Lab Report 5_CH 237-016

PART ONE: Preparation of FECNS* Solution Prepare the two solutions in table 1 by accurately measuring the required volumes of distilled water and CNS into two labeled test tubes. The absorbance of the solutions must be measured soon after adding the Fe" solution from a buret. TABLE 1 Fe 5 ml 5S mL Solution Distilled Water CNS 2 mL Total Volume 3 ml 2 ml 10 ml 3 mL 10 ml In this part of the experiment you are to explore what the above quote means. As a PRELIMINARY Exercise, formulate a hypothesis as to what would happen under each of the following circumstances: 1. 1ml of 0.0020 M CNS' solution is added to the unused portion of solution 1 in the test tube 2. One drop of 0.20 M CNS solution is added to the unused portion of solution 2 in the test tube.

How does ammonia, dimethylglyoxime (DMG), and 8-hydroxyquinoline (8HQ) interact with your cations, leading to the evolution of colored species?   Context: Paper chromatography experiment (separation of inorganic cations) with a 9:1 acetone/ HCl solvent

Identify the detectors in gas chromatography that can be used for the detection of each type of analyte. More than one detector may be appropriate for a given analyte, and a given detector may be appropriate for more than one type of analyte. compounds ionized by UV radiation sulfur or nitrogen containing compounds halogenated compounds flame ionization Answer Bank mass spectrometer nitrogen and phosphorous containing compounds thermal conductivity electrolytic conductivity hydrocarbons electron capture thermionic photoionization

Three students did a chromatography experiment, where Rf = distance of solute / distance of solvent. What could be the possible errors why student 3 had results that are quite far from that of students A and B?

4) If the classification of the chromatography run is a reverse-phase chromatography, discuss the relative polarities of caffeine, aspartame and benzoate

Why chromatography is an important tool for analysis of organic compounds?

use the following chromatogram and table as your data.       What is the %composition of the Vitamin A peak in the sample?     78.43%        77.73%     7.867%       72.74%

Explain the following Chromatography (for drug analysis) Thin-layer chromatography (TLC) Gas chromatography (GC) Liquid chromatography (LC) (i.e, high performance liquid chromatography or HPLC)

D. Solvent Extraction Samples Upper phase Lower phase Oil + Water Kerosene + Oil

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An oil sample had its iodine number determined using the pyridinium tribromide method. The sample and reagents used are as follows: Oil sample: 0.19 mL, density: 0.954 g/mL Pyridinium tribromide: 0.472 g Na2S203: 0.1 M, endpoint 27.68 mL %3D What is the approximate Bromine Number? O 138 89 O 120 O 200

Consider the following molecules. Which statement(s) is TRUE? CH3 CH3 но ČH3 но ČD3 i. You could differentiate between the two with a spot test. ii. You could differentiate between the two with liquid chromatography. iii. You could differentiate between the two with TLC. iv. You could differentiate between the two with a microcrystalline test. O a. i and iv only O b. ii and iii only O c. iii only O d. i only e. Neither i, ii, iii, nor iv are correct statements.

PLEASE Answer within 20-30 minutes. Thank you!

A student performed a chromatography experiment to determine the Rf value of an unknown amino acid. The distances traveled by the amino acid and the solvent line were 3.0 cm and 8.5 cm, respectively. What is the Rf value for this amino acid? 0.3 cm O 0.35 1.8 5.5 0.85 cm 0.65 O 2.8

The protein concentration of a protein isolate was determined using the Bradford assay. Five dilution of bovine serum albumin (BSA) were prepared from a 5.00 mg/mL BSA stock solution. To these dilutions, 100 µl of Bradford reagent were added. After 5 minutes, the absorbance was taken at 595 nm. Standard # BSA, in mg/mL Volume of Bradford reagent, A595 in mL 1 5.0 0.000 1.00 5.0 0.134 3 2.00 5.0 0.265 4 3.00 5.0 0.388 4.00 5.0 0.497 The supernatant dilution was prepared by mixing 49 µL of the protein isolate with 16 µL water. The absorbance was taken 5 minutes after addition of 100 mL Bradford reagent. Calculate the protein concentration (in mg/mL) of the original isolate if the absorbance at 595 nm was 0.413. Note: Final answer format must be x.xxx (three decimal places). Round off only in the final answer. Do not round off in the middle of calculation.

