RESUMO
Pheniramine is an over-the-counter antihistamine drug. Its accessibility and low cost made it more popular among drug abusers in Pakistan. In this study, pheniramine was quantified in both conventional and alternative specimens of twenty chronic drug abusers, aged 16-50 years, who were positive for pheniramine in comprehensive toxicological screening for drugs by gas chromatography with mass spectral detection in positive electron impact mode. Pheniramine was extracted from biological specimens using solid phase extraction and liquid chromatography tandem mass spectrometry was employed for quantification. Chromatographic separation was carried out on a Poroshell120EC-18 (2.1 mm × 50 mm × 2.7 µm) column using water-acetonitrile in formic acid (0.1%) mobile phase in gradient elution mode with 500 µL/min flow rate. Positive electrospray ionization mode and multi-reaction monitoring with ion transitions m/z 241.3 â 195.8 and 167.1 for pheniramine and m/z m/z 247.6 â 173.1 for pheniramine-d6 were employed. The quantification method showed good linear ranges of 2-1000 ng/mL in blood, urine, and oral fluid; 2-1000 ng/mg in hair and 5-1000 ng/mg in nail with ≥ 0.985% coefficient of linearity. The retention time of pheniramine was 3.0 ± 0.1 min. The detection and lower quantification limits were 1 ng/mL and 2 ng/mL for blood, urine, oral fluid and hair whereas 2.5 ng/mg and 5 ng/mg for nail, respectively. Mean extraction recovery and ionization suppression ranged 86.3-95.1% and -4.6 to -14.4% in the studied matrices. Intra-day and inter-day precision were 4.1-9.3% and 2.8-11.2%, respectively. Pheniramine levels in specimens of drug abusers were 23-480 ng/mL in blood, 72-735 ng/mL in urine, 25-379 ng/mL in oral fluid, 10-170 ng/mg in hair and 8-86 ng/mg in nail specimens. Alternative specimens are of utmost significance in clinical and medico-legal cases. In this study, authors compared matrix-matched calibration curves to blood calibration curve and obtained results within ± 10%; thereby justifying the use of blood calibration curve for urine, oral fluid, hair, and nail specimens.
RESUMO
OBJECTIVE: To optimize and validate a specific, sensitive and fast liquid Chromatography coupled to triple quadrupole Mass Spectrometric (LC-MS / MS) technique for accurate detection of serum α-tocopherol (Vitamin E) levels. STUDY DESIGN: An experimental based study. PLACE AND DURATION OF STUDY: The Clinical and Forensic Toxicology section of Chughtai Lab, Jail Road Lahore, from April to September 2022. METHODOLOGY: Methanol was used to deproteinize serum samples. The chromatographic separation was achieved using an Agilent Infinity-Lab Poroshell 120EC-C18 column, Agilent 6470 LC-MS/MS (equipped with an Electron Spray Ionization source) in gradient elution mode using 0.1% LCMS grade formic acid in water and LCMS-grade methanol as mobile phases. Hexa-deuterated α-tocopherol was employed as internal standard to minimise matrix interferences. RESULTS: The retention time of α-tocopherol was 3.0 ± 0.1 minutes. The linear concentrations obtained were ranged from 0.05-2 mg/dL with ≥0.985% coefficient of linearity. Detection and lower quantification limits determined were 0.025mg/dL and 0.05mg/dL, respectively. Recovery ranged from 96.5 to 99.8% and ionization suppression was -15.2% and -15.9% at high and low concentrations of α-tocopherol in serum. Intra-day and inter-day coefficient variation values were 4.2-4.9% and 5.0-5.9%, respectively. CONCLUSION: An efficient and reliable tandem mass spectrometric technique for vitamin E analysis in serum was optimized, validated, and applied to 80 patient samples. This method has usefulness in clinical application for the accurate determination of vitamin E without potential matrix interferences. KEY WORDS: Vitamin E, LC-MS/MS, Tocopherol, Internal standard, Validation.
