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Featured Application: LPGC-MS Pesticides Analysis in Strawberries

Speed Up Multiresidue Pesticides Analysis in Food with Low-Pressure GC-MS

  • 3x faster than conventional methods.
  • Get the speed advantage of LPGC-MS with a simple column change.
  • Robust, factory-coupled column kit ensures leak-free performance.
  • Integrated transfer line reduces background and stabilization time.
 

Multiresidue pesticides analysis is a cornerstone of food safety testing, and labs are generally are under pressure to manage both a high volume of samples and rapid turnaround time requirements. This creates demand for faster GC-MS and GC-MS/MS methods, but typical approaches involve expensive instrumentation or “fast GC” techniques that have capacity issues (narrow-bore columns) or MS-compatibility concerns (hydrogen carrier gas). Low-pressure GC-MS (LPGC-MS) is option that can provide significant speed gains without these drawbacks, but, historically, the challenging setup has been a barrier to implementation. As shown in this LPGC-MS pesticides analysis of 209 compounds in strawberry, all analytes elute quickly with deltamethrin eluting last at 8.33 minutes. This time is three-fold faster than our analysis of the same extract on a conventional 30 m, 0.25 mm ID, 0.25 µm 5-type column where deltamethrin was again the final compound and eluted at 26.34 minutes.

This LPGC-MS pesticides analysis utilizes a unique low-pressure GC column kit that is comprised of a narrow restrictor column (5 m x 0.18 mm ID) that is factory coupled to a wider Rtx-5ms analytical column (15 m, 0.53 mm ID, 1 µm plus 1 m integrated transfer line on the outlet end). The manufactured connection is tested to ensure leak-free performance and is more robust than manual connections. Using this kit allows the speed gains of LPGC-MS to be obtained by making a simple column change and updating the instrument method with the new column dimensions, oven ramp, and flow rates. Note that for this particular LPGC-MS pesticides analysis, the GC oven must be capable of a 35 °C/min ramp rate at oven temperatures in excess of 300 °C. For 120V ovens, an oven insert kit will be necessary to achieve this rate.

While this LPGC-MS setup provides a significant speed gain; tall, narrow peaks that may improve sensitivity; and high capacity from the thick film analytical column, the overall plate count will be somewhat lower than on conventional columns. Although peak resolution will be lower with LPGC-MS, the mass spectrometer can offset this effect by spectrally distinguishing most target analytes. However, it is important to note that isobaric compounds must be chromatographically separated because the MS cannot resolve them. For example, in this analysis, isobars 4-4’-DDD and 2,4’-DDT are not fully resolved, so if their separation is critical, further method development would be needed. The other highlighted separations are compounds that either have both shared and unique ion transitions (trifluralin/benfluralin and cyhalothrin/acrinathrin); are adequately separated (cis- and trans-permethrin); or are commonly reported as a group (cyfluthrin and cypermethrin isomer clusters) and thus are still quantifiable even though they may not be completely chromatographically resolved.

For busy food labs needing faster methods, the speed gains of LPGC-MS pesticides analysis are an effective way to increase sample throughput. This once-challenging setup is now much simpler to implement using a low-pressure GC column kit from Restek.

