Direct chemical inspection of eye shadow and lipstick solid samples using laser-induced breakdown spectroscopy (LIBS) and chemometrics: proposition of classification models

Abstract

22mg kg -1 , 29 were correctly predicted and 1 sample was incorrectly predicted.Only 2 samples were considered as not belonging to any of the classes, and thus the model presented satisfactory results. In the case of PLS-DA, the average accuracy was 77%, and 3 latent variables were selected for each class. The KNN and SIMCA chemometric strategies presented good results for the two classes; however, the KNN model showed better accuracy (98% on average). Table 3 shows the results for KNN, SIMCA and PLS-DA and some figures of merit (%) for the proposed models (accuracy, sensitivity, false alarm rate and specificity). 42As can be noted in Table 3, the accuracy for KNN and SIMCA ranged from 96 to 98%. This parameter is related to the number of correct predictions. The average sensitivity for KNN was 97%. This parameter is related to the samples that belong to a certain class and were predicted to belong to the other class. The sensitivity for class 1 (below) in KNN, for example, was 94%, which means that one sample from class 2 (above) was predicted as class 1. On the other hand, the sensitivity for class 2 was 100%, which means that no sample from class 2 was predicted as class 1.The average sensitive was 97% ((94+100)/2). Specificity is the inverse of sensitivity, and false alarm rate for class 2, for example, is the number of samples from class 2 predicted as belonging to class 1 divided by the total

Laser Induced-Breakdown Spectroscopy (Libs): Histórico, Fundamentos, Aplicações E Potencialidades

“…68 A utilização dessas ferramentas são indispensáveis quando o objetivo é usar as informações espectrais para proposição de modelos de classificação. As ferramentas referidas foram empregadas com sucesso na proposição de modelos de classificação para amostras de ligas metálicas, 43 polímeros, 44 couros, 86 cosméticos, 87 pinturas pré-histórica, 88 forense, 89 rochas vulcânicas 90 entre outros. [91][92][93] Os métodos não supervisionados de reconhecimento de padrões, como a principal component analysis (PCA) e hierarchical cluster analysis (HCA) também são empregados.…”

Direct solid sample analysis of low-cost jewelry using spectroanalytical techniques: exploratory chemical data evaluation and metal migration with synthetic sweat

“…3 Furthermore, the toxic effects of Cd and Pb are already known for humans, especially for children, where neural development can be compromised, oen leading to death due to the ingestion of these metals. 4,5 These metals can also be found in toys, 6,7 cosmetics, 8,9 school supplies, 10 and jewelry destined to children,. 11,12 When in prolonged contact with sweat, it promotes several reactions due to the presence of electrolytes in the corporal uids, releasing metallic ions (M n+ ).…”

Electrochemical Characterization and Detection of Lead in Water Using SPCE Modified with BiONPs/PANI

“…However, the detection of heavy metals is a complicated procedure, often involving widespread processes of preparation of sample leading to the measurement, when analytical techniques are employed [15]. Such standard techniques for the detection of heavy metal ions such as inductively coupled plasma optical emission spectrometry (ICP-OES) [16][17][18], UV-Vis spectrometry, [19][20][21] atomic absorption/emission spectroscopy [22][23][24] and laser-induced breakdown spectroscopy (LIBS) [25,26], would not be suitable for in situ, fast, easy and low-cost operation.…”