# A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods
## 3 Chromatography
### Liquid Chromatography and Mass Spectrometry
#### 3.3.2 LC-MS for Quantitative Analysis
[PERSON] and [PERSON] [269] developed a highly accurate quantitation method for aflatoxin B\({}_{1}\) using 2D-LC and double isotope dilution MS. Aflatoxin B\({}_{1}\) was carefully separated from matrix-components using heart-cutting 2D-LC and measurement uncertainty related to extraction efficiency and matrix effects was minimized using \({}^{13}\)C-IS. In tested matrices (cereal-based baby food, maize and maize-based feed), the expanded uncertainty of aflatoxin B\({}_{1}\) at 0.197 ppb is 0.017 \(\upmu\)g/kg (8.9%). The application of 2D-LC-MS might not be suited for routine sample analysis but is appreciated for measurements that require high accuracy such as characterization of certified reference materials. Recently, [PERSON] et al. [270] reported determination of aflat, ochratoxin A, fumonisins B\({}_{1}\) and B\({}_{2}\) in beer using 2D-LC-MS. For fumonisins and ochratoxin A, the 2D-LC separation eliminated co-eluted interfering compounds, permitting quantification by solvent-only calibration standards. In contrast, matrix suppression was still observed for aflat, requiring matrix matched calibration standards for quantitation. Co-contamination of aflat and other mycotoxins in foods and feeds is well known. How to efficiently monitor co-occurrence of aflat and other mycotoxins has been a challenge for mycotoxin researchers [271; 272; 273]. When multiple mycotoxins are needed to be analyzed, it is clear that LC-MS would be a better analytical tool as it can achieve identification, quantitation and confirmation for multiple mycotoxins in one analysis, a desirable feature that other techniques lack. For example, the survey work performed by [PERSON] et al. and [PERSON] et al. report mycotoxins in infant foods from the retail market, and provide a good comparison of the application of LC-MS-basedmultimycotoxin analysis vs. LC-FLD-based single mycotoxin analysis [274; 275]. Without LC-MS, multiple LC-FLD methods had to be used to collect information of individual mycotoxins such as aflat, deoxynivalenol and ochratoxin A, while using LC-MS, these mycotoxins could be identified and quantitated by one method. For multimycotoxin analysis, using multiple single mycotoxin methods would be much less practical than using a multimycotoxin method. As LC-MS could simultaneously detect a large number of mycotoxins in one analysis, the current trend is to develop multimycotoxin procedures, taking advantage of the analytical capacity of LC-MS, hence improving throughput. A variety of LC-MS-based multimycotoxin methods have been developed. In these methods, aflat and other mycotoxins of interest are extracted from samples, followed by cleanup procedures, if necessary, and then analyzed by LC-MS. In a series of studies [276; 277; 278; 281], the number of mycotoxins that could be simultaneously detected in one LC-QQQ-MS analysis has been expanded from 39 to 300. Each mycotoxin is monitored by two unique MRM transitions and retention time, which is sufficient to achieve confident identification [282]. It is evident that for multimycotoxin analyses, the capacity of conventional TLC or LC-UV/FLD is unrivaled to modern LC-QQQ technologies. With increasing number of mycotoxins, researchers need to find appropriate extraction and sample clean up procedures for target mycotoxins with different physicochemical properties. Practically, it is also a QA/QC and logistical challenge to trace, store and prepare calibration standards for a large number of analytes. [PERSON] et al. [43] extracted 33 mycotoxins including aflat in various products (peanuts, pistachios, wheat, maize, cornflakes, raisins and figs) using acetonitrile-water (80:20, _v/v_) and methanol-water (70:30, _v/v_), followed by dilution with water and LC-MS/MS analysis. Although matrix-matched calibration standards were prepared for quantitation, the practice is considered less laborious than using SPE or immunoaffinity columns for cleanup.