Plasticizers are non-volatile organic compounds used as additives in other materials (usually a plastic or an elastomer), deposited in the amorphous regions of the polymer matrix to make those materials more pliable [1]. The most frequently used are phthalate-based plasticizers such as bis(2-ethylhexyl) phthalate [2]. However, the large consumption of plastics also leads to the exposure of the living environment to a large quantity of toxic plasticizers. Due to aging and the influence of certain external conditions, the plasticizer can leak into the surroundings posing environmental and health risks. Plastic pollution is one of the biggest environmental challenges worldwide. Therefore, the negative impact of traditional phthalate-based plasticizers on the environment and health shifted the direction of development towards bio-based plasticizers, also known as bioplasticizers or green plasticizers [3] with the development of bioplastics.

Another factor influencing the development of bioplasticizers is the lack of fossil resources [4]. Additionally, the toxicity and non-degradability of fossil fuels and their derivatives pose significant environmental and health risks [4]. Bioplasticizers are mainly derived from biomass sources through further modifications of oils, triglycerides, starch, cellulose, citric acids, and glycerol. These include substances such as epoxidized plant oils, cardanol, citrates, and isosorbide esters [5]. There are also other sources of bioplasticizers investigated, such as spices like curcumin or cinnamon [6,7]. These bio-based plasticizers are being developed aiming towards low toxicity and low migration properties, becoming very attractive as the replacement of phthalate-based plasticizers. Bioplasticizers offer advantages such as recyclability and low volatility, which have a strong environmental impact. Among other properties expected of bioplasticizers are good miscibility with polymers, higher efficiency than common phthalate-based plasticizers, high resistance to polymer leaching, and relatively low production costs [8].

Bioplastics are used in agriculture, for example, to cover fertile soil and prevent the spread of weeds. During harvest, these bioplastics are chopped by harvesters and mixed into the soil for biodegradation by microorganisms. However, during the degradation of bioplastics in the soil, bioplasticizers can leak into the environment and enter the surrounding soil and water due to the absence of strong bonds with the bioplastic polymer. As bioplastics break down, a significant amount of bioplasticizers is released into the environment, making it necessary to monitor their occurrence and quantities for bioaccumulation control.

The presence and determination of traditional plasticizers in environmental samples have been studied [9,10], however, bioplasticizers are a fairly new issue in the field of analytical chemistry. Although research on their production development or sustainability studies can be found [4,11], there is no knowledge of previous methods for analysis of bioplasticizers in waters. This fact shows the need of the proposed method and its novelty. Since bioplastics are used to manufacture bottles for drinking water, the concentrations of bioplasticizers that need to be monitored should fall within the ppb to ppt range.

Due to the complexity of environmental samples, it is very important to pay attention to sample preparation methods. Extractions like liquid-liquid extraction and solid phase extraction are the most common procedures used for water samples. However, both techniques need large volumes of organic solvents and samples to achieve the required sensitivity (ppb, ppt) [12].

SPME is a miniaturized extraction method that complies with the principles of “green chemistry” because of the reduction of sample volume and the amount of organic solvent. This technique enables simultaneous extraction, concentration, and purification of samples, achieving low limits of detection (ppb, ppt) which are comparable or even lower than those achieved by liquid-liquid extraction or solid phase extraction [13]. Compared to conventional methods used for the extraction of phthalates, micro-extractions are faster, simpler, more cost-effective, and environmentally friendly [14].

In terms of instrumental analysis, gas chromatography-mass spectrometry analysis (GC–MS) has been implemented exclusively for the identification of additives and bioplasticizers in a study [15] investigating the toxic effects of three innovative bioplastic products: polylactic acid cups (PLA), polyhydroxybutyrate resin (PHB) and a 3D printing filament of polylactic acid/polyhydroxyalkanoate (PLA / PHA), in comparison with a synthetic polyvinyl chloride toy (PVC) in Paracentrotus lividus sea urchin larvae. GC-MS analysis revealed the presence of a variety of additives [15]. However, the selectivity and efficiency of the GC–MS method might be influenced by sample matrix interferences. Hence to achieve lower limits of detection (LODs) without extensive sample preparation procedure, GC–MS/MS is to be implemented and provide a more sensitive and selective identification of analytes at trace levels in complex matrices [16,17].

The objective of this work was the development and validation of an SPME-GC–MS/MS method for the determination of selected bioplasticizers in water matrices. Microextraction was performed with SPME in direct immersion (DI) mode. DI-SPME minimized the sample handling with an online automation to the chromatographic system, improving precision and minimizing contamination and human errors. This resulted in high selectivity and sensitivity in combination with GC–MS/MS. The proposed method was applied to some real agricultural water samples, and also water samples from plastic bottles and the sea. Some bioplasticizers were found indicating need for further studies of their impact.