Determination of orthophthalaldehyde in air using 2,4-dinitrophenylhydrazine-impregnated silica cartridge and high-performance liquid chromatography

A new method is described for the determination of orthophthalaldehyde in air which is used for the disinfection of various instruments (e.g. endoscopes) in hospital. Orthophthalaldehyde in air was collected with a silica gel cartridge impregnated with acidified 2,4-dinitrophenylhydrazine (DNPH-cartridge) and derivatives were analyzed by high-performance liquid chromatography (HPLC). In this study, the derivatization was examined by comparing the process with three phthalaldehyde isomers (ortho-, iso- and tere-). In the case of iso- and tere-phthalaldehyde, derivatives synthesized with excess of aldehyde consisted mainly of mono-derivatives, and derivatives synthesized with excess of DNPH consisted mainly of bis-derivative. In the case of orthophthalaldehyde, derivative consisted of only bis-derivative and mono-derivative was never observed under any conditions. Orthophthalaldehyde was completely retained by the DNPH-cartridge during air sampling, however, the derivatization reaction was incomplete and unreacted orthophthalaldehyde was flushed from the cartridge during the subsequent solvent extraction process. Unreacted orthophthalaldehyde and DNPH reacted again in the extraction solvent solution. Immediately after the solvent extraction, both mono- and bis-DNPhydrazone derivatives of orthophthalaldehyde were present in the solution. However, over time, the mono-derivative decreased and bis-derivative increased until only the bis-derivative was left allowing accurate determination of the orthophthalaldehyde concentration. The transformation of mono-derivative to bis-derivative was faster in polar aprotic solvents such as acetonitrile, dimethyl sulfoxide and ethyl acetate. Transformation was found to occur most quickly in acetonitrile solvent and was completed in 4 h in this case. It was possible to measure orthophthalaldehyde in air as bis-derivative using a DNPH impregnated silica cartridge and HPLC analysis.     

涂布2,4-二硝基苯肼的环形溶蚀器/滤膜系统和高效液相色谱法检测大气中二羰基化合物

建立了环形溶蚀器/滤膜系统(Annular denuder/filter pack system)和2,4-二硝基苯肼(DNPH)-高效液相色谱法(HPLC)采集和检测大气中气相和颗粒相二羰基化合物的方法。DNPH作为吸附剂分别涂布在环形溶蚀器的内壁和3层滤膜上,当大气样品经过环形溶蚀器时,含有气相二羰基化合物的气体吸附到环形溶蚀管内壁上与DN-PH发生反应,而颗粒相部分穿过环形溶蚀管,采集到滤膜上。样品经乙腈洗脱、浓缩后,采用HPLC进行分析。根据不同的采样流速、采样时间和DNPH的涂布量采集到的二羰基化合物的浓度,确定的最佳采样条件为:采样流速4 L/min,采样时间4~5 h,DNPH浓度0.47 g/L。使用Tedlar bag验证环形溶蚀器乙二醛和甲基乙二醛的采集效率(分别为82%和85%)。利用此方法对实际大气中的二羰基化合物进行了检测。     

A Fractional Factorial Design Applied to the Optimization of Microwave- and Ultrasound-Assisted Acid Leaching Methods for Heavy Metals Determination in Sludges by Flame Atomic Absorption Spectrometry

Abstract

The sampling performance of C₁₈ cartridges coated with DNPH has been studied for twenty four C₁-C₉ carbonyls in experiments involving sampling of parts per billion levels of carbonyls in urban air. indoor air and laboratory experiments. The cartridge background carbonyl content in thirty six batches of cartridges averaged 85, 137 and 155 nanogram/cartridge for formaldehyde, acetaldehyde and acetone, respectively, and was below analytical detection for all other carbonyls. Carbonyl-DNPH derivative recovery from the cartridge was complete in the first elution with 2 mL acetonitrile, and this for twenty four carbonyls at concentrations of 0.02–73 μg carbonyl/cartridge. Studies carried out using two cartridges in series showed no breakthrough, for the sixteen carbonyls tested, at concentrations of 0.10–49 μg carbonyl/cartridge and volumes of air sampled = 6–370 L. Average relative standard deviations (RSD) for replicate analyses were 0.20–13.2% for twenty one carbonyls. Average RSD for co-located samples were 0.9–16.2% for eighteen carbonyls. Comparison of RSD for replicates and RSD for co-located samples for thirteen carbonyls indicated that the overall method precision was limited by sampling precision rather than by analytical precision.     

