Solid-phase micro-extraction of drugs from biological matrices

Solid phase micro-extraction was originally designed as a technique for the solvent-free analysis of volatile organic contaminants in environmental samples. However, a wide variety of applications are now being pursued, including the analysis of drugs from a variety of matrices. In this review, the analysis of drugs by SPME from biological and related matrices, including water, urine, blood, hair and saliva, is discussed. A general overview of the special problems and techniques involved in SPME from biological matrices is presented, along with specific references and discussion of the analysis of many types of drugs and metabolites. It is seen that SPME is a highly versatile and flexible technique for these analyses.     

Solid-phase microextraction in bioanalysis: New devices and directions

The primary objective of this review is to discuss recent technological developments in the field of solid-phase microextraction that have enhanced the utility of this sample preparation technique in the field of bioanalysis. These developments include introduction of various new biocompatible coating phases suitable for bioanalysis, such as commercial prototype in vivo SPME devices, as well as the development of sampling interfaces that extend the use of this methodology to small animals such as mice. These new devices permit application of in vivo SPME to a variety of analyses, including pharmacokinetics, bioaccumulation and metabolomics studies, with good temporal and spatial resolution. New calibration approaches have also been introduced to facilitate in vivo studies and provide fast and quantitative results without the need to achieve equilibrium. In combination with the drastic improvement in the analytical sensitivity of modern liquid chromatography–tandem mass spectrometry instrumentation, full potential of in vivo SPME as a sample preparation tool in life sciences can finally be explored. From the instrumentation perspective, SPME was successfully automated in 96-well format for the first time. This opens up new opportunities for high-throughput applications (>1000 samples/day) such as for the determination of unbound and total drug concentrations in complex matrices such as whole blood with no need for sample pretreatment, studies of distribution of drugs in various compartments and/or determination of plasma protein binding and other ligand–receptor binding studies, and this review will summarize the progress in this research area to date.     

Solid-phase micro-extraction procedure for the determination of 1,3-dichloro-2-propanol in water by on-fibre derivatisation with bis(trimethylsilyl)trifluoroacetamide

The headspace solid-phase micro-extraction technique with on-fibre derivatisation followed by gas chromatography-tandem mass spectrometry has been evaluated for the analysis of 1,3-dichloro-2-propanol in water. An asymmetric factorial design has been performed to study the influence of five experimental factors: extraction time and temperature, derivatisation time and temperature and pH. The best extraction performance is achieved in the headspace mode, with 5 mL stirred water samples (pH 4) containing 1.3 g of NaCl, equilibrated for 30 min at 25 °C, using divinylbenzene-carboxen-polydimethylsiloxane as the fibre coating. On-fibre derivatisation has been used for the first time with 50 μL of bis(trimethylsilyl)trifluoroacetamide at 25 °C during 15 min, leading to effective yields. The proposed method provides high sensitivity, good linearity and repeatability (relative standard deviation of 5.1% for 10 ng mL⁻¹ and n = 5). The limits of detection and quantification were 0.4 and 1.4 ng mL⁻¹, respectively. Analytical recoveries obtained for different water samples were approx. 100%.     

利用荷移反应分光光度法测定注射液中的盐酸利多卡因

采用分光光度法研究了电子受体2,3-二氯-5,6-二氰基-1,4-对苯醌(DDBQ)与电子供体利多卡因(LD)的荷移反应,发现DDBQ与LD在乙腈中生成稳定的离子缔合物,并通过Job's plot确定DDBQ和LD的摩尔比为1:1.LD与DDBQ在587nm处形成强特征吸收峰.据此建立了一种测定注射液中LD含量的荷移分...     