The spectroscopic data in the table is generated with five solutions of known concentration. Concentration (M) 0.0133 m= 0.0266 0.0532 0.106 0.213 Absorbance 0.1271 What is the intercept of the linear regression line? 0.08531 0.5388 1.069 Use a spreadsheet program, such as Microsoft Excel, to graph the data points and determine the equation of the best-fit line. 1.954 What is the slope of the linear regression line formed by these points? M-1

Which is correct?     Random errors affect accuracy and systematic errors affect precision.     An accurate result shows agreement with the true or accepted value.     Precise results can contain significant random error, but little systematic error.     The standard deviation is a good measure of accuracy.   Polydimethylsiloxane (PDMS) stationary phases have low polarities.  Which of the following statements is TRUE about gas chromatography using PDMS stationary phases?     The gas chromatography column is typically packed with silica microparticles.     An oven is used to control the column temperature because a constant temperature is always needed in gas chromatography     Octane (C8H18, boiling point: 126 ºC) is eluted later than dodecane (C12H26, boiling point: 216 ºC)     3-Pentanone ((C2H5)2CO, boiling point: 102 ºC) is eluted later than propanol (CH3CH2CH2OH, boiling point: 97 ºC)

The spectrophotometer is set at 600 nm. The absorbance of each cuvette is read. The data is shown below: Cuvette 1 is the clank Cuvette # ml albumin Absorbance 0. 0.2 .063 3 0.4 .163 4. 0.6 .187 0.8 .253 1.0 .289 Using this data, plot an Excel graph showing absorbance (y-axis) vs ml albumin (x-axis). Find the correlation coefficient (r). R2 > 0.99 = excellent data; r2 0.98-0.95 good data r2 0.94 -0.90 = fair data. How would you describe this data?- To find the relative sensitivity, for each of tubes 2-6 (neglect blank), perform the following operation absorbance (Lowry)/Absorbance (Biuret x 0.5 gram albumin (Biuret)/0.05 gram (Lowry) x 200 ml (Lowry)/100 mL (Biuret). This implifies to Relative sensitivity = 20 dilution factor x absorbance (Lowry)/Absorbance (Biuret). Report your relative sensitivity as an average of all 5 values.

What are the differences between systematic and random errors and how do they effect accuracy and precision?   In what circumstances would you use standard addition (versus a normal calibration curve) to determine the amount of an analyte in a sample?   A urine sample, containing analyte Z is analysed by the standard addition method where 5 mL of the original sample was mixed with increasing amounts of a Z standard and each solution diluted to a volume of 50 mL prior to analysis. A plot of the final concentration of the standard in each of the 50 mL samples (x axis) versus   The measured signal from the analysis of each 50 mL sample (on y axis) produced a straight line with the general equation:   y = 44.72x + 4.06   what was the final concentration of Z in the 50 mL standard addition sample? what was the initial concentration of Z in the original urine sample?

Question:  Using a sample of aspirin for HPLC analysis. If the aspirin was contaminated (wet) with trace amounts of a solvent such as ethyl acetate, hexane, or water, would this contaminant be detected and appear as a peak in the HPLC chromatogram? Briefly explain based on the type of detector used in HPLC analysis and what type of compounds can be detected. My Answer: The HPLC analysis detects chromophores, compounds with multiple double bonds. Since water, ethyl acetate, and hexane all lack multiple pi bonds this will not be detected in the HPLC.  -Question for you, is this complete (and correct), and should I include anything about UV detection? Is UV detection used in HPLC? I thought it was only used on TLC to show compunds that arent visable.

