Matrix optimization for the MALDI-TOF-MS analysis of trace biodiesel components

Casey R. McAlpin,'2 Kent J. Voorhees, Teresa L. Alleman,? and Robert L. McCormick?

ot.
ON
‘Oge
National Renewable
Energy Laboratory

+ Cold weather operability sa limiting factor in expanding
the use of biodiesel Atlow temperatures, biodiesel can
form precipitates, thought to be complex mixtures of trace
‘components

+ Previously, trace components were problematicto
characterize because ofthe complex nature ofthe uel

+The optimized MALD-TOF method was designed to

circumvent problems encountered wth tradional lon i=
tases Va i
+ The opined mati system was hypothesized tobe a ?

‘catchall’ matix for inlzing the range of trace compounds eel 2

Inbiodiese,

+ Standards and mintures of standards were analyzed to
represent the range of compounds present in biodiesel

+ Optimized MALD-TOF analysis can be used a high
‘throughput fel screening tool,

+ TOF/TOF mass analysis can be performed to very peak
assignment of compounds presentin mixtures and neat

fuels

Le

Figure 1 The spect above re of monsteain (and dain) anlyze th Na-doped HCA and Ne-doped optnied matic mitre
nt and back, respectively), The sodlated lone are absent fram the spectra obtained with only HCCA and Nal

=
IR
a

1 Monopalmitinsta
2 DilinleineNa

3 Monootsins Ns

4 Distearins na

5 Tioleinsta

6 Stigmasterol+Na
7 Mized sterol glucosidessNa

Figure 3. The specttum (above lft) monostearn selected
from the monoacylycerde region’ ofthe spectrum. The
Hq i ‘monostearin was then extracted for CID analysis, esuting
. Inthe observed fragmentation spectrum (bottom left) The
= ea = “© peaks labeled A-Kare identified in the table at right.

+ Standards of mono: dh, and ticylalycries were obtained, as wellas standards offre sterols
and sterol glucosides representative of compounds present as trace components in blodisel

+ Samples of standards were analyze fest with traditional matrix systems, then with mixtures
thereof. A mined system was explored because ofits proven potential to fonze certain analytes
more effectively. After several miures were teste, an optimized system was chosen,

References

inert hefermance has epie as sopona one
Frenne merce ios ene

+ With the use fan optimized mixed matric system itis possibleto

+ The optimized misture consisted of approximately equal parts of. dihydronybenzoic
acid (25 DHB), dithranl and a yano4hydrony-innamic acid (HCA). Previous work wth

‘phospholipid indicated that sample teatment with Nal promotes the formation af sodlated
fons ad increases the sensitivity and SIN ratio of the measurement? Sodium iodide was added
tothe mined and individual matixsystems to determine its effect on ionization

+ Aminture ofthe aforementioned compounds was then analyzed to ensure lnization ofall of
the components. The data from the optimized system miture analysis was also compared with
tational matics,

+ To confirm peak dents, TOFTOF colson Induced dissociation experiments were performed.

Figure 2. shown above the spectrum ofthe analysis ofa seven-component mixture withthe optimized
[Nat doped mati The components listed above) were all successfully Sodlated and analyzed

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy operated by the Alisnce for Sustainable Energy, LLC.

characterize ace biodiesel components in one rapid analysis.

+ The use of MALDHTOF MS cicumvents complications aking from complex
Separation techniques an has high throughput. allowing many samples to
bbe analyzed and compared in one experiment.

+ The med optimized matrix when doped with Nal has higher sensitivity
‘than doped and undoped pure matrices.

+ Tandem MS can be employed in complex mixtures to confirm peak dentites

Posh uinghALDF OF NS Contec eo Pete ome
Preenman atom spc 20287
[Acknowledgement

‘Theauthos hank the US. Deparment of Eney Velie
“Technologies Progam fo project finding and spor.

‘Weal tankthe Unvetstye Coad Schal of Pharmacy
Mass Specromeny Fact for nayang samples

7h American Society for Mass Spectrometry (ASMS) n Philadelphia, Pennsyvania » May 31~June 4, 2008 » NREL/PO-540-45770