GC_FS0572
PeakstR (min)Precursor IonProduct IonCollision EnergyConfirmation Precursor IonConfirmation Product IonCollision Energy
1.Allidochlor3.37138818132566
2.Dichlobenil3.6317110025136100.110
3.Biphenyl3.75154.111525152.1126.123
4.Mevinphos3.88192127.110127.19516
5.3,4-Dichloroaniline3.921639016161126.18
6.Pebulate4.012031288128578
7.Etridiazole4.02211139.922182.8139.916
8.N-(2,4-Dimethylphenyl) formamide4.1012110681207715
9.Tetrahydrophthalimide4.10151.180.16151.112210
10.Methacrifos4.1924018010125796
11.Chloroneb4.242061911019111313
12.2-Phenylphenol4.31170.2141.222141115.112
13.Pentachlorobenzene4.332501423025017930
14.Propachlor4.601765781207719
15.Tecnazene4.60260.9202.913214.9178.98
16.Diphenylamine4.63169.1167.125169.1168.112
17.Cycloate4.672151546154838
18.2,3,5,6-Tetrachloroaniline4.692311223023116022
19.Chlorpropham4.70213.1171.18171127.18
20.Ethalfluralin4.75316.1276.110276.1202.115
21.Trifluralin4.78306.1206.212306.1264.18
22.Benfluralin4.80292160.120292264.18
23.Sulfotep4.853221462320214610
24.Diallate 14.89234.115018234.1192.112
25.Phorate4.90260.1758121.16510
26.Diallate 24.95234.115018234.1192.112
27.α-BHC5.00219183818114515
28.Hexachlorobenzene5.02283.8213.930248.9213.914
29.Dicloran5.03206147.91817614810
30.Pentachloroanisole5.04279.9236.923266.9238.910
31.Atrazine5.05215173.18200.1122.110
32.Clomazone5.10204107181258913
33.β-BHC5.12219183818114515
34.Profluralin5.14330.16925318.119917
35.Terbuthylazine5.16229.1173.18172.8137.98
36.Terbufos5.172311292323117512
37.γ-BHC5.16219183818114515
38.Propyzamide5.181731092717314513
39.Diazinon5.19304179.112137.184.112
40.Fonofos5.19246.1137.18137.11096
41.Quintozene5.19294.823715236.811922
42.Fluchloralin5.21306.1159.720306.12648
43.Pentachlorobenzonitrile5.212752053027323817
44.Pyrimethanil5.21198.1118.132198.118316
45.Tefluthrin5.24177127.115177137.115
46.Disulfoton5.25153.1971288.159.96
47.Terbacil5.26161144141601178
48.Isazophos5.29172.113010161.11198
49.δ-BHC5.31219183818114515
50.Triallate5.322701861826818420
51.Chlorothalonil5.342661702326416823
52.Anthracene (IS)5.3517815220
53.Endosulfan ether5.42240.920613238.920413
54.Propanil5.4421916382171618
55.Pentachloroaniline5.452651942226319220
56.Dimethachlor5.46197148813410513
57.Acetochlor5.482231322017414612
58.Transfluthrin5.4816314313127.191.18
59.Vinclozolin5.502852121221217212
60.Chlorpyrifos methyl5.522869322286207.912
61.Methyl parathion5.5226310910263136.28
62.Tolclofos-methyl5.542672521026525010
63.Alachlor5.55188160101461188
64.Metalaxyl5.56220.1160.210160.1145.110
65.Propisochlor5.562231321816212013
66.Fenchlorphos5.592872721128524023
67.Heptachlor5.59272237131006512
68.Prodiamine5.6332127962792038
69.Pirimiphos methyl5.65305.1180.18290.112522
70.Fenitrothion5.662771091626012512
71.Linuron5.6924861818712421
72.Malathion5.691739913127996
73.Dichlofluanid5.722241231212377.116
74.Pentachlorothioanisole5.732962463229626312
75.Metolachlor5.762381621016213313
76.Chlorpyrifos5.77314257.912196.9168.914
77.Fenthion5.772781091827816917
78.Parathion5.78291.2109.110109818
79.Anthraquinone5.79208.1180.110180.1152.112
80.Triadimefon5.79208110.924208180.810
