Classification of Chemicals 

in Black Locust Robinia 

pseudoacacia Wood and Bark

Roderquita K. Moore

Doreen Mann

United States Department of Agriculture

Forest

Service

Forest Products

Laboratory

Research Note

FPL–RN–0386

September

2020

Contour Plot

Surface Plot

Retention time (s)

Retention time (s)

2nd Retention time (s)

1st Retention time (s)

1st Retention time (s)
September 2020

Moore, Roderquita K.; Mann, Doreen. 2020. Classification of chemicals in 

black locust Robinia pseudoacacia wood and bark. Research Note 

FPL-RN-0386. Madison, WI: U.S. Department of Agriculture, Forest 

Service, Forest Products Laboratory. 9 p.

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Abstract

Black locust (Robinia pseudoacacia) is a native tree in 

southeastern United States. The wood from this tree is 

known for resistance to decay and excellent longevity 

even in soil contact. It is a durable species used for fence 

post material. It is also known for the stilbene chemicals 

resveratrol and piceatannol. These chemicals exhibit 

biological activities, mainly antioxidant properties. 

Identifying the chemicals that contribute to the durability 

of black locust could lead to the development of relevant 

medicinal alternatives and other products. In this study, 

black locust wood and bark were extracted using acetone–

water solutions. Using the extractions, we analyzed 

mixtures from the bark and wood. Two-dimensional gas 

chromatography-time of flight mass spectrometry 

(GC×GC-TOFMS) Pegasus BT 4D was used to characterize 

and identify the chemical composition of the extracts. The 

chemicals were categorized based on their functionality. 

The chemicals identified were separated into two categories, 

those shared by both wood and bark and those not 

shared. The extractions had some of the same chemicals 

as identified in the NIST and Wiley libraries. After the 

chemicals were categorized, we were able to determine 

which chemicals were specific to wood and bark.

Keywords: GC×GC, extractives, Robinia pseudoacacia, 

wood, bark

Contents

Introduction..........................................................................1

Experimental........................................................................1

Results and Discussion ........................................................2

Conclusions..........................................................................9

Acknowledgments................................................................9

References............................................................................9
Classification of Chemicals in Black Locust 

Robinia pseudoacacia Wood and Bark

Roderquita K. Moore, Research Chemist

Doreen Mann, Physical Science Technician

USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin, USA

Introduction

Wood chemical research has been around since the early 

1900s. Years ago, it was called “naval stores” research. 

Separation and isolation of complex mixtures were difficult 

to accomplish because of similarity in the chemical formula, 

functional groups, and volatility of the compounds. Naval 

stores research was important, but analytical techniques for 

resolving the complex mixture were limited. In the twentyfirst century, instrumental analysis is more advanced and is 

well-equipped to handle the resolution needed to identify 

and characterize trace components. GC×GC is well-suited 

to investigate trace chemical composition in black locust. 

Sarikurkcu and others (2015) investigated antioxidant and 

enzyme inhibitory activity in various solvents. Sergent and 

others (2014) identified the stilbene chemicals resveratrol 

and piceatannol between leaves during different seasons. 

Kirker and others (2013) isolated and monitored fatty 

acids contribution to the overall wood durability of wood 

species. Moore and others (2015a, 2015b, 2017a, 2017b, 

2017c) identified chemicals using gas chromatographymass analyzer and found that the concentration plays a role 

in the number of chemicals identified from the chemical 

fractionations. In this study, GC×GC was used to compare 

chemicals identified in the wood and bark of black locust. 

This technique is important for identifying chemicals with 

low concentrations. Chemical mapping is facilitated by 

the easy visualization of 3D chromatographic results. The 

same solvent solutions were used for extracting wood and 

bark. GC×GC was used to identify chemical differences 

and similarities of bark and wood. The chemicals were 

categorized and classified on the chromatograms.

Experimental

Materials

Solvents were purchased from Thermo Fisher Scientific 

(Waltham, Massachusetts, USA). Tetracosane 99% was used 

for the calibration standard and was purchased from SigmaAldrich (St. Louis, Missouri, USA).

