Automated sample preparation using in-tube solid-phase microextraction and its application -- a review

Sample preparation, such as extraction, concentration, and isolation of analytes, greatly influences their reliable and accurate analysis. In-tube solid-phase microextraction (SPME) is a new effective sample preparation technique using an open tubular fused-silica capillary column as an extraction device. Organic compounds in aqueous samples are directly extracted and concentrated into the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and they can be directly transferred to the liquid chromatographic column. In-tube SPME is an ideal sample preparation technique because it is fast to operate, easy to automate, solvent-free, and inexpensive. On-line in-tube SPME-performed continuous extraction, concentration, desorption, and injection using an autosampler, is usually used in combination with high performance liquid chromatography and liquid chromatography-mass spectrometry. This technique has successfully been applied to the determination of various compounds such as pesticides, drugs, environmental pollutants, and food contaminants. In this review, an overview of the development of in-tube SPME technique and its applications to environmental, clinical, forensic, and food analyses are described.     

Chromatographic methods for tetracycline analysis in foods.

The tetracyclines have served for decades as an important class of antibiotics in food animal health and production. As such, they have also been a source of concern for residue monitoring authorities around the world. In response to this concern a number of microbial inhibition, immunoassay and bacterial receptor methods have evolved for the detection of this class of compounds in various foods of animal origin. However, these methods often lack specificity and are subject to false positive and false negative results. For these reasons a number of chromatographic methods for the separation and determination of the tetracyclines isolated from foods have been developed that are capable of identifying and quantifying individual tetracycline drugs. We present here an overview of tetracycline analytical methods, including microbial inhibition, immunoassay and receptor technologies for detection, techniques for isolation from food matrices, and thin-layer chromatographic, high-performance liquid chromatographic, gas chromatographic and mass spectrometric procedures for determination of this class of compounds. A discussion of the variables involved in such methodology and a review of method criteria are offered.     

分子印迹聚合物在抗生素残留测定中的应用

抗生素的滥用及残留对生物体和环境造成极大危害,其含量低、种类多、基质复杂,通常需要进行样品前处理结合色谱分析以实现灵敏测定。分子印迹聚合物（MIPs）能选择性识别、有效富集目标分析物并消除干扰,已广泛用于抗生素的样品前处理中。该文对MIPs制备中面临的挑战进行了总结;对2016年以来抗生素MIPs的固相萃取应用进行了综述和展望,主要包括固相萃取、分散固相萃取、磁固相萃取、基质固相分散萃取、固相微萃取、搅拌棒吸附萃取。此外,该文重点介绍了抗生素MIPs的印迹新策略,如多模板、多功能单体、虚拟模板、刺激响应、亲水性印迹等。最后,该文对抗生素MIPs的制备和前处理应用进行了展望。     

Chromatographic methods for the determination of toxicants in faeces.

Modern chromatographic techniques and their application in the determination of toxic compounds in faeces are reviewed. Faecal analysis may be of importance in toxicokinetic studies of xenobiotics in order to determine factors such as metabolism, body burden and major routes of elimination. Compounds of interest include various food constituents, drugs and occupational or environmental factors. Further, various mutagenic or carcinogenic compounds which are excreted by faeces have been indicated to represent risk factors for colorectal cancer. In this context, the chromatographic determination of the endogenously generated fecapentaenes and bile acids, both postulated etiological factors in colorectal carcinogenesis, is reviewed. For fecapentaene determination, several high-performance liquid chromatographic (HPLC) methods are available; however, the applicability of some of these methods is limited owing to insufficient separation of various isomeric forms or discrimination between fecapentaenes and their precursors. For the determination of bile acids in faeces, many chromatographic procedures have been reported, and the characteristics of the most relevant methods are compared and discussed. It is concluded that separation by gas chromatography (GC) in combination with mass spectrometry provides the highest selectivity and sensitivity. A relatively rapid alternative analysis for the determination of total and aqueous faecal bile acids is proposed. Further, methods for the determination of polycyclic aromatic hydrocarbons (PAHs) are reviewed. Although the use of radiolabelled PAHs in animal studies has many advantages, it cannot be applied for human biological monitoring and HPLC and GC provide sensitive alternatives. An HPLC method for the determination of non-metabolized PAHs in faeces is described.     

Chromatographic methods for the determination of mycotoxins in food products

Chromatographic methods for the determination of mycotoxins from different classes in food products of plant and animal origins are surveyed. The procedures of sample preparation and extract purification and the use of various chromatographic analysis techniques are considered.     

Chromatographic analysis of penicillins in pharmaceutical formulations and biological fluids

Natural penicillin (benzylpenicillin) is the oldest antibiotic observed by Alexander Fleming in 1928. To broaden its spectrum of activity, natural penicillin was modified, giving rise to a group of antibiotics under the name 'penicillins'. Although an increasing number of bacteria appear to be resistant to them, penicillins are used to treat a variety of bacterial infections including Gram-positive, Gram-negative aerobic and anaerobic bacteria. Consequently, they are widely used in human and veterinary medicine to prevent and treat diseases. This review covers the analytical methodologies, mainly chromatographic, employed to the penicillins determination in pharmaceutical formulations, biological fluids and in production-scale fermentations reported in the literature. Results of published assays are comparatively presented focusing on sample preparation regarding isolation and purification, chromatographic conditions and method validation. Information on chemical structure, spectrum of activity and action mechanism of common penicillins has also been given.     