Solid-phase extraction in the determination of gold, palladium, and platinum

A simple classification of various sorbents and solid-phase extraction procedures used for preconcentration of trace levels of Au, Pd, and Pt from different sample types is proposed in this review article. The large variety of available sorbents/procedures has been organized according to expected mechanisms of sorption process (complex formation; ion exchange; adsorption; ion-imprinted or molecularly imprinted polymers); according to the kind of monomeric units of the polymer matrix as well as on the basis of the kind of functional group responsible for main performance characteristics (selectivity, capacity) of the sorbent. Advantages of chemically modified sorbents, sulfur-containing sorbent extractants, and ion-imprinted polymers, together with rational pretreatment by means of microwave treatments, scaling down of enrichment, and quantification by means of flow and flow injection approaches are given. Preferred instrumental techniques for quantification of ppb levels of Au, Pd, and Pt in prepared concentrates/column eluates are multielement instrumental techniques: inductively coupled plasma optical emission spectrometry (ICP-OES), and inductively coupled plasma mass spectrometry (ICPMS). Excellent limits of detection at picogram levels of these analytes are provided by electrothermal atomic absorption spectrometry (ETAAS), generally in single-element mode and the neutron activation analysis (NAA), while X-ray fluorescence spectrometry and flame AAS are rarely applied because of lack of sensitivity at sub-ppm levels of Au, Pd, and Pt. Some problems of atomic spectrometric quantification techniques and their representative limits of detection are given. Recent applications to geological, industrial, pharmaceutical, biological, and other materials are tabulated. References have been selected mostly from the period 1995 to 2010.     

Single drop micro-extraction with O,O-diethyl dithiophosphate for the determination of lead by electrothermal atomic absorption spectrometry

Lead was extracted as the O,O-diethyldithiophosphate (DDTP) complex from aqueous solution into a drop of CHCl(3) immersed in the solution. Unlike previously reported procedures using single drop micro-extraction (SDME) for the extraction of inorganic analytes, the complexation reaction was conducted in the aqueous phase, as the ammonium salt of DDTP is soluble in water. The concentration of DDTP was optimized as 0.01% (m/v). Experimental parameters such as extraction time (7min) and organic drop volume (3microL) were optimized and selected as a compromise between sensitivity and stability of the organic drop in the aqueous solution. The sensitivity with electrothermal atomic absorption spectrometry (ET AAS) was low, probably due to infiltration of the organic drop into the totally pyrolytic graphite platform. To overcome this problem, tungsten (400microg) was thermally deposited onto the platform surface. A short pyrolysis stage at 700 degrees C was included to reduce background absorption. Under these conditions, five certified reference materials with different characteristics were analyzed using calibration against aqueous standards submitted to the SDME procedure, resulting in good agreement between certified and found concentration values at a 95% confidence level. Two real water samples have also been analyzed, with recoveries ranging from 85 to 92% after enrichment with Pb. An enhancement factor of 52 allowed a detection limit of 0.2microg L(-1) or 0.04microg g(-1), demonstrating the high detection capability of the proposed procedure, with a relative standard deviation typically below 4%.     

Hollow-fiber liquid-liquid-solid micro-extraction of lead in soft drinks and determination by graphite furnace atomic absorption spectrometry

A novel hollow-fiber liquid-liquid-solid micro-extraction technique based on simultaneous liquid-liquid micro-extraction and solid phase micro-extraction using a polypropylene microporous membrane has been developed. The applicability of the proposed procedure was evaluated by extraction of Pb(II) from aqueous solutions and soft drinks. The parameters affecting the extraction efficiency were optimized using multivariate methodology, and the analytical features were established. Under optimized conditions, Pb(II) was concentrated for 20 min on three microporous membrane hollow fibers of 6 mm of length each, placed into 20 mL of sample containing 60 μL of toluene and ammonium O,O-diethyl dithiophosphate. The fibers were introduced directly into the graphite furnace as a solid sample, and the analyte was thermally desorbed from the fiber and atomized using ruthenium as a permanent modifier. A detection limit of 7 ng L⁻¹ Pb was obtained for soft drink samples and good repeatability was found for all samples. The enrichment factor varied between 22 and 66, depending if only one or all three hollow fibers were used for the determination of lead. The results suggest that the proposed procedure represents a simple and low-cost micro-extraction alternative rendering adequate limits of quantification for the determination of Pb(II) in soft drink samples.     

Solid-phase microextraction for herbicide determination in environmental samples

Liquid-liquid extraction or solid-phase extraction followed by gas chromatography (GC) or high-performance liquid chromatography are traditional herbicide residue determination methods for environmental samples. Solid-phase microextraction (SPME) is a solventless, fast, and sensitive alternative herbicide residue extraction method that can be applied to numerous environmental matrices. The objective of this paper was to review SPME literature regarding extraction theory, extraction modes, fiber types, and method optimization in conjunction with present and future SPME applications for herbicide determination in environmental samples.     