81.Aldrin5.80298263826319331
82.Chlorthal-dimethyl5.81331.83018298.9220.924
83.4,4'-Dichlorobenzophenone5.81139752711175.112
84.Pirimiphos ethyl5.85318.2166.112304.1168.112
85.Fenson5.8626877.11814177.18
86.Cyprodinil5.87225.2209.812224.1208.120
87.Diphenamid5.88239167816711540
88.Isopropalin5.89280.1118.125280.1238.18
89.MGK 264 15.89164.18024164.193.112
90.Bromophos-methyl5.903313161332931413
91.Chlozolinate5.95331259.1818614516
92.Pendimethalin5.95281.1252.28252.1162.110
93.Bioallethrin5.96136.19311123.281.18
94.Fipronil5.973672133036921530
95.MGK 264 25.971646710164.18024
96.Isodrin5.97260.9190.92819312330
97.Metazachlor5.972091321513311725
98.Penconazole5.97248.1192161598930
99.Chlorfenvinphos 16.043232671026715915
100.Tolylfluanid6.052401371023813710
101.Bromfenvinphos-methyl6.0629510915109795
102.Heptachlor epoxide6.073532631326319329
103.Quinalphos6.07298156.18146.1118.110
104.Triadimenol6.07168.170.11012865.122
105.Triflumizole6.09205.917914179143.814
106.Captan6.101491056106.87912
107.Procymidone6.1128367.1282839610
108.Folpet6.14259.913016103.97610
109.Chlorbenside6.15268125.1812589.117
110.Bromophos-ethyl6.17358.930317330.93038
111.trans-Chlordane6.193752661827223712
112.Paclobutrazol6.19237.812710236.1125.112
113.2,4'-DDE6.193162461524617630
114.Tetrachlorvinphos6.203331091733110920
115.Fenamiphos6.25303.1195.182172029
116.Flutolanil6.262811731017314514
117.Prothiofos6.263092391526722116
118.cis-Chlordane6.273752661827223712
119.Bromfenvinphos6.273252691032326710
120.Fludioxonil6.2724812730153.81278
121.Flutriafol6.27219.112314123.19512
122.Iodofenphos6.273773323037736215
123.Pretilachlor6.27262202816213218
124.Profenofos6.273391883033726713
125.Chlorfenvinphos 26.273232671026715915
126.Endosulfan I6.28241206101951596
127.trans-Nonachlor6.284092632540930023
128.Chlorfenson6.2930217581751118
129.Oxadiazon6.33258175817511213
130.Oxyfluorfen6.3430022315252.1146.133
131.Myclobutanil6.38179125141791528
132.Bupirimate6.39316.2208.28273.1193.28
133.Flusilazole6.39233.1164.918206.113720
134.4,4'-DDE6.403162461524617630
135.Tricyclazole6.41189135.21818916212
136.2,4'-DDD6.42235165.121235199.116
137.Dieldrin6.42277241826319334
138.Fluazifop-P-butyl6.42383.1268.28383.1282.212
139.Chlorfenapyr6.46247227.1121377528
140.Ethylan6.462231671222319328
141.Nitrofen6.4928320210202139.120
142.Chlorthiophos 16.50256.916526256.923912
143.Chlorobenzilate6.522511391413911112
144.Endrin6.552631933024517325
145.Ethion6.58231129241539710
146.4,4'-DDD6.59235165.121235199.116
147.Chlorthiophos 26.61325269142972698
148.2,4'-DDT6.62235165.121235199.116
149.Triazophos6.65256.9161.78161134.18
150.cis-Nonachlor6.654092632540930023
151.Sulprofos6.66322156815614113
152.Carfentrazone ethyl6.67340.2312.210330310.18
153.Endrin aldehyde6.68344.9243.117344.9244.914
154.4,4'-Methoxychlor olefin6.70308223.130238.1152.135
155.Carbophenothion6.7034215710125976
156.Norflurazon6.74303145171459518
157.Edifenphos6.75310109291731098
158.Lenacil6.76153135.714135.852.918
159.4,4'-DDT6.61235165.121235199.116
160.Endosulfan sulfate6.81272237102412068
161.Hexazinone6.83171.171.1161288310
162.Piperonyl butoxide6.83176.110326176.1131.114
