GC analysis of guanidino compounds in serum and urine of healthy volunteers and uremic patients using methylglyoxal and ethyl chloroformate as derivatizing reagent

Abstract

Gas chromatographic (GC) determination of 9 guanidino compounds: guanidine, methylguanidine, guanidinoacetic acid, guanidinopropionic acid, guanidinobutyric acid, guanidinosuccinic acid, arginine, creatinine and creatine have been examined from the serum and urine of healthy volunteers and uremic patients using precolumn derivatization with methylglyoxal and ethyl chloroformate. GC elution and separation was from the column HP-5 (30 m × 0.32 mm id) with film thickness 0.25 μm within 10.5 min. The detection was carried out using FID. The linear calibration curves for guanidino compounds were within 0.1–20.0 μmol L⁻¹ and the lower limits of detection were 0.014–0.027 μmol L⁻¹. The amounts of guanidino compounds observed in the serum of healthy volunteers were 0.2–88.0 μmol L⁻¹ as compared to that of uremic patients at 0.8–521 μmol L⁻¹, with relative standard deviations (RSDs) within 1.5–3.7% and 1.0–3.8%, respectively. The guanidino compounds in the urine of healthy volunteers and uremic patients were observed in the range below the limit of detection (BLOD) to 7304 μmol L⁻¹ and below LOD – 7541 μmol L⁻¹, with RSDs 1.1–3.7% and 1.0–3.8%, respectively. The derivatization, separation and quantitation were repeatable with RSD < 4%. Recovery of the guanidino compounds calculated by standard addition from serum and urine was obtained within 93–105% and 89–99%, with RSDs 1.4–2.9% and 1.8–4.3%, respectively.