## 3 Results and Discussion
### HPLC Analysis of Real Samples
#### 3.7.2 Analysis of Food Samples
reported lutein concentrations ranging from 16.4 mg/kg FW in cultivar Abata to 38.2 mg/kg FW in cultivar Super Caesar Red [51], while [PERSON] et al. determined concentrations from 5.58 mg/kg FW in Green Salanova to 13.38 mg/kg FW in Red Salanova, depending on the variety [52]. [PERSON] et al. found high lutein concentrations of 754.5 and 746.0 mg/kg DW in the cultivars Red Salanova and Baby Romaine, respectively, while the lowest lutein concentration was determined in cultivar Lollo Verde (176.9 mg/kg DW) [53]. [PERSON] et al. reported that the 'Outredgeous Red Romaine' cultivar contained 3160 mg/kg DW [54]. In our investigation, the concentration of lutein in lettuce was 1179.246 mg/kg DW. [PERSON] et al. [55] determined lutein concentrations of 100.05 mg/kg FW in the Winterbor kale cultivar and 71.58 mg/kg FW in the Maribor kale cultivar. [PERSON] et al. [56] reported an average of 50.6 mg/kg FW, while 16.57 mg/kg FW was determined by [PERSON] et al. and the same authors determined 15.1 mg/kg FW in later research [57]. [PERSON] et al. reported a lutein concentration of 619.37 mg/kg FW in a sample of Chinese kale [58]. [PERSON] et al. investigated lutein concentrations in varieties of Chinese kale and determined concentrations ranging from 660 mg/kg DW to 2530 mg/kg DW. In our investigation, a kale sample contained a lutein concentration of 966.543 mg/kg DW [59]. [PERSON] et al., using TLC, reported lutein concentrations in carrot between 0.830 and 1.665 mg/kg FW, depending on standing time in acetone [60]. [PERSON] et al. determined a lutein concentration of 22.30 mg/kg FW in a sample of carrot [58]. [PERSON] et al. analyzed lutein concentrations in selected carrot lines and determined lutein concentrations between 4.9 and 15.2 mg/kg FW [61]. [PERSON] et al. found a lutein concentration of 57.58 mg/kg DW in black carrot [62]. Our investigation determined a lutein concentration of 15.734 mg/kg DW in a carrot sample. In buttrentup pumpkin, [PERSON] et al. [63] determined a lutein concentration of 16.8 mg/kg FW. [PERSON] et al. determined lutein in a higher concentration of 383.98 mg/kg FW in a sample of pumpkin [58]. In our investigation, the concentration of lutein in buttrentup squash was 3.592 mg/kg FW. [PERSON] et al. investigated the influence of ultrasound, steaming, and dipping on the lutein concentration in parsley and reported a lutein concentration of 413.0 mg/kg DW [64]. The same authors, in a previously conducted study, determined lutein concentrations in the range of 811.0-1306.0 mg/kg DW [65]. [PERSON] et al. investigated the influence of cultivation systems on lutein concentration in parsley. The obtained results showed the highest concentration in parsley cultivated indoors (780.52 mg/kg DW) [66]. In our investigation, parsley leaves showed a lutein concentration of 1581.489 mg/kg DW. The paprika spice sample in our investigation showed a lutein concentration of 522.734 mg/kg DW. Chili pepper had the highest lutein concentration (61.4 mg/kg DW under an organic production system and 55.0 mg/kg DW under a conventional production system) in research conducted by [PERSON] et al. [67]. [PERSON] et al. used methanol:acetone (1:1, \(v/v\)) as a solvent mixture for carotenoid extraction from paprika samples, but without the saponification step, and they did not confirm the presence of lutein in their research samples [68]. Research conducted by [PERSON] et al. demonstrated that the concentration of lutein in paprika depends on the cultivation method and color. The highest concentration was obtained in orange papers grown using a soil-based cultivation method (376.9 mg/kg DW), while in yellow peppers with a soilless cultivation method, the highest concentration was 291.0 mg/kg DW [69]. [PERSON] et al. determined that the lutein concentration in heirloom varieties of corn grains ranged from 8.53 mg/kg DW to 10.08 mg/kg DW [70], while [PERSON] et al. found 27.59 mg/kg DW [71]. [PERSON] et al. determined a lutein concentration of 2438.18 mg/kg DW in the corn grain of one Chinese cultivar [72].