title: Analysis of citrate in low-volume seminal fluid samples using a time-gated measurement of europium luminescence.
abstract: This work aims to develop and validate a rapid analytical method that enables the measurement of citrate in seminal fluid samples. Samples were obtained from men who were within 9 weeks of a vasectomy operation. Two age ranges were examined, between 40-43 and 50-53 years old, with nearly 100 samples in each case. No patient clinical history was available for this anonymous study, simulating a random screening cohort. The concentration of citrate in 0.5 μL seminal fluid samples was assessed, using a europium emission luminescence method. This involves the ratiometric analysis of two well-separated europium(III) emission bands. Spectral data were obtained using a time-gated spectrometer whose construction and modification is described. Citrate values were confirmed by independent measurements using a citrate lyase enzymatic assay and by 700 MHz ¹H NMR analysis of the seminal fluid. Citrate concentrations were not statistically different between age groups and averaged 35.0(±14.6) mM for the 40-43 group, and 28.2(±12.7) mM for the 50-53 cohort; in each case a polymodal distribution was observed.
authors.affiliation: Department of Chemistry, Durham University, South Road, Durham DH13LE, UK. robert.pal@dur.ac.uk
authors.forename: Robert
authors.initials: R
authors.lastname: Pal
authors.forename: Andrew
authors.initials: A
authors.lastname: Beeby
authors.forename: David
authors.initials: D
authors.lastname: Parker
mesh_terms: D000328:Adult; D019343:Citric Acid / Q000032:analysis*; D005063:Europium / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009097:Multienzyme Complexes / Q000737:chemistry; D007652:Oxo-Acid-Lyases / Q000737:chemistry; D011874:Radiometry; D015203:Reproducibility of Results; D012661:Semen / Q000737:chemistry*; D055101:Semen Analysis / Q000379:methods*; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014659:Vasectomy
chemical_list: D009097:Multienzyme Complexes; D019343:Citric Acid; D005063:Europium; D007652:Oxo-Acid-Lyases; C019909:citrate (pro-3S)-lyase