Development of visual analytical methods for trace determination.

In this paper our recent progress in the field of simple analytical methods is reviewed, with particular focus on the development of rapid, inexpensive, yet sensitive techniques to visualize trace elements of medical, industrial, and environmental importance. Our objective is to solve long-standing practical problems in these fields. We have repeatedly shown that visual perception is remarkably sensitive when used with our new techniques. The applicability of the proposed methods to real samples is also discussed. Making measurements visually is a method free from machinery malfunctions and serves as a simple and sensitive analytical technique, avoiding all of the practical disadvantages associated with sophisticated instrumentation as well as tedious procedures.     

Review of analytical methods for the determination of chlorine dioxide

The present study reviews more than twenty years (1985-present) of published research on the development and application of analytical procedures for the determination of chlorine dioxide, a widely used disinfectant and bleaching agent. The review covers a variety of techniques including batch and automated spectrophotometry and fluorimetry, electroanalysis and chromatography. The analytical figures of merit to the methods are presented, while critical discussion regarding their advantages and disadvantages is addressed.      

六氯丁二烯分析方法研究进展

六氯丁二烯是一种持久性有机污染物,于2015年和2017年分别被列入《斯德哥尔摩公约》附件A和附件C的受控污染物名单中。六氯丁二烯的来源、环境赋存和影响等研究对控制该新增受控持久性有机污染物污染具有重要意义,而灵敏可靠的六氯丁二烯分析方法是开展相关研究的前提和基础。近年来已有不少学者将六氯丁二烯作为分析目标物之一进行了检测或方法学研究。基于这些研究成果,该文综述了六氯丁二烯分析方法的研究进展,其中重点介绍了空气、水体、土壤、污泥、生物组织等多种介质中六氯丁二烯的样品前处理方法,并比较了各方法的优缺点,以期为该领域的进一步研究提供参考。空气中六氯丁二烯主要由泵抽气通过吸附管而采集,再经热脱附后进行仪器分析,检出限在ng/m³水平。也有研究应用聚氨酯泡沫被动采样器和吸附剂填充聚氨酯泡沫被动采样器采集大气中六氯丁二烯及其他污染物。基于吸附剂填充聚氨酯泡沫被动采样器的分析方法灵敏度较高,其对六氯丁二烯的检出限低至0.03 pg/m³。然而目前被动采样体积仅根据六氯丁二烯的log K_OA系数估算,未来仍需进一步实验校正。水体样品前处理通常也较简单,通过吹扫捕集、液-液萃取或固相萃取目标物后进行仪器分析。固相萃取法能够同步实现目标物的提取、净化和浓缩,在水样中六氯丁二烯分析方面具有明显优势。固相萃取柱类型以及干燥步骤中柱中残留水分去除率均会影响六氯丁二烯的回收率。灰尘、土壤、沉积物、污泥和生物组织等固体介质样品基质最为复杂,需联合多种方法进行前处理。固体样品中六氯丁二烯提取方法包括索氏提取,加速溶剂萃取和超声萃取,其中超声萃取法应用最为广泛。固体基质净化方面主要采用层析柱色谱法,多根净化柱联用或多层复合柱能够提升净化效果。仪器分析方面,六氯丁二烯主要采用气相色谱和质谱联用检测,高性能质谱检测器如串联质谱能够大大提高六氯丁二烯的检测灵敏度,具有较大的应用潜力。     

Validation of analytical methods used for determination of nitrate in soil

The standard method (ISO/DIS 14255) and the quick test were used for determination of nitrate in soil. We validated both methods using parameters such as accuracy, reproducibility within 1 day and between days, limit of detection and limit of quantification. The accuracy of the results was determined using the analysis of samples from the international interlaboratory scheme WEPAL. The accuracy of the standard method was good, while for the quick test the results were not accurate. The standard method showed a solid reproducibility of measurement results (in 1 day, relative standard deviation, RSD=0.2%; between days, RSD=0.8%). The quick test gave poorer results (in 1 day, RSD=6%; between days, RSD=7%). We tried to established the compatibility of both methods on real soil samples and we were satisfied to obtain the correlation coefficient 0.98 using the regression straight line. The analyses with the quick field instrument are much simpler and cheaper than the standard laboratory analyses and can be used for advising on nitrogen fertilisation.     

