chemistry spreadsheet and

Make a graph of this data and determine the linear portion of the graph.

Determine the best linear curve through the data.

Determine the calibration sensitivity.

Compare the analytical sensitivities for 4 and 18 ppm. Verify the statements that distinguished the calibration sensitivity from analytical sensitivity.

Calculate the coefficient of variation for 10 ppm Pb’

6. Determine the signal at the detection limit. Sm=S

7. What is the concentration detection limit. Report the detection limit with confidence limits at a 95 and 99% confidence level. Comment on the range of the confidence limits at the two levels of confidence.

Requirements: 1 spreadsheet | .xls file

CHEM 3201L: Instrumental and Data Analysis Laboratory

Instrumental Analysis Computer Exercise

Introduction

The figures of merit can be used to determine whether an instrumental method is suitable for addressing an analytical problem. This laboratory exercise will consider investigate the concepts of precision, bias, sensitivity, detection limit, and the dynamic range. Students will also be introduced to spreadsheet calculations and linear-regression analysis.

Problem

Standard aqueous solutions of lead were measured by an instrumental method to determine the concentration of Pb in a sample. The following calibration data in arbitrary units were obtained:

Make a graph of this data and determine the linear portion of the graph.

Determine the best linear curve through the data.

Determine the calibration sensitivity.

Compare the analytical sensitivities for 4 and 18 ppm. Verify the statements that distinguished the calibration sensitivity from analytical sensitivity.

Calculate the coefficient of variation for 10 ppm Pb2+.

Determine the signal at the detection limit; .

What is the concentration detection limit. Report the detection limit with confidence limits at a 95 and 99% confidence level. Comment on the range of the confidence limits at the two levels of confidence.

The unknown sample gave a signal of 22.6 units. Determine the analyte concentration and confidence limits at a 95% confidence level. The confidence limits are given by x0 ? tsx0; where x0 = the analyte concentration, and t = a number corresponding to the number of degrees freedom (n ? 2) at a particular level of confidence. In our case, the number of degrees freedom is equal to the number of points on our calibration curve minus 2 giving us 6.

The value of sx0 is by:

where sy/x is a statistical parameter called the standard error and is used to determine the error in the slope and intercept of the regression line (y = bx + a);

Note that m = slope, a = the number of readings, and n = number of points on the calibration curve. You will have to calculate the numerator and the summation in the denominator of the last term.

You do not have to perform this calculation. Click the data tab in excel and look for Data Analysis? tab. If it is not available, then click File Options Add-Ins Analysis ToolPac Go Analysis ToolPac?. Conduct a data analysis and locate the standard error. You can now calculate the standard deviation associated with your sample and the confidence limits of your analyte concentration at a 95% confidence level.

9. What happens to the confidence interval as the number of replicate measurements increase? Prove your response by comparing the confidence interval obtained from a =1 and a = 4 using Equation 1.

10. Make a general statement relating the confidence interval and the number of replicate measurements.

11. The dynamic range extends from limit of quantitation (LOQ) to the limit of linearity (LOL). The LOQ is the smallest concentration of analyte that can be quantitatively be measured. The LOQ can be determined at ten times the standard deviation of the blank signal (10sbl = 10 x 0.004 units). The concentration that corresponds to a signal of 0.04 units is equal to ??.. The LOL is the concentration at which the curve departs from linearity.

Determine the standard deviations for the slope and intercept.

Determine the new concentration for each signal using the equation for the linear curve. Verify that these concentrations exactly correlate to the signals. The new concentrations are nearly the same as the original concentrations suggesting that there is a perfect correlation between the calculated signals and the original concentrations.

Calculate the 95% confidence limits for each concentration by using: x0 ? tsxo.

On the same graph, plot the calibration curve and the 95% confidence limits for each concentration. What region of the calibration curve has the smallest confidence interval?

**
Elitecustomessays.com Plagiarism Free Papers
**

Are you looking for custom essay writing service or even dissertation writing services? Just request for our write my paper service, and we\’ll match you with the best essay writer in your subject! With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.

**Why Hire Elitecustomessays.com writers to do your paper?**

Quality- We are experienced and have access to ample research materials.

We write plagiarism Free Content

Confidential- We never share or sell your personal information to third parties.

Support-Chat with us today! We are always waiting to answer all your questions.

The price is based on these factors:

Academic level

Number of pages

Urgency

Basic features

- Free title page and bibliography
- Unlimited revisions
- Plagiarism-free guarantee
- Money-back guarantee
- 24/7 support

On-demand options

- Writer’s samples
- Part-by-part delivery
- Overnight delivery
- Copies of used sources
- Expert Proofreading

Paper format

- 275 words per page
- 12 pt Arial/Times New Roman
- Double line spacing
- Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Delivering a high-quality product at a reasonable price is not enough anymore.

That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

Read moreEach paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

Read moreThanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

Read moreYour email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

Read moreBy sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Read more