Sample Preparation

Black locust wood chips and bark were collected and Wileymilled to 40 mesh. A soxhlet extraction with 9:1 acetone/

water was run for 10 hours on the wood and bark samples 

separately. The solvent extracts were dried by a rotary 

evaporator and placed in the freezer.

Instrumentation Operations

GC×GC TOFMS was used to analyze the black locust 

extractives. Table 1 is the list of the oven and mass 

spectrometer parameters. The methodology was the same 

for each run. The injection temperation and transfer lines 

were the same for each run. The split ratio and modulation 

time changed according to concentration and chemicals. The 

splits were dependent on the concentration of the samples. 

The modulation time changed according to the chemicals 

retained on the second dimension column.

Table 1. Gas chromatography (GC) and two-dimensional 

gas chromatography-time of flight mass spectroscopy 

(GC×GC-TOFMS) (Pegasus BT 4D) instrument 

parameters

Gas chromatograph agilent 7890B with LECO dual stage quad jet 

modulator and LPAL 3 autosampler

Injection 1 uL, split 20–150:1 at 250 °C

Carrier gas He at 1.4 mL/min

Primary column Rxi-5 ms, 30-m by 0.25-mm i.d. by 

0.25-μm coating (Restek, Bellefonte, 

PA, USA)

Secondary column Rxi-17SilMS, 0.60-m by 0.25-mm by 

0.25-μm coating (Restek, Bellefonte, 

PA, USA)

Oven programming Primary column starting temperature 

50 °C, ramped 10 °C/min to 

320 °C, held 5 min. Secondary column 

temperature parallel ramp offset by 

+5 °C (total run time 32 min).

Modulation 3–5 s with temperature maintained 

+15 °C relative to second oven.

Transfer line 280 °C

Mass spectrometer LECO Pegasus BT 4D

Ion source temperature 250 °C

Mass range 50–650 m/z

Acquisition rate 150 spectra/s (2D)
Research Note FPL–RN–0386

2

Results and Discussion

A mixture of acetone and water (9:1) was used to remove 

extracts from the black locust wood (blw) and bark (blb). 

GC×GC-TOFMS was calibrated with known concentrations 

of tetracosane. Tetracosane was also tested as an unknown 

standard. Both extracts were injected in replicates. There 

were 1,343 and 1,868 chemicals from the acetone extracts 

of blw and blb, respectively. The NIST and Wiley libraries 

were used to identify these chemicals. Table 2 shows the 

number of chemicals detected at various similarity matches. 

There were 566 and 857 unknown chemicals detected for 

blw and blb extracts, respectively.

Because high concentration produced tailing, some 

chemicals were duplicated. All chemicals identified more 

than once were removed from the list of chemicals. Any 

chemical with isomers was not included in the final list. 

From the list of chemicals detected, 106 and 180 were left 

with greater than 800 similarity for blw and blb extracts, 

respectively. This is not shown in Table 2, but 83 chemicals 

were shared between extracts. They were not included in the 

total for each extract.

The list of chemicals in Tables 3 and 4 are from the bark 

and wood solvent extractions, respectively. There are no 

duplicates, and the chemicals are specific to their solvent 

extractions. The chemicals listed have spectral similarity 

value greater than 900. The percentage peak area was 

calculated using the sum of all chemicals with matches 

greater than 800 similarity. The blw extracts did not yield 

as many spectral matches with 900 similarity as did the blb 

extracts.

Chemicals in Table 3 with significant peak area were lactic 

acid 5.2% and dihydro-3-methylene-5-methyl- 2-furanone 

3.67%. There were other significant peak area percentages 

not shown in the table because they did not have spectral 

matches greater than 900, including b-d-glucopyranose 

3.80%; stigmast-4-en- 3-one 10.44%; 3-hydroxypropane1,2-diyl diacetate 6.38%; and l-sorbose 8.46%. B-dglucopyranose is a synthetic simple monosaccharide used 

as an energy source. L-sorbose is the sugar known as 

monosaccharide, which has the configuration of a natural 

sugar. Stigmast-4-en-3-one is a sito-sterol used to decrease 

cholesterol levels. Of the chemicals shown in Table 4, 

heptadecane had the most significant peak area at almost 

5.60%. Chemicals that were under the 900 similarity were 

2,4-dihydroxy-benzaldehyde 5.13%; 3-methoxymethylhept1-yn-3-ol 4.26%; and 4-methoxy-2-pentanone 30.56%.