User-oriented software for determination of the precision of signal-integrating analytical methods

A software package for the determination of the uncertainty in signal-integrating analytical techniques is presented. The program can be used to calculate detection limits and to determine baseline drift properties, the influence of drift-correcting procedures and integration time, etc. Complete analytical procedures, e.g., chromatography or atomic emission spectrometry, or parts of a system can be tested. No profound theoretical knowledge is required by the user; confidence intervals are calculated where necessary. The theoretical basis and the structure of the program are evaluated.     

Immunochemical analytical methods for the determination of peanut proteins in foods

Peanut proteins can cause allergenic reactions that can result in respiratory and circulatory effects in the body sometimes leading to shock and death. The determination of peanut proteins in foods by analytical methods can reduce the risk of serious reactions in the highly sensitized individual by allowing for the detection of these proteins in a food at various stages of the manufacturing process. The method performance of 4 commercially available enzyme-linked immunosorbent assay (ELISA) kits was evaluated for the detection of peanut proteins in milk chocolate, ice cream, cookies, and breakfast cereals: ELISA-TEK Peanut Protein Assay, now known as "Bio-Kit" for peanut proteins, from ELISA Technologies Inc.; Veratox for Peanut Allergens from Neogen Corp.; RIDASCREEN Peanut Kit from R-Biopharm GmbH; and ProLisa from Canadian Food Technology Ltd. The 4 test kits were evaluated for accuracy (recovery) and precision using known concentrations of peanut or peanut proteins in the 4 food matrixes. Two different techniques, incurred and spiked, were used to prepare samples with 4 known concentrations of peanut protein. Defatted peanut flour was added in the incurred samples, and water-soluble peanut proteins were added in the spiked samples. The incurred levels were 0.0, 10, 20, and 100 microg whole peanut per g food; the spiked levels were 0.0, 5, 10, and 20 microg peanut protein per g food. Performance varied by test kit, protein concentration, and food matrix. The Veratox kit had the best accuracy or lowest percent difference between measured and incurred levels of 15.7% when averaged across all incurred levels and food matrixes. Recoveries associated with the Veratox kit varied from 93 to 115% for all food matrixes except cookies. Recoveries for all kits were about 50% for cookies. The analytical precision, as measured by the variance, increased with an increase in protein concentration. However, the coefficient of variation (CV) was stable across the 4 incurred protein levels and was 7.0% when averaged across the 4 food matrixes and analytical kits. The R-Biopharm test kit had the best precision or a CV of 4.2% when averaged across all incurred levels and food matrixes. Because measured protein values varied by test kit and food matrix, a method was developed to normalize or transform measured protein concentrations to an adjusted protein value that was equal to the known protein concentration. The normalization method adjusts measured protein values to equal the true protein value regardless of the type test kit or type food matrix.     

GC-MS analytical methods for the determination of personal-care products in water matrices

This article discusses the more recent methods combining gas chromatography and mass spectrometry (GC-MS) for analysis of personal-care products (PCPs) in water matrices. We describe different procedures for sample extraction and preparation as well as different instrumental methods commonly used for these compounds. GC-MS and GC-tandem MS (GC-MS²), which are complementary to liquid chromatography combined with MS (LC-MS), allow identification and quantification of PCPs belonging to different classes with the sensitivity and the selectivity necessary for environmental monitoring. The compounds investigated include fragrances (e.g., nitro and polycyclic musks), antimicrobial compounds (e.g., triclosan), ultraviolet blockers (e.g., methylbenzylidene camphor), antioxidants and preservatives (e.g., phenols and p-hydroxybenzoic acid (parabens)) and insect repellents (e.g., N,N-diethyl-m-toluamide (DEET)). We critically review data in the literature by focusing attention on analytical methods devoted to simultaneous detection and quantification of structurally diverse pharmaceuticals and PCPs.     

Novel analytical methods for the determination of steroid hormones in edible matrices

This paper reviews recently published multi-residue chromatographic methods for the determination of steroid hormones in edible matrices. After a brief introduction on steroid hormones and their use in animal fattening, the most relevant EU legislation regarding the residue control of these substances is presented. An overview of multi-residue analytical methods, covering sample extraction and purification as well as chromatographic separation and different detection methods, being in use for the determination of steroid hormones (estrogens, gestagens and androgens), is provided to illustrate common trends and method variability. Emphasis was laid on edible matrices and more specifically on meat, liver, kidney, fat and milk. Additionally, the possibilities of novel analytical approaches are discussed. The review also covers specific attention on the determination of natural steroids. Finally, the analytical possibilities for phytosterols, naturally occurring steroid analogues of vegetable origin and a specific group of steroid hormones with a hemi-endogenous status are highlighted.     

