1

Fast Mineral Oil Analysis using LTM

Matthew S. Klee, Ph.D.Agilent Technologies

Wilmington, Delaware, USA

2

59905990--4851EN4851EN

3

Mineral Oil Analysis(HOI: hydrocarbon oil index)• Mineral Oil analysis is in top 5 of current

environmental analyses (next to VOCs, PAHs, pesticides)

• Analysis is done by GC-FID (replaces old extraction – FTIR analysis)

• Technique is similar to “TPH” (Total Petroleum Hydrocarbon) analyses done in the U.S.A.... #1 LTM application in U.S.A.

Ref: ISO 9377-2, ISO 9377-4, EN 14039, DIN H53,…

4

What is included in “Mineral Oil” analysis?

Any mixture of compounds that:1. are extracted by hydrocarbon solvent (from soil or

water)2. are not adsorbed by Florisil (used for cleanup)3. elute from an apolar column between decane

(C10) and tetracosane (C40)

5

Typical HOI analytical procedure

1. ExtractWater: extract 1 L water with hexaneSoil: extract by ASE

2. Clean-upFlorisil (removes polar and semi-polar solutes such as sterols and lipids)

3. Concentrate to 1 mLN2 purge

4. Analyze extract by “discrimination free” injection, GC-FID, area sum between C10 and C40

6

Analytical requirements

Non-discriminatory injection:– COC

• concerns about dirty samples– PTV– SSL (splitless)

• concerns about discrimination against high boilersLow bleed column

– Must elute C40 (thin film, high phase ratio)– Needs to separate solvent and 1st peak (decane)

• can be problematic with splitless injection (wide solvent peak), so low initial temperature is required

7

Typical GC-FID conditions

Agilent S/Sl: 1 µL injection in SL mode

Others: COC or PTV (if S/Sl discriminates)

Column: 5-25 m x 0.25-0.53 mm ID 0.1-0.5 µm HP-1 or HP-535-40°C init to 300-350°C

Current disatisfier: Cycle time (~ 20-30 min without cool-dow)Limited ramp rate or lab GCsCool-down time

8

Typical Hydrocarbon Index Analysis by GC(Application note 5988-0621EN)

15 m x 0.53 mm id x 1.5 µm HP-1He: 7.4 mL/min, constant flow35°C (1.5 min) → 60°C@ 5°C/min→ 350°C (5 min) @ 15°C/min

4.20

7

13.3

31

22.5

35

pA

10

20

30

40

50

60

70

80

90

min5 10 15 20 25

9

“LTM” (Low Thermal Mass) Directly Heated Column Technology (Patented)

10

LTM System Installed on 7890A

11

The LTM Advantage

• Total cycle time for an analysis can be cut by a factor of 3 or more (compared to same columns in air oven and LTM)

• 1-4 independent column modules per GC– Dual column module configurations allow simultaneous

parallel analyses– Each module can have a different column type– Temperature programs for modules are independent

• Compatible with CFT devices for splitting, multidimensional separations, and/or for backflush

12

LTM method 1 (hot splitless)

1 µL splitless injection, 320°CGC oven: 340°CFID: 340°CLTM: 10 m x 0.32 mm ID x 0.1 µm DB-5HT• 40°C (0.5 min) → 240°C @ 200°C/min → 340°C (0.5 min)

@ 100°C/min (3 min total)Carrier: He • 120 kPa (0.5 min) → 160 kPa @ 40 kPa/min → 180 kPa

(0.5 min) @ 20 kPa/min

13

n-Alkane test mixture

C10 C20

C40

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.800

400000

800000

1200000

1600000

2000000

2400000

2800000

Time

Response

14

n-Alkane test mixture

Retention time repeatability (n=6)• C10: tR = 0.812 min, s = 0.001 min, RSD = 0.06%• C20: tR = 1.501 min, s < 0.001 min, RSD < 0.01%• C40: tR = 2.633 min, s = 0.003 min, RSD = 0.10%Peak Area repeatability• C10: mean area = 4265145, RSD = 0.86%• C20: mean area = 4578586, RSD = 1.05% • C40: mean area = 4117178, RSD = 0.85% Discrimination test• Relative peak area C40/C20 = 0.899 (RSD: 1.31%)

(criterion: > 0.80)

15

Calibration diesel/motor oil 400 mg/L

0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.800

400000

800000

1200000

1600000

2000000

2400000

2800000

Time

Response

Motor oil

Diesel

16

Mineral Oil calibration

Calibration from 40 – 1000 mg/LLinearity: r² > 0.999Repeatability at 400 mg/L: • RSD on peak area = 0.64%LOD: < 25 mg/L

R2 = 0.9991

0

200

400

600

800

1000

1200

0 200 400 600 800 1000 1200

mg/L

Are

a (x

10-6

)

17

Calibration 100 mg/L

0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80

50000

150000

250000

350000

450000

550000

Time

Response

18

Extra benefit: sensitivity gain

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.000

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

2000000

2200000

2400000

2600000

2800000

Time

Response_

Signal: SENS-TEST07.D\FID1A.chSignal: SENS-TEST05.D\FID1A.ch (*)

21 min run3 min run

19

HOI analysis with LTM - conclusions

• Sample analysis cycle time is reduced to 5 min!• Analysis time: 3 min• Cool-down time to 40°C < 2 min

• Meets all method requirements with hot splitless and Agilent ALS

• Excellent repeatability, linearity• High sensitivity (“signal compression”)• Dual column module configuration with

simultaneous injection and parallel analyses will maximize throughput

20

Thank you for you interest.

Questions?

This information is subject to change without notice.© Agilent Technologies, Inc. 2010