Exam (elaborations)
Entregas Análisis Ambiental
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Ejercicios obligatorios de la asignatura análisis ambiental
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ANÁLISIS QUÍMICO AMBIENTALACTIVIDAD 1 (fecha de entrega 1 de marzo de 2024)
ALUMNO Fatima Zohra Saffar
PROBLEMA
Se puso a punto un nuevo método para llevar a cabo la determinación del contenido total de
arsénico en muestras de hígado de ciervo.
Para evaluar el método se analizó una muestra de hígado bovino que contenía una cantidad
certificada de arsénico (0,360±0,038 µg/g). Se realizaron 8 determinaciones repetidas que se
muestran a continuación:
0,343
0,340
0,361
0,345
0,349
0,369
0,336
0,358
Calcular:
a) Si el valor de concentración 0,336 µg/g fuera sospechoso, ¿se debería aceptar o
rechazar?
(x-media)^2
1 0,343 0,000051
2 0,340 0,000103
3 0,361 0,000118
4 0,345 0,000026
5 0,349 0,000001
6 0,369 0,000356
7 0,336 0,000200
8 0,358 0,000062
suma 2,801 0,000917
Media =2.801/8=0.350
0.000917
Desviación estándar= √ =0.011
8−1
Grado de libertad = n-1= 8-1=7
t de student (7, 95%)= 2.36
0.011
Intervalo de confianza=0.350 ± 2.36 × = 0.350 ± 0.0092 (si la haces con Excel
√8
sale 0.350±0.0095)
➢ Cota superior = 0.350+0.0092=0.359
➢ Cota inferior =0.350-0.0092=0.341
Conclusión→ el valor de concentración 0,336 µg/g se debe rechazar.
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