Critical review of analytical methods for determination of inorganic mercury and methylmercury compounds

This review describes determinations of mercury compounds under three categories: total mercury; separate determinations of inorganic mercury(II) and organomercury compounds by selective reduction; and speciation of inorganic mercury(II), monomethylmercury cation, and dimethylmercury. Topics described for each category include sample treatment, separation, detection, and limit of detection. Finally, we note that most methods would not detect dimethylmercury if it were present.     

Application of different analytical methods for determination of volatile chlorination by-products in drinking water

Four analytical methods have been applied for the determination of volatile chlorination by-products in drinking water, based on the following techniques: liquid-liquid extraction-gas chromatography-electron capture detection (LLE-GC-ECD); liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS); purge and trap-gas chromatography-mass spectrometry (purge and trap-GC-MS); and headspace-gas chromatography-mass spectrometry (headspace-GC-MS). The compounds studied were trihalomethanes, haloacetonitriles, haloketones, chloral hydrate and chloropicrin. LLE-GC-ECD method proved to be the most sensitive for determination of all compounds studied, followed by LLE-GC-MS. Purge and trap-GC-MS method gave good results in the case of trihalomethanes, but had high detection limits for the other volatile chlorination by-products. Headspace-GC-MS method had acceptable recoveries for trihalomethanes, but the detection limits were higher.     

环境样品中多溴联苯醚分析方法的研究进展

多溴联苯醚(PBDEs)作为一类应用广泛的溴代阻燃剂,具有持久污染性、易于从被应用产品中脱离出来进入环境介质等特性,目前已对全球环境造成了严重危害.近年来针对PBDEs分析检测技术的报道愈来愈多,然而PBDEs不仅含量极低,而且所处基体复杂,因此样品前处理技术成为分析PBDEs类化合物的一个重要步骤,受到科学工作者的广泛重视.本文作者综述了近年来分析环境样品中PBDEs的样品前处理技术和分析检测方法的研究进展,为更好的发展准确、灵敏、快速的分析方法提供重要的参考.     

A review of analytical methods for the determination of 5-fluorouracil in biological matrices

5-Fluorouracil (5-FU) is a cytostatic agent that has been widely used in the treatment of various solid tumours for more than 20 years, and is still considered to be among the most active antineoplastic agents in advanced colorectal cancer and malignancies of the head and neck. A large number of non-chromatographic and chromatographic methods for the quantitation of 5-FU, related prodrugs and their metabolites in biological matrices have been developed in the last 30 years to support preclinical and clinical studies. However, 5-FU monitoring has not been widely used, at least not in the USA, and certainly not outside the clinical research setting, given the absence of simple, fast and inexpensive testing methods for 5-FU monitoring. Recent developments with testing based on liquid chromatography–tandem mass spectrometry and a nanoparticle antibody-based immunoassay may facilitate routine monitoring of 5-FU in daily clinical practice. In this review the advantages and disadvantages of the bioanalytical methods developed and used for 5-FU, its metabolites and related prodrugs are discussed.     

Comparison of three analytical methods for the determination of trace elements in whole blood

Three different analytical techniques were compared in a study of the role of trace elements in multiple sclerosis. Data for eight elements (Cd, Co, Cr, Cu, Mg, Mn, Pb, Zn) from neutron activation, flame atomic absorption and electrothermal atomic absorption methods were compared and evaluated statistically. No difference (probability less than 0.001) was observed in the elemental values obtained. Comparison of data between suitably different analytical methods gives increased confidence in the results obtained and is of particular value when standard reference materials are not available.     

Review of analytical methods for the determination of estrogens and progestogens in waste waters

Steroid sex hormones and related synthetic compounds, e.g. those used in contraceptive pills, have been shown to be present in the aquatic environment, mainly as a result of inefficient removal in waste-water-treatment plants (WWTP). The concentrations of the compounds, although very low (low ng L(-1)), are sufficient to induce estrogenic responses and alter the normal reproduction and development of wildlife organisms. The compounds have been determined, by a variety of analytical procedures, in the influents and effluents of WWTP, within research programs conducted in different countries to evaluate the efficiency of the waste-water-treatment processes currently in use. Determination of natural and synthetic estrogens and progestogens in waste water is, however, a difficult analytical task, because the very low detection limits required and the complexity of the waste-water matrix necessitate the execution of a considerable number of steps. Thus, in general, complicated, time-consuming extraction and purification processes, usually based on the application of solid-liquid extraction, are performed before final determination by immunoassay, high-performance liquid chromatography, or, most often, gas chromatography coupled with mass spectrometry. This paper reviews the analytical methods so far described for the analysis of these important environmental pollutants in waste water and discusses the key procedural steps, from sampling to analysis, and the techniques most commonly used in the determination.     

