A titrimetric method for the determination of calcium in limestone was tested with the analysis of a NIST limestone containing 30.15% CaO. The mean of the four analyzes is 30.26% CaO with a standard deviation of 0.085%. From the data accumulated from many analyzes, s→ϭ=0.094% CaO was found. a) Do the data indicate the presence of systematic error at the 95% confidence level? b) When a value for ϭ is unknown, do the data show a systematic error at the 95% confidence level?

A titrimetric method for the determination of calcium in limestone was tested with the analysis of a NIST limestone containing 30.15% CaO. The mean of the four analyzes is 30.26% CaO with a standard deviation of 0.085%. From the data accumulated from many analyzes, s→ϭ=0.094% CaO was found. a) Do the data indicate the presence of systematic error at the 95% confidence level? b) When a value for ϭ is unknown, do the data show a systematic error at the 95% confidence level?

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter3: Statistical Tests With Excel

Section: Chapter Questions

Problem 2P

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A titrimetric method for the determination of calcium in limestone was tested by analysis of an NIST limestone containing 30.15% CaO. The mean result of four analyses was 30.26% CaO, with a standard deviation of 0.085%. By pooling data from several analyses, it was established that s   = 0.094% CaO.a. Do the data indicate the presence of a systematic error at the 95% confidence level?b. Do the data indicate the presence of systematic error at the 95% confidence level if no pooled value for s was available?
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.
Titration of an oxalate sample gave the following percentages: 15.07 % , 15.58 % , and 15.42 % . Calculate the average. Calculate the standard deviation.
A method for the determination of the corticosteroid methylprednisolone acetate in solutions obtained from pharmaceutical preparations yielded a mean value of 3.7 mg mL with a standard deviation of 0.3 mg mL. For quality control purposes, the relative uncertainty in the concentration should be no more than 3%. How many samples of each batch should be analyzed to ensure that the relative standard deviation does not exceed 9% at the 95% confidence level? samples
For the determination of iron in used jet engine oil, 30 analyzes with 3 repetitions each were made by atomic absorption method and the standard deviation was found s=2.4 µg Fe/mL. Since this standard deviation value is close to the ϭ value, the iron concentration of 18.5 µg Fe/mL(a) by a single analysis,(b) as the average of the two analyzes,(c) Calculate the 80% and 95% confidence intervals if found as the mean of four analyses.
A method for the detection of morphine is used to generate a calibration curve in which the assay response (y) is plotted versus morphine concentration (x, in mg/L). This gives a straight line with a slope (m) of 0.241 and a y-intercept (b) of 0.011, where y = mx + b. The slope of this line has a standard deviation of ±0.007, and the standard deviation of the intercept is ±0.006. If the sample from an athlete gives a response of 0.506 ± 0.013 in this method, what is the concentration of morphine in the sample and estimated precision of this concentration?
[References) A method for the determination of the corticosteroid methylprednisolone acetate in solutions obtained from pharmaceutical preparations yielded a mean value of 3.7 mg mL with a standard deviation of 0.3 mg mL. For quality control purposes, the relative uncertainty in the concentration should be no more than 3%. How many samples of each batch should be analyzed to ensure that the relative standard deviation does not exceed 9% at the 95% confidence level? samples
To test the quality of the work of a commercial laboratory, duplicate analyses of apurified benzoic acid (68.8% C, 4.953% H) sample were requested. It is assumed that therelative standard deviation of the method is sr →  = 4 ppt for carbon and 6 ppt forhydrogen. The means of the reported results are 68.5% C and 4.882% H. At the 95%confidence level, is there any indication of systematic error in either analysis?
(a) For use in an iodine titration, you prepare a solution from 0.222 2 (+0.000 2) g of KIO3 [FM 214.001 0 (+0.000 9)] in 50.00 (+0.05) mL. Find the molarity and its uncertainty with an appropriate number of significant figures. (b) Would your answer be affected significantly if the reagent were only 99.9% pure?
In a volumetric determination of an analyte A, the data obtained and their standard deviations are as follows: Initial buret reading 0.19 mL 0.02 mL Final buret reading 7.86 mL 0.03 mL Sample mass 63.0 mg 0.2 mg From the data, find the coefficient of variation of the final result for the %A that is obtained by using the equation that follows and assuming there is no uncertainty in the equivalent mass. %A= titrant volume x equivalent mass x 100 %/ sample mass Coefficient of variation = Submit Answer % Try Another Version 10 item attempts remaining
Suppose that a lead determination has a standard deviation of 3 mg. If the sample has a mean value of 60 mg, the CV is 5%. For a sample containing only 15 mg, the CV is
A young researcher was evaluating a standard method for determining the methylmercury content in blue fin tuna using high performance liquid chromatography (HPLC). She determined the standard deviation (?)(s) for the method to be 0.440.44 ppb and assumed that ?s was a good approximation of ?σ . As a test, she used this method to evaluate the methylmercury content in a National Institutes of Standards and Technology (NIST) standard and determined the unknown amount to be within 0.210.21 ppb (?)(μ) of the known mean with 99% probability. How many replicate measurements of the NIST standard did the researcher perform?