Biodiesel GC Plus Gas Chromatograph
TT-Biodiesel GC Plus Gas Chromatograph
Biodiesel GC Plus Gas Chromatograph - Interest in biodiesel as a clean-burning alternative fuel derived from renewable sources like vegetable oils has surged in recent years.
This surge is primarily due to its reduced environmental impact compared to conventional petro-diesel. Biodiesel can be used as a pure fuel or blended with petroleum diesel at any level. For biodiesel to be commercialized as a pure biofuel or blending stock for heating and diesel fuels, it must meet a set of requirements outlined in ASTM D6751 and EN 14214 standard specifications. These standards specify the maximum allowable concentrations of contaminants in the pure (B100) finished product, along with other chemical and physical properties necessary for safe and satisfactory engine operation.
ASTM D6584: Standard Test Method for Determination of Total Monoglyceride, Total Diglyceride, Total Triglyceride, and Free and Total Glycerin in B-100 Biodiesel Methyl Esters by Gas Chromatography
EN14103: Fat and Oil Derivatives - Fatty Acid Methyl Esters (FAME) - Determination of Ester and Linolenic Acid Methyl Ester Contents
EN14110: Fat and Oil Derivatives - Fatty Acid Methyl Esters (FAME) - Determination of Methanol Content
Instrumentation and Reagents
The analysis of glycerin, mono-, di-, and triglycerides by gas chromatography (GC) necessitates a non-discriminative injection system capable of transferring both volatile and heavy compounds without discrimination or degradation. For this purpose, a TRACE GC Ultra equipped with a true cold On-column inlet and a flame ionization detector (FID), automated by a TriPlus Autosampler for liquids, was utilized and controlled through the Thermo Scientific Chrom-Card data system. The true cold On-column injector, available on the TRACE GC Ultra, is a permanently cold system designed to prevent discrimination of the heavier fraction and eliminate any risk of degradation of labile components like triglycerides, thereby ensuring excellent recovery and proven sample integrity.
The analytical column used is a non-polar Thermo Scientific TRACE™ TR-BIODIESEL(G), 10 m long with a 0.32 mm inner diameter and a 0.1 μm film thickness. This column is specifically designed to deliver excellent performance for high-temperature GC methods, featuring enhanced mechanical robustness at high oven temperatures and thus prolonged lifetime. A 1 m long, 0.53 mm inner diameter pre-column is used, connected to the analytical column via a leak-free high T purged connection.
A low dead volume leak-free metal tee has been specially designed to provide a reliable connection between the guard column and the analytical column during high-temperature operation, thereby eliminating the need for normal glass press-fit unions. This connector has demonstrated its leak-free performance even under extremely large and frequent oven temperature variations.
Calibration is achieved using two internal standards – 1,2,4-butanetriol (IS1) for glycerine and tricaprin (IS2) for mono-, di-, and triglycerides, along with four reference compounds – glycerol, mono-olein, di-olein, and tri-olein.
Because glycerin, mono-, and di-glycerides are polar and high boiling components, they must be derivatized to increase their volatility and reduce activity before injection into the GC. The method requires derivatization with MSTFA (N-methyl-N-trimethylsilyltrifluoroacetamide) in pyridine, which transforms these compounds into more volatile silylated derivatives. Below is a list of required reagents:
- MSTFA (N-methyl-N-trimethylsilyltrifluoroacetamide)
- n-Heptane
- Pyridine
- 1,2,4-Butanetriol – internal standard solution 1,1 mg/mL in pyridine (IS1)
- 1,2,3-Tricaproylglycerol (tricaprin) - internal standard solution 2, 8 mg/mL in pyridine (IS2)
- Reference materials: glycerol (glycerin), 1-monooleoylglycerol (monoolein), 1,3-di-oleolglycerol (diolein), 1,2,3-tri-oleoylglycerol (triolein)
- Mono-glycerides check mix (monopalmitin, monostearin, and monoolein), in pyridine
1. The KN-Biodiesel GC Plus Gas Chromatograph features a 10.2-inch touch LCD display. It provides real-time operation conditions and temperature monitoring for each channel, enabling online monitoring.
2. It offers independent temperature control for six channels and utilizes a five-stage program for temperature rise.
3. The apparatus includes a self-diagnosis function that automatically displays fault phenomena, codes, and causes in case of failure, facilitating quick troubleshooting by the operator.
4. Over-temperature protection is available, allowing users to set protective temperature limits. If any channel exceeds the set temperature, the apparatus automatically powers off and issues an alarm.
5. Carrier gas protection is integrated to safeguard the chromatographic column and thermal conductivity detector. In case of carrier gas pressure abnormalities, the apparatus automatically shuts down and stops heating.
6. An intelligent fuzzy control back gate system ensures precise temperature control under room conditions by automatically tracing temperature and dynamically adjusting the back gate angle.
7. It comes equipped with packed column, glass-lined, and capillary split/splitless sampling devices with membrane cleaning function. Additionally, the apparatus can accommodate a gas sampler.
8. The GC offers high precision and stable dual-way operation, supporting the installation of up to four types of detectors.
9. It features an advanced gas routing system, allowing the use of hydrogen flame detectors and thermal conductivity detectors.
10. Both Flame Ionization Detector (FID) and capillary tube inlet are electronically pressure controlled (EPC).
11. Users can select an electronic flow pressure display system and internal workstation device as optional features.
12. The apparatus includes a 19-digit automatic liquid sampler.
Technical Parameters:
Temperature Control Index:
1. Temperature Control Range: Room temperature 5°C to 400°C, Increment: 0.1°C.
2. Temperature Control Accuracy: Better than ±0.1°C.
3. Temperature Programming: Five stages with constant temperature time between stages ranging from 0 to 999 minutes, Increment: 0.1 minute. Temperature increment: 0.1°C. Heating rate: Maximum 40°C/min below 200°C, Maximum 20°C/min above 200°C.
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LOD |
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Compound
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Max % m/m (EN 14214)
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Glycerin |
0.02
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Mono-glycerides
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0.8
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Di-glycerides
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0.2 |
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Tri-glycerides
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0.2
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Total Glycerin
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0.25
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