Application of the QuEChERS method combined with UHPLC-QqQ-MS/MS for the determination of isoprocarb and carbaryl pesticides in Indonesian coffee.

The performance of the QuEChERS method in this study, as indicated by a high percentage (>90%) of recovery observations falling within the range of 60-140% and a sample replicate deviation (% RSD) of <20%, for the routine analysis of isoprocarb and carbaryl pesticides, has been evaluated over a 14-month period for the export of Indonesian coffee. Following a seven-day observation of the stability of these pesticides in coffee extract, it was found that the added standard calibration solution remained stable and useable for seven days when stored at 4 °C and -20 °C. This validated method, with high sensitivity (a LOQ of 0.001 mg kg-1 for isoprocarb and carbaryl), has been employed to monitor residues in Indonesian coffee exports to comply with maximum residue limits (MRLs). The samples with higher contamination levels were predominantly from robusta coffee (57.76%), followed by arabica coffee (6.17%). The detection rates for residues decreased by more than 90% in the last two months of the method's application. In the observation of coffee processing, it was found that isoprocarb residues in contaminated samples could be transferred to the processed coffee (roasted and its infusion) to a limited extent, while residues from the carcinogenic carbaryl were not detected due to evaporation. Additionally, chronic dietary risk assessment showed that contaminated samples of robusta and arabica coffees should not be considered a significant public health concern (hazard index HI < 1). However, continuous monitoring of pesticide residues in Indonesian coffee is still recommended, not only to conform to the MRLs of importing countries but also to ensure food trade.

Highly selective electrochemical nanofilm sensor for detection of carcinogenic PAHs in environmental samples.

A highly sensitive sensor based on molecularly imprinted polymer film was devised for determination of polycyclic aromatic hydrocarbon (PAHs) in aquatic solutions. In this paper we report, electro-polymerisation of 4-vinyl pyridine (4VP) and target, pyrene, using cyclic voltammeter in electrolyte medium, forming the pyrene imprinted polymer. After polymerisation, the pyrene was removed from imprinted polymer using methanol to produce sensory nanofilm characterised by infrared spectrometer, optical and atomic force microscopy. The mechanism of nanofilm sensing was established using atomic models and electrochemical response by differential pulse voltammeter with the redox system of ([Fe(CN)6]3-/[Fe(CN)6]4-). The π-π interaction between pyrene and 4VP was primary cause for pyrene recognition in aqueous solutions and the model binding score for this interaction was -5.10 kcal mol-1. The electrochemical sensor determined pyrene in the concentration range of 1 × 10-4 - 1 ng L-1, resulting best linear regression (r2 > 0.9) and detection limit of 0.001 ng L-1. The recovery percentage of pyrene from the nanofilm was 83-110% in water samples and the imprinting factor value was 2.67. Therefore, the novel imprinted polymer nanofilm sensor showed highest sensitivity for target pyrene in aqueous samples compared to reported sensors.

Determination of Fumonisin B1 in maize using molecularly imprinted polymer nanoparticles-based assay.

Fumonisin B1 (FB1) is a carcinogenic mycotoxin produced by Fusarium species contaminating maize. At present, fumonisin determination is performed using costly and demanding chromatography techniques or immunoassays. Recently, a molecularly imprinted polymer nanoparticles (nanoMIPs) - based assay (MINA) has been developed for FB1 detection. Herein, we have applied MINA for the determination of FB1 in naturally contaminated maize samples and results were compared with those obtained with ELISA and a reference HPLC method (AOAC No. 2001.04). The nanoMIPs as a recognition element mimicking antibodies used in ELISA were produced by solid phase synthesis and used in MINA for FB1 determination in 53 maize samples. As a result, 18 maize samples were contaminated with FB1 at levels higher than 0.25 mg/kg. Fumonisin concentrations from samples measured by MINA were well correlated with those using ELISA and HPLC. Therefore, MINA could be used as an alternative technique for FB1 determination in maize.

Molecularly imprinted polymer nanoparticle-based assay (MINA): application for fumonisin B1 determination.

The enzyme-linked immunosorbent assay (ELISA) has been used as a standard tool for monitoring food and animal feed contamination from the carcinogenic fumonisin B1 (FB1). Unfortunately, ELISA is not always efficient due to the instability of the antibody and enzyme components in the immunoassay, the presence of natural enzyme inhibitors in the samples and the high levels of non-specific protein binding. Additionally, the production of antibodies for ELISA can be time-consuming and costly, due to the involvement of animals in the manufacturing process. To overcome these limiting factors, a molecularly imprinted nanoparticle based assay (MINA) has been developed, where the molecularly imprinted nanoparticles (nanoMIPs) replace the primary antibody used in a competitive ELISA. Herein, computational modelling was used to design the nanoMIPs by selecting monomers that specifically interact with FB1. The affinity of the monomers to FB1 was verified by measuring their binding in affinity chromatography experiments. The nanoMIPs were produced by solid phase synthesis and the results showed that nanoMIPs had a hydrodynamic diameter of around 249 ± 29 nm. The assay tested in model samples is highly selective and does not show cross-reactivity with other mycotoxins such as fumonisin B2 (FB2), aflatoxin B1 (AFB1), citrinin (CTT), zearalenone (ZEA), and deoxynivalenol (DON). The MINA allows the detection of FB1 in the concentration range of 10 pM-10 nM with a detection limit of 1.9 pM and a recovery of 108.13-113.76%.