Determination of sorbic acid in urine by gas chromatography-mass spectrometry.

The average daily uptake of the common food preservative sorbic acid is estimated to range from 0.01 to 1.1 mg kg-1. Sorbic acid mainly is metabolised to carbon dioxide. Minor amounts are converted to trans,trans-muconic acid (ttMA) as well as excreted unchanged into the urine. Since urinary ttMA is a biomarker for the occupational and environmental exposure to benzene, there is an additional need for monitoring the uptake of sorbic acid, particularly at low, environmental benzene exposure levels. For this purpose, a simple, robust and rapid method for the determination of sorbic acid in urine at trace levels was developed. After addition of 10 ml of water and 5 ml of 8 M hydrochloric acid to 10 ml of the thawed urine, the sample was water steam distilled using an automated distillation device. A total of 100 ml of the distillate were solid-phase extracted. After washing, the sorbic acid was eluted with 4 ml methanol. The eluate was reduced under a stream of nitrogen to a volume of 300 microliters. After addition of 500 microliters boron trifluoride in methanol and incubation for 1 h at 60 degrees C, the resulting sorbic acid methyl ester was extracted three times with 1 ml heptane. To the combined heptane layers, sorbic acid ethyl ester was added as an internal standard. After reducing to a volume of 100 microliters in a stream of nitrogen, the final analysis was performed by GC-MS using the fragment ions m/z 126 for the analyte and m/z 140 for the internal standard. The limit of detection was 0.7 ng ml-1 urine and the R.S.D. of 69 duplicate determinations was 7.5%. In a controlled, experimental study and in a field study, we were able to show that urinary sorbic acid is a marker for the dietary uptake of sorbic acid and that sorbic acid is converted to ttMA. On average, 0.1% of the dietary sorbic acid is excreted unchanged into the urine. Excretion is complete within 24 h. We found that, on average, 0.23% of the oral dose of sorbic acid is excreted as urinary ttMA. There was a significant correlation between urinary excretions of sorbic acid and ttMA (r = 0.74, n = 69). We conclude that urinary sorbic acid can be used to correct the urinary ttMA level in order to determine the portion related to benzene exposure. This appears to be necessary particularly at low, environmental benzene levels.     

Simultaneous determination of trans-resveratrol and sorbic acid in wine by capillary zone electrophoresis

A method for separation and determination of sorbic acid, a food and beverage preservative, and trans-resveratrol, a biomedically active substance, in wine by capillary zone electrophoresis is described. A solid-phase extraction step on C18-column prior to the electrophoretic separation providing lower detection limits was used for trans-resveratrol determination. For determination of sorbic acid direct analysis of wine (without a preconcentration step) was used. The method is rapid and sensitive and was applied to the analysis of wines from Alsace, France.     

Spectrophotometric method for the determination of sorbic acid in various food samples with iron(III) and 2-thiobarbituric acid as reagents

A simple, rapid and accurate spectrophotometric method has been developed for the determination of sorbic acid in various food samples based on the oxidation of sorbic acid by iron(III) at 100 degrees C to malonaldehyde, which then reacts with 2-thiobarbituric acid to form a reddish brown product. The optimum experimental conditions for colour development have been assessed. Absorbance measurements were made at 529 nm in the presence of 0.4% m/V citric acid. The calibration graph was linear for 0-6 micrograms ml-1 of sorbic acid with a slope of 0.131 A micrograms-1 ml. The recoveries of sorbic acid at concentrations of 164-557 micrograms ml-1 ranged from 96 to 103%. The relative standard deviations of ten replicate determinations of sorbic acid in a synthetic cream soda sample spiked with 573 micrograms ml-1 of sorbic acid and in an onion juice sample containing 82 micrograms ml-1 of sorbic acid were 1.6 and 1.9%, respectively. Interferences from several common food additives can be minimised by extracting sorbic acid with diethyl ether and then back-extracting the acid with sodium hydrogen carbonate. The method has been applied successfully to the determination of sorbic acid in a wide range of food samples including beverages, cake, cake mate, garlic bread sprinkle, onion juice, oyster flavoured sauce and grenadine syrup.     

高效液相色谱-串联质谱法测定调味料中的痕量苯甲酸与山梨酸

建立了调味料中痕量苯甲酸、山梨酸的高效液相色谱-串联质谱检测方法.调味料样品经盐酸酸化后用乙醚多次提取,酸性氯化钠洗涤提取液,挥干后用1 mL90% 0.2 mmol/L NH4OAc(pH 5.0)的乙腈溶液溶解,过膜备用.采用电喷雾负离子电离(ESI-)模式和单反应监控(SRM)模式检测,外标法定量.该方法在0.5...     

反相高效液相色谱法测定化妆品中的苯甲酸和山梨酸

建立了反相高效液相色谱法测定化妆品中苯甲酸和山梨酸的分析方法.样品经甲醇超声提取后,直接过滤进样检测.采用Sinochrom C18色谱柱,以0.02 mol/L乙酸铵-甲醇(体积比为85:15)为流动相,流速为2.0 mL/min,检测波长为230 nm.结果表明:苯甲酸和山梨酸浓度在2.00～12.00 μg/mL...     

