Gas chromatographic determination of hydroxyproline in urine hydrolysates

Quantitation of hydroxyproline in bone by gas chromatography-mass spectrometry

A validated gas chromatography (GC)-mass spectrometric (MS) method for the analysis of hydroxyproline in rat femur is reported. Hydroxyproline in bone hydrolysates was extracted with an anion exchange resin and the N(O)-tert-butyldimethylsilyl derivatives analyzed by GC-MS. The hydroxyproline concentration was estimated relative to pipecolic acid, 3,4-dehydroproline and n-tetracosane as internal standards. The mass-to-charge ratios (m/z) for the ions used for quantitation by single ion monitoring were 314 m/z for hydroxyproline, 198 m/z for pipecolic acid, 256 m/z for dehydroproline and 57 m/z for n-tetracosane. A coefficient of variation of 5.8% was achieved and the limit of detection was calculated to be 0.233 micromol/l bone hydrolysate.

Hydroxyprolinuria in normal Zairean children

Hydroxyprolinuria has been measured in 378 normal Zairean children aged between 3 and 13 years using the Kivirikko's method; 192 of them were boys and 186 were girls. Results show an age-related increase of urinary excretion of hydroxyproline in both sexes, girls having higher absolute values than boys. However, this difference is pronounced when values are corrected according to body size. Our values are slightly higher than those found in the literature.

Selective and sensitive determination of urinary total proline and hydroxyproline by gas chromatography with flame photometric detection

A selective and sensitive method for the determination of total urinary proline (Pro) and hydroxyproline (Hyp) by gas chromatography (GC) was developed. After acid hydrolysis of urine, primary amino compounds were eliminated by reaction with o-phthaldialdehyde. Subsequently, Pro and Hyp were converted into their N-dimethylthiophosphoryl methyl ester derivatives and then determined by GC with flame photometric detection using a DB-5 capillary column. The derivatives were volatile and stable, giving single and symmetrical peaks. The detection limits for Pro and Hyp were 0.1 and 0.2 pmol injected, respectively. 3,4-Dehydroproline was used as an internal standard. The calibration curves for Pro and Hyp in the range 0.4-10 nmol were linear and sufficiently reproducible for quantitative determination. Overall recoveries of Pro and Hyp added to urine samples ranged from 93% to 103%. By using this method, Pro and Hyp in a small urine sample could be accurately and precisely determined without any influence from other constituent substances.

Determination of 4-hydroxyproline in collagen by gas chromatography/mass spectrometry

Derivatization of 4-hydroxyproline (Hyp) in collagen using trifluoroacetylation and methanol esterification produces two derivatives when analyzed by gas chromatography/mass spectrometry (GC/MS). The diacyl derivative N,O-bis(trifluoroacetyl)-4-hydroxy-L-proline methyl ester (N,O-TFA-Hyp) formed in this manner has a shorter retention time and different fragmentation pattern by GC/MS as compared to the slower eluting monoacetylated species N-trifluoroacetyl-4-hydroxy-L-proline methyl ester (N-TFA-Hyp). By selected ion monitoring of the appropriate ions of either N,O-TFA-Hyp (m/z 164, 278) or N-TFA-Hyp (m/z 164, 182) efficient quantitation of Hyp in collagen is possible within the broad range of 5-1000 ng with a lower limit of detection of 0.5 ng per injection. Measurement of 18O2 incorporation into collagen is possible by selected ion monitoring of the m/z 182 ion formed only from the monoacetylated derivative, N-TFA-Hyp, produced by methanol solvolysis of the N,O-TFA-Hyp derivative, as proposed herein.

An enzymatic estimation of free hydroxyproline in tissue hydrolysates

An enzymatic method using 4-hydroxyproline 2-epimerase (EC 5.1.1.9), D-amino acid oxidase (EC 1.4.3.3.), and a colorimetric reagent of the mixture of Ti(IV) and 4-(2-pyridylazo)-resorcinol was found to be useful in the spectrophotometric assay for hydroxyproline in collagenous tissue hydrolysates. It was possible to determine free hydroxyproline in 250 microliter of tissue hydrolysates at concentrations ranging from 1 to 12.5 micrograms. The coefficient of variation was less than 3%, and the correlation between the proposed method and the colorimetric method (K.I. Kivirikko, O. Laitinen, and D. J. Prockop (1967) Anal. Biochem. 19, 249-255) was 0.973. Thus, this method is convenient because it requires less time than the above colorimetric method, and is also reproducible and sensitive.