Question 33 use the following standard chromatogram of caffeine: 80 I mg/L 5 mg/L 10 mg/L 20 mg/L 30 mg/L 40 mg/L 50 mg/L 60 40 20s 20 Concentration (mg/L) 7.0 7.5 8.0 8.5 9.0 Retention Time (min) Which of the following statements best describe the chromatogram? Multiple runs of caffeine prepared at different concentrations. One run of a mixture of caffeine prepared at different concentrations. One run of caffeine prepared at different conditions, injected at different times. O Multiple runs of a mixture of caffeine prepared at different concentrations. Intensity (mV)

Question 33 use the following standard chromatogram of caffeine: 80 I mg/L 5 mg/L 10 mg/L 20 mg/L 30 mg/L 40 mg/L 50 mg/L 60 40 20s 20 Concentration (mg/L) 7.0 7.5 8.0 8.5 9.0 Retention Time (min) Which of the following statements best describe the chromatogram? Multiple runs of caffeine prepared at different concentrations. One run of a mixture of caffeine prepared at different concentrations. One run of caffeine prepared at different conditions, injected at different times. O Multiple runs of a mixture of caffeine prepared at different concentrations. Intensity (mV)

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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Table of caffeine standards concentration . Sample Conc, ppm Std1 16 Std2 32 Std3 48 Std4 64 Std5 80 If the volume used to make 100 mL of std 1 is 2 uL what is the concentration in M used to make std calibration curve ? The standards are going to be used to build calibration curve to analyze caffeine in an energy drink. if 500 mL of the energy drink has target of 400 mg , how will you prepare the sample if you need 10 mL for the analysis ? Caffeine MM=194.19 g/mol.
Hydrocarbons in the cab of an automobile were measured during trips on the New Jersey Turnpike and trips through the Lincoln Tunnel connecting New York and New Jersey. The total concentrations ( ± standard deviation) of m- and p-xylene wereTurnpike: 31.4 ± 27.0 μg/m3 (32 measurements)Tunnel: 54.9 ± 29.8 μg/m3 (32 measurements)Do these results different at the 95% confidence level?
Choose correct letter of the answer. 1. Column/s used for normal phase chromatography- a.ODS b. C18, C8 c. silica, alumina d. ODS silica gel 2. The following statements are true for any chromatographic analysis except:a. The analyte component interacting most strongly with the stationary phase elute faster than those with weaker interactions. b. On the other hand, those with least interaction with the mobile phase elute the slowest. c. Interactions between mobile phase – analyte – stationary phase can be both chemical and physical in nature. d. Chromatography is a separation technique.
Q4 (a) Analyze the importance of dropping mercury electrode on polarography. (b) (i) Calculate the molarity of MgSO4 in a solution containing 1.5 g ofMgSO4 in a volume of 250 mL?(ii) Calculate the weight of MgSO4 in grams which is present in 100mL of 0.076 M MgSO4?(c) Evaluate the key differences between paper chromatography and gaschromatography
Replicate water samples are analyzed for water hardness with the following results: 102.2, 102.8, 103.1, and 102.3 ppm CaCO3. What is the (a) the standard deviation, (b) the relative standard deviation, (c) variance.
In thin-layer chromatography, what is the Rf value of a compound if the solute travels 2.9 cm and the solvent moves 4.5 cm after 5 minutes? Note: Express answers up to TWO decimal places.
5. A new method for measuring NO2 in air was developed and compared to a conventional method with the results summarized in the following table: Method Average concentration (ppb) Standard deviation (ppb) Number of measurementsConventional 56.0 3.1 7New 51.9 2.8 8 a) Is the standard deviation for the new method significantly different from that of the conventional method? b) Does the new method give an average concentration similar to the conventional method at the 95% confidence level?
2. A study of body mass index (BMI) in adults showed that for men aged 40–44, the mean BMI level is 26.7 with a standard deviation of 3.7. Assuming a normal distribution, what percentage of men in this age group have a BMI between 30.0 and 35.0?
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.
In a thin layer chromatography (TLC) experiment, solute A traveled 20 mm while solute B traveled 30 mm. The solvent traveled 40 mm. Which has the greater affinity for the solvent? a. not enough data b. solute B c. solute A d. both A & B have equal affinity
Chromatography 1. External Standard Method A. Calculate the regression equation and the R-squared value. B. Calculate the concentration of cocaine found in the blood samples of the presidentiables. Which presidential candidate “reliably” tested positive for cocaine? 2. Internal Standard Method >Calculate the concentration of party drug X in the blood samples of the presidential candidates. >Suppose the LOD for party drug X is 0.200 ppm, which of the presidential candidates “reliably” tested for party drug X?
The gravimetric factor used to express CoCBr6·H20 in a sample that is finally weighed as PbClBr is choose below: FW PbClBr / 6 x FW CoCBr6·H20 FW CoCBr6·H20 / FW PbClBr FW CoCBr6·H20 / 6 x FW PbClBr 6 x FW PbClBr / FW CoCBr6·H20