Derivatization Instruction Sheet for ASTM D6584 - Sigma

This Data Sheet Contains Important Information About The Product.
Derivatization Instruction Sheet for ASTM D6584
Determination of Free and Total Glycerin in B-100
Biodiesel Methyl Esters by Gas Chromatography
This derivatization procedure is adapted from ASTM D6584 Determination of Free and Total
Glycerin in B-100 Biodiesel Methyl Esters by Gas Chromatography. The sample is analyzed
by gas chromatography, after silyating with N-methyl-N-trimethylsilytrifluoroacetamide
(MSTFA). Calibration is achieved by the use of two internal standards and four reference
materials. Mono-, di-, and triglycerides are determined by comparing to monoolein, diolein,
and triolein standards. Average conversion factors are applied to the mono-, di-, and
triglycerides to calculate the bonded glycerin content of the sample.
Always take proper safety precautions when using a silyating reagent – consult MSDS for
specific handling information.
ASTM D6584 Procedure for Using Calibration Stock Solutions
The following single component mixtures and internal standards are included in this kit
(44898-U) to prepare the calibration standards.
Table 1. Stock Solutions
44892-U
Glycerin (CAS#: 56-81-5), 500 µg/mL pyridine
44893-U
Monoolein (CAS#: 111-03-5), 5000 µg/mL pyridine
44894-U
Diolein (CAS#: 2465-32-9), 5000 µg/mL pyridine
44895-U
Triolein (CAS#: 122-32-7), 5000 µg/mL pyridine
44896-U
Butanetriol (CAS#: 42890-76-6), Internal Standard #1,
1000 µg/mL pyridine
44897-U
Tricaprin (CAS#: 621-71-6), Internal Standard #2,
8000 µg/mL pyridine
1 x 1 mL
1 x 3 mL
1 x 2 mL
1 x 2 mL
1 x 5 mL
1 x 5 mL
Procedure
●
Label five empty 15 mL vials 1 thru 5.
●
Transfer the specified volumes from Table 2 by means of microliter syringes to the 15
mL vials.
●
100 µL of MSTFA is added to each of the five standards.
●
Close the 15 mL vial and shake.
●
Allow the vial to stand at room temperature for 10 to 15 minutes.
●
Add approximately 8 mL of n-Heptane to the vial and shake.
●
Prepare a reagent blank in a 15 mL vial by adding 100 µL of MSTFA and 8 mL of nHeptane.
●
The standards and reagent blank are ready to assay according to the operating
conditions listed in ASTM D6584.
T705005B
©2005 Sigma-Aldrich Co.
SUPELCO
Bellefonte, PA
Table 2. Preparation of the Five Standard Solutions
Std Sol
Part Number
44892-U
44893-U
44894-U
44895-U
44896-U
44897-U
Standard
Solution 1
10 µL
20 µL
10 µL
10 µL
100 µL
100 µL
Standard
Solution 2
30 µL
50 µL
20 µL
20 µL
100 µL
100 µL
Standard
Solution 3
50 µL
100 µL
40 µL
40 µL
100 µL
100 µL
Standard
Solution 4
70 µL
150 µL
70 µL
70 µL
100 µL
100 µL
Standard
Solution 5
100 µL
200 µL
100 µL
100 µL
100 µL
100 µL
Observations
1. When transferring the ampulized sample to a vial — blanket with nitrogen.
2. Teflon lined septa are a more suitable material for the solutions. Pyridine is less
problematic with rubber.
3. Standards can be refrigerated, however, refrigeration of the actual biodiesel product
can cause glycerides to precipitate.
Ordering Information:
Description
Cat. No.
MSTFA Derivatization Reagent
5 mL
394866-5ML
10 x 1mL
394866-10x1ML
25 mL
394866-25ML
Column
HT-5, 12 m x 0.32 mm x 0.10 µm
25002
Guard Column, 5 m x 0.53 mm blank
Custom
Hamilton® Microliter Syringes
100 µL cemented needle, pt style 5, 22s ga, cone tip, side-port
24535
100 µL cemented needle, pt style 2, 22s ga, bevel tip
20737
250 µL cemented needle, pt style 5, 22s ga, cone tip, side-port
24536
250 µL cemented needle, pt style 2, 22s ga bevel tip
20738
Vials & Caps
15 mL, clear glass graduated vial with cap & PTFE/silicone septum
27519
15 mL clear glass graduated vial with solid cap and Teflon® liner
27508
15 mL, clear glass vial with phenolic solid-top screw cap, Teflon liner
27161
15 mL amber glass vial with phenolic solid-top screw cap, Teflon liner
27003
15 mL, amber glass, thread, 18-400
27088-U
15 mL, vial screw cap with hole and PTFE/silicone septum
27020
15 mL, clear vial, phenolic open-top screw cap, PTFE/red rubber septum
27158
15 mL, amber vial, phenolic open-top screw cap, PTFE/red rubber septum
27014-U
Teflon is a registered trademark of E.I. duPont de Nemours & Co., Inc.
Hamilton is a registered trademark of Hamilton Co.