Because they are part of the same tree structure, bark 

and wood are expected to have similar chemicals. There 

were 83 shared chemicals in both extraction systems. 

Wood chemicals are known to migrate throughout the life 

of the tree. Tables 5 and 6 list chemicals from bark and 

Table 2. Number of chemicals detected by twodimensional gas chromatography-time of flight mass 

spectrometry (GC×GC-TOFMS) and identified by NIST 

(blw) and Wiley (blb) libraries

Extract

Total 

>700

Peaks 

unknown

Peaks 

known

>800 

known

>800 

knowna

blw 1,343 566 777 455 106

blb 1,868 857 1,011 573 180

a

Number of known chemicals after removing duplicates, shared, and 

isomers.

wood, respectively, with spectral matches greater than 900 

similarity. 2-propanone 5.67%; (pyro)-catechol 4.10%; 

glycerin 27.1%; mome inositol 21.6%; and 1,3- benzenediol 

5.50% had the highest peak area among the 900 similarity 

matches. Benzene 10.57% also had a significant peak area 

even though it was below the 900 similarity criteria.

In Table 6, pyro-catechol 4.85% was significant. Other 

chemicals with percentages higher than pyro-catechol 

were 1,2,3 benzenetriol 5.30%; resorcinol 64.4%; and 

4-(3-hydrooxyprop-1-en-1yl)-2-methoxyphenol 7.77%. 

These were not shown in Table 6 because they fell below the 

similarity cut off. Resorcinol is extremely concentrated and 

is part of the benzenediol group. Benzenediols are known 

for having antimicrobial activity. Resorcinol is used in 

antiseptic and disinfectant topical pharmaceutical products 

for treatment of skin disorders and infections such as acne, 

dermatitis, eczema, calluses, and warts.

When injected into the GC×GC TOFMS, complex mixtures 

display various classes of chemicals in different regions 

on the chromatogram. We call this molecular chemical 

mapping (MCM). This is similar to the periodic table. 

GC×GC chromatograms can be used to create a fingerprint 

for various complex mixtures. This is one of the best ways 

to visually and chemically identify unknown chemicals in 

complex mixtures.

Figures 1, 2, and 3 have similar profiles. Figures 1 and 2 

are the first 20 min, and Figure 3 started at 11 min into the 

run of the extractives. Figure 3 is the rest of the full analysis 

of black locust wood and bark. The bark chemicals were 

more concentrated than the wood chemicals. Most of the 

chemicals observed in the bark were also observed in the 

wood but at lower concentrations. These chromatograms 

follow the same profile as the other complex extract 

mixtures. The labeling of the regions is similar. On the 

bottom right are long chain hydrocarbons eluting according 

to the volatility. On the top right are the sterol chemicals. 

And in the bottom middle are fatty acids. On the top in 

the middle between 1.8 and 2.8 seconds in the second 

dimension, there are several identified pyranose and sugar 

chemicals. The majority of the chemicals between second 

dimension 1.5 and 3 seconds are aromatic chemicals with 

alcohols, acids, and methoxy groups as the ring substituents.
Classification of Chemicals in Black Locust Robinia pseudoacacia Wood and Bark

3

Table 3. Two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) list 

of compounds specifically identified in black locust bark acetone extracts >900 similarity

Number Chemical identifieda Formula

Peak area 

(%)

