# Fabric Sol-gel Phase Sorptive Extraction Technique: A Review
## 7 Automated Fabric Phase Sportive Extraction  
Current trends in analytical chemistry, are mainly focused on three significant objectives namely miniaturization, simplification, and automation. During recent years, noteworthy progress has been made in order to enhance the quality of analytical results and follow the concept of green analytical chemistry. The implementation of flow-based sample pretreatment methodologies used for fluidic  
Figure 5: Schematic presentation of stir-bar FPSE and magnetic stir-FPSE procedure. Reproduced from [32] with permission of Elsevier.  
manipulation and on-line sample/reagent pretreatment holds many advantages in contrast with the batch mode of sample preparation. These include low consumption of solvents and reagents and thus low cost of total analysis as well as a significant improvement of the repeatability of the extraction procedure. The combination of flow injection analysis (FIA), sequential injection analysis (SIA), and related techniques with atomic spectrometry (AS) [6; 39] provide unique capabilities and enhanced performance of the developed methods. Despite the numerous advantages of the FPSE technique, there is a need for automation in order to reduce sample preparation time extremely and considerably improve the analytical characteristics of each developed method.  
Very recently, [PERSON] et al. [36], demonstrated and successfully evaluated for the first time, an automated platform using the FPSE technique in an on-line column preconcentration system. The novel automated on-line flow injection fabric disk sorptive extraction system (FI-FDSE) coupled with flame atomic absorption spectrometry (FAAS), was applied for the preconcentration and determination of lead and cadmium in environmental water samples. Generally, the automation of the FPSE technique is based on the effective packing of a minicolumn with FPSE sorbent media in a shape of disks packed in a series and fixed appropriately. The minicolumn was incorporated onto the FIA system as shown in Figure 6. Four different FPSE sorbent media, sol-gel PDMDPS coated on a polyester substrate, sol-gel PTHF, sol-gel PEO-PPO-PEO triblock copolymer, and sol-gel graphene coated on cellulose substrates, were examined through the developed FPSE platform. Sol-gel PDMDPS presented the highest extraction sensitivity and very good reproducibility in comparison to the other FPSE media, so it was selected for further experiments. The way of FPSE media preparation as well as the way of the minicolumn packing are given elsewhere [36].  
Figure 6: Schematic diagram of the FI-FDSE-FAAS manifold for metal preconcentration and determination by FAAS. APDC, aqueous solution 0.2% (m/v) ammonium pyrrolidine dithiocarbamate; MIBK, methyl isobutyl ketone; W, waste; P, peristaltic pump; SP, syringe pump; IV, injection valve in the load or elution position; V, two-position valve; FC, flow compensation unit; C, FPSE minicolumn. **(a)** Sample loading step, **(b)** elution step. Reproduced from [36] with permission of Elsevier.  
Briefly, the FPSE minicolumn was created using the body of a polyethylene syringe (4.0 mm i.d.) shortened to 1.5 cm and packed with 38-40 disks FPSE disks in a row as shown in Figure 7. No frits or glass wool were used at either end of the column to block fabric disks.  
This configuration of the minicolumn provides limited backpressure due to the easy permeation of the incoming flow through the pores of the FPSE substrate. Thus, high loading flow rates can be applied, resulting in higher extraction efficiency and lower time of analysis. Enrichment factors of 140 and 38 and detection limits of 1.8 and 0.4 ug\(\cdot\)L\({}^{-1}\) were achieved for lead and cadmium determination, respectively, with a sampling frequency of 30 h\({}^{-1}\) for 90 s preconcentration time. The precision as relative standard deviation (RSD) was 3.1% and 3.3% for lead and cadmium respectively. The FPSE minicolumn was efficient and stable for at least 500 sorption/elution cycles.