Tim is interested in analyzing for Pyraclostrobin (pesticide) in strawberries using QuECHers method for extraction and clean up before analysis with HPLC-uv. The concentration of the Pyraclostrobin in the fruits that he sampled is thought to be between 1-10 ng pesticide per g fruit fresh weight. The HPLC-uv instrument he is using has a LoQ of 5 ppb for Pyraclostrobin. Tim is starting out with 500 mg of the sliced fruit

Tim is interested in analyzing for Pyraclostrobin (pesticide) in strawberries using QuECHers method for extraction and clean up before analysis with HPLC-uv. The concentration of the Pyraclostrobin in the fruits that he sampled is thought to be between 1-10 ng pesticide per g fruit fresh weight. The HPLC-uv instrument he is using has a LoQ of 5 ppb for Pyraclostrobin. Tim is starting out with 500 mg of the sliced fruit

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter27: Gas Chromatography

Section: Chapter Questions

Problem 27.19QAP

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▪ In a blood alcohol analysis by GC-FID, methanol elutes at 1 min, ethanol at 2 min, IPA at 3 min, and IS at 4 min. In the patient sample, the analyte elutes t 2 min and the IS at 8 min. What is the relative retention time and the analyte in the patient? A) methanol B) Ethanol chu C) IPA
A young researcher set out to develop a method for quantifying the polycyclic aromatic hydrocarbon (PAH) content in a contaminated soil sample using open tubular gas chromatography. During the initial stages of method development, the researcher was unable to separate the early eluting compounds, anthracene and naphthalene, with baseline resolution. Select the possible modifications the researcher could make to improve the resolution. use a column with a smaller inner diameter decrease the column length increase the stationary phase thickness increase the temperature choose a different stationary phase
Below is the procedure described for determination of paracetamol according to BP: "Weigh and powder 20 tablets. Add a quantity of powder equivalent to about 0.35 g paracetamol to 50 ml of 0.1 M NaOH, dilute with water to 200 ml and shake for 15 min. Add sufficient water to make up 250 ml. Filter the solution and dilute 5 ml of the filtrate to 100 ml with water. Dilute further 10 ml to 100 ml. Measure the absorbance at 257 nm. The A," following is correct? 715 at 257 nm". Which of the O a. An analyst can take 0.37g of the powdered tablets instead of 0.35. O b. An analyst can replace NaOH with HCI OC. An analyst can skip the shaking step O d. B andC O e. All of the above
A sample of explosives residue is dissolved in an appropriate solvent and is injected into HPLC. The column contains a non- polar stationary phase. The sample revealed three chemical compounds that are commonly present in homemade explosives. ТAТP DADP HMTD 1 2 3 4 5 6 7 8 Retention time (minutes) a) determine the retention time of TATP. b) which one elute first :DADP,TATP or HMTD? c) State and explain which compound is most polar. d) If you are investigating this terrorist attacks, state one way in which the information in the chromatogram would be useful.
Below is the procedure described for determination of paracetamol according to BP: "Weigh and powder 20 tablets. Add a quantity of powder equivalent to about 0.35 g paracetamol to 50 ml of 0.1 M NaOH, dilute with water to 200 ml and shake for 15 min. Add sufficient water to make up 250 ml. Filter the solution and dilute 5 ml of the filtrate to 100 ml with water. Dilute further 10 ml to 100 ml. Measure the absorbance at 257 nm. The A, = 715 at 257 nm". Which of the following is correct? O a. An analyst can take 0.37g of the powdered tablets instead of 0.35. O b. An analyst can replace NaOH with HCl O c. An analyst can skip the shaking step O d. B andC O e. All of the above
▪ In a blood alcohol analysis by GC-FID, methanol elutes at 1 min, ethanol at 2 min, IPA at 3 min, and IS at 4 min. In the patient sample, the analyte elutes t 2 min and the IS at 8 min. What is the relative retention time and the analyte in the patient? ▪ A) methanol B) Ethanol ▪ C) IPA
Below is the procedure described for determination of paracetamol according to BP: "Weigh and powder 20 tablets. Add a quantity of powder equivalent to about 0.35 g paracetamol to 50 ml of 0.1 M NaOH, dilute with water to 200 ml and shake for 15 min. Add sufficient water to make up 250 ml. Filter the solution and dilute 5 ml of the filtrate to 100 ml with water. Dilute further 10 ml to 100 ml. Measure the absorbance at 257 nm. The A = 715 at 257 nm". Which of the following is correct? O a. An analyst can take 0.37g of the powdered tablets instead of 0.35. O b. An analyst can replace NAOH with HCI C. An analyst can skip the shaking step d. B and C e. All of the above
analyte concentration(C)(mg/ml) injection volume (ul) elution time (time) peak DAD signal(mAU) caffeine 1 1 4.67 302.85 aspartame 5 1 7.53 15.83 benzoic acid 1 1 8.14 89.98 saccharin 1 1 1.91 84.86 mixture(add everything above with 1:1:1:1 ratio) 1 4.47 69.58 How to get the concentration of the mixture in this case?
In a Bradford assay, 11 µl of a protein isolate sample was diluted by adding 21 µl of water prior to the addition 2.0 mL Bradford reagent. Calculate the protein concentration (in mg/mL) of the original protein isolate sample whose absorbance reading at 595 nm is 0.304 after dilution. The protein standard solutions used for the calibration curve of the Bradford assay was constructed using bovine serum albumin (BSA) stock solution whose concentration is 200 µg/mL. The concentration and the corresponding absorbance reading at 595 nm of the protein standard solutions are summarized in the table below: Standard soln # 1 2 13 4 6 conc of BSA 12.00 24.00 36.00 48.00 60.00 (pg/mL) Absorbance at 595 nm 0.000 0.156 0.249 0.328 0.411 0.528 zNote: 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 the calculation.
During an assay of paracetamol by UV an analyst prepares a series of calibration solutions containing approximately 3-15 mcg/mL paracetamol as follows: 140.1 mg of pure paracetamol was added to a 200 mL volumetric flask. 0.1 M NaOH (50 mL) was added, the mixture well shaken and made up to volume with deionized water 10 mL of the above solution was diluted to 100 mL 1)What is the concentration of the final diluted solution in mcg/mL?(1 decimal) 2) What volume of the diluted solution is required to prepare 100 mL of a 8 mcg/mL standard solution? (1 decimal)
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?
The following data are from the HPLC assay of paracetamol 500 mg tablets using the calibration curve method: - Weight of active ingredient in powdered tablets taken for analysis: 180 mg • Initial extraction volume: 200 mL - Dilution steps: 10 mL into 100 mL, then 5 mL into 100 mL - Linear equation: y = 12000x - 50 %3! - Area of chromatographic peak for sample is 4750. What is the theoretical concentration in final solution in mg/100 mL? (2 decimal places). Please do not write the units, just numerical value. Answer: