Gas Chromatography Lab Report

Objective: To determine the concentration of the three analytes ( EtAc, MeBuOH , PrOH, BuOH) or impurities in the whiskey sample by gas chromatography.

Background:

An alcoholic beverage such as whiskey is a source of ethanol, but with different brands there will be a complex blend of trace impurities. Gas Chromatography is an inexpensive apparatus separation is based on partition between mobile phase and stationary phase. Major components used in gas chromatography are gas inlets, injector, column, detector and amplifier. Detector used in FID, flame ionization detector that uses a flame in the column for the compounds exiting gas chromatography.2 The combination of two methods is called GC/ FID, used for the separation of many organic compounds,

It is usually 40 %, the contents of EtAc, PrOH, MeBuOH were tested in the whiskey sample and this will be simulated a whiskey sample by using 40% ABV solution of ethanol in water. The mass of all three analytes were weighed into a 50 ml bottle and 40% ABV of ethanol in water was added to 50 ml bottle, followed by preparation of whiskey simulated sample with (IS) its concentration is targeted as 1000 ppm (w/w) so 80µL is transferred to 10 ml bottle and its mass was weighed as (0.0127 g) and total mass of solution was calculated as 12.7 g after adding whiskey to butanol. Next the individual standard solutions were prepared the concentration of each individual standard is calibrated to determine retention time. For each 8µL of all three solutions were transferred to 10 ml bottle then 40% ABV solution of 10 ml of ethanol in water was added to 10 ml bottle. Finally mixed standard solution was prepared so butanol of 1000 ppm was transferred to 50 ml bottle and its mass was recorded and its total mass was calculated, 40µL of EtAc, PrOH, MeBuOH was transferred to 50 ml bottle and weight was recorded then finally 40% ABV solution of ethanol in water was added to 50 ml bottle till mass of solution was

Simulated whiskey samples with concentrations. sample Peak area PrOH Peak area

EtAc Peak area

MeBuOH Ppm of PrOH Ppm of EtAc Ppm of MeBuOH

1 101594 56486 105979 1141.5 1107.5 1103.94

2 99241 55083 103861 115.06 1080.05 1081.88

3 98822 54002 102856 1110.35 1058.86 1071.41

Calculation of Average concentration of PrOH:

Avg conc. = 1141.5 + 1115.06+ 1110.35 / 3 = 1122.30 ppm

Table 7. Average ppm and Standard deviation values.

Standard solution Avg ppm Standard deviation

PrOH 1122.30 16.78

EtAc 1082.13 24.38

MeBuOH 1085.46 16.60

Standard deviation for PrOH:

S.D = ? (1141.5 – 1122.30)2 + (1115.06 – 1122.30)2 + (1110.35 – 1122.30)2 / 3-1 = ? 368.25 + 52.70 + 142.80 / 2 = ? 563.75 / 2 = ?281.64 = 16.78 Calculation for RRF of PrOH in Mixed Solutions:

RRF = RF of PrOH / RF of BuOH

RRF = 77.28 / 81.78

RRF = 0.94497

Table 8. RRF values of the three impurities.

Standard solution RRF PrOH RRF EtAc RRF MeBuOH

1 0.944 0.548 1.0121

2 0.946 0.549 1.0127

3 0.953 0.546 1.0365

Average of RRF 0.947 0.5476 1.0202

Calculation for concentration of PrOH by RRF value:

Con, of PrOH = Peak area PrOH/ Peak area of BuOH x 1 / RRF x conc, of