163.Propargite6.83201.181.110135.110714
164.Resmethrin6.83143.112810123.281.28
165.Tebuconazole6.85250.1125.2221258916
166.Nitralin6.95316.12748274216.26
167.Captafol6.99150.878.9187977.112
168.TPP (IS)6.993261693032621520
169.Iprodione7.0131424514187124.124
170.Bifenthrin7.05181.1166.110165.1115.130
171.Fenpropathrin7.05265210818115224
172.Pyridaphenthion7.05340.1199.18199.177.126
173.Tetramethrin7.06164772516410712
174.Bromopropylate7.08340.818315183154.912
175.Azinphos-ethyl7.8016077181327712
176.EPN7.1116977221691418
177.Phosmet7.11160772416013310
178.Methoxychlor7.122271413322716925
179.Tebufenpyrad7.12333276827617110
180.Endrin ketone7.13317101213152798
181.Phenothrin7.19183.1168.112123.281.18
182.Tetradifon7.252271991015913110
183.Pyriproxyfen7.28226.1186.116136.17820
184.Phosalone7.293671113618211114
185.Leptophos7.31377269371717718
186.λ-Cyhalothrin7.31197.1141.1101979126
187.Acrinathrin7.32289.193102899124
188.Pyrazophos7.41265.1210.110221.1193.110
189.Mirex7.442742391527223715
190.Fenarimol7.46219107.11213911116
191.Azinphos-methyl7.4616077181327712
192.Pyraclofos7.473601391419413818
193.cis-Permethrin7.54183.1153.112163127.16
194.trans-Permethrin7.58183.1153.112163127.16
195.Pyridaben7.62147117201471198
196.Coumaphos7.663621091721018210
197.Fluquinconazole7.663401084234029814
198.Prochloraz7.67308701318013812
199.Cyfluthrin7.73226.1199822615130
200.Cypermethrin7.83181.112728181.1152.120
201.Flucythrinate 17.86199.1157.18157.1107.113
202.Acequinocyl7.89342.4188.11418813210
203.Etofenprox7.90163.110718163.1135.110
204.Flucythrinate 27.91199.1157.18157.1107.113
205.Fluridone8.03328.1127.140328.125926
206.Fenvalerate8.10169.1127.110167.11258
207.Tau-fluvalinate8.152525517250.15523
208.Fenvalerate8.16169.1127.110167.11258
209.Deltamethrin8.33252.993.119181.115220
ColumnLow-pressure GC column kit (factory-coupled restrictor column [5 m x 0.18 mm ID] and Rtx-5ms analytical column [15 m, 0.53 mm ID, 1 µm plus 1 m integrated transfer line on the outlet end]) (cat.# 11800)
SampleGC multiresidue pesticide kit (cat.# 32562)
Triphenylphosphate (cat.# 33258)
Anthracene (cat.# 33264)
Diluent:Acetonitrile
Conc.:1 µg/mL
Injection
Inj. Vol.:1 µL splitless (hold 0.5 min)
Liner:Topaz 4.0 mm ID single taper inlet liner w/ wool (cat.# 23447)
Inj. Temp.:250 °C
Oven
Oven Temp.:80 °C (hold 1 min) to 320 °C at 35 °C/min (hold 5 min)
Carrier GasHe, constant flow
Flow Rate:2 mL/min
DetectorTSQ 8000
SIM Program:35-550 m/z
Transfer Line Temp.:290 °C
Analyzer Type:Quadrupole
Source Temp.:325 °C
Solvent Delay Time:2 min
Tune Type:PFTBA
Ionization Mode:EI
InstrumentThermo Scientific TSQ 8000 Triple Quadrupole GC-MS
NotesSample preparation: 10 g of homogenized strawberries were fortified with the internal standards at 20 ppb and then extracted with 10 mL of acetonitrile and QuEChERS EN 15662 salts (cat.# 25850). After centrifugation, 1 mL of supernatant was added to a 2 mL dSPE vial containing magnesium sulfate and PSA (cat.# 26124) for cleanup. The cleaned extract was spiked with GC multiresidue pesticide mix at 1 ppm.
FSFA3504-UNV

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