A new method was created to determine arsenic in rice. To validate this method, a reference standard was used with a certified concentration of 2.1 ppm of Arsenic, with a standard deviation of 0.7 ppm . When analyzing the reference standard 7 times, with the new method, an average of 2.87 ppm was obtained with a standard deviation of 0.4 ppm. These results show that the new method Has it been validated? Does it have systematic errors? Has a precision similar to that of the reference standard

A new method was created to determine arsenic in rice. To validate this method, a reference standard was used with a certified concentration of 2.1 ppm of Arsenic, with a standard deviation of 0.7 ppm . When analyzing the reference standard 7 times, with the new method, an average of 2.87 ppm was obtained with a standard deviation of 0.4 ppm. These results show that the new method Has it been validated? Does it have systematic errors? Has a precision similar to that of the reference standard

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter16: Applications Of Neutralization Titrations

Section: Chapter Questions

Problem 16.17QAP

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How would you calculate Standard Deviation?
8) Two different analytical methods are compared for determining Ca. The following are two sets of data. Set 1 Set 2 155.779 155.784 155.787 155.787 155.813 155.765 155.781 155.793 i. i. Determine the mean and the standard deviation in Set 1. Calculate the 95% confidence limit for data in Set 1. Identify a possible outlier in Set 2. Use the Q-test to determine whether it can be retained or rejected at 95% confidence level. ii.
Calculate the standard deviation for an element whose % in a sample were found to be20.8, 21.6, 22.1, 22.0, 23.3, 21.9 and 22.8%
An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling 30 triplicate analyses to have a standard deviation s = 3.1 µg Fe/mL. If s is a good estimate of o, calculate the 95 and 99% confidence intervals for the result 21.7 µg Fe/mL if it was based on the following criteria. (a) a single analysis 95% confidence interval= 21.7 + 99% confidence interval = 21.7 + (b) the mean of two analyses 95% confidence interval = 21.7 + 99% confidence interval= (c) the mean of six analyses 21.7 ± 95% confidence interval = 21.7 + 99% confidence interval= 21.7 + μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL
6 A new method for the determination ofanthracene in crude oil is in the developmental phase. Preliminary results using the new method give a standard deviation of 3 ppm when 5 replicates are used. The ‘traditional’ method gives a standard deviation of 7 ppm when 4 replicates are used. Is there a significant difference in the standard deviations for these methods at 95% CL?
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Titration of an oxalate sample gave the following percentages: 15.07 % , 15.58 % , and 15.42 % . Calculate the average. Calculate the standard deviation.
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