Retention time 

(s) Similarity

1 2-Pentanone, 4-hydroxy-4-methyl- C6H12O2 0.256 200 3.429 933

2 2,3-Dimethylfuran C6H8O 0.178 204.998 3.221 927

3 2-Furanmethanol C5H6O2 0.318 214.993 1.064 932

4 2,5-Furandione C4H2O3 0.170 214.993 1.429 960

5 (E)-4-(1’,1’-Bis(ethoxycarbonyl)ethyl)-4- C20H34O5 0.163 219.991 0.607 944

6 L-Lactic acid C3H6O3 5.151 219.991 0.955 942

7 2-Hydroxy-gamma-butyrolactone C4H6O3 0.121 319.943 1.811 914

8 4-Hydroxy-5,6-di-hydro-(2H)-pyran-2-one C5H6O3 0.019 324.941 1.522 948

9 Cyclohexene, 1-methyl-4-(1-methylethenyl)-, C10H16 0.550 354.927 0.954 907

10 1,2-Propadiene-1,3-dione C3O2 0.042 354.927 1.927 961

11 Benzene, methyl- C7H8 0.073 379.915 1.048 912

12 2H-Pyran-2-one, tetrahydro- C5H8O2 0.048 379.915 1.908 904

13 Dihydro-3-methylene-5-methyl-2-furanone C6H8O2 3.669 394.908 1.798 920

14 1-(2-Furanyl)-2-hydroxyethanone C6H6O3 0.174 399.905 1.563 931

15 p-(1-Propenyl)-toluene C10H12 0.314 409.901 1.143 923

16 1,2,3-Propanetriol, 1-acetate C5H10O4 0.365 409.901 1.512 930

17 Benzeneethanol C8H10O 0.038 429.891 1.453 901

18 Benzoic acid C7H6O2 0.437 464.875 1.354 904

19 1-Propanone, 1-phenyl- C9H10O 0.079 474.87 1.445 957

20 (S)-(+)-2’,3’-Dideoxyribonolactone C5H8O3 0.134 489.863 2.152 947

21 5-(1-Hydroxyethyl)-2-oxolanone C6H10O3 0.213 499.858 1.971 911

22 (5R)-5-(Hydroxymethyl)-2-oxolanone C5H8O3 0.666 509.853 1.800 928

23 Erythritol C4H10O4 0.684 529.844 1.837 919

24 Benzeneacetic acid C8H8O2 0.491 539.839 1.446 936

25 (5E)-6,10-Dimethyl-5,9-undecadien-2-one C13H22O 0.135 704.761 1.174 921

26 DL-Arabinitol C5H12O5 1.933 739.745 1.962 903

27 Vanillic acid C8H8O4 1.332 784.723 1.756 908

28 Pentadecanal- C15H30O 0.047 889.674 1.067 905

29 1,2,3,4,5,6-Hexanehexol C6H14O6 1.141 939.65 2.198 932

30 (9E)-9-Hexadecen-1-ol C16H32O 0.177 989.626 1.074 927

31 11-Hexadecen-1-ol, (Z)- C16H32O 1.179 1,104.57 1.136 944

32 Octadecanal C18H36O 0.165 1,239.51 1.117 908

33 Eicosanoic acid C20H40O2 0.342 1,254.5 1.167 908

34 Docosanal C22H44O 0.256 1,284.49 1.152 917

35 2,6,10,14,18,22-Tetracosahexaene, 

2,6,10,15,19,23-hexamethylC30H50 1.148 1,464.4 1.381 935

36 7-exo-Acetylmethylbicyclo[4.1.0]hept-2-ene C11H18O 0.044 1,479.39 4.356 928

37 7-Hydroxy-7-phenyl-3,9-diisopropyl-2,10-

dioxadispiro[3.3.3.1]dodecan-1,11-dione

C22H28O5 0.402 1,779.25 0.978 969

a

Name from Wiley library.

Identifying regions for classes of chemicals (RCC) 

located on the GC×GC chromatograms is important when 

characterizing complex mixtures. GC×GC is being used to 

create a standard way to establish a fingerprint for complex 

mixtures. Because of the resolving power and the visual 

view of MCM on a GC×GC chromatogram, we can better 

identify chemicals in extracts. This development will change 

the way we investigate complex mixtures.
Research Note FPL–RN–0386

4

Table 4. Two-dimensional gas chromatography-time of flight mass spectroscopy (GC×GC TOFMS) 

list of compounds specifically identified in black locust wood acetone extracts >900 similarity

Number Chemical identifieda Formula

Peak area

(%)