Derivatization procedures and their analytical performances for HPLC determination in bioanalysis

Derivatization, or chemical structure modification, is often used in bioanalysis performed by liquid chromatography technique in order to enhance detectability or to improve the chromatographic performance for the target analytes. The derivatization process is discussed according to the analytical procedure used to achieve the reaction between the reagent and the target compounds (containing hydroxyl, thiol, amino, carbonyl and carboxyl as the main functional groups involved in derivatization). Important procedures for derivatization used in bioanalysis are in situ or based on extraction processes (liquid–liquid, solid‐phase and related techniques) applied to the biomatrix. In the review, chiral, isotope‐labeling, hydrophobicity‐tailored and post‐column derivatizations are also included, based on representative publications in the literature during the last two decades. Examples of derivatization reagents and brief reaction conditions are included, together with some bioanalytical applications and performances (chromatographic conditions, detection limit, stability and sample biomatrix).     

Multiple headspace single-drop micro-extraction for quantitative determination of lactide in thermally-oxidized polylactide

Single-drop micro-extraction (SDME), an emerging micro-extraction technique, was combined with multiple headspace (MHS) extraction to allow quantitative determination of lactide in thermally-oxidized polylactide. Different solvents, drop sizes and extraction times were tested to obtain best extraction efficiency and the method was further developed to obtain a linear regression plot for the multiple extractions. The combination of SDME and MHS extraction offered several advantages over traditional liquid-solid and headspace extraction techniques. No concentration step was needed and loss of volatiles was prevented as the ageing and extraction were performed in a closed system. Matrix effects, that disturb the quantitation of analytes in solid samples, were removed by the multiple headspace extraction.     

分散液相微萃取-分光光度法测定水样中痕量肼

建立了分散液相微萃取-分光光度法测定痕量肼的新方法.在0.2 mol/L HCl介质中,以对二甲氨基苯甲醛(PDAB)为显色剂,三氯甲烷为萃取剂,乙醇为分散剂分离富集溶液中痕量肼.优化了反应酸度、萃取剂与分散剂的选择和用量、显色剂用量、显色时间和萃取时间等影响因素.最佳实验条件下,方法的线性范围0.80~120μg/L(r=0.999 5),检出限0.26μg/L.应用于实际水样测定,回收率在98.0%~103.4%之间,RSD在2.7%~3.2%之间.     

Electrochemically controlled solid-phase micro-extraction of proline using a nanostructured film of polypyrrole, and its determination by ion mobility spectrometry

We report on a fast, simple and accurate method for the determination of proline in urine samples by employing a nanostructured film of conducting polypyrrole for electrochemically controlled solid-phase microextraction, and ion mobility spectrometry (IMS) for detection. This method has the advantages of simple sample preparation and a sensitivity of IMS to proline that is higher than that for other amino acids. The calibration curve is linear in the range of 0.5–60 μg L^?1 (4–521 nmol L^?1), and the detection limit is 0.2 μg L^?1. The electrochemical potentials for uptake and release were optimized. The method was successfully applied to the clean-up and quantitation of trace amounts of proline in urine samples.

Use of solid-phase micro-extraction as a sampling technique in the determination of volatiles emitted by flowers,isolated flower parts and pollen

The volatiles emitted by fresh whole flowers or isolated flower parts of mandarin, Citrus deliciosa Ten. (Rutaceae), were sampled using solid-phase micro-extraction (SPME). This technique offers several advantages over dynamic headspace sampling techniques used in previous investigations. In particular, SPME requires smaller sample sizes and very short sampling times, which can minimize the formation of artifacts due to damage to the plant, and contaminations or loss of compounds. This was especially applicable to the collection of volatiles from pollen.     

Solid-phase extraction for multiresidue determination of sulfonamides, tetracyclines, and pyrimethamine in Bovine's milk

This paper describes a systematic approach to the development of a solid-phase extraction method for simultaneous extraction of 10 antibiotic residues in bovine milk, belonging to groups of sulfonamides, tetracyclines, and pyrimethamine. The sample preparation steps include acidic deproteinization of milk proteins followed by sample enrichment and cleanup using a polymer-based Oasis HLB solid-phase extraction cartridge. The analyses were carried out by using a method based on liquid chromatography-electrospray ionisation-mass spectrometry with positive ion mode. The parameters affecting the extraction efficiency such as sample loading pH, SPE wash solvent composition, and eluting solution pH were carefully investigated and optimized. The developed solid-phase extraction procedure coupled to multiresidue liquid chromatography-electrospray ionization-mass spectrometry method was applied for the analysis of 10 antibiotic residues in milk samples, and it proved to be simple, sensitive, and selective providing a recovery ranging from 70 to 106%.     

Simultaneous determination of ethamsylate, tramadol and lidocaine in human urine by capillary electrophoresis with electrochemiluminescence detection

Ethamsylate, tramadol and lidocaine, partly excreted by the kidney, are generally used as hemostatic, analgesic and local anesthetic in surgery. We developed a simple and sensitive method for their simultaneous monitoring in human urine based on CE coupled with electrochemiluminescence detection by end-column mode. Under optimized conditions the proposed method yielded linear ranges from 5.0 x 10(-8) to 5.0 x 10(-5), 1.0 x 10(-7) to 1.0 x 10(-4) and 1.0 x 10(-7) to 1.0 x 10(-4) M with LODs of 8.0 x 10(-9) M (36 amol), 1.6 x 10(-8) M (72 amol) and 1.0 x 10(-8) M (45 amol) (S/N = 3) for ethamsylate, tramadol and lidocaine, respectively. The RSD for their simultaneous detection at 1.0 x 10(-6) M was 2.1, 2.8 and 3.2% (n = 7), respectively. For practical application an extraction step with ethyl acetate at pH 11 was performed to eliminate the influence of the sample ionic strength. The recoveries of ethamsylate, tramadol and lidocaine at different levels in human urine were between 87 and 95%. This method was used for simultaneous detection of ethamsylate, tramadol and lidocaine in clinic urine samples from two medicated patients. It was valuable in clinical and biochemical laboratories for monitoring these drugs for various purposes.     

Solid-phase extraction and determination of trace aroma and flavour components in cider by GC-MS

Summary Minor volatile compounds are responsible for the aromas of cider. A simple technique for the analysis of these components is described based on solid-liquid phase extraction followed by quantitation by gas chromatography-mass spectrometry (GC-MS). The method is quantitative for analysis of alcohols, esters, lactones, phenols, and medium and long chain-length fatty acid.     

Solid-phase ultraviolet sensing system for determination of methylxanthines

In this study the use of a single continuous-flow solid-phase UV spectrophotometric sensing system for determination of methylxanthines was evaluated. Two methods were developed to determine caffeine (CF) and theophylline (TP) in pharmaceuticals and CF and theobromine (TB) in food and beverages. The sensor is based on transient and sequential retention of the analytes on a hydrophobic sensing solid zone (octadecyl silane C₁₈ gel) and detection of their intrinsic UV absorbance. Temporary sequencing of the arrival of the analytes at the sensing zone is achieved by on-line separation of one of the analytes using a pre-column of the same particulate material, placed just before the flow cell. After TB or TP had been carried toward the sensing zone (by the appropriate carrier solution), produced its transitory signal, and been eluted by the carrier, an appropriate eluting solution (25% MeOH) was used to elute CF, which was strongly retained on the minicolumn, so that its transient signal could be recorded. The sensing zone was completely regenerated with this eluting solution, and so was ready for analysis of another sample. After selecting the most suitable conditions, the sensing system was calibrated in the range 1–16 and 1–12 mg L^–1 for CF and TP–TB, respectively, giving detection limits below 0.1 mg L^–1 with RSD values less than 3%. The usefulness of this approach has been evaluated by applying it to the determination of caffeine, theobromine, and theophylline in different samples of food, beverages, and pharmaceutical formulations. The results were in satisfactory agreement with those obtained by use of an HPLC reference method.     

Solid-phase spectrophotometric determination of lead using chromazurol S

The complex formation between lead and chromazurol S in the phase of an AB17×8 ion-exchanger has been studied. The data obtained have been used to develop a procedure for the solid-phase spectrophotometric determination of lead in drinking water. The sensitivity of the determination is 0.02 μg/mL.