Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used whenA) the quantity of sample analyzed or the instrument response varies from run to run. B) the standard solutions and the unknown solution all have similar characteristics are unaffected by the other material in the sample. C) the sample composition is unknown or complex and affects the analytical signal.

Analytical chemistry is a branch of chemistry that deals with the separation and identification of…

Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used when

Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used when

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter4: Least-squares And Calibration Methods

Section: Chapter Questions

Problem 12P

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The method of standard additions was used to determine nitrite in a soil sample. A 1.00-mL portions of the soil extract sample was transferred to four 25-mL volumetric flasks. To each flask, increment volumes of a 1.00 x10-3M nitrite was added according to the table below. A colorimetric reagent was added to each flask to convert the nitrite into a colored product, and finally diluted to volume. What is the concentration of the nitrite in the soil extract based on the absorbance data below (with blank correction included)? Vol. of standard nitrite added, ml Absorbance 5.00 0.079 10.00 0.161 15.00 0.236 20.00 0.318 25.00 0.403
a sample of butyl benzoate is prepared to use as an internal standard. The results of a preliminary run, which used a solution known to contain 1.53 mg/mL of methyl benzoate (peak A) and1.68 mg/mL of butyl benzoate (peak B), are shown. The area of peak A is determined to be 352 and the area of peak B is determined to be 416 measured in arbitrary units by the computer. To measure the sample, 1.00 mL of a standard sample of butyl benzoate containing 2.19 mg/mL is mixed with 1.00 mL of the plant stream material. Analysis of the mixture gave a peak area of 449 for peak A and 411 for peak B. What is the concentration of methyl benzoate in the plant stream? concentration of methyl benzoate = ____________________ mg/mL
A. A group of students are doing an analysis of copper in 1-peso coin. They were tasked to prepare standard solutions and weigh the analyte as the end-product of their experiment. Explain the type of error they are incurring in their experiment. A. Marikit had very good precision but poor accuracy in her data. B. Volumetric flasks were placed inside the oven for drying before it was used. C. Trial 1 and 2 have values close to 30.0 mL while trial 3 gave 55.0 mL. D. The reagent used in determining copper was added incorrectly and gave a low yield.
A variation of the indicator-dilution method (see preceding problem) is used to measure total blood volume. A known amount of a tracer is injected into the bloodstream and disperses uniformly throughout the circulatory system. A blood sample is then withdrawn, the tracer concentration in the sample is measured, and the measured concentration [which equals (tracer injected)/(total blood volume) if no tracer is lost through blood vessel walls] is used to determine the total blood volume.In one such experiment, 0.60 cm3 of a solution containing 5.00 mg/L of a dye is injected into an artery of a grown man. About 10 minutes later, after the tracer has had time to distribute itself uniformly throughout the bloodstream, a blood sample is withdrawn and placed in the sample chamber of a spectrophotometer. A beam of light passes through the chamber, and the spectrophotometer measures the intensity of the transmitted beam and displays the value of the solution absorbance (a quantity that…
I got a task in analytical chemistry to calibrate, standardize, verify and validate an analytical balances
Preparation of 0.25N NaOH Objective: Apparatus and Materials: Procedure : Calculate the exact mass of NaOH needed to prepare 1.0L of 0.25N NaOH for standardization. Show your computations. Using the triple beam balance, weigh the desired amount of NaOH. Place the weighed amount of NaOH into the 500 mL volumetric flask and add distilled water until it reaches the mark. Agitate and transfer the solution into the reagent bottle. Add again distilled water to the same volumetric flask until it reaches the mark and pour it to the same reagent bottle, thus having a total volume of 1.0 L. Label the reagent bottle, 0.25N NaOH. Data and Computations: Conclusion:
The concentration of purified OXA-M290 is tested with a BCA assay. Serial dilutions of a bovine serum albumin (BSA) stock solution are prepared, then pipetted into a 96-well plate; each dilution of the BSA standard is tested in triplicate. Then, bicinchoninic acid and Cu2+ ions are added to all of the wells of the plate. After incubating the plate for 1 hour, a microplate reader is used to measure the absorbance of all of the wells in the plate at 560 nm. This generates the following data: BSA conc. (μg/mL), Replicate 1 Absorbance, Replicate 2 Absorbance, Replicate 3 Absorbance 40, 1.360, 1.403, 1.481 20, 0.750, 0.745, 0.810 10, 0.380, 0.344, 0.398 5, 0.198, 0.160, 0.183 2.5, 0.090, 0.100, 0.085 1.25, 0.038, 0.043, 0.051 0.625, 0.024, 0.028, 0.019 Prepare a calibration curve using these data. You can use Excel, R, SPSS or an equivalent graphing software. In this graph, plot absorbance (y-axis) against the concentration of the protein standard (x-axis). Calculate and plot…
25 ml of pickled brine was taken from an apple pickled with vinegar and diluted to 500 ml, 25 ml of this was taken and acidity was determined with 0.2 N (Factor: 1.05) NaOH. In the main trials, 6.3 ml - 6.5 ml - 6.9 ml, respectively, 0.1 ml base was used in the analysis without using the sample.For example, how many ppm is its acidity?
In a chromatography experiment, a solution containing 0.083 7 M X and 0.066 6 M S gave peak areas of AX = 423 and AS 5 347. (Areas are measured in arbitrary units by the instrument.) To analyze the unknown, 10.0 mL of 0.146 M S were added to 10.0 mL of unknown, and the mixture was diluted to 25.0 mL in a volumetric flask. This mixture gave the chromatogram in Figure 5-8, with peak areas AX = 553 and AS = 582. Find the concentration of X in the unknown.
Here is a use objective for a chemical analysis to be performed at a drinking water purification plant: “Data and results collected quarterly shall be used to determine whether the concentrations of haloacetates in the treated water demonstrate compliance with the levels set by the Stage 1 Disinfection By-products Rule using Method 552.2” (a specification that sets precision, accuracy, and other requirements). Which one of the following questions best summarizes the meaning of the use objective?(i) Are haloacetate concentrations known within specified precision and accuracy?(ii) Are any haloacetates detectable in the water?(iii) Do any haloacetate concentrations exceed the regulatory limit?
Determine the concentration of linalool in a highly valued lavender essential oil. The peak areas of a series of standard solutions (calibrations standards) acquired from GC-MS (gas chromatography-mass spectrometry) is presented below. Concentration (mg/L) Peak area 0 201 25 5214 50 14658 75 23647 100 32657 125 42652 150 52478 QUESTION: Calculate the concentration of linalool in yourhighly valued lavender essential oil which returns a peak area of 27235.
Standardization of Sodium Thiosulfate Solution Primary Standard used: Potassium Dichromate Formula mass of 1o standard: __________________ % Purity of 1o standard: 99.80% Trials 1 2 3 Weight of K2Cr2O7 (g)Weight of K2Cr2O7 (g) 0.0315 0.0331 0.0380 Final Volume Reading Na2S2O3 (ml) 27.50 27.50 34.90 Initial Volume Reading Na2S2O3 (ml) 1.10 0.00 1.00 Net Volume Na2S2O3 used (ml) Molarity of Na2S2O3