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The performance of acid extraction, dry ashing, and microwave digestion was evaluated for voltammetric cadmium quantification in oil crops with sunflower (Helianthus annuus) seeds as an example. Standard additions, reference material analysis, and comparison to graphite furnace atomic absorption spectrometry were employed for validation. The main aim of the study was to address the difficulties of oil crop mineralization such as high fat content, material inhomogeneity, and complications in maintaining sample representativeness. 6 brands of fried sunflower seeds (Krasnodar region, Russia) were studied. Acid extraction with nitric acid and hydrogen peroxide provided low digestion efficacy, while dry ashing provided efficient sample decomposition, however, resulted in considerable time frame extension. Microwave-assisted digestion provided the best performance with a dynamic range of 0.05–0.75 μg g−1, detection limit of 0.02 μg g−1, spike recoveries of 95–100%, and within-run relative standard deviation of 5–7%, when using anodic striping voltammetry for Cd quantification.

The simple and easy performed automated method for the IR determination of petroleum products (PP) in water using extraction-chromatographic cartridges has been developed. The method assumes two stages: on-site extraction of PP during a sampling by using extraction-chromatographic cartridges and subsequent determination of the extracted PP using sequential injection analysis (SIA) with IR detection. The appropriate experimental conditions for extraction of the dissolved in water PP and for automated SIA procedure were investigated. The calibration plot constructed using the developed procedure was linear in the range of 3–200 μg L −1 . The limit of detection (LOD), calculated from a blank test based on 3σ was 1 µg L −1 . The sample volume was 1 L. The system throughput was found to be 12 h −1 .