Akdeniz Bölgesinde Yetiştirilen Sebzelerin Nitrat Düzeylerinin Tespiti ve Validasyonu

Bu çalışmada, validasyon, sadece marul örneklerinde nitrat etken maddesinin kalıntı analizi için 24 ve 200 mg/kg seviyelerinde zenginleştirme ile yapılmıştır. Analizler ise marul, ıspanak, baş salata ve roka örneklerinde yüksek performanslı sıvı kromatografi (HPLC) kullanılarak gerçekleştirilmiştir. Matris etkisini elimine etmek için, matrisli kalibrasyon yani marul örneklerine ait kalibrasyon kullanılmıştır. Metodun validasyonu; kesinlik, tekrarlanabilirlik, tekrarlanabilirlik limiti, tekrar üretilebilirlik, tekrar üretilebilirlik limiti, doğruluk, kalibrasyonun doğrusallığı, geri alım gibi kriterler ile gerçekleştirilmiştir. Kalibrasyon eğrisi, 0,2-40 mg/kg aralığında lineer olarak bulunmuştur. Örneklerden geri alım %97,3-100,2 arasındadır. Tekrarlanabilirlik değerleri, iki konsantrasyon için sırasıyla 1,89 (matrix+24 ppm) ve 3,65 (matrix+200 ppm), tekrar üretilebilirlik değerleri ise 3,951 (matrix+24 ppm) ve 3,456 (matrix+200 ppm) olarak belirlenmiştir. Dolayısıyla tekrarlanabilirlik ve tekrar üretilebilirlik limiti değerleri kabul edilebilir sınırlar içerisindedir. Doğruluk sırasıyla 0,015 (matrix+24 ppm) ve 0,004 (matrix+200 ppm), kesinlik 0,039 (matrix+24 ppm) ve 0,006 (matrix+200 ppm), birleştirilmiş belirsizlik sırasıyla 0,041 (matrix+24 ppm) ve 0,007 (matrix+200 ppm), genişletilmiş belirsizlik (%95 güvenle; k=2) 0,082 (matrix+24 ppm) ve 0,014 (matrix+200 ppm) olarak bulunmuştur. Çalışmamızda, toplam 102 adet numunede en yüksek nitrat oranı, 3.486 mg/kg ile ıspanakta görülmüştür. Ispanağı izleyen marul (2.825 mg/kg), daha düşük nitrat içeriği gösterirken, sırayla baş salata (1.985 mg/kg) ve rokada (1.870 mg/kg) daha düşük konsantrasyonlarda nitrat tespit edilmiştir. Sonuçlar, sebze üreticileri ve günlük diyetimizdeki nitrit ve nitratın insan sağlığı üzerindeki etkileri üzerine araştırmalar için vücuda alım seviyelerinin tahmin edilmesinde faydalı olabilecektir. Ayrıca çalışmada analizi yapılan sebzelerdeki nitrat oranlarının, Akdeniz bölgesinde azotlu gübre kullanımının yüksek olduğunun göstergesi olup, fakat insan ve hayvan sağlığı açısından bir sorun oluşturmayacağını göstermiştir.

Determination and Validation of Nitrate Levels of Vegetables Grown in the Mediterranean Region

In our study, validation was carried out at 24 and 200 mg/kg enrichment for residue analysis of nitrate active substance only in lettuce samples. Analyses were performed by using high performance liquid chromatography (HPLC) in lettuce, spinach, salad and arugula samples. In order to eliminate the matrix effect, matrix calibration was used, ie calibration of lettuce samples. Validation of the method was performed with criteria such as precision, repeatability, repeatability limit, reproducibility, repeatability limit, accuracy, linearity of calibration and recovery. The calibration curve was found as linear in the range of 0.2-40 mg/kg. The recovery from the samples is between 97.3-100.2 %. The repeatability and reproducibility values for the two concentrations were 1.89 (matrix+24 ppm) and 3.65 (matrix+200 ppm), 3.951 (matrix+24 ppm) and 3.456 (matrix+200 ppm), respectively. The repeatability and reproducibility limit values are within acceptable limits. Accuracy, precision, combined uncertainty and extended uncertainty (95% confidence: k=2) were found as 0.015 (matrix+24 ppm) and 0.004 (matrix+200 ppm), 0.039 (matrix+24 ppm) and 0.006 (matrix+200 ppm), 0.041 (matrix+24 ppm) and 0.007 (matrix+200 ppm), 0.082 (matrix+24 ppm) and 0.014 (matrix+200 ppm). In our study, the highest nitrate ratio was determined in spinach with 3486 mg/kg in total 102 samples. Lettuce following spinach (2825 mg/kg) showed lower nitrate content, while lower concentrations of nitrate were detected in iceberg (1985 mg/kg) and arugula (1870 mg/kg), respectively. The results may be useful in estimating body intake levels for research on the effects of nitrite and nitrate on human health in vegetable producers and in our daily diet. In addition, the nitrate content of the vegetables analysed in the study is an indicator of the use of nitrogenous fertilizers in the Mediterranean region, but showed no problem for human and animal health.

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