Standard Solutions in Human Urine Spiked with Barbiturates

After minimal sample preparation (dilute-and-shoot approach), spiked urine samples were analyzed using a C18 Column. The analysis was based on a Separation of Standards [1]. The obtained Peaks were Symmetrical (As<1.05) and Efficient (> 106 pl/m). No shift in retention Times was observed after the samples were diluted ten-fold (data not shown). Matrix effects that would diminish the signal intensity were less than 5%.

This Method shows a possible Application for Analysis of these Compounds in Forensic Samples.



Peaks:
1. Phenobarbital-D5 m/z = 236.1089,
2. Phenobarbital m/z = 231.0775,
3. Butalbital-D5 m/z = 228.1402,
4. Butalbital m/z = 223.1088,
5. Pentobarbital-D5 m/z = 230.1558,
6. Pentobarbital m/z = 225.1245,
7. Secobarbital m/z = 237.1245

Method Conditions
Column: Cogent Bidentate C18™, 4μm, 100Å
Catalog No.: 40018-05P-2
Dimensions: 2.1 x 50mm
Mobile Phase:
A: DI Water with 10mM Ammonium Formate
B: 95:5 Acetonitrile / DI Water with 10mM Ammonium Formate (v/v)
Gradient:

Time (minutes) %B
0 10
1 10
10 45

Post Time: 3 minutes
Injection vol.: 1µL
Flow rate: 0.4mL / minute
Detection: ESI – NEG – Agilent 6210 MSD TOF Mass Spectrometer
Sample Preparation: Stock solutions of Barbiturates were prepared at a concentration of 1mg / mL in Methanol. Then 2mL of a urine sample was spiked with the stock solutions diluted, (dilution 1:100) and filtered through a 0.45μm Nylon Syringe Filter (MicroSolv Tech Corp.) into Autosampler Vials.
t0: 0.3 minutes



[1] J.J.Pesek, M.T. Matyska, A.M. Kim, J. Sep. Sci. 2013, 36, 2760–2766.

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