Challenges in the determination of aminoglycoside antibiotics,a review

Residues of antibiotics (ABs) in the aquatic environment and in food of animal origin represent a major concern, as prolonged exposure to ABs is a serious health hazard, related to both the side effects of prolonged use and the risk of developing bacterial resistance to various ABs. Given the low levels of the AB residues in complex matrices, the development of sensitive analytical methods represents a major challenge. This is certainly true for the aminoglycoside ABs (AGs) which lack a chromophore and show poor chromatographic properties in reversed-phase liquid chromatography. This paper reviews the current state of the art in the determination of AGs. Attention is paid to extraction, sample clean-up, chromatographic separation, and detection of AGs in both environmental and food samples and in plasma and serum. A general workflow for the analysis of AGs is presented which takes into account the matrix and required level of information.     

Βisphenol A and its analogs migrated from contact materials into food and beverages: An updated review in sample preparation approaches

Bisphenols are used as monomers in the production of plastic materials, and they are likely to be detected in food contact materials. Due to their migration from these plastic packaging materials into food and beverages, the organoleptic properties of the products are changing and plenty of harmful effects on human health are caused, especially if consumers are exposed to higher levels of bisphenols than those established by legislation. However, because of their trace-level presence, their determination into food and beverage matrices is rather difficult. For this reason, sensitive, simple, rapid, and green methods are required to extract and preconcentrate the analytes of interest. Effective and representative tests are required as well, to evaluate the migration of bisphenols from plastic materials under realistic usage conditions. This review provides a detailed background of bisphenol A chemistry and legislation. Furthermore, it refers to bisphenol A migration test procedures and the recent advances of the last decade in the extraction of bisphenols from various matrices by using different sample preparation techniques prior to their chromatographic determination.     

Simultaneous determination of artificial sweeteners, preservatives, caffeine, theobromine and theophylline in food and pharmaceutical preparations by ion chromatography.

A novel ion chromatographic method was proposed for the simultaneous determination of artificial sweeteners (sodium saccharin, aspartame, acesulfame-K), preservatives (benzoic acid, sorbic acid), caffeine, theobromine and theophylline. The separation was performed on an anion-exchange analytical column operated at 40 degrees C within 45 min by an isocratic elution with 5 mM aqueous NaH2PO4 (pH 8.20) solution containing 4% (v/v) acetonitrile as eluent, and the determination by wavelength-switching ultraviolet absorbance detection. The detection limits (signal-to-noise ratio 3:1) for all analytes were below the sub-microg/ml level. Under the experimental conditions, several organic acids, including citric acid, malic acid, tartaric acid and ascorbic acid, did not interfere with the determination. The method has been successfully applied to the analysis of various food and pharmaceutical preparations, and the average recoveries for real samples ranged from 85 to 104%. The levels of all analytes determined by this method were in good agreement with those obtained by the high-performance liquid chromatographic procedure. The results also indicated that ion chromatography would be possibly a beneficial alternative to conventional high-performance liquid chromatography for the separation and determination of these compounds.     

Determination of iodide and bromide by ion chromatography with post-column reaction detection

During an investigation into the mechanism of the biosynthesis of thyroid hormones, it became necessary to determine traces of iodide and bromide in biological matrices as well as in food. A vydac 302-IC anion-exchange column with methanesulphonic acid as the mobile phase was used for the ion chromatographic separation of iodide and bromide. A post-column reaction detector was developed based on the reaction between iodide or bromide, chloramine-T and 4,4'-bis(dimethylamino)diphenylmethane. Methods with minimal sample preparation are described for determination of iodide or bromide in serum, milk, salt and water. The detection limit is ca. 20 pg iodide and 15 ng bromide injected.     

Methods of sample preparation for determination of pesticide residues in food matrices by chromatography–mass spectrometry-based techniques: a review

Much progress has been made in pesticide analysis over the past decade, during which time hyphenated techniques involving highly efficient separation and sensitive detection have become the techniques of choice. Among these, methods based on chromatographic separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for determination of pesticide residues. Even with such powerful instrumental techniques, however, the risk of interference increases with the complexity of the matrix studied, so sample preparation before instrumental analysis is still mandatory in many applications, for example food analysis. This article summarizes the analytical characteristics of the different methods of sample-preparation for determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with chromatographic mass spectrometric analysis. We discuss the advantages and the disadvantages of the different methods, address instrumental aspects, and summarize conclusions and perspectives for the future.     

