Qualitative and quantitative analysis of hydrochlorothiazide in equine plasma and urine by high-performance liquid chromatography.

This research article presents a new sensitive method that can measure the presence of a drug named hydrochlorothiazide in equine plasma and urine. It utilizes a type of chromatography to screen unknown samples first and then confirm with another type of chromatography and mass spectral confirmation.

Explanation of the Research

• The study revolves around the development and utilization of a sensitive and quantitative approach to determine the presence of hydrochlorothiazide, a drug, in equine plasma and urine. Hydrochlorothiazide is a diuretic often used to treat high blood pressure and swelling due to fluid build-up.
• Screening of the drug in unknown samples is carried out through thin-layer chromatography (TLC), a technique used to separate non-volatile mixtures. In this particular study, the TLC screening methods used are capable of detecting minimum concentrations of 50 nanograms per millilitre (ng/mL) in plasma and 25 ng/mL in urine.

Role of Silica Micro Chromatography Column

• A silica micro chromatography column is used in the study to ‘clean up’ or purify ethyl acetate extracts before they are analyzed through high-performance liquid chromatography (HPLC).
• HPLC is a technique used to separate, identify, and quantify each component in a mixture. The cleaned-up extracts from the silica micro chromatography column are then subjected to HPLC analysis for substance identification and categorization.

Application of an Internal Standard

• This research makes use of an internal standard, trichloromethiazide, to procure quantitative data. An internal standard in an analytical chemistry context is a chemical substance that is added in a known amount to a sample to aid in its analysis.
• In this study, trichloromethiazide (a drug similar to hydrochlorothiazide) is used as the internal standard and helps derive quantitative data for plasma disappearance curves and urinary excretion rates. The use of this standard allows for accurate measurements at low concentrations as small as 25 ng/mL.
• The mass spectral confirmation mentioned in the abstract likely refers to a mass spectrometry process applied lastly to confirm the presence and amount of hydrochlorothiazide in the samples.