Solid-phase extraction cleanup

Dqbrowska H, Dqbrowski L, Biziuk M, Gaea J, Namiesnik J. Solid-phase extraction cleanup of soil and sediment extracts for the determination of various types of pollutants in a single run. J. Chromatogr. A 2003 1003 29-42. 

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in bovine tissues, especially in liver, which is among the last tissues to contain diethystilbestrol after cattle are withdrawn from receiving tire drug (101, 102).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). 

For analyzing amphenicol residues in liquid samples such as milk, a pretreatment centrifugation step for fat removal is usually required (21, 22). Dilution of milk samples with water prior to solid-phase extraction cleanup is also often needed (23, 24). Semisolid samples such as muscle, kidney and liver, require, however, more intensive sample pretreatment. The most popular approach for tissue break-up is through use of a mincing and/or a homogenizing apparatus. 

Detection in liquid chromatography is mostly performed by fluorescence and/or ultraviolet absorption. In a few instances, electrochemical detection has also been employed (357, 368). For compounds that exhibit inherent intense fluorescence such as albendazole and metabolites (319, 320, 338, 355), closantel (344), and thiabendazole and metabolites (378), fluorometric detection is the preferred detection mode since it allows higher sensitivity. Compounds that do not fluoresce such as eprinomectin, moxidectin, and ivermectin, are usually converted to fluorescent derivatives prior to their injection into the liquid chromatographic analytical column. The derivatization procedure commonly applied for this group of compounds includes reaction with trifluoroacetic anhydride in presence of A-methylimidazole as a base catalyst in acetonitrile (346, 347, 351, 352, 366, 369, 372-374). The formation of the fluorophore is achieved in 30 s at 25 C and results in a very stable derivative of ivermectin and moxidectin (353) but a relatively unstable derivative of eprinomectin (365). However, the derivatized extracts are not pure enough, so that their injection dramatically shortens the life of the liquid chromatographic column unless a silica solid-phase extraction cleanup is finally applied. 

Total thiamine Baby food cereals cookies Acid hydrolysis with 0.1 M hydrochloric acid at 100°C for 30 min enzymatic hydrolysis of thiamine phosphates to thiamine with takadiastase at 47°C for 3 h weak ion-exchange (methyl-carboxylatein, add form) solid-phase extraction/ cleanup Analytical Lichrospher 100RP-18 (125 X 4 mm, 5 /u.m Merck ). Isocratic methanol + 10 mM phosphate buffer, pH 2.8 containing 5 mM sodium hexane-sulphonate + tri-ethylamine (15 + 84.9 + 0.1, v/v/v). 1.0 ml/min. UV absorbance 254 nm. External standardization. 79 Linear range = LoD to 7 /zg/ml thiamine, r = 0.9995. Reproducibility CV < 3% using food samples (n = 10). Recoveries 92.1-96.0% thiamine using baby food (n = 3). Samples spiked before hydrolysis. 

C protein precipitation with trichloroacetic acid at 100°C for 10 min C,8 solid-phase extraction/cleanup. method (r = 0.987). 

M Hiemstra, JA Joosten, A De Kok. Fully automated solid-phase extraction cleanup on-line liquid chromatographic determination of benzimidazole fungicides in fruit and vegetables. J AOAC Int 78 1267-1274, 1995. 

A de Kok, M Hiemstra. Optimization, automation, and validation of the solid-phase extraction cleanup and on-line liquid chromatographic determination of V-methylcarbamate pesticides in fruits and vegetables. J Assoc Off Anal Chem 75 1063-1072, 1992. 

Relative standard deviation of repeat HPLC analysis of a drug metabolite standard was between 2 and 5%. Preliminary measurements of several serum samples via solid-phase extraction cleanup followed by HPLC analyses showed that the analyte concentration was between 5 and 15 mg/L and the standard deviation was 2.5 mg/L. The extraction step clearly increased the random error of the overall process. Calculate the number of samples required so that the sample mean would be within +1.2 mg/L of the population mean at the 95% confidence level. 

Goldade, D.A., Primus, T.M., Johnston, J.J., Zapien, D.C. (1998). Reversed-phase ion-pair high-performance liquid chromatographic quantitation of difethialone residues in whole-body rodents with solid-phase extraction cleanup. J. Agric. Food Chem. 46(2) 504-8. 

Lagana, A. et al., Sample preparation for determination of macrocyclic lactone myco-toxins in fish tissue, based on on-line matrix solid-phase dispersion and solid-phase extraction cleanup followed by liquid chromatography/tandem mass spectrometry, J. AOACInt., 86(4), 729, 2003. 

Hurlbut J, Carr j, et al. Solid-phase extraction cleanup and liquid chromatography with ultraviolet detection of ephedrine alkaloids in herbal products. JAOAC Int 1998 81 1121-7. 

Figure 12-8. A solid phase extraction cleanup apparatus.

Pichon, V., Cau dit Coumes, C., Chen, L., and Hennion, M. C., Solid phase extraction, cleanup, and liquid chromatography for routine multiresidue analysis of neutral and acidic pesticides in natural water in one run, Int. J. Environ. Anal. Chem., 65, 11-25, 1996. 

Yang Z, Hayes M, Fang X, Daley MP, Ettenberg S, Tse FL. LC-MS/MS approach for quantification of therapeutic proteins in plasma using a protein internal standard and 2D-solid-phase extraction cleanup. Anal Chem 2007 79(24) 9294 9301. 

Yang, R. Z, Wang, J. H., Wang, M. 1., Zhang, R., Lu, X. Y., and Liu, W. H. 2011. Dispersive solid-phase extraction cleanup combined with accelerated solvent extraction for the determination of carbamate pesticide residues in radix glycyrrhizae samples by UPLC-MS-MS. J. Chromatogr. Sci. 49 702-708. 

LaCroix, D.E., Wolf, W.R., and Vanderslice, J.T., 1999. Determination of niacin in infant formula and wheat flour by anion-exchange liquid chromatography with solid phase extraction cleanup. Journal of AOAC International. 82 128-133. 

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