.研究了不同样品前处理方法对甲醛提取和测定的影响,探讨了水发食品中的甲醛本底值及其是否被人为添加甲醛的判断标准.此方法的特点是样品前处理与显色反应同时进行,在10min内即可完成对水发食品中甲醛含量的定量测定.