Determination of acrolein and other carbonyls in cigarette smoke using coupled silica cartridges impregnated with hydroquinone and 2,4-dinitrophenylhydrazine

A new method for the determination of acrolein and other carbonyls in cigarette smoke using a dual cartridge system has been developed. Each cartridge consists of reagent-impregnated silica particles. The first contains hydroquinone (HQ) for the inhibition of acrolein polymerization, while the second contains 2,4-dinitrophenylhydrazine (DNPH) for the derivatization of carbonyls. Smoke samples were firstly drawn through the cartridge containing HQ-impregnated silica (HQ-silica) and then through the DNPH-impregnated silica (DNPH-silica). Acrolein in the sample was completely trapped in the first HQ-silica cartridge. Some other airborne carbonyls were also trapped by the HQ-silica, and those that pass through were trapped in the second DNPH-silica cartridge. Extraction was performed in the reverse direction to air sampling. When solvent was eluted through the dual-cartridges, excess DNPH was washed into the HQ bed where it reacted with acrolein and other trapped carbonyls to form the corresponding hydrazone derivatives. All of the hydrazones derived from airborne carbonyls were completely separated and measured using high-performance liquid chromatography. This HQ-DNPH-method can be applied for the determination of acrolein and other α,β-unsaturated aldehydes, such as crotonaldehyde, in cigarette smoke.     

高效液相色谱法测定乙醛溶液中的乙二醛和乙醛酸

利用醛基与2,4-二硝基苯肼(DNPH)反应得到的腙产物对紫外-可见光有吸收的特性,采用高效液相色谱法(HPLC)测定乙醛溶液中乙二醛和乙醛酸的含量。结果表明,DNPH衍生乙二醛成腙反应的适宜条件为: 反应温度70 ℃, pH 1.75, DNPH与羰基的物质的量比为6,反应时间150 min。在20 ℃、pH 1.75的乙腈溶液中,乙二醛二腙的溶解度为20.2 mg/L。乙二醛质量浓度在2～20 mg/L范围内,乙二醛二腙的峰面积与乙二醛的质量浓度之间呈良好的线性关系;乙醛酸质量浓度在10～100 mg/L范围内,乙醛酸腙的峰面积与乙醛酸的质量浓度之间呈良好的线性关系。用HPLC测定乙醛硝酸氧化法制乙二醛反应液中乙二醛和乙醛酸的含量,结果的重复性好;对乙二醛的测定结果与应用化学分析法测定结果的平均相对误差为1.77%;对反应液中乙二醛、乙醛酸含量的测定有着较高的加标回收率,分别为99.6%～103.3%和98.1%～102.4%。所建立的方法为醛及二羰基化合物的测定提供了准确、便捷的方法。     

Evaluation of silica gel cartridges coated in situ with acidified 2,4-dinitrophenylhydrazine for sampling aldehydes and ketones in air

A procedure for coating in situ silica gel in prepacked cartridges with 2,4-dinitrophenylhydrazine (DNPH) acidified with hydrochloric acid is described. The coated cartridge was compared with a validated DNPH impinger method for sampling organic carbonyl compounds (aldehydes and ketones) in diluted automotive exhaust emissions and in ambient air for subsequent analysis of the DNPH derivatives by high performance liquid chromatography. Qualitative and quantitative data are presented that show that the two sampling devices are equivalent. The coated cartridge is ideal for long-term sampling of carbonyls at sub to low parts-per-billion level in ambient air or for short-term sampling of carbonyls at low ppb to parts-per-million level in diluted automotive exhaust emissions. An unknown degradation product of acrolein has been tentatively identified as x-acrolein. The disappearance of acrolein in the analytical sample matrix correlates quantitatively almost on a mole for mole basis with the growth of x-acrolein. The sum of the concentration of acrolein and x-acrolein appears to be invariant with time.     

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Within the framework of a European interlaboratory exercise, the Vito facility for the generation of controlled atmospheres was used to test the suitability of four sampling techniques for priority aldehydes namely formaldehyde, acrolein, acetaldehyde, and glutaraldehyde at the ranges of 0.5 to 150 microg x m(-3). The samplers are DNPH-containing impingers, DNPH-impregnated cartridges and filters, and 2-HMP coated XAD-2 tubes. The three first DNPH samplers are to be analyzed by HPLC and the latter by GC-MS for the oxazolidine derivatives. The intermethod comparison comprises two to five sets of experiments depending on the compounds of interest. The aim of the exercise was also to assess the chemical interferences caused by ozone, nitrogen dioxide, and ammonia when using different techniques for sampling and analysis. The active DNPH method (with minor modifications such as shorter sampling time, immediate elution after sampling, and/or eventually wetting of samplers) delivered results within the 30% overall relative uncertainty for formaldehyde, acetaldehyde, and acrolein at the upper microg x m(-3) levels. However, the results suggest that the current DNPH methods for aldehydes do not comply with the 30% minimum performance criteria at the sub microg x m(-3) level. Sampling of aldehydes in the presence of ozone and NO2 interferences by using a "scrubber" cartridge appears to be beneficial to the quality of results.     