Determination of sorbic acid in margarine and butter by high-performance liquid chromatography with fluorescence detection

A procedure is reported for the separation and determination of sorbic acid, as a derivative of 4-bromoethyl-6,7-dimethoxycoumarin, by reversed-phase high-performance liquid chromatography with fluorescence detection using enanthic acid as an internal standard. Sorbic acid, separated from samples of commercial margarine and butter by steam distillation, was evaluated using the proposed procedure and by UV absorption and visible spectrophotometric methods (AOAC). The preparation of the calibration graph and the determination of sorbic acid with the visible spectrophotometric method was improved. The sorbic acid content determined using UV and visible spectrophotometric methods was higher than that obtained with the reversed-phase performance liquid chromatographic method owing to the presence of interfering substances in the samples. The range of recovery and the precision of the proposed method and the reference methods are also reported.     

Direct colorimetric determination of small amounts of tungsten in titanium

There is need for a rapid and accurate method for the determination of small amounts of tungsten in titanium. In this paper a direct colorimetric method is proposed for the determination of tungsten in titanium that is applicable to the range of 0.005 to 0.3 per cent. tungsten. The sample is dissolved in hydrochloric acid and the titanium and tungsten reduced with metallic zinc. Thiocyanate is added and the yellow color read at 410 millimicrons with a spectrophotometer. A study was made of the best conditions for developing the color, including the effect of varying amounts of titanium, thiocyanate and hydrochloric acid. An investigation was made to determine the proper wave length for reading the color, the stability of the color and effect of interferences.     

湿法消解-电感耦合等离子体原子发射光谱(ICP-AES)法测定含铑废催化剂冶金废水中铑

摘 要：建立了硫酸、过氧化氢湿法消解、ICP-AES测定铑派克洗水铑的含量的分析方法。确定了硫酸碳化有机物,过氧化氢溶解煮沸,氢氟酸除硅,于4mol/L盐酸体系,碲共沉淀富集铑,10%盐酸介质,电感耦合等离子体发射光谱仪测定铑量。在选定条件下,测定含铑有机物洗水中0.0003 g/L～0.010 g/L的铑,相对标准偏差（RSD,n=7）和加标回收率分别为：铑0.545%～2.91%和99.62%%～100.55%。。方法准确、快速、简便,测定结果与火试金富集分析方法结果吻合。     

测定抗坏血酸的亚甲蓝褪色光度法

确定了亚甲蓝与抗坏血酸褪色反应的最佳条件,在 pH=2的缓冲溶液和对氨基苯磺酸存在的条件下,抗坏血酸能够很快还原亚甲蓝并使之褪色,褪色反应的体系具有很好的稳定性。该反应的摩尔吸光系数为 2.0× 103 L· mol－ 1· cm－ 1,线性范围 0.4～ 40.0 mg/L。该法具有优良的选择性,常见的能够与抗坏血酸共存的阴、阳离子和还原剂、表面活性剂不干扰测定,应用于药品、饮料、蔬菜中抗坏血酸的测定,获得满意结果。     

紫外光谱法测定甲壳素的脱乙酰化值

用紫外光谱测定甲壳素脱乙酰程度，该法快速简便，重现性好，试样无需特殊处理。     

Simultaneous determination of sorbic and benzoic acids in food dressing by headspace solid-phase microextraction and gas chromatography

A facile headspace solid-phase microextraction (HS-SPME) procedure using 85 microm polyacrylate (PA) fiber is presented for the simultaneous determination of preservatives (sorbic and benzoic acids) in food dressing, including Thousand Island Dressing, HellMANN'S Salad Dressing and Tomato Ketchup, by gas chromatography (GC) with flame ionization detector (FID). The method presented preserves the advantages typical of HS-SPME such as simplicity, low intensity of labor, low cost and solvent free. The main factors affecting the HS-SPME process, such as extraction temperature and time, desorption temperature and time, the acidity and salt concentration of the solution, were optimized. Limits of detection (LODs) of the method were 2.00 microg/L for sorbic acid and 1.22 microg/L for benzoic acid. Relative standard deviations (RSDs) for quintuplicate analyses at three concentration levels of 0.10, 2.0 and 20 mg/L ranged between 3.86 and 14.8%. The method also showed good linearity n a range from 0.02 to 40 mg/L with correlation coefficients (R2) of 0.9986 for sorbic acid and 0.9994 for benzoic acid. Recoveries for the two analytes in all the samples tested ranged from 83.44 to 113.2%. Practical applicability was demonstrated through the simultaneous determination of sorbic and benzoic acids in the three complex samples.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定进口酸泥中砷和汞

本文采用硝酸和盐酸的混合酸低温溶解酸泥后,运用ICP-AES法同时测定进口酸泥中砷和汞。建立了最佳实验方法,确立各项分析条件,砷的测定范围：0.01%~10%,汞的测定范围：0.005%~10%。测定值相对标准偏差小于3%,加标回收率在97%~105%之间,该方法简单快速,准确度高,完全满足酸泥中砷和汞的测定要求。     