Retention time

(s) Similarity

1 2-Furancarboxaldehyde C5H4O2 0.159 204.998 1.155 901

2 4-Hydroxy-4-methylpentane-2-one C6H12O2 0.905 209.995 0.987 938

3 2,4-Dihydroxy-2,5-dimethyl-3(2H)-furan-3-one C6H8O4 0.161 309.948 1.120 912

4 Nonanal C9H18O 0.349 414.898 1.069 922

5 1,2,4,5-Tetroxane 3,3,6,6-tetramethyl- C6H12O4 0.441 479.868 0.549 939

6 1,3-Isobenzofurandione C8H4O3 0.039 604.808 1.922 910

7 Heptadecane C17H36 5.594 644.789 0.864 910

8 Vanillin C8H8O3 0.673 669.778 1.809 928

9 Benzaldehyde 2,4-dihydroxy- C7H6O3 5.138 699.763 1.697 946

10 p-Hydroxyphenylacetone C9H10O2 0.179 699.763 1.829 902

11 6-Hydroxybenzofuran-3-one C8H6O3 0.804 824.704 2.033 907

12 (2R,3S,5α,22R,23R,24S)-25-Methoxy6,6-(ethylenedioxy)-2,3;22,23- 

bis(isopropylidenedioxy)ergostane-22,23-diol

C37H62O7 0.474 1,174.54 0.511 925

13 Benzene 1-[[(1-ethenyl-5-ethoxy-2-methoxy-4-

pentynyl)oxy]methyl]-4-methoxy- [S-(R*,S*)]-

C18H24O4 0.032 1,329.47 2.786 944

14 Squalene C30H50 1.208 1,464.4 1.383 935

15 2-Ethyl-3-(n-butyl)penta-3,4-dienoic acid C11H18O2 0.318 1,524.37 4.564 900

16 2-(5-Hydroxy-1-benzofuran-3-yl)

benzene-1,4-diol

C14H10O4 0.019 1,554.36 3.882 901

17 Hentriacontane C31H64 1.598 1,569.35 1.306 940

18 9,19-Cyclolanost-24-en-3-ol (3β)- C30H50O 0.673 1,709.29 3.802 911

19 1H-Indene 3-(4-methoxyphenyl)-2-phenyl- C22H18O 0.013 1,819.23 2.832 919

a

Name from NIST library.
Classification of Chemicals in Black Locust Robinia pseudoacacia Wood and Bark

5

Table 5. Two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) list of 

shared compounds identified in black locust bark acetone extracts >900 similarity

Number Chemical identifieda Formula

Peak area 

(%)

Retention time 

(s) Similarity

1 Butyrolactone C4H6O2 0.110 259.972 1.656 933

2 Benzene, (1-methylethyl)- C9H12 0.233 264.969 0.979 904

3 2-Hydroxy-2-cyclopenten-1-one C5H6O2 0.156 264.969 1.313 902

4 1,3-Dioxolane-4-methanol, 2,2-dimethyl- C6H12O3 0.482 279.962 1.094 913

5 Glycerin C3H8O3 27.057 294.955 1.590 934

6 Phenol C6H6O 0.441 309.948 1.234 931

7 Furan, 2-pentyl- C9H14O 0.618 319.943 0.958 955

8 2-Propanone C3H6O 5.674 324.941 0.569 960

9 Ethanol, 2-(2-ethoxyethoxy)- C6H14O3 0.193 329.938 1.204 924

10 p-Cymene C10H14 0.577 349.929 1.033 934

11 Cyclohexene, 1-methyl-4-(1-methylethenyl)-, (S)- C10H16 0.550 354.927 0.954 907

12 2(3H)-Furanone, dihydro-3-hydroxy-4,4-dimethyl-, (±)- C6H10O3 2.319 359.924 1.548 937

13 Phenol, 2-methoxy- C7H8O2 0.592 409.901 1.401 903

14 Undecane C11H24 0.079 414.898 0.810 916

15 4H-Pyran-4-one, 3-hydroxy-2-methyl- C6H6O3 0.105 429.891 1.570 902

16 4H-Pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl- C6H8O4 2.080 454.879 1.489 929

