Caracterização dos nutrientes minerais e determinação de pesticidas em hortaliças consumidas na cidade de Salvador, Bahia.

Abstract

In this work, two methods of determination of minerals, present in chapter I and pesticides, in chapter II, were developed, both aiming to nutritionally evaluate mustard and chicory vegetables consumed in the city of Salvador, Bahia. In the first chapter, two grams of mustard and chicory samples were digested in a block for two hours, using 3 and 4 mL, respectively, of acid and 1 mL of hydrogen peroxide, the minerals (Ba. Ca, Fe, K, Mg, Na, P, S e Zn) were determined using ICP OES. To validate the method, the merit parameters were obtained, the precision was between 0.2-8.8%, the LD and LQ values were considered satisfactory, and the accuracy evaluation was due to the use of the CRM NIST 1515 sheets of apple, which considering the t-test and the F-test, within a 95% confidence interval confirms the accuracy of the method. The different cooking methods were evaluated: steam, cooked in a conventional stove and microwave. With the results, it was possible to infer that the cooking process influences the composition and availability of nutrients, showing the pattern of nutrient loss: raw>steam>cooked>microwave, while the PCA and HCA allowed to recognize that the samples that passed by the same cooking method they formed the four distinct groups, indicating the similarity of the samples and the LDA allowed a clear separation of classes between the samples of each type of cooking, with rates of 100% selectivity, accuracy and without the presence of false positives or negative. In the second chapter, an adapted method was developed using the low temperature partition technique in order to determine twenty-six pesticides by GC-MS, consisting of the extraction of 4g of sample previously macerated with a combination of ethyl acetate/water ( 8:1, v/v), this mixture is vortexed for 10 min, centrifuged for 3 minutes at 300 rpm and taken to the freezer (-20ºC) until freezing, approximately 3h. The results obtained were satisfactory with good linearity (r2: 9936-0.9994), LD ranging from 0.1-0.4 μg L-1 and LQ ranging from 0.34-1.9 μg L-1. The inter and intra-day precision were within the reference parameters, between 6.3-23.4% and 2.7-18.3%, respectively. To verify the accuracy, three-level fortification recovery tests were performed and all results were above a 70% recovery. All data indicate that the method is robust, accurate and reliable. Of the twenty-five pesticides studied, three had concentrations below the detection limit and thirteen were not detected, indicating the absence of these substances in the samples, but three pesticides were detected with concentrations above the maximum limit allowed by legislation.