固相萃取技术-HPLC测定复方甘草片中吗啡的含量

报道了用ＳＥＰ－ＰＡＫＣ１８小预柱固相萃取技术和反相高效液相色谱法测定复方甘草片中微量吗啡含量的方法。对固相萃取条件进行了研究,最终选择１０％甲醇溶液为清洗溶液,７０％甲醇溶液为洗脱溶液,基本消除了干扰组分对测定的影响,色谱图背景吸收小,基线平稳。色谱柱为μ－ＢｏｎｄａｐａｋＣ１８柱,流动相为０．１ｍｏｌ／ＬＮａＨ２ＰＯ４溶液－甲醇（５１）,检测波长为２８６ｎｍ。平均回收率为（１０１．２±１．５）％,ＲＳＤ为１．５％。     

Trace analysis of carbonyl compounds by liquid chromatography-mass spectrometry after collection as 2,4-dinitrophenylhydrazine derivatives.

This study describes the utilization of carbonyl- 2,4-dinitrophenylhydrazine (DNPH) derivatives for the determination of a micro amount of carbonyl compounds in air by liquid chromatography-mass spectrometry (LC-MS). After the carbonyl compounds are collected using a Waters Sep-Pak C18 cartridge column with-impregnated DNPH on octadecylsilica, they are eluted by acetonitrile as carbonyl-DNPH derivatives. A 20-mm3 aliquot of eluent is injected into the LC-MS system. The four derivatives (formaldehyde-, acetaldehyde-, acrolein- and acetone-DNPH) were eluted within 7 min with acetonitrile-water (60:40, v/v) as the mobile phase. The proposed method offers sub-ppb sensitivity and good reproducibility and was applied to the determination of these carbonyl compounds in actual air samples from store rooms, laboratories and offices. The relative standard deviations for these samples (n = 6) were 1 to 3%.     

Simultaneous determination of HCHO,CH3CHO and O(x) in ambient air by hydrazine reagent and hplc

Formaldehyde, acetaldehyde, ozone and nitrogen dioxide in ambient air are simultaneously collected on silica gel cartridges coated with 1-methyl-1-(2,4-dinitrophenyl)hydrazine (MDNPH), where the two aldehydes are derivatized to their respective hydrazones, while the two oxidants are converted into N-methyl-2,4-dinitroaniline (MDNA). The three products are then separated and quantified by HPLC with UV detection at 360 nm. The stoichiometric factors of the MDNPH reactions with O3 and NO2 in laboratory tests correspond to 2.0 +/- 0.1 moles of MDNA per mole of O(x) (O3 + NO2). The limits of detection (LOD) are 0.7 ppbv HCHO, 0.8 ppbv CH3CHO and 1.6 ppbv O(x) for 30 L (1 h) air sampled. The sampling performance is insensitive to relative humidities encountered in real atmospheres. When compared with Sep-Pak DNPH silica cartridges as well as with ozone photometric and nitrogen dioxide chemiluminescent analyzers, the proposed chromatographic method demonstrates a very good accuracy (12% for HCHO, 14% for CH3CHO and 7% for O(x), on the average) under field sampling conditions at concentrations lower than 3 and 1 ppbv, for HCHO and CH3CHO, respectively and ranging from 28 to 62 ppbv for O(x).     

Determination of ofloxacin, norfloxacin, and ciprofloxacin in sewage by selective solid-phase extraction, liquid chromatography with fluorescence detection, and liquid chromatography--tandem mass spectrometry