17 Butanedioic acid C4H6O4 0.202 459.877 1.322 929

18 Octanoic acid C8H16O2 0.033 469.872 1.056 927

19 (Pyro)-catechol C6H6O2 4.135 499.858 1.462 935

20 Nonanoic acid C9H18O2 0.027 549.834 1.071 913

21 1,3-Benzenediol C6H6O2 5.506 564.827 1.685 908

22 Phenol, 2,6-dimethoxy- C8H10O3 0.448 629.797 1.692 931

23 2-Propenal, 3-(2-furanyl)- C7H6O2 0.067 699.763 0.520 954

24 β-D-Glucopyranose, 1,6-anhydro- C6H10O5 2.199 724.752 2.200 932

25 Benzoic acid, 4-hydroxy- C7H6O3 0.177 739.745 1.731 901

26 Vanillic acid C8H8O4 1.332 784.723 1.756 908

27 Mome inositol C7H14O6 21.607 859.688 1.999 920

28 Myristic acid C14H28O2 0.036 914.662 1.091 924

29 Benzoic acid, 4-hydroxy-3,5-dimethoxy- C9H10O5 0.613 954.643 1.968 901

30 Hexadecanoic acid C16H32O2 1.488 1,039.6 1.108 923

31 Hexadecanal C16H32O 0.120 1,334.46 1.175 919

32 1-Docosene C22H44 1.047 1,409.43 1.239 935

33 1,15-Pentadecanediol C15H32O2 0.174 1,449.41 1.585 905

34 2,6,10,14,18,22-Tetracosahexaene, 

2,6,10,15,19,23-hexamethylC30H50 1.148 1,464.4 1.381 935

35 Octacosanol C28H58O 0.777 1,494.39 1.370 938

36 Campesterol C28H48O 0.421 1,634.32 2.750 915

37 Stigmasterol C29H48O 0.719 1,649.31 2.854 929

38 β-Sitosterol C29H50O 1.981 1,674.3 3.119 933

39 Lup-20(29)-en-3-one C30H48O 1.855 1,704.29 4.136 930

40 Lupeol C30H50O 0.511 1,714.28 4.226 943

41 Furan, 2,3-dihydro- C4H6O 0.137 1,849.22 0.394 999

a

Name from Wiley library.
Research Note FPL–RN–0386

6

Table 6. Two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) list of 

shared compounds identified in black locust wood acetone extracts >900 similarity

Number Chemical identifieda Formula

Peak area 

(%)

Retention time

(s) Similarity

1 2-Propanone C3H6O 0.650 214.993 0.168 972

2 (Furan-2-yl)methanol C5H6O2 0.051 214.993 1.086 929

3 2-Propenal, 3-(2-furanyl)- C7H6O2 0.164 224.988 0.360 929

4 Butyrolactone C4H6O2 0.083 259.972 1.677 930

5 2(5H)-Furanone C4H4O2 0.041 259.972 1.720 946

6 Benzene, (1-methylethyl)- C9H12 0.283 264.969 0.992 925

7 1,3-Dioxolane-4-methanol, 2,2-dimethyl C6H12O3 1.613 274.965 1.126 956

8 Hexanoic acid C6H12O2 0.132 299.953 0.989 935

9 2,4-Dihydroxy-2,5-dimethyl-3(2H)-furan-3-one C6H8O4 0.161 309.948 1.120 912

10 Phenol C6H6O 0.889 309.948 1.238 937

11 Furan, 2-pentyl- C9H14O 0.498 319.943 0.964 961

12 Ethanol, 2-(2-ethoxyethoxy)- C6H14O3 0.253 329.938 1.212 950

13 3-Hydroxy-4,4-dimethyldihydro-2(3H)-furanone C6H10O3 1.329 359.924 1.552 947

14 Phenol, 2-methoxy- C7H8O2 1.160 409.901 1.406 919

15 Undecane C11H24 0.060 414.898 0.814 951

16 4H-Pyran-4-one, 3-hydroxy-2-methyl- C6H6O3 0.128 429.891 1.576 929

17 2,3-Dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one C6H8O4 0.307 454.879 1.489 908

