A 20 mM solution of ethanol is diluted 1 in 8. The diluted ethanol solution was used for an alcoholdehydrogenase assay that had a total volume of 1.5 mL. 20 μL of alcoholdehydrogenase was used for the assay. The reaction was followed spectrophotometrically and a progress curve plotted from the spectrophotometric data. Using the progress curve, the initial velocity was calculated as 0.30 AA/min. The assay was repeated as above, with a different volume of alcoholdehydrogenase. The initial velocity was 0.01 AA/s. What volume (in µL) of alcoholdehydrogenase was used for the assay? (do not include units in the answer

A 20 mM solution of ethanol is diluted 1 in 8. The diluted ethanol solution was used for an alcoholdehydrogenase assay that had a total volume of 1.5 mL. 20 μL of alcoholdehydrogenase was used for the assay. The reaction was followed spectrophotometrically and a progress curve plotted from the spectrophotometric data. Using the progress curve, the initial velocity was calculated as 0.30 AA/min. The assay was repeated as above, with a different volume of alcoholdehydrogenase. The initial velocity was 0.01 AA/s. What volume (in µL) of alcoholdehydrogenase was used for the assay? (do not include units in the answer

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter6: Random Errors In Chemical Analysis

Section: Chapter Questions

Problem 6.15QAP

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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?
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.
A 0.0200 gram blood sample was decomposed by a microwave digestion technique followed by dilution to 100.0 mL in a volumetric flask. Aliquots of the sample solution were treated with a lead complexing reagent and water as follows: Solution 1: 10.0 ml blood sample + 20.0 mL complexing agent + 30.0 mL H20. Solution 2: 10.0 ml blood sample + 20.0 mL complexing agent + 26.0 mL H20 + 4.00 mL of 78 ppb Pb2+ standard. The resulting solutions were analyzed by UV/Vis at 375 nm. Absorbance for solution 1 = 0.155 and for solution 2 = 0.216. Calculate the concentration of lead (ppb) in the original sample.
The percentage purity of a paracetamol sample was determined by a reversed phase HPLC method as follows: • A calibration curve of peak area versus concentration (ug/mL) of pure paracetamol was constructed The paracetamol sample for analysis was prepared by taking 10.0254 g of powder and dissolving it in IL of distilled water (solution A). 1 mL of the latter solution was further diluted to 1L with distilled water (solution B). Solution B was analysed by HPLC analysis Results • The equation for the best-fit line of the calibration curve is: y = 26811x – 1313.8 The average peak area for the paracetamol sample (solution B) was 266796.2 Calculate the percentage purity of the paracetamol powder.
Five different fertilizers were analyzed by two methods. Phosphate (P.Os) was analyzed using gravimetric analyse and spectrophotometric method. Analyze the results of the two methods and answer the following questions. Sample Gravimetric result Spectrophotometric results 1 25.5% 24.4% 2 9.2% 10.0% 3 26.2% 25.8% 4 50.5% 47.3% 5 25.6% 28.6% a Calculate the average content of P:Os in the fertilizers for each method. Compare the difference between the two average values.
Time on hotplate (min) 60, 66, 68, 75, 85, 95, Mass of ZnCO3 + Filter paper (g) 3.7123, 2.7035, 2.6574, 2.5213, 2.3548, 2.239 Use the following data table and steps a-d below to calculate the concentration of the zinc carbonate. The mass of the filter paper alone (no ZnCO3) was 1.3457 g. The ZnNO3 solution (10.00 mL) was mixed with 15.00 mL of the 1.00 M Na2CO3. Calculate the mass of zinc carbonate formed. How many moles of zinc carbonate formed? Calculate the moles of zinc in the zinc nitrate solution used. Calculate the concentration of the zinc in the zinc nitrate solution.
An active air sampler was used to trap polyaromatic hydrocarbons (PAHs) in the air above the sea area with massive oil spill. Air was pumped through an activated charcoal adsorbent material at a flow rate of 10 L per min for 12 hrs. The PAHs were then eluted out of the adsorbent material using 10 mL hexane. The eluate was analyzed by GC-MS. Anthracene was one of the PAHs detected and was found to be present at a concentration of 81.1 µg/mL. Determine the concentration of anthracene in the air above the oil spill. Report your answer in mg/m³.
1) 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).
Order: heparin sodium 20,000 units IV in 500 mL of 0.5 NS to infuse at 1,200 units/hour. What is the flow rate in mL/h? (Enter numeric answer rounded to the nearest whole number.)
The concentration of acetylsalicylic acid in an antipyretic tablet was determined by HPLC using a normal calibration curve. Standard solutions of acetylsalicylic acid were prepared and analysed using a 10µL loop. The results obtained for the standards are tabulated below: Conc. of Acetylsalicylic Acid (ppm); Signal (arbitrary units) 50; 6352 100; 12869 150; 19175 200; 25536 250; 31936 To determine the concentration of acetylsalicylic acid in an antipyretic tablet, 10 tablets were weighed (6.500 g total) and crushed to a fine powder using a mortar and pestle. A quantity of powder equal the mass of one tablet was added to a 100 mL volumetric flask. The tablet powder was dissolved with 20 mL of methanol and the flask was made to volume using water. The solution was filtered. A 1.000 ml aliquot was transferred to a 10 ml volumetric flask, which was then made to volume with water. Analysis was conducted using a Bio Sil HL C18, 250mm x 4.6mm column; 5um, with a mobile phase of acetonitrile:…
PBL 1: An enzyme with a Km = 1 X 102 M was assayed to convert the substrate with initial co ncentration of 3 X 10$M. Find the time required to convert 70% of substrate when Vmax = 2.167 M/min. Km In So 1 - (So – S) t = Vmax S' Vmax S = So - xS,
A volume of 250 ml of a 0.05 M solution of a reagent of formula weight (relative molecular mass) 40 was made up, the weighing being done by difference. The standard deviation of each weighing was 0.0001 g. 1 (a) What were the standard deviation and relative standard deviation of the weight of reagent used?