How else can chromatography be used?   None of these answers are correct.   To wash (or remove) unwanted solvents from a mixture.   To identify or exclude components in a mixture.   To generate IUPAC names for hydrocarbons.

anch of the following components cannot be detected by gas chromatography? 4 Essential oils Alcohols b) Volatile compounds d) Non-volatile compounds 13- is measured as time elapsed from the point of injection to the peak maximum? a)-Column efficiency d)- Delectability c)-Retention time 14- Which of the following can be used to detect the components in gas chromatography a) non-volatile compounds b) volatile compounds c) Salts d) b&c 15-Which of the following methods is often referred to as mechanical separation processes. a)-Gas Chromatography b)-column chromatography c)- Sedimentation 16- For obtaining better resolution in TLC. and then developed with a second solvent at right angles to the first a) Stepwise b) Descending e) Ascending 17- This is defined as transport of electrically charged particles in a direct-current electric field a) ion exchange chromatography b) Electrophoresis c) ultracentrifuge d) exclusion 18-This figure indicates to schematic Diagram of a) Gas chromatography…

Table 2: Absorbance Values of Standards and Unknowns. Sample Blank Standard Solution 1 Standard Solution 2 Standard Solution 3 Standard Solution 4 Standard Solution 5 Water Sample 1 Water Sample 2 Phosphate Concentration (in ppm) Y17 0 ppm 0.02 ppm 0.04 ppm 0.08 ppm 0.16 ppm 0.32 ppm Freeman Lake 0.001 0.325 0.292 0.413 0.315 0.039 0.054 0.049 Absorbance at 2= 690 nm Calculations: 1. Construct a phosphate standard curve in Excel by plotting concentration (in ppm) on your x-axis and Absorbance (unitless) on your y-axis for your known solutions. Label the axes on the graph and provide the curve with a title. Use a linear trendline to generate a best fit line to your data. Label the graph with the equation and the R" value. Insert your labeled graph in the space below. X

The amount of caffeine in an analgesic tablet was determined by HPLC using a normal calibration curve. Standard solutions of caffeine were prepared and analyzed using a 10-µL fixed-volume injection loop. Results for the standards are summarized in the following table. Concentration of Standards Signal (arbitrary units) (ppm) 50.0 8354 100.0 16925 150.0 25218 200.0 33584 250.0 42002 The sample was prepared by placing a single analgesic tablet in a small beaker and adding 10 mL of methanol. After allowing the sample to dissolve, the contents of the beaker, including the insoluble binder, were quantitatively transferred to a 25-mL volumetric flask and diluted to volume with methanol. The sample was then filtered, and a 1.00-mL aliquot was transferred to a 10-mL volumetric flask and diluted to volume with methanol. When analyzed by HPLC, the signal for the caffeine was found to be 21469. Report the number of milligrams of caffeine in the analgesic tablet.

Color BEFORE adding Color AFTER adding Intensity of color AFTER adding FeCl3 Test Tube # FeCl3 FeCl3 #1 (salicylic acid) clear lilac 100% #2 (commercial aspirin A) clear slightly pink 50% #3 (commercial aspirin B) clear lilac 95% #4 (aspirin from your clear pink 20% synthesis above) #5 (control) clear clear 0% Based on this data and the melting point of Aspirin, how pure is the synthesized product?

What is the relative abundance of 35Cl in this sample? 42.9%, 57.1%, or 52.8%

■ True or False: in a TOF analyzer, a fragment of low mass reaches the detector first ▪ In GCMS when we know what analytes we are measuring we use not know what analytes are in the sample we use than scan. ▪ A) Scan; SIM ■ B)SIM; scan • C) SIM; SIM mode. When we do mode. SIM allows greater sensitivity

Can paper chromatography be used to separate and identify very volatile substances? Why? Please explain comprehensively.

In spectrophotometry, does the sample tested contain the allowable concentration of Allura red as prescribe by the FDA?