18 (Pyro)-catechol C6H6O2 4.852 499.858 1.462 911

19 Nonanoic acid C9H18O2 0.028 549.834 1.071 920

20 Phenol, 2,6-dimethoxy- C8H10O3 0.778 629.797 1.692 928

21 1,4-Benzenediol, 2-methoxy- C7H8O3 0.083 664.78 1.790 918

22 Vanillin C8H8O3 0.673 669.778 1.809 928

23 β-D-Glucopyranose, 1,6-anhydro- C6H10O5 2.348 724.752 2.195 929

24 Mome inositol C7H14O6 2.376 844.695 2.052 921

25 Myristic acid C14H28O2 0.052 914.662 1.090 919

26 n-Hexadecanoic acid C16H32O2 0.491 1,039.6 1.100 933

27 9,12-Octadecadienoic acid (Z,Z)- C18H32O2 0.359 1,134.56 1.235 936

28 9,12,15-Octadecatrienoic acid, (Z,Z,Z)- C18H30O2 0.234 1,139.56 1.284 932

29 1-Docosene C22H44 0.109 1,314.47 1.168 948

30 Hexadecanal C16H32O 0.037 1,334.46 1.178 906

31 Squalene C30H50 1.208 1,464.4 1.383 935

32 Heptacosane C27H56 0.141 1,489.39 1.156 930

33 Campesterol C28H48O 0.470 1,634.32 2.750 909

34 Stigmasterol C29H48O 0.829 1,649.31 2.855 928

35 β-Sitosterol C29H50O 0.975 1,674.3 3.122 928

36 Lup-20(29)-en-3-one C30H48O 0.063 1,704.29 4.128 905

37 Octacosanol C28H58O 0.084 1,734.27 2.771 917

a

Name from NIST library.
Classification of Chemicals in Black Locust Robinia pseudoacacia Wood and Bark

7

Figure 1. Two-dimensional gas chromatography (GC×GC) chromatogram contour plot of black locust bark acetone extracts.

Figure 2. Two-dimensional gas chromatography (GC×GC) chromatogram contour plot for black locust wood acetone extracts.

First dimension (s)

First dimension (s)

Second dimension (s) Second dimension (s)
Research Note FPL–RN–0386

8

Figure 3. Two-dimensional gas chromatography (GC×GC) chromatogram contour plots for black locust (a) bark and (b) wood 

acetone extracts starting at 11 min into the run of the extractives.

(b)

(a)

First dimension (s)

First dimension (s)

Second dimension (s) Second dimension (s)
Classification of Chemicals in Black Locust Robinia pseudoacacia Wood and Bark

9

Conclusions

Black locust is known for being a durable wood species. 

Identifying the chemicals that contribute to the durability 

can lead to other relevant research on medicinal alternatives. 

GC×GC technology opens the peak capacity where trace 

components are observed and can be detected in a complex 

mixture. One of the best techniques for characterizing 

black locust extracts is GC×GC TOFMS. There were 1,343 

and 1,868 chemicals detected in blw and blb extracts, 

respectively. NIST and Wiley libraries were used to identify 

the chemicals based on the spectral matches. There were 

unknown chemicals detected in blw (566) and blb (857) 

extracts. Benzenediols were highly concentrated in the 

bark and wood. This chemical is one of several reasons 

black locust has high decay resistance when placed in soils. 

Various classes of chemicals were identified and labeled on 

the chromatogram. The molecular mapping on GC×GC will 

assist with labeling and classifying the unknown chemicals 

detected in the bark and wood extracts for future work. 

This will lead to developing or isolating chemicals with 

alternative medicinal applications.

Acknowledgments

Research support was provided by the University of 

Wisconsin-Madison and the USDA Forest Service, Forest 

Products Laboratory. Zinan Yu assisted with GC×GC sorting 

and data collection. This research was presented at the 

20th International Symposium on Wood Fibre and Pulping 

Chemistry (ISWFPC) in Tokyo, Japan, and was submitted 

for the proceedings.

References

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