Pesticides are used on fruit and vegetable crops to obtain greater yield and quality. Residues can be detected in these crops or their products if applied pesticides do not degrade naturally. Therefore, this study aimed to estimate pesticide residues in some strawberry and tomato-based products available in the market for human consumption and associated dietary risks. Contamination with 3-15 pesticides in the tested samples was found. The total number of pesticides detected in the tested samples was 20, belonging to the group of insecticides (84%) and fungicides (16%). Pesticides of cypermethrin, thiamethoxam, chlorpyrifos, and lambda-cyhalothrin appeared at 100% in a number of samples, where the most detected was cypermethrin followed by thiamethoxam. The average values of pesticide residues detected in the tested samples ranged from 0.006 to 0.568 mg kg^-1, where it was found that cypermethrin had the highest residue value and appeared in strawberry jam obtained from the market. The recovery rate of pesticides from fortified samples with pyrethroids ranged from 47.5% (fenvalerate) to 127% (lambda-cyhalothrin). Home processing of fortified tomato and strawberry samples had a significant effect on reducing residues in tomato sauce and strawberry jam, where the reduction reached 100%. The results of acute and chronic risk assessment showed that their values were much lower than 100%, indicating minimal risk of dietary intake.

Heavy single-chain antibodies (VHH or nanobodies) are popular in the medical and analytical fields due to its small size, high solubility, stability, and other advantageous features. However, the usage of VHHs is limited by the low yield of its production and purification. In order to determine the optimal purification strategy for VHH to improve the yield, a method to monitor purification at the intermediate steps is needed. In this study, a simple, sensitive, low-cost sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitate VHHs throughout the purification steps. Under optimized conditions, the assay has a sensitivity of 0.149 OD·mL/ng and a limit of detection (LOD) of 0.029 ng/mL. The average recoveries of the assay against the spiked samples were 101.9-106.0% and 100.7-108.0%. The method was applied to a variety of real samples for the detection of different VHHs in bacterial cell media. High amount of VHHs (up to 41.3 mg/mL), which are comparable to the average yield of VHH in standard production protocols, were detected in the media. This study raises attention to the problem of protein losses in cell culture supernatants and provides a method for the continuous detection of the protein abundance to optimize the expression and purification protocols especially for nanobodies.

The use of pesticides leads to an increase in agricultural production but also causes harmful effects on human health when excessively used. For safe consumption, pesticide residues should be below the maximum residual limits (MRLs). In this study, the residual levels of pesticides in vegetables and fruits collected from farmers' markets in Sharkia Governorate, Egypt were investigated using LC-MS/MS and GC-MS/MS. A total number of 40 pesticides were detected in the tested vegetable and fruit samples. Insecticides were the highest group in detection frequency with 85% and 69% appearance in vegetables and fruits, respectively. Cucumber and apple samples were found to have the highest number of pesticide residues. The mean residue levels ranged from 7 to 951 µg kg^-1 (in vegetable samples) and from 8 to 775 µg kg^-1 (in fruit samples). It was found that 35 (40.7%) out of 86 pesticide residues detected in vegetables and 35 (38.9%) out of 90 pesticide residues detected in fruits exceeded MRLs. Results for lambda-cyhalothrin, fipronil, dimothoate, and omethoate in spinach, zucchini, kaki, and strawberry, respectively, can cause acute or chronic risks when consumed at 0.1 and 0.2 kg day^-1. Therefore, it is necessary for food safety and security to continuously monitor pesticide residues in fruits and vegetables in markets.

Occupational medical surveillance is highly desirable in manufacturing facilities where exposure to chemicals is significant. The insecticide fipronil is generally considered safe for humans but with increasing use, exposure to fipronil is of concern. Identification of urinary metabolites of fipronil may allow development of affordable, cheap and rapid procedures for human exposure evaluation. In this study we developed a fast and easy approach for synthesis of hydroxy-fipronil, a potential urinary metabolite of fipronil. This standard was used to develop a sensitive analytical LC-MS/MS method with a limit of quantification (LOQ) of 0.4ng/mL. Fipronil sulfone, a known metabolite, and hydroxy-fipronil were quantified in urine samples from rats treated with a fipronil containing diet. Fipronil sulfone concentration centered around 20ng/mL, while the concentration of hydroxy-fipronil was dose-dependent ranging in 10-10,000ng/mL and thus being a more sensitive marker of fipronil exposure. A fipronil immunoassay with cross-reactivity to hydroxy-fipronil showed a good correlation in signal intensity with LC-MS data. It was also used to demonstrate the applicability of the method for sample screening in the evaluation of exposure levels.