食品中氨基甲酸酯农药残留的分析方法

综述了近年来食品中氨基甲酸酯农药残留的分析方法。分别对样品预处理、色谱检测方法以及近年来发展起来的新技术,如超临界流体色谱、色质联用及一些非色谱技术如免疫检测、生物传感器等进行了讨论,并对农残检测的发展前景进行了展望。     

碳点在抗生素分析检测中的应用

抗生素的过度使用对环境造成了极大破坏,对其进行监测控制刻不容缓.常用的分析检测技术,如高效液相色谱(HPLC)、气相色谱(GC)、高效液相色谱-串联质谱(HPLC-MS/MS)等具有高效快速、重现性好、可自动化操作等优点.但对环境样品中抗生素的检测存在样品前处理过程繁琐、检测灵敏度低、实验成本高等问题.结合现有的检测技...     

The preparation of sorbents for the analysis of human antithrombin III by means of high performance affinity chromatography

Summary Antithrombin III (AT III) is an anticoagulant present in blood. It is responsible among other things for blood coagulation and the wrong amount can lead to various health problems. The level of AT III can be taken as an indicator of many pathological states. Due to the very complex composition of blood, high performance affinity chromatography seems to be one of the best methods for the quantitative determination of AT III. The present paper deals with the preparation and properties of sorbents for AT III analysis. The behaviour of the chromatographic packings obtained by the bonding of heparin (used as a complementary ligand interacting with AT III) to cross-linked polysaccharide layers deposited on controlled porosity glass is discussed.     

Polarographic study on the presence of antibiotics in food

EU and Italian laws dealing for the presence of antibiotics or, more in general, drags in food established limits for different kinds of food. Suitable rules exist about the medical treatment of cattle in relation to the production of milk and meat. The adoption of a procedure to check the respect of the law limits is necessary. In this paper, the presence of different classes of antibiotics in milk and in homogenised meat is investigated. Generally, HPLC methods are applied for this purpose. In this paper, the application of polarographic analysis is studied and the results are compared with the chromatographic ones. The comparison is relative to all the phases of analysis including the sample preparation. The results show the advantage of the proposed procedure.     

A quantitative method for the detection of sulfonamide residues in meat and milk samples with a high-performance thin-layer chromatographic method.

Sulfonamides are widely used in veterinary medicine for prophylactic purposes and for the treatment of various infections of food-producing animals. This means that residues of these drugs and their possible metabolites may occur in food of animal origin. In Belgium, a zero tolerance level for sulfonamides in edible animal tissues has been set. In order to check this zero level on a routine basis, a rapid and sensitive method has to be available. For this purpose, a quantitative high-performance thin-layer chromatographic (HPTLC) method for the detection of sulfonamide residues in animal tissue and milk samples has been developed. The sample preparation consists of a liquid extraction followed by a solid phase extraction (SPE) on disposable columns for the meat samples and a matrix solid phase dispersion (MSPD) for the milk samples. A three-multiple development chromatographic system is used for the separation and a derivatization with fluorescamine decreases the minimal detectable quantity per spot from 1.42 to 0.32 ng. The limit of quantification is 4 micrograms/kg for milk and meat samples.     

Recent applications of thermal lens spectrometry in food analysis and environmental research

This review summarizes the most recent achievements related to the application of thermal lens spectrometry (TLS) in food analysis and environmental research. All the applications are associated with the use of an appropriate analytical procedure providing sufficient selectivity, that cannot be achieved by TLS itself. Several selective reagents, biosensors and chromatographic separation procedures (IC, HPLC), used for this purpose, and their performance in combination with TLS, are described. Heavy metals and related species, pesticides, carotenoids, fatty acids, and their determination in samples such as water, fruit juices, oils and marine phytoplankton were given most consideration. The main advantages of novel analytical methods include improved sensitivity and selectivity, simplicity, minimized need for sample preparation and handling as well as reduced time of analysis.     

Determination of Oligosaccharides by Conventional High-Resolution Gas Chromatography

This paper describes a simple gas chromatographic method for the analysis of (higher) oligosaccharides without needing a high-temperature procedure. The newly developed method used an ordinary capillary column and a temperature program with 360 °C as the maximum temperature. Sample preparation consisted of the oxymation and silyation of the sugars. Oligosaccharides with degrees of polymerisation of up to 7 could be determined with good repeatability (variation coefficient < 7.5%), reproducibility (variation coefficient < 11.8%) and accuracy (mean recovery 103.9%). Analysis of oligosaccharide-enriched food products demonstrated that this cheap and easy procedure could be a valuable and reliable tool for the quantitative determination of oligosaccharides in foodstuffs.     

Determination of oligofructose, a soluble dietary fiber, by high-temperature capillary gas chromatography

A high-temperature capillary gas chromatographic method was developed for the quantitative determination of oligofructose in foods and food products. Sample preparation involves oxymation and silylation of the extracted sugars. The oximetrimethylsilyl derivatives are analyzed on an apolar capillary column, with detection by flame ionization. The method is accurate, with recovery of spiked samples at >96%. Repeatability was excellent; RSD values of 1.1% were obtained. Other common oligosaccharides, such as malto-, isomalto-, and galactooligosaccharides, and levan do not interfere, making the method specific and reliable.