Urine, solid phase extraction

The first bioanalytical application of LC-GC was presented by Grob et al. (119). These authors proposed this coupled system for the determination of diethylstilbe-strol in urine as a replacement for GC-MS. After hydrolysis, clean-up by solid-phase extraction and derivatization by pentafluorobenzyl bromide, the extract was separated with normal-phase LC by using cyclohexane/1 % tetrahydrofuran (THE) at a flow-rate of 260 p.l/min as the mobile phase. The result of LC-UV analysis of a urine sample and GC with electron-capture detection (ECD) of the LC fraction are shown in Ligures 11.8(a) and (b), respectively. The practical detection limits varied between about 0.1 and 0.3 ppb, depending on the urine being analysed. By use of... 

D. BaiTon, J. Barbosa, J. A. Pascual and J. Segura, Dkect deteimination of anabolic steroids in human urine by online solid-phase extraction/liquid cliromatography/mass specti ometi y , 7. Mass Spectrom. 31 309-319 (1996). 

K. Haitonen and M. L. Riekkola, Detection of /3-blockers in urine by solid-phase extraction-supercritical fluid exti action and gas cliromatogi aphy-mass spectrometi y , 7. Chromatogr. B 676 45-52 (1996). 

Chiaia AC, Banta-Green C, Field J (2008) Eliminating solid phase extraction with large-volume injection LC/MS/MS analysis of illicit and legal drags and human urine indicators in US wastewaters. Environ Sci Technol 42(23) 8841-8848... 

A new technique has been developed to analyze a- and (3-endosulfan concentrations in human urine (Vidal et al. 1998). Samples are mixed with a buffer solution and then passed through solid phase extraction cartridges for analysis using gas chromatography-tandem mass spectrometry (GC-MS-MS). 

Van der Hoeven, R.A. et al. 1997. Liquid chromatography/mass spectrometry with on-line solid-phase extraction by a restricted-access C18 precolumn for direct plasma and urine injection. J. Chromatosr. A. 762 193-200. 

Chen Y., Wang C., and Wu K., 2005. Analysis of N7-(benzo[a]pyrene-6-yl)guanine in urine using two-step solid-phase extraction and isotope dilution with liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Spectrom 19 893. 

Kahlich R. et al., 2006. Quantitative determination of piritramide in human plasma and urine by off- and online solid-phase extraction hquid chromatography coupled to tandem mass spectrometry. Rapid Commun Mass Spectrom 20 275. 

Kato K. et al., 2003. Determination of three phthalate metabolites in human urine using online solid-phase extraction-liquid chromatography-tandem mass spectrometry. J Chromatogr B 788 407. 

MOR were comparable (10 ng mL4), whereas those for DHC and EMOR were about fourfold lower. Furthermore, glucuronides were shown to react like the corresponding free opioids. Validation with real urine samples was performed with identification of the peaks by capillary electrophoresis-ion-trap mass spectrometry (CE-MS) after solid-phase extraction. 

The analytes are typically extracted from the biological matrix using solvent extraction or solid phase extraction (SPE). Most analytes require some form of chemical derivatization prior to analysis by GC-MS techniques, whereas with LC-MS-MS no further treatment of the extract is required. The extracts obtained from urine are relatively dirty because of the many endogenous compounds that are present. It is for this reason that the very selective techniques of GC-MS-MS, GC-HRMS, or LC-MS-MS are required to detect some of the prohibited substances that have low detection levels. 

The biological applications of NMR include the study of the structure of macromolecules such as proteins and nucleic acids and the study of membranes, and enzymic reactions. Newer methods and instruments have overcome, to a large extent, the technical difficulties encountered with aqueous samples and the analysis of body fluids is possible, permitting the determination of both the content and concentration of many metabolites in urine and plasma. NMR is not a very sensitive technique and it is often necessary to concentrate the sample either by freeze drying and dissolving in a smaller volume cm- by solid phase extraction methods. 

