Worldwide survey of pesticide residues in citrus-flavored soft drinks

After more than ten years since pesticide residues were detected in citrus-flavored soft drinks, this study reveals that the situation has not changed. A new sensitive multiresidue UHPLC-MS/MS method has been validated for 88 pesticides, which was used to analyze 200 samples manufactured in 67 countries, 80% corresponding to fruit-based soft drinks. The results show that 98% of the samples collected worldwide contained at least one pesticide, and 85% of them contained more than 4 pesticides. 40 out of 88 target compounds were quantified among the screened samples. Europe was the world region with the highest total amount of pesticides, probably due to the higher content of juice concentrate in samples, which may be the main source of the pesticide residues. Nevertheless, residues were also found in samples with no juice, so water quality also plays an important role as the main ingredient of citrus-flavored soft drinks.

[Preparation of samples for proficiency testing of pesticide residue analysis in processed foods]

To conduct proficiency testing for the analysis of pesticide residues in processed foods, fortified samples of retort curry and pancake were examined. In the case of retort curry, heating and mixing were necessary at the time of preparation to provide a homogenous analytical sample. A mixture of 4 carbamates and 11 organophosphorus pesticides was spiked and 14 of them showed consistent results in the samples. In the case of pancake, 10 kinds of pesticides were added to the pastry. The prepared pastry was them cooked. The relative concentrations of most of the pesticides in the pancake were not affected and all the pesticides showed consistent results in the samples. These results showed that the two tested samples were suitable for proficiency testing.

Liquid chromatographic determination of endogenous phytohormones in vegetable samples based on chemical derivatization with 6-oxy(acetylpiperazine) fluorescein

In phytohormone analysis, mass spectrometry (MS)-based methods are primary and powerful tools. However, complex sample preparation and high cost are problems for their application. As a complement for MS-based methods, a new fluorescent labeling reagent for carboxylic acids, 6-oxy(acetylpiperazine) fluorescein (APF), has been used for the determination of endogenous phytohormones, including indolebutyric acid, 1-naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid. The derivatization yield was maximized by optimizing derivatization conditions in detail, and the derivatives of three phytohormones could be separated completely in 15 min on a C18 column with fluorescence detection at lambda(ex)/lambda(em) = 467/512 nm. The derivatization limits could reach 0.1 microM, and the detection limits (signal-to-noise ratio = 3) were 4.43-14.2 nM. The proposed method has been applied to the determination of the exogenous phytohormones in the crude extracts of vegetable samples without extra purification and enrichment with recoveries of 94.2-102.4%.