## 1 Introduction  
Due to consumer awareness regarding the consumption of health-beneficial foods with a positive effect on health, numerous plant-based foods are a part of the human diet. In this context, different species of berries have been recognized as being useful for human nutrition and health for thousands of years. They are some of the most essential and high-valued plant-based foods, representing one of the most important modern-day \"superfoods\" [1]. These forest fruits are versatile, being consumed fresh in juices and beverages, frozen, dried, or as extracts. Berry fruits are good sources of phenolic compounds (phenolic acid, flavonoids anthocyanins, and tannins), vitamins (ascorbic acid), and minerals [2], their consumption leading to a positive impact on human health. Fruits and herbal supplements containing berries have antimicrobial, anti-inflammatory, and antioxidant properties [3], and are used for the alleviation of indications related to the gastrointestinal tract and diabetes. Due to these properties, they are highly appreciated and consumed worldwide, their consumption having a trend of stable increase. Thus, in recent years, berry trade and production are expanding globally, being in a period of continuous and rapid growth [4]. For example, between 2010 and 2019, blueberry production almost doubled, growing from 439,000 tons to around 1 million [5]. In addition, from 2010 to 2019, the world naspberry production has grown by 80%, from 373,000 tons to 684,000 tons [6]. In Romania, on the sunny slopes of the Carpathians, significant quantities of berries grow. In addition, more and more berry farms are appearing; Romania currently has over 350 berry growers but it also has an annual production that allows for export, especially since in recent years there has been a very high demand for these products. According to the Payments and Intervention Agency for Agriculture, the area cultivated with forest fruits such as raspberries, blueberries, and currants has increased seven times since 2010 and reached 5000 hectares. Consumers prefer wild berries versus cultivates ones for many reasons: wild berries have a more intense flavor and less sugar compared with their cultivated counterpart; wild berries maintain their shape, color, and texture when used in baking or undergoing manufacturing processes. They freeze very well and maintain their quality for over 2 years when frozen [7]. Given the importance of the consumption of berry fruits, there is a need for studies regarding the quality and authenticity of different species of berries. This issue is important both for consumers and producers. Over the last few decades, different analytical methods, such as isotope ratio mass spectrometry (IRMS), inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES), gas chromatography mass spectrometry (GS-MS), and high-performance liquid chromatography (HPLC) have been employed for the investigation of berry fruits based on isotopic fingerprint [3,8,9], elemental profile [3,10,11], volatile compounds [12,13,14], and phenolic compounds content [15,16,17]. In addition, the analytical results corroborated with chemometric methods (e.g., PCA, LDA, PLS-DA, etc.) represent important tools for the authenticity and quality control of berries, and also for tracing similarities or differences between different fruit species [1,8,11,18,19,10,11,18,20]. The aim of this preliminary study was to characterize the isotopic and elemental composition (\(\delta^{13}\)C, \(\delta^{2}\)H, \(\delta^{18}\)O, Li, Na, Mg, P, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Ag, Cd, Ba, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb), as well as to develop models for differentiating berry samples coming from the Romanian market according to the botanical origin (raspberry, seaberry, blackberry, cranberry, and blueberry) and growing system (wild and cultivated) using partial least squares discriminant analysis (PLS-DA).