J.M. Pozzebon, S.C.N. Queiroz, L.F.C. Melo, M.A.Kapor and I.C.S.F. Jardim, Application of new high-performance liquid chromatography and solid-phase extraction materials to the analysis of pesticides in human urine. J. Chromatogr.A 987 (2003) 381-387. 

Z. Kuklenyik, X. Ye, J.A. Reich, L.L. Needham and A.M. Calafat, Automated online and off-line solid-phase extraction methods for measuring isoflavones and lignans in urine. J. Chromatogr. Sci. 42 (2004) 495-500. 

Li, L., Zhang, J., Sheng, Y., Ye, G., Guo, H.-Z., and Guo, D.-A. (2004b). Liquid chromatographic method for determination of four active saponins from Panax notoginseng in rat urine using solid phase extraction. /. Chromatogr. B 808,177-183. 

Abu Ruz S, Millership J, Heaney L, McElnay J. 2003. Simple liquid chromatography method for the rapid simultaneous determination of prednisolone and cortisol in plasma and urine using hydrophilic lipophilic balanced solid phase extraction cartridges. J Chromatogr B Biomed Sci Appl 798(2) 193-201. 

Dams R, Benijts T, Lambert WE, De Leenheer AP. 2002. Simultaneous determination of in total 17 opium alkaloids and opioids in blood and urine by fast liquid chromatography-diode-array detection-fluorescence detection, after solid-phase extraction. J Chromatogr B Analyt Technol Biomed Life Sci 773(1) 53-61. 

Hernandez R, Falco P, Cabeza A. 1997. Liquid chromatographic analysis of amphetamine and related compounds in urine using solid-phase extraction and 3,5-dinitrobenzoyl chloride for derivatization. J Chromatogr Sci 35(4) 169-175. 

Molins-Legua C, Campinc-Falco P, Sevillano-Cabeza A, Ped-r6n-Pons M. 1999. Urine polyamines determination using dansyl chloride derivatization in solid-phase extraction cartridges and HPLC. Analyst 124 477-482. 

Rule G, Henion J. 1999. High-throughput sample preparation and analysis using 96-weU membrane solid-phase extraction and liquid chromatography—tandem mass spectrometry for the determination of steroids in human urine. J Am... 

When using PFT with a neutral selector, it is quite difficult to avoid any entrance of the chiral selector into the ionization source, particularly at a high pH, where EOF is important. The use of BGE at low pH and/or coated capillary to minimize EOF is therefore mandatory. However, the coaxial sheath gas, which generally assists the ionization process, leads to an aspirating phenomenon of the chiral selector in the MS direction. Javerfalk et al. were the first to apply PFT with a neutral methyl-/i-CD for the separation of racemic bupivacaine and ropivacaine with a polyacrylamide-coated capillary and an acidic pH buffer (pH 3). Cherkaoui et al. employed another neutral CD (HP-/1-CD) with a PVA-coated capillary for the analysis of amphetamines and their derivatives. To prevent a detrimental aspiration effect, analyses were carried out without nebulization pressure. Numerous other studies presented excellent results such as the enantioselective separation of adrenoreceptor antagonist drugs using tandem mass spectrometry (MS/MS) the separation of clenbuterol enantiomers after solid-phase extraction (SPE) of plasma samples or the use of CD dual system for the simultaneous chiral determination of amphetamine, methamphetamine, dimethamphetamine, and p-hydroxymethamphetamine in urine. 

Ho, E.N.M., Leung, D.K.K., Wan, T.S.M. and Yu, N.H. (2006) Comprehensive Screening of Anabolic Steroids, Corticosteroids, and Acidic Drugs in Horse Urine by Solid-Phase Extraction and Liquid Chromatography-Mass Spectrometry. J Chromatopfr A, 1120, 38. 