Comparison of two analytical methods for the determination of organotin compounds in marine organisms

Two analytical procedures were used for the determination of butyltin compounds in mussels.Both methods include extraction with methanol containing tropolone, derivatization, purification on Florisil and GC–MS analysis. The main difference between the procedures is in the derivatization step: one employs a Grignard reagent (n-pentylmagnesium bromide) while the other uses sodium tetraethylborate (STEB).Quantitative determinations were carried out in single ion monitoring using tripropyltin as internal standard. The accuracy of the procedures was verified on a certified reference material (ERM 477), providing good results for both methods.All the considered compounds showed lower detection limits with STEB derivatization; in particular for tributyltin (TBT), the difference between the two methods overcame one order of magnitude.An in vivo experiment was then performed, exposing mussels (Mytilus galloprovincialis) to known amount of TBT for 7 days; control and contaminated tissues were analyzed using the STEB derivatization method. Results showed the accumulation of TBT, especially in the gills.     

Comparative study of analytical methods for the determination of chromium in groundwater samples containing iron

Determination of chromium in groundwater samples containing iron may pose analytical problems due to sorption and fixation of chromium species onto Fe(III) hydroxides. Parks et al. (Water Res. 2004, 38, 2827) hypothesized that chromium species trapped inside Fe(III) hydroxides i.e. “fixed chromium” may not be soluble by HNO₃ digestion (APHA method 3030 B). In such cases, hydroxylamine digestion is required to release “fixed chromium”. To verify the hypothesis, we carried out this study on groundwater samples containing chromium and iron, using different methods of APHA and EPA. The results showed the presence of “fixed chromium”, ranged between 0.1 and 19.2 μg L^{− 1}, contributing 0.2 to 14.1% towards true total chromium. Digestion of samples with HNO₃ released Cr(III) bound to organic complexes, but not the “fixed chromium”. The hydroxylamine digestion released “fixed chromium”, but not the Cr(III) bound to organic complexes. Microwave digestion of samples with HNO₃ + HCl was effective for the release of both “fixed” and “Cr(III)-organic complexes”. Cr(III) was only adsorbed onto suspended matter, whereas Cr(VI), and Cr(III)-organic complexes were not adsorbed onto suspended matter due to their solubility. Sample pH, buffering capacity, and matrix have a significant influence on the adsorption and fixation of chromium species onto Fe(III) hydroxides.     

The development of analytical methods for the determination of ions and acidity in individual raindrops

Summary In this publication the first results of a microanalytical investigation of individual rain droplets are given. Analytical methods for a sampling procedure as well as analysis in the ultra trace level with volumes less than 1 l have been developed. Because of the small volumes chromatographic methods are to be preferred.     

A review of analytical methods for the determination of sulfolane and alkanolamines in environmental studies

Sulfolane and alkanolamines are used extensively in the processing of sour natural gases. Over many years of operation, there have been inadvertent leaks of these chemicals to groundwater and wetlands surrounding gas processing facilities, leading to uptake by vegetation. Because sulfolane and alkanolamines are extremely water-soluble, their analysis has presented challenges, particularly requirements for suitable extraction from biological matrixes and soil, along with sensitive detection using commonly available instrumentation. Analytical methods usually use gas chromatography or liquid chromatography with a variety of detector systems. Sample preparation techniques may include extraction with organic solvents, water, or a combination of these. In some cases, direct aqueous injections have been used. Derivatization of alkanolamines has been used to improve the chromatographic separations and detection. More recent procedures, using positive-ion electrospray ionization mass spectrometry (MS), have been useful for the confirmation of uptake of the alkanolamines and transformation products by wetland vegetation. Future developments will likely center on further MS analyses for identification of metabolites and transformation products in aquatic environments.     

Comparison of two methods for the optimization of the analytical conditions for the determination of total sulfur

Response surface and simplex methods were used for optimizing the determination of total sulfur present in gaseous samples using a quartz crystal microbalance. The optimization methodology increased the analytical signal from three to five times. The simplex method showed the highest efficiency in the search for the maximum sensor response. However, the response surface allows ranking the variables according to their effects and highlights the existence of a plateau in the optimal region.