a) Interpretation: Two 1 HNMR spectra belonging to crotonic acid (trans-CH 3 CH=CHCOOH) and methacrylic acid (H 2 C=C (CH 3 ) COOH) are given. Which corresponds to which is to be explained. 1 HNMR: Spectrum (a): 1.91 δ (Rel.area: 3.00), 5.83 δ (Rel.area: 1.00), 7.10 δ (Rel.area: 1.00), 12.21 δ (Rel.area: 1.00). Concept introduction: Crotonic acid (trans-CH 3 CH=CHCOOH) and methacrylic acid (H 2 C=C (CH 3 ) COOH) can be easily distinguished by looking the signal for the methyl protons in these two compounds. To explain: Of the two 1 HNMR spectra given, which belongs to crotonic acid (trans-CH 3 CH=CHCOOH) and methacrylic acid (H 2 C=C (CH 3 ) COOH).

Question

On the next page is an LC separation of the parabens found in baby wash. Parabens are suspected in a link to breast cancer therefore an accurate way to quantitate them is desired. a. In the chromatogram, estimate k' for ethyl paraben. Clearly indicate what values you used for all the terms in your calculation. b. Is this a "good" value for a capacity factor? Explain. c. What is the resolution between n-Propyl paraben and n-Butyl paraben? Again, indicate clearly what values you used in your calculation. MAU | Methyl paraben 40 20 0 -2 Ethyl paraben n-Propyl paraben n-Butyl paraben App ID 22925 6 8 min

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Question

Chapter 20.SE, Problem 67AP

Interpretation Introduction

a)

Interpretation:

Two ¹HNMR spectra belonging to crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH) are given. Which corresponds to which is to be explained.

¹HNMR: Spectrum (a): 1.91 δ (Rel.area: 3.00), 5.83 δ (Rel.area: 1.00), 7.10 δ (Rel.area: 1.00), 12.21 δ (Rel.area: 1.00).

Concept introduction:

Crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH) can be easily distinguished by looking the signal for the methyl protons in these two compounds.

To explain:

Of the two ¹HNMR spectra given, which belongs to crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH).

Interpretation Introduction

b)

Interpretation:

Two ¹HNMR spectra belonging to crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH) are given. Which corresponds to which is to be explained.

¹HNMR: Spectrum (b): 1.93 δ (Rel.area: 3.00), 5.66 δ (Rel.area: 1.00), 6.25 δ (Rel.area: 1.00), 12.24 δ (Rel.area: 1.00).

Concept introduction:

Crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH) can be easily distinguished by looking the signal for the methyl protons in these two compounds.

To explain:

Of the two ¹HNMR spectra given, which belongs to crotonic acid (trans-CH₃CH=CHCOOH) and methacrylic acid (H₂C=C (CH₃) COOH).

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On the next page is an LC separation of the parabens found in baby wash. Parabens are suspected in a link to breast cancer therefore an accurate way to quantitate them is desired. a. In the chromatogram, estimate k' for ethyl paraben. Clearly indicate what values you used for all the terms in your calculation. b. Is this a "good" value for a capacity factor? Explain. c. What is the resolution between n-Propyl paraben and n-Butyl paraben? Again, indicate clearly what values you used in your calculation. MAU | Methyl paraben 40 20 0 -2 Ethyl paraben n-Propyl paraben n-Butyl paraben App ID 22925 6 8 min

d. In Figure 4, each stationary phase shows some negative correlation between plate count and retention factor. In other words, as k' increases, N decreases. Explain this relationship between k' and N. Plate Count (N) 4000 3500 2500 2000 1500 1000 Figure 4. Column efficiency (N) vs retention factor (k') for 22 nonionizable solutes on FMS (red), PGC (black), and COZ (green). 3000 Eluent compositions (acetonitrile/water, A/W) were adjusted to obtain k' less than 15, which was achieved for most solutes as follows: FMS (30/70 A/W), PGC (60/40), COZ (80/20). Slightly different compositions were used for the most highly retained solutes. All columns were 50 mm × 4.6 mm id and packed with 5 um particles, except for COZ, which was packed with 3 um particles. All other chromatographic conditions were constant: column length 5 cm, column j.§. 4.6 mm, flow rate 2 mL/min, column temperature 40 °C, and injection volume 0.5 μL Log(k'x/K'ethylbenzene) FMS 1.5 1.0 0.5 0.0 ཐྭ ཋ ཤྩ བྷྲ ; 500 0 5 10…

f. Predict how the van Deemter curve in Figure 7 would change if the temperature were raised from 40 °C to 55 °C. Figure 7. van Desmter curves in reduced coordinates for four nitroalkane homologues (nitropropane, black; nitrobutane, red; nitropentane, blue; and nitrohexane, green) separated on the FMS phase. Chromatographic conditions: column dimensions 50 mm × 4.6 mm id, eluent 30/70 ACN/water, flow rates 0.2-5.0 mL/min, injection volume 0.5 and column temperature 40 °C. No corrections to the plate heights have been made to account for extracolumn dispersion. Reduced Plate Height (h) ° 20 40 60 Reduced Velocity (v) 8. (2) A water sample is analyzed for traces of benzene using headspace analysis. The sample and standard are spiked with a fixed amount of toluene as an internal standard. The following data are obtained: Ppb benzene Peak area benzene Peak area toluene 10.0 252 376 Sample 533 368 What is the concentration of benzene in the sample?