# A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods
## 2 Sample Preparation
### Extraction
#### 2.2.2 Solid Phase Extraction
Test samples were extracted with acetonitrile-water (9:1, _v/v_) and resulting extracts were passed through the column. Aflatoxins were analyzed by LC-FLD. The column was tested using extracts from a variety of representative commodities such as corn, tree nuts, cereal grains, seeds and mixed feeds. The average recoveries of total aflat were greater than 95% total aflat and coefficients of variation were less than 3%, providing a selective one-step clean-up strategy for sample preparation. Successful developments of SPE applications using different adsorbents are also reported in other studies. [PERSON] et al. [101] developed an SPE procedure for aflatoxin analysis in medicinal herbs. Samples were extracted with methanol-water (8:2, _v/v_) and passed through an Oasis HLB cartridge (packed with polymeric adsorbents) conditioned with methanol and equilibrated with water. After washing the cartridge with methanol-water (3:7, _v/v_), aflat were eluted with methanol. The eluted extract was analyzed by LC-MS. [PERSON] and [PERSON] [102] used Sep-Pak silica SPE tubes to clean up rice samples for aflatoxin B1 analysis. Rice samples were extracted using 80% methanol and the purified extracts were analyzed using LC-FLD. Recoveries were between 80 and 90% with RSDs \(<\) 6%. Using SPE packed with Florisil, [PERSON] [103] purified aflat from corn, brown and white rice, cottonseed, almonds, Brazil nuts, pistachios, walnuts and hazelnuts. Samples were extracted using methanol-water (8:2, _v/v_), followed by an SEP clean-up step. Eluted aflat were quantified by LC-FLD. Recoveries of aflat B1, B2, G1 and G2 were between 90 and 100% with RSDs \(<\) 5% in tested matrices. [PERSON] et al. [104] developed a multimycotoxin method, in which aflat B1, B2, G1, G2 and M1, fomonisin B1 and B2, deoxynivalenol, ochratoxin A, HT-2 and T-2 toxins and zearalenone were extracted from beer using C18 SPE cartridges. Key parameters such as the type of adsorbent, elution solvents and dilution factors were evaluated. After sonication, beer samples were directly loaded onto a C18 cartridge conditioned with a mixture of acetonitrile-methanol (6:4, _v/v_) and water. Mycotoxins were eluted by the same mixture of acetonitrile-methanol and analyzed by LC-MS. Recoveries of all targeted mycotoxins ranged from 76 to 10% with RSDs \(<\) 21%. To simplify SPE, researchers have developed matrix solid-phase dispersion (MSPD) clean-up, a technique that does not need cartridges but directly mixes samples and adsorbents together. The mixture is then packed in a glass column, followed by the elution of target analytes [105]. The approach is generally applied to small test portions (e.g., 0.5-2 g) so it is better suited for instruments with sufficient sensitivity, otherwise additional evaporation and concentration steps are needed. [PERSON] et al. [106] developed an MSPD procedure for the analysis of aflatoxin B1, B2, G1 and G2 in peanuts using C18 bonded silica as the dispersive adsorbents and acetonitrile as the eluting solvent. Eluted aflat were concentrated via evaporation and quantified using LC-FLD and identity of aflat were further confirmed using LC-MS. Recoveries of spiked aflat at 2.5 and 5.0 ng/g ranged between 78 and 86% with RSDs \(<\) 10%. The LOQs were 0.125-2.5 ng/g. Unlike conventional SPE, magnetic solid-phase extraction (MSPE) use superparamagnetic nanoparticles (e.g., Fe\({}_{3}\)O\({}_{4}\)) as an adsorbent. In MSPE, the adsorbent is directly added into the sample solution to extract analytes. After extraction, the adsorbent is separated using magnetic decantation via an external magnet. Therefore, no conditioning, washing or elution is needed. [PERSON] et al. (2017) used polydopamine-coated magnetic nanoparticles (PD-MNPs) as the adsorbent to extract aflat from wine. The nanoparticles were prepared using an in situ oxidative self-polymerization procedure and characterized using transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR).