Q25. Estimate the minimum concentration limit of detection (CLOD) in mg/mL and mass limit of detection in mg on a GC column equipped with a thermal conductivity detector when naphthalene was injected at 2.0 mg/mL using a 5 μL injector producing a chromatogram as shown below. Please show all your work for full credit. (10 pts) h noe causes 2.0 mg/ml 5ML

Chemistry The levels of an organic pollutant (P) in the groundwater at the perimeter of a plant were a cause for concern. A 10 mL sample of the water was taken and the pollutant was extracted with 95% efficiency using 25 mL of diethyl ether. GC was used to analyse the concentration of P in diethyl ether. A calibration curve was plotted for a series of standards of P which yielded the following results: Peak Area Toluene Conc. (µg/ml) 12,000 2.6 23,700 5.0 35,500 7.7 46,800 9.9 31,250 Sample Determine the concentration of P in ppb in the initial groundwater sample.

Internal standard (As , Cs ), analyte with known concentration (Ax , Cx ) In a chromatographic equipment, a solution containing 0.006727 X and 0.008331 M S give peak area of Ax= 2316 and As= 207. To analyze an unknown sample, 5.0mL of 0.008331M S was added to 5.0mL of X, and the mixture was diluted to 50.0mL. This mixture gave a chromatography spectrum with area Ax= 3206 and As= 200. Find Cx.

A new method is proposed to simultaneously detectand separatefour foodadditives by reversed-phase liquid chromatography. The data were obtained using theliquid chromatographic column with a flow rate of 0.5 mL per min and with the followingparameters: Pore size  100 A Particle Size 3.5  Internal diameter 4.6 mm Length 150 mm The food additives found in the sample resulted in the following data: ( see image for table)  a.Calculate the number of plates from each peak. b.Calculate the plate height for the column. c.Retention factor for each peak.

A solution is prepared by weighing 5.0000 g of cesium iodide into a 100-mL volumetric flask. The balance used has a precision of 0.2 mg reported as a standard deviation, and the volumetric flask could be filled with a precision of 0.15mL also reported as a standard deviation. What is the estimated standard deviation of concentration (g/mL)?

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

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. The standard deviation of the volume of solvent used was 0.05 ml. Express this as a relative standard deviation. Hence calculate the relative standard deviation of the molarity of the solution.

6. The concentration of caffeine in an energy soft drink was determined by standard addition using HPLC. The following procedure was used: a standard caffeine solution was prepared by adding 0.09850g of caffeine to 25.0 cm3 of water.A series of solutions were prepared by adding known volumes of the standard solution to the soft drink before diluting to 100 cm3. The volume of standard and the caffeine peak area are shown in the table: Energy Drink (cm3) Added caffeine Std (cm3) Peak area       15 0 965   15 5 1352   15 10 1739   15 15 2126   15 20 2513       Determine the concentration of caffeine in the soft drink as mg cm-3.   A. 3.3 B. 2.3 C. 4.3 D. 7.3

In a chromatography experiment, a solution containing 0.083 7 M X and 0.066 6 M S gave peak areas of AX = 423 and AS 5 347. (Areas are measured in arbitrary units by the instrument.) To analyze the unknown, 10.0 mL of 0.146 M S were added to 10.0 mL of unknown, and the mixture was diluted to 25.0 mL in a volumetric flask. This mixture gave the chromatogram in Figure 5-8, with peak areas AX = 553 and AS = 582. Find the concentration of X in the unknown.

The following results were obtained in the replicate determination of the lead content of a blood sample: 0.752, 0.756, 0.752, 0.751, and 0.760 ppm Pb. Calculate the relative standard deviation and coefficient of variation of this set of data