A solid-phase extraction (SPE) and liquid chromatographic (LC) method was developed for the determination of selected fluoroquinolone (FQ) drugs including ofloxacin, norfloxacin, and ciprofloxacin in municipal wastewater samples. Extraction of the FQs was carried out with a weak cation exchanger SPE cartridge, the Oasis WCX. The cartridge was washed with water and methanol as a cleanup before the FQs were eluted by a mixture of methanol, acetonitrile, and formic acid. Separation of the FQs was achieved by using a Zorbax SB-C8 column under isocratic condition at a flow rate of 0.2mL/min. Recoveries of the FQs in spiked final effluent samples were between 87 and 94% with a relative standard deviation of less than 6%. Several techniques have been evaluated for the detection of FQs in sewage extracts; they included fluorescence detection and electrospray ionization (ESI) mass spectrometry using either mass-selective detection or tandem mass spectrometry (MS/MS). When they were applied to sewage influent and effluent samples, the LC-MS/MS technique operating in the multiple reaction monitoring (MRM) mode proved to be best suited for the determination of FQs in sewage samples as it provided the highest sensitivity (limit of quantification 5ng/L) and selectivity. The observation of signal suppression (matrix effect) for some FQs in ESI LC-MS and LC-MS/MS is discussed and a solution is proposed. The three FQs were detected in all the sewage samples tested in this work, with median concentrations between 34 and 251ng/L.     

Improvement of 2,4-dinitrophenylhydrazine derivatization method for carbon isotope analysis of atmospheric acetone

Through simulation experiments of atmospheric sampling, a method via 2,4-dinitrophenylhydrazine (DNPH) derivatization was developed to measure the carbon isotopic composition of atmospheric acetone. Using acetone and a DNPH reagent of known carbon isotopic compositions, the simulation experiments were performed to show that no carbon isotope fractionation occurred during the processes: the differences between the predicted and measured data of acetone-DNPH derivatives were all less than 0.5 per thousand. The results permitted the calculation of the carbon isotopic compositions of atmospheric acetone using a mass balance equation. In this method, the atmospheric acetone was collected by a DNPH-coated silica cartridge, washed out as acetone-DNPH derivatives, and then analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using this method, the first available delta13C data of atmospheric acetone are presented.     

气相色谱-质谱法测定化妆品中的丙烯腈

建立了化妆品中丙烯腈的气相色谱-质谱分析方法.不同类型的化妆品样品中加入甲醇超声提取,经高速离心处理浓缩后,采用Oasis HLB固相萃取柱净化,1 mL 20%甲醇溶液淋洗,3 mL 80%甲醇溶液洗脱,收集洗脱液,浓缩后经无水硫酸钠脱水,进行气相色谱-质谱定性及定量分析.选用HP-INNOWax(60 m×0.25...     

Simultaneous determination of formic acid and lower carbonyls in air samples by DNPH derivatization

The classical derivatization method of carbonyls based on 2,4-dinitrophenylhydrazine (DNPH)-coated silica cartridges was tested to concurrently measure lower carbonyls and carboxylic acids in air samples. The performance of these cartridges with respect to formic and acetic acids was evaluated in a number of laboratory measurements on collection and reaction efficiencies. The results showed that HCOOH appeared to have been efficiently collected and derivatized (at 80 degrees C for 8 h) up to air-flow rates of 350 mL/min, while CH(3)COOH was almost completely lost from the cartridge above 100 mL/min. Also due to the high LOD of HCOOH (0.8 microg/m(3)) for 120 L of air sampled during 8 h, the DNPH method might be used only in indoor environments polluted by formic acid as well as carbonyls.     

A diffusive sampling device for simultaneous determination of ozone and carbonyls

A new diffusive sampling method for the simultaneous determination of ozone and carbonyls in air has been developed. In this method, silica gel impregnated with a mixture of trans-1,2-bis(2-pyridyl)ethylene (2BPE) and 2,4-dinitrophenylhydrazine (DNPH) is used as the absorbent; further, a porous sintered polyethylene tube (PSP-diffusion filter), which acts as a diffusive membrane, and a small polypropylene syringe (PP-reservoir) for elution of the analytes from the absorbent are used. The carbonyls present in air react with DNPH in the absorbent to form hydrazone derivatives. Concurrently, ozone in the air reacts with 2BPE to form pyridine-2-aldehyde, which immediately reacts with DNPH to form a pyridine-2-aldehyde hydrazone derivative. All the hydrazones derived from airborne carbonyls, including pyridine-2-aldehyde (formed from ozone), are completely separated and analyzed by high-performance liquid chromatography. The sampling rates of ozone (44.6 mL min(-1)) and formaldehyde (72.0 mL min(-1)) are determined by comparison with the rates obtained in an active sampling method. The sampling rates of other carbonyl compounds are calculated from the respective molecular weights according to a rule based on Graham's law. The calculated sampling rates agree with the experimental values. The DSD-BPE/DNPH method is advantageous because it is simple and allows for the simultaneous analysis of ozone and carbonyls.     

Determination of trace amounts of bisphenol A in urine by negative-ion chemical-ionization-gas chromatography/mass spectrometry.

We improved an analytical method for determining trace amounts of bisphenol A (BPA) in urine. BPA was subjected to enzymolysis and then to solid phase extraction with a C18 cartridge. The extract was eluted with methanol, and the eluate was concentrated under a nitrogen stream, and then pentafluorobenzylized in an alkali solution. The obtained pentafluorobenzylized compound was purifed using a florisil cartridge, followed by a determination using NCI-GC/MS. This method exhibited an excellent selectivity and reproducibility with a determination limit of 0.1 ng/ml.     

Ozone measurement with silica cartidges and HRGC-MS analysis

Ozone in ambient air is collected onto silica gel cartridges impregnated with pentafluorophenylhydrazine (PFPH) and 1,2-di(4-pyridyl)ethylene (DPE), so that the pyridine-4 aldehyde formed by DPE oxidation is converted into the corresponding PFPH derivative (PPH). The latter product is determined by HRGC/MS. Since the ozonolysis reaction proceeds stoichiometrically on the cartridge, there is no need for calibration in the gas phase with a standardized ozone source. When compared with UV photometry analyzers, this active chromatographic method (ACM) demonstrates a very good accuracy (ACM/UV photometer = 0.97) and precision (12.0-14.0%) under both laboratory and field sampling conditions at ozone concentrations of 20-200 microg m(-3) and exposure times of 1-3 h. The sampling performance was found to be insensitive to relative humidity (r.h.) variations in the 25-90% range and any interference effects could not be observed from various agents, except light, which can be eliminated by using an aluminium shelter. The detection limit for ozone achievable with the ACM in air samples collected at 0.5 L min(-1) for 1 h was found better than 0.5 microg m(-3).     

A simple and rapid in situ preconcentration method for trace ammonia nitrogen in environmental water samples using a solid-phase extraction followed by spectrophotometric determination.

A simple and rapid in situ preconcentration method for the spectrophotometric determination of trace ammonia nitrogen in environmental water samples has been developed based on solid-phase extraction using a small column packed with octadecyl group-bonded silica gel (Sep-Pak C18 cartridge). A water sample was taken into a graduated syringe for easy and simple operation and prevention of contamination immediately after sample collection. Ammonia in the sample was reacted with hypochlorite and thymol to be converted into indothymol blue; then the formed indothymol blue was collected as an ion pair between indothymol blue and tetrabutylammonium ion on a Sep-Pak C18 cartridge. The indothymol blue on the cartridge was stable for 4 days. The retained indothymol blue was easily eluted with a mixture of methanol and 0.01 mol/l sodium hydroxide solution. The color intensity due to the indothymol blue was spectrophotometrically measured at 725 nm. The proposed method was successfully applied to environmental water samples such as river water.     

Development and laboratory investigation of a denuder sampling system for the determination of carbonyl compounds in stack gas

A method for sampling and detection of low volatile carbonyl concentrations (aldehydes and ketones) in stack gas is proposed. For this purpose, a novel fourfold glass annular-denuder, coated with acidified 2,4-dinitrophenylhydrazine (DNPH) has been developed for the sampling of carbonyl compounds under high temperature and high humidity emission conditions. After sampling, the hydrazones are eluted with acetonitrile and analyzed using RP-HPLC. They are detected by UV-absorbance, with maximum sensitivity obtained between 350 and 380 nm. The sampling efficiency has been investigated for different flow rates, temperatures and relative humidities. The influence of other trace gases (ozone, nitrogen dioxide) on the sampling system was investigated as well.     

Evaluation of beta-cyclodextrin bonded silica as a selective sorbent for the solid-phase extraction of 4-nitrophenol and 2,4-dinitrophenol.

A beta-cyclodextrin bonded silica was synthesized by using a convenient method, and was evaluated as a selective sorbent for the solid-phase extraction of 4-nitrophenol and 2,4-dinitrophenol. When double-distilled water was used as the sample matrix, the sorbent showed a strong capacity to adsorb 4-nitrophenol and 2,4-dinitrophenol; the recoveries were found to be 96% and 99%, respectively, with a 1 L water sample. The selectivity of the sorbent was investigated by using a washing step with methanol. Most of the phenols were washed out with 5 mL of methanol, while 4-nitrophenol and 2,4-dinitrophenol still gave recoveries of 94% and 90%. The solution for efficiently eluting the analytes was optimized and the effect of the inorganic salt on the extraction was examined. In order to investigate the potentiality of the sorbent in dealing with real water samples, water from Donghu lake (Wuhan, China) spiked with nine phenolic compounds at microgram per liter levels were preconcentrated on this cartridge.