Derivatisation of carboxylic acid groups in pharmaceuticals for enhanced detection using liquid chromatography with electrospray ionisation tandem mass spectrometry

Tris(2,4,6-trimethoxyphenyl)phosphonium propylamine bromide (TMPP) has been used for the derivatisation of maleic, fumaric, sorbic and salicylic acids to facilitate determination using liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) in positive ion mode. Detection limits, achieved using multiple reaction monitoring mode, were 2, 4, 0.4 and 540 fmol (5 muL injection) for derivatised fumaric, sorbic, maleic and salicylic acids, respectively. In comparison, detection limits achieved in negative ion mode for the underivatised acids were 24, 51, 2, and 117 fmol, respectively. The method was successfully used for the determination of sorbic acid in a sample of Panadol. The derivatisation of salicylic acid was not as successful, probably due to poor reaction efficiency.     

冷原子吸收光谱法测定塑料玩具中可溶性镉

建立冷蒸气发生–原子吸收光谱法测试玩具中可溶性镉的检测方法。采用0.07 mol/L的盐酸溶液提取玩具中可溶性镉,在酸性介质中,还原剂硼氢化钠将镉离子还原生成镉蒸气,用载气将镉蒸气导入石英管,在波长228.8 nm处用原子吸收光谱法进行测定。选择溶液酸度介质为体积分数4%的盐酸溶液、NaBH4质量分数为2.5%、增敏剂加入量为2.0 mL。在优化的实验条件下,方法的检出限为0.065μg/kg。加标回收率为96.8%～104.2%,测定结果的相对标准偏差小于4.5%(n=11)。该方法具有快速、准确,灵敏度高,经济实用等优点,可用于塑料玩具中可溶性镉的测定。     

The rapid spectrophotometric determination of copper in non-ferrous alloys

A very simple method has been established for the rapid determination of copper, employing the formation of the chlorocupric anion by means of concentrated hydrochloric acid. The absorption of the chlorocupric anion is measured spectrophotometrically at a wavelength of 950 mμ. The method is applicable to a wide variety of samples, including many non-ferrous alloys.     

薄层色谱法测定调味品中苯甲酸的研究

提出了聚酰胺薄膜上分析调味品中苯甲酸的样品处理方法及标准样品加标法。样品在展开剂上行展开10cm,该方法不需要大型仪器和特殊试剂,适用于多个样品的快速检测,也适用于山梨酸的检测。     

Rapid estimation of chlorate in presence of perchlorate

Summary A rapid and simple method is described for the determination of chlorate in the presence of a large amount of perchlorate. The solution containing the mixture is acidified with either sulphuric acid or hydrochloric acid and titrated in the presence of sodium bromide directly against titanous chloride using quinoline yellow as indicator near the end point. The limit of uncertainty of the method is 0.361 mg for a sample analysing 52.48 mg of sodium chlorate.     

乳及乳制品中多种防腐剂和甜味剂的同时测定

建立了高效液相色谱法同时测定乳及乳制品中安赛蜜、苯甲酸、糖精钠、山梨酸和阿斯巴甜的方法。通过加入适量沉淀剂除去样品中绝大部分蛋白质后,采用C18色谱柱分离,以甲醇-0.05 mol/L磷酸二氢钾溶液为流动相梯度洗脱,用二极管阵列检测器于230 nm波长处检测安赛蜜、苯甲酸和山梨酸,于210 nm波长处检测糖精钠和阿斯巴甜。被测物的回收率为96.0%～103.5%,精密度(以相对标准偏差(RSD)计)为1.93%～2.76%,安赛蜜、苯甲酸、糖精钠、山梨酸和阿斯巴甜的检出限分别为1.0, 1.0, 0.5, 1.0, 1.5 μg/g。该方法可用于乳及乳制品中这5种添加剂的同时测定。     

Dosage simultane par chromatographie liquide a haute performance de l'acide benzoique et de l'acide sorbique: High-performance liquid chromatographic determination of benzoic and sorbic acids

High-performance liquid chromatographic determination of benzoic and sorbic acids. Quantitative h.p.l.c. for benzoic and sorbic acids in foodstuffs, especially soft drinks, is described. Recoveries were 101.49% ± 1.39 for sorbic acid and 99.52% ± 1.05 for benzoic acid in the concentration ranges normally used (50–100 mgl^-1).     

La détermination indirecte du tungsténe dans les minerais par voie complexométrique

The determination of tungsten by gravimetric methods is time-consuming and requires special precautions. A simple and rapid method is described for the indirect determination of tungsten in minerals by means of complexometric titration.The separation of tungsten (in the form of sodium, tungstate) is obtained by precipitation of this soluble salt by means of calcium chloride. The precipitate of calcium tungstate is filtered and decomposed into calcium chloride and tungstic acid (insoluble) by treating with concentrated hydrochloric acid.The filtrate is made alkaline and serves for the titration with a 0.1M solution of Complexon III. One ml of this solution corresponds to 23.1867 mg of WO₃. This determination of Lungyten takes 3 to 4 hours.