Determination of trace levels of benzodiazepine in urine using capillary electrochromatography‐time of flight mass spectrometry

Abstract

This paper details a method for the separation and determination of ten benzodiazepines in urine using CEC-MS(TOF) and an hexyl acrylate-based porous monolith. The TOF mass spectrometer provides an exact mass of protonated benzodiazepines to three decimal places (1-6 ppm). This high selectivity along with the CEC separation, provides an effective method for the identification of benzodiazepines. Linearity is satisfactory for all compounds in the concentration range of 25-500 ng/mL for lorazepam and 12.5-500 ng/mL for the others. The RSDs are between 1.4-2.3% for retention times and 1.1-9.2% for relative areas. Using the monolithic stationary phase, a preconcentration step is achievable and permits an 75-140-fold improvement in sensitivity. This strategy permits the quantification of these drugs down to 1 ng/mL in urine. This method was used for the analysis of benzodiazepines in spiked urine samples.

Development of Advanced Capillary Electrophoresis Techniques with UV and Mass Spectrometry Detection for Forensic, Pharmaceutical and Environmental Applications

“…In CEC a high voltage is applied across the capillary, to generate EOF and move the mobile phase along with analytes through the column. Separations for CEC are a consequence of both differential partitioning and electrophoretic migration in mobile phases, which typically include a mixed aqueous/organic buffer [58]. Since CEC is a hybrid of CE and HPLC, high pressure is introduced to the system in order to assist with the electrophoretic mobility as well as reducing the formation of bubbles when preparing monolithic capillary columns.…”

“…Lastly, unreacted components are removed and a detector window is created by exposing a section to UV light [27,58]. The polymerization mixture is made of monomers, a chemical initiator, and the porogen.…”

“…Blas et al [58] described the separation and detection of benzodiazepines in urine samples using monolithic CEC-TOF-MS. Enhanced sensitivity was achieved because of two factors: the usage of the TOF-MS system and preconcentration at the tip of the capillary containing the monolithic materials.…”

“…For example, hydrophobicity can be altered through increases in the length of the carbon side group from hexyl to octadecyl acrylate. Charge density and pore size can also affect separation through changes in sulfonate concentration and through increased addition of cross linkers [57][58][59].…”

Development of a Surface-Enhanced Raman Spectroscopy Method for the Detection of Benzodiazepines in Urine

“…6,72 Since LLE can be an important method for the isolation of interest, a search was made for a method capable of utilizing the benefits of LLE (speed, ease of use, low cost) without many of the downsides (coextractions of interferences and salts).…”