Answer: 7. The level of ethyl acetate is determined in colchicines by headspace gas chromatography. A solution containing 4.361g/100 ml of colchicines in water was prepared. An aqueous standard containing 0.5912 mg/100 ml of ethyl acetate was also prepare. Headspace analysis of 2 ml volumes of the two solutions produced GC peaks for ethyl acetate with the following areas: Colchicines solution: Peak area 13457 Ethyl Acetate solution: Peak area 14689 Calculate the ethyl acetate content in the colchicines sample in pp,/

Answer: 7. The level of ethyl acetate is determined in colchicines by headspace gas chromatography. A solution containing 4.361g/100 ml of colchicines in water was prepared. An aqueous standard containing 0.5912 mg/100 ml of ethyl acetate was also prepare. Headspace analysis of 2 ml volumes of the two solutions produced GC peaks for ethyl acetate with the following areas: Colchicines solution: Peak area 13457 Ethyl Acetate solution: Peak area 14689 Calculate the ethyl acetate content in the colchicines sample in pp,/

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter8: Sampling, Standardization, And Calibration

Section: Chapter Questions

Problem 8.16QAP

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A scientist wishes to measure the concentration of methyl benzoate in a plant stream by gas chromatography. He prepares a sample of butyl benzoate to use as an internal standard. The results of a preliminary run, which used a solution known to contain 1.37 mg/mL of methyl benzoate (peak A) and 1.51 mg/mL of butyl benzoate (peak B), are shown. The area of peak A is determined to be 3.40×102 and the area of peak B is determined to be 398 measured in arbitrary units by the computer. To measure the sample, 1.00 mL of a standard sample of butyl benzoate containing 2.49 mg/mL is mixed with 1.00 mL of the plant stream material. Analysis of the mixture gave a peak area of 437 for peak A and 415 for peak B. What is the concentration of methyl benzoate in the plant stream?
Louie performed paper chromatography to identify which among the four availablereference mixtures — WAR, OFF, YIN, MEW — have the same components as hisunknown sample, GUN. He spotted the standards and the sample in a Whatman No. 1filter paper, which he placed in a developing chamber containing 3% KCl. After 20minutes, Louie obtained the chromatogram below, immediately noting that the distancetravelled by the solvent from the origin is 79.0 mm. On the other hand, the distances (incm) traveled by the developed spots were tabulated as follows.(see attached) Questions: 1. Is the type of paper chromatography performed normal or reversed? Why?2. Calculate the Rf of the spots from the samples. Report your answers in four decimal places.
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…
A brewed tea brand sample was subjected to solvent extraction to extract caffeine. The cup of tea measuring 200 mL was extracted with petroleum ether. With KD = 20.0 (caffeine in pet ether-water), the % caffeine (194.10) extracted after 3 extractions with a total of 75.0 mL pet ether used is: A. 97.7% B. 28.6% C. 71.4% D. 2.33%
A 25 g of butyric acid was extracted with 400 mL ether from 400 mL water (Kd=3.0 at 25 °C) Using single-step extraction, what is the amount of butyric acid in water layer? What is the total amount of butyric acid extracted using two successive extractions? Calculate the % efficiency of two-step extraction over single
4.Consider the peaks for pentafluorobenzene and benzene in the gas chromatogram shown here. The elution time for unretained solute is 1.06 min. The open tubular column is 30.0 m in length and 0.530 mm in diameter, with a layer of stationary phase 3.0 μm thick on the inner wall. a) Measruing the width, w, at the baseline on the chromatogram, find the number of plates for these two compounds b) Use your answer to (a) to find the resolution between the two peaks c) Using the number of plates N=sqrtN1*N2 with the values from (a) calcuate what the resolution should be and compare your answer with the measured resolution in b
1) How many milliliters of 70% ethanol and 20% ethanol must be mixed to prepare 500ml of 30% ethanol? 2) A gaseous blend of nitric oxide and nitrogen (NOmax) contains 0.09% v/v nitric oxide (NO) and 99.92% v/v nitrogen. Express the strength of nitric oxide in PPM (round to whole number) 3) The ratio strength of a 10mL vial of neostigmine methylsulfate injection USP is 1:1500.Calculate the amount of neostigmine methylsulfate in milligrams contained in the 10mL vial. (Round to the whole number).
which of the four binary mobile phase compositions (mixing ratio 1: 1) shown below will have the highest solvent strength ε ° on a normal phase hplc column? silica is used as a stationary phase. pentane + toluene methanol + acetone pentane + ethyl ethanoate propan-2-ol + ethyl ethanoate also need explaination why other options are incorrect
125.1 mg of streptomycin sulphate are dissolved in 10 ml of water. A GC headspace analysis is carried out in order to determine the methanol content of the drug. A peak for methanol is produced which has 73.2% of the area of a peak for a methanol standard containing 0.532 mg/100 ml of methanol in water analysed under exactly the same conditions, What is the methanol content of the streptomycin sulphate in ppm and %w/w? Answer: 311.3 ppm, 0.3113 % w/w.how??
Internal standard. A mixture containing 12.8 mM analyte (X) and 44.4 mM standard (S) gave chromatographic peak areas of 306 for X and 511 for S. A second solution containing an unknown quantity of X plus 55.5 mM S had peak areas of 251 for X and 563 for S. Find [X] in the second solution.
Oral rehydration salts are stated to contain the following components: Sodium Chloride 3.5g Potassium Chloride 1.5g Sodium Citrate 2.9g Anhydrous Glucose 20.0g 8.342 g of oral rehydration salts are dissolved in 500 ml of water. 5 ml of the solution is diluted to 100 ml and then 5 ml is taken from the diluted sample and is diluted to 100 ml. The sodium content of the sample is then determined by flame photometry. The sodium salts used to prepare the mixture were: Trisodium citrate hydrate (C6H5Na3O7, 2H2O) MW 294.1 and sodium chloride (NaCl) NW 58.5. Atomic weight of Na = 23. The content of Na in the diluted sample was determined to be 0.3210 mg/100 ml. Determine the % of stated content of Na in the sample. The stated should be 104.5, how??
Oral rehydration salts are stated to contain the following components: Sodium Chloride 3.5g Potassium Chloride 1.5g Sodium Citrate 2.9g Anhydrous Glucose 20.0g 8.342 g of oral rehydration salts are dissolved in 500 ml of water. 5 ml of the solution is diluted to 100 ml and then 5 ml is taken from the diluted sample and is diluted to 100 ml. The sodium content of the sample is then determined by flame photometry. The sodium salts used to prepare the mixture were: Trisodium citrate hydrate (C6H5Na3O7, 2H2O) MW 294.1 and sodium chloride (NaCl) NW 58.5. Atomic weight of Na = 23. The content of Na in the diluted sample was determined to be 0.3210 mg/100 ml. Determine the % of stated content of Na in the sample.