Solid‐Phase Extraction and Clean‐Up Procedures in Pharmaceutical AnalysisUpdate based on the original article by P. Campíns‐Falcó, A. Sevillano‐Cabeza, R. Herráez‐Hernández, and C. Molins‐Legua, Encyclopedia of Analytical Chemistry , © 2000, John Wiley & Sons, Ltd.

Abstract

Solid‐phase extraction (SPE) using small cartridges filled with sorbents of a small particle size has rapidly established itself as an important sample clean‐up technique. It has prospered at the expense of liquid‐liquid extraction (LLE), which is considered labor intensive and frequently plagued by problems, such as emulsion formation and use of large volumes of hazardous solvents. A remarkable characteristic of SPE is its easy adaptation to on‐line mode by column‐switching techniques; switching can be effected manually or by automated controllers. The same analyte/sorbent interactions that are exploited in liquid chromatography (LC) are of use in SPE, but particle sizes employed are greater. Chemically bonded silica (SI), usually with C 18 and C 8 organic groups, is by far the most commonly used material. Cross‐linked polystyrene and other polymeric resins and mixed‐mode SPE sorbents are also widely used. Recently, different sorbents have been introduced to improve the selectivity, such as molecularly imprinted polymers (MIPs) and immunoaffinity sorbents, or to improve the extraction capacity through the increment of the surface‐to‐volume ratio (i.e. hypercross‐linked resins). A guide to improve sample clean‐up procedure can be established. Current trends in SPE are aimed toward the development of miniaturized systems that facilitate its automation and increase its precision, throughput, and cost‐effectiveness. Examples of such trends are the new formats of SPE such as tip‐based microextraction and solid‐phase microextraction with capillary columns (in‐tube solid‐phase microextraction, IT‐SPME). There are different approaches to automation for both off‐line and on‐line SPE, which involve different levels of apparatus cost. SPE is generally easier and cheaper than LLE. The precision obtained is similar for both techniques, while the recoveries obtained by SPE are generally better than those obtained by LLE. Enrichment and derivatization can also be carried out by use of sorbents as supports.

Gold‐functionalized stainless‐steel wire and tube for fiber‐in‐tube solid‐phase microextraction coupled to high‐performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons

“…The results indicated the method can provided good extraction repeatability and ensure the accuracy of the experiment. As shown in Table 2, the sensitivity and F E obtained in this work were compared with that obtained by several other approaches [13,23,[29][30][31][32]. In this work, LOQs, defined as a concentration of the analytes with S/N = 10, were 0.15-0.3 g/L.…”

“…This method Gold functionalized SS fiber-in-tube 0.05-0.1 0.15-0.3 61-121 SPME-HPLC-FLD [29] CP-Sil 19CB capillary column 0.32-4.63 -18-47 SPME-HPLC-FLD [30] SE-54 capillary column 0.05-0.6 0.165-1.98 -SPME-HPLC-FLD [31] Sol-gel-based copper tube device 0.005-0.5 0.01-1 20-100 SPME-HPLC-UV [32] Metal-organic hybrid gels 0.24-0.4 -21.1-55.6 SPME-HPLC-DAD [24] Copper fiber-in-tube 0.001-0.01 -268-2497…”

“…It allows for convenient automation of extraction process and analysis process [7], which not only shortens the analysis time but also provides better accuracy, precision and sensitivity relative to off-line manual techniques [6]. Therefore, in-tube SPME is an important sample preparation technique [8].…”

Principais técnicas de preparo de amostra para a determinação de resíduos de agrotóxicos em água por cromatografia líquida com detecção por arranjo de diodos e por espectrometria de massas

“…Uma alternativa ao SPME na forma apresentada usualmente é a SPME em tubo, onde o material adsorvente recobre internamente um tubo muito fino, por onde é percolada a amostra e, posteriormente, os analitos retidos são dessorvidos para a análise. Esta técnica foi aplicada por Campíns-Falcó et al 76 para a determinação de agrotó-xicos em água utilizando uma coluna capilar para GC (5% fenil 95% metilpolisiloxano; 80 cm x 0,32 µm de diâmetro interno e 0,3 µm de espessura de filme). A quantificação dos analitos foi por LC-DAD com LDs entre 0,008 e 0,2 µg L -1 .…”

Automation and Miniaturization of Sample Treatment

“…In each of these approaches, the coating may be supported on a fused-silica rod, or on the inside of a tube or capillary [18]. In each of these approaches, the coating may be supported on a fused-silica rod, or on the inside of a tube or capillary [18].…”