Determination of aflatoxins in rice from Penang, Malaysia by dispersive liquid–liquid micro-extraction and LC–MS/MS Sofiyatul Akmal Salim, Nur Harniada Baharudin, Nur Shahila Ibrahim, Zalilawati Abd Ghani, Mohd Nazri Ismail Food Additives and Contaminants Part A, 2024 Rice is one of the crops cultivated in Malaysia, and it is the main diet for most of the population. In this study, dispersive liquid-liquid micro-extraction (DLLME) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to develop, optimise and validate a reliable, easy-to-use and quick approach to detect aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). The extraction recoveries in DLLME were enhanced by the addition of 5% salt, utilising chloroform as the extraction solvent and acetonitrile as the dispersive solvent. The DLLME parameters - the extraction solvent volume, salt concentration and dispersive solvent volume were optimised with Box-Behnken design (BBD) and response surface methodology (RSM). Under optimised experimental conditions, excellent linearity was obtained with a limit of detection (LOD) ranging from 0.125 to 0.25 ng g-1, a limit of quantitation (LOQ) ranging from 0.25 to 0.3 ng g-1 and a correlation value (R2) of 0.990. The matrix effects were between -11.1% and 19.9%, and recoveries ranged from 87.4% to 117.3%. The optimised and validated method was used effectively to assess aflatoxins contamination in 20 commercial rice samples collected from local supermarkets in Penang, Malaysia. AFB1 was detected at 0.41-0.43 ng g-1 in two rice samples, below the regulatory limit.
Dispersive Liquid–Liquid Microextraction (DLLME) and LC-MS/MS Analysis for Multi-Mycotoxin in Rice Bran: Method Development, Optimization and Validation Sofiyatul Akmal Salim, Rashidah Sukor, Mohd Nazri Ismail, Jinap Selamat Toxins, 2021 Rice bran, a by-product of the rice milling process, has emerged as a functional food and being used in formulation of healthy food and drinks. However, rice bran is often contaminated with numerous mycotoxins. In this study, a method to simultaneous detection of aflatoxins (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), deoxynivalenol (DON), fumonisins (FB1 and FB2), sterigmatocystin (STG), T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and zearalenone (ZEA) in rice bran was developed, optimized and validated using dispersive liquid–liquid microextraction (DLLME) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In DLLME, using a solvent mixture of methanol/water (80:20, v/v) as the dispersive solvent and chloroform as the extraction solvent with the addition of 5% salt improved the extraction recoveries (63–120%). The developed method was further optimized using the response surface methodology (RSM) combined with Box–Behnken Design (BBD). Under the optimized experimental conditions, good linearity was obtained with a correlation coefficient (r2) ≥ 0.990 and a limit of detection (LOD) between 0.5 to 50 ng g−1. The recoveries ranged from 70.2% to 99.4% with an RSD below 1.28%. The proposed method was successfully applied to analyze multi-mycotoxin in 24 rice bran samples.
Evaluation of methods for purifying erythropoietin from urine using immunoaffinity applications S.H. Kwan, F. Baharudin, S.A. Salim, M.N. Ismail International Journal of Biological Chemistry, 2015 Erythropoietin (EPO), a hormone that regulates the synthesis of red blood cells, is frequently abused by athletes. Sodium dodecyl sulphate poly acrylamide gel electrophoresis (SDS-PAGE) is an essential analytical technique in all anti-doping laboratories in order to detect the abuse of EPO. An immunoaffinity purification step is now considered essential for the pre-treatment of urine samples to isolate EPO prior to gel electrophoresis. In this study, we have compared the performance of two immunoaffinity purification techniques in EPO anti-doping analysis, i.e., the anti-EPO micro well plate and anti-EPO monolith column. The anti-EPO monolith column is efficient in removing undesirable proteins except for the Bovine Serum Albumin (BSA) as seen on SDS-PAGE. The BSA was eventually removed from the protocol and the undesirable protein band was eliminated without affecting the performance of the method. Throughout the study, the antiEPO monolith column emerged as a better option, as it provided a higher sensitivity and higher throughput analysis when compared to the anti-EPO micro well plate. The anti-EPO monolith column has shown consistent results with the EPO recovery rate of 72%, while the limit of detection is as low as 0.5 mIU mLG1.