Significant improvements in the isolation of pharmaceutical compounds from plasma, serum and urine, have been achieved using ultra low mass sorbent bed and thin disk solid-phase extraction (SPE) material. The use of low sorbent masses or disk SPE material has allowed a significant reduction in solvent usage and extraction times. Several SPE RP-HPLC methods have been developed using these materials, including... 

Watson DG, Oliviera EJ. Solid-phase extraction and gas chromatography-mass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets. J Chromatogr B Biomed Sci Appl 1999 723 203-210. 

An analytical technique has been developed for the determination of selenium species in urine to identify selenium containing compounds by combining electrospray MS/MS with ICP-MS after preparative solid phase extraction and final reversed phase HPLC separation.69... 

The applicability of the APCI interface is restricted to the analysis of compounds with lower polarity and lower molecular mass compared with ESP and ISP. An early demonstration of the potential of the APCI interface is the LC-APCI-MS-MS analysis of phenylbutazone and two of its metabolites in plasma and urine (128). Other applications include the LC-APCI-MS analysis of steroids in equine and human urine and plasma (129-131), the determination of six sulfonamides in milk samples after a simple solid-phase extraction and LC separation (132), of tetracyclines in muscle at the 100 ppb level (133), of fenbendazole, oxfendazole, and the sulfone metabolite in muscle at the 10 ppb level, and of five thyreostats in thyroid tissue at the 1 ppm level (134). 

Despite the distinct advantages of pneumatic nebulizers, ultrasonic nebulizers may alternatively be used, in some instances, with success. In a recent application, a variation of ultrasonic nebulizer called spray nozzle-rotating disk FTIR interface was successfully applied to confirm the presence of methyltestosterone, testosterone, fluoxymesterone, epitestosterone, and estradiol and testosterone cyp-ionate in urine, after solid-phase extraction and reversed-phase LC separation (151). Using a commercial infrared microscopy spectrometer, usable spectra from 5 ng steroid deposits could be readily obtained. To achieve success with this interface, phosphate buffers in the mobile phase were not used because these nonvolatile salts accumulate on the collection disk and their spectra tend to swamp out small mass deposits. Another limitation of the method was that only nonvolatile analytes could be analyzed because volatile compounds simply evaporated off the collection-disk surface prior to scanning. 

Diethylstilbestrol is particularly difficult to quantitate below 1.0 ppb in bovine tissues, especially in liver, which is among the last tissues to contain diethystilbestrol after cattle are withdrawn from receiving tire drug (101, 102). Interferences from tissue matrix constitute a major problem that might be due to nonspecific interference of lipids and fatty compounds (103, 104). In addition, problems with false-positive results often appear in urine analysis unless a chromatographic step such as a solid-phase extraction cleanup (105, 106) is introduced. Simple sample preparation procedures such as those based on solvent extraction and liquid-liquid partitioning do not usually give satisfactory results (107, 108). 

To overcome this problem, a radioimmunoassay method was developed (155) in which urine is enzymatically hydrolyzed to be subsequently purified by Ci8 solid-phase extraction. Elution was carried out using ethyl acetate, and the extract was analyzed by reversed-phase LC. The fraction containing the analyte was collected, evaporated, and submitted to radioimmunoassay. In this way, dexamethasone separated from natural corticosteroids and other synthetic corticosteroids that could cross-react in the assay. 

Solid-phase extraction for milk, urine, and feces samples is carried out by washing the loaded Cig cartridge successively with 5 ml water, 5 ml acetone/ water (20 80), 5 ml methanol/water (20 80), 5 ml dichloromethane/hexane (20 80), and 5 ml ethyl acetate/hexane (10 90). The corticosteroids are eluted with 3 ml ethyl acetate. The eluate is evaporated, and the residual is reconstituted in 0.5 ml ethanol and 5 ml phosphate-buffered saline, pending subsequent immunoaffinity column cleanup. The solid-phase extraction procedure differs for liver samples. In that case, washing of the cartridge is performed with 5 ml water, 5... 

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