Determination of dextropropoxyphene and nordextropropoxyphene in urine by liquid chromatography-electrospray ionization mass spectrometry

Dextropropoxyphene and nordextropropoxyphene were extracted from urine samples with mixed mode solid-phase extraction cartridges. After elution and evaporation to dryness, the eluate was dissolved in mobile phase and each sample was injected in a LC-ESI-MS system. Quantification was carried out in the selected ion monitoring mode. This article shows the possibility to analyse drugs of abuse substances in urine with a single quadrupole mass spectrometer if only a thorough work-up procedure and a sufficient chromatographic separation is accomplished. In order to enhance the fragmentation of the analytes, in-source fragmentation was carried out. One fragment and the pseudomolecular ion per analyte together with chromatographic retention times were sufficient to verify that the sought compound was found in the samples. In- and between day variation was lower than 10% and the recovery was well above 90%. The analytes were quantified in the range 100-10000 ng/ml urine.     

Precipitation of collagens by polyethylene glycols

Types I, II, and III collagens are readily precipitated at neutral pH by polyethylene glycols (PEG). As the molecular weight fraction of the polyethylene glycols increases, they become more effective as precipitants on a weight basis. The amount of PEG required for precipitation depends on the pH, the ionic strength, and the nature of the buffer or salts present. In tissue culture media, low concentrations of collagens and procollagens may be quantitatively precipitated and readily collected by low-speed centrifugation. Polyethylene glycol precipitation can be used to obtain collagens and procollagens from tissue culture media at either analytical or preparative scale, and since the polyethylene glycols do not bind to collagens, the precipitates may be further analyzed directly by chromatographic or electrophoretic methods.     

19-Nor-deoxycorticosterone in the neutral fraction of human urine

19-Nor-deoxycorticosterone (19-nor-DOC), in the neutral fraction of human urine, was isolated and quantitated as the acetate derivative using ultraviolet absorption of the peak emerging from a high-pressure liquid chromatographic column. Identification of 19-nor-DOC in a pooled collection of urine after ACTH administration included identical chromatographic mobilities as the parent compound and acetate derivative compared to authentic 19-nor-DOC and mass spectral analysis of the acetate derivative. Values obtained for control and post-ACTH urines were 528 +/- 100 (SE) ng/24 hours and 8851 +/- 824 ng/24 hours, respectively. One patient with primary aldosteronism excreted 1894 ng/24 hours.     

New extraction procedure and high-performance liquid chromatographic method for analyzing polyethylene glycol-400 in urine

We describe a new, highly efficient method for extracting polyethylene glycol-400 from urine and for its analysis by isocratic reverse-phase high-performance liquid chromatography. This method is an improvement over previously published methods in that it does not require the use of ion-exchange resins and lyophilization prior to extraction, nor does it require the separation and analysis of the individual polymers of polyethylene glycol. The procedure described in this report entails extraction with a salt—solvent combination of ammonium sulfate and dichloromethane and analysis by reversed-phase high-performance liquid chromatography. The lower limit of detection was approximately 0.25 g/l with a 2-ml urine sample. Analytical recoveries of polyethylene glycol-400 added to urine at 2.5 and 5.0 g/l averaged 97 and 96%, respectively (n = 10). Within- and between-day coefficients of variation were less than 5% at 2.5 and 5.0 g/l. Studies of various urine samples from patients receiving polyethylene glycol-400 revealed no interferences from other urine substances.     

Hemoglobin precipitation by polyethylene glycols leads to underestimation of membrane pore sizes

The size of pores formed in the plasma membrane by various substances is frequently determined using polyethylene glycols as osmotic protectants. In this work, we have found that the size of pores formed by saponin in the red blood cell membrane determined by hemolysis versus molecular weight of polyethylene glycol was different to that estimated by light dispersion of cell suspensions. After complete swelling of cells induced by saponin in semiisotonic salt media containing 150 mOsm PEG-4000 or PEG-3000, a significant increase in the light absorbance at 640 nm was developed resulting from the formation of hemoglobin precipitates. Easily sedimenting aggregates were also formed when the supernatant of lysed cells was added to the equiosmotic solutions of polyethylene glycols with molecular weight higher than 1000. We suggest that the real size of large pores could be underestimated due to the phenomenon of hemoglobin precipitation by polyethylene glycols.     

Confirmatory analysis for drugs of abuse in plasma and urine by high-performance liquid chromatography-tandem mass spectrometry with respect to criteria for compound identification

Recently, high-performance liquid chromatography-tandem mass spectrometry (LC/MS/MS) has become a powerful tool for quantitative confirmatory analysis of drugs of abuse and has begun to spread in the field of forensic toxicology. Guidelines for confirmatory analysis by GC/MS and LC/MS/MS have been published recently by several organizations (WADA, IOC, SOFT, GTFCh, EU). However, these guidelines have not yet been included in procedures for drug analysis with LC/MS/MS. The prerequisites for forensic confirmatory analysis by LC/MS/MS with respect to EU guidelines are chromatographic separation, a minimum number of two MS/MS transitions to obtain the required identification points and predefined thresholds for the variability of the relative intensities of the MS/MS transitions (MRM transitions) in samples and reference standards. LC/MS/MS methods for determination of several classes of drugs of abuse including some basic drugs (opiates, stimulants), cannabinoids and some of their phase-I- and phase-II-metabolites (especially glucuronides) in urine and serum of drug abusers and/or crime offenders or victims have been developed and validated following current recommendations and are presented in this paper. At least two MRM transitions for each substance were monitored to provide sufficient identification of drugs, deuterated analogues of analytes were used as internal standards for quantitation where possible and chromatographic separation has been performed on reversed-phase columns with gradient elution. Validation data obtained and the application to real samples show that the requested criteria for confirmatory analysis of drugs of abuse by EU guidelines can be fulfilled with a total number of four identification points by LC/MS/MS methods using a triple-quadrupole mass spectrometer. Furthermore, the methods are sufficiently sensitive to meet current requirements for confirmatory analysis of drugs of abuse in driving under the influence of drugs (DUID) cases established by the Society of Toxicological and Forensic Chemistry (GTFCh).     

Quantitative Urine Culture by Surface Drop Method

A simple drop method for quantitative urine culture was developed and tested in comparison with standard methods for bacterial urinary counts. In a group of 452 urines all yielding Escherichia coli, 74 showed counts of more than 100,000 colonies, and 16 showed counts between 10,000 and 100,000 colonies per ml. Of these 90 urines, 3 of the 16 in the doubtful group were false negative with the drop method. Another 7 urines in the total number of 452 showed discrepancies, but, because all would have been repeated, the second urine sample would have corrected the primary result. The ease and cleanliness of the method render it a suitable technique for screening normal and patient populations. The method was applied on a population sample of 1,330 persons from whom unwashed mid-stream urine was collected and yielded figures comparable with results published in the literature. The method discriminates between steps of 10-fold difference, whereas more accurate count methods show a standard error of +/-25% and are reliable in a double dilution series.     

Activator protein required for the enzymatic hydrolysis of cerebroside sulfate. Deficiency in urine of patients affected with cerebroside sulfatase activator deficiency and identity with activators for the enzymatic hydrolysis of GM1 ganglioside and globotriaosylceramide

Urine specimens from two sibs affected with cerebroside sulfatase activator deficiency were examined to ascertain whether the deficiency of the supplementary activator protein required for the enzymatic hydrolysis of cerebroside sulfate was also evident in urine. Material from chromatographic fractionations was examined for the activator activity to avoid ambiguities resulting from protein inhibition. There were substantial deficits in all chromatographic fractions corresponding to activator-containing fractions of control urines. Since patient urines contained elevated amounts of lactosylceramide, digalactosylceramide, and globotriaosylceramide and since similarities between activators for cerebroside sulfate and GM1 ganglioside hydrolyses had been noted previously, the chromatographic fractions were also examined for activators in other glycosphingolipid hydrolase systems. There was coincidence of activators for the GM1 ganglioside/beta-galactosidase and the globotriaosylceramide/alpha-galactosidase A reactions with the cerebroside sulfatase activator in control urine fractions, and the patients' urines were deficient in activator activities for the three reactions. Identity of the three activators was suggested and antiserum to purified GM1 ganglioside activator was used to test this possibility. There were depressed levels of cross-reacting material in fractions of patient urines by Ouchterlony double diffusion and in unfractionated urine by enzyme-linked immunosorbent assay. Purified activators for the cerebroside sulfate and GM1 ganglioside systems showed lines of identity with no spurring on Ouchterlony double diffusion, identical mobility on immunoelectrophoresis, and similar stimulatory activities toward hydrolysis of the three glycosphingolipid species by their respective enzymes. Finally, the three activator activities were retained by anti-GM1-activator IgG coupled to Sepharose 4B. The results suggest strongly that the same protein entity serves as activator for the enzymatic hydrolysis of cerebroside sulfate, GM1 ganglioside, and globotriaosylceramide.     

Analysis of the variability of human normal urine by 2D-GE reveals a "public" and a "private" proteome

The characterization of the normal urinary proteome is steadily progressing and represents a major interest in the assessment of clinical urinary biomarkers. To estimate quantitatively the variability of the normal urinary proteome, urines of 20 healthy people were collected. We first evaluated the impact of the sample conservation temperature on urine proteome integrity. Keeping the urine sample at RT or at +4°C until storage at -80°C seems the best way for long-term storage of samples for 2D-GE analysis. The quantitative variability of the normal urinary proteome was estimated on the 20 urines mapped by 2D-GE. The occurrence of the 910 identified spots was analysed throughout the gels and represented in a virtual 2D gel. Sixteen percent of the spots were found to occur in all samples and 23% occurred in at least 90% of urines. About 13% of the protein spots were present only in 10% or less of the samples, thus representing the most variable part of the normal urinary proteome. Twenty proteins corresponding to a fraction of the fully conserved spots were identified by mass spectrometry. In conclusion, a "public" urinary proteome, common to healthy individuals, seems to coexist with a "private" urinary proteome, which is more specific to each individual.     

Hair testing for drugs of abuse

Hair testing for drugs of abuse is a developing technology, which offers the possibility of longer detection times than is commonly obtained with urine analysis. It is the main method for evaluation of an individual's drugs of abuse history. In many countries hair analysis is routinely used to detect drug abuse in forensic cases, occupational and traffic medicine and clinical toxicology. Hair analysis in pregnant women, neonates and infants is a useful tool for the detection of drug exposure in utero. In Croatia hair testing for drugs of abuse is performed at the Institute for Medical Research and Occupational Health. Three-year experience in drugs of abuse analysis in hair is described. In 331 hair samples (270 from adolescents and 61 from adults) opiates and metabolites, cocaine, methadone, and amphetamines were analyzed by gas chromatography/mass spectrometry. Most prevalent drugs of abuse in adolescents were amphetamines, and in adults heroin. From the examples cited and samples analyzed it is evident that hair testing is emerging as a reliable biological marker for cumulative account of individual exposure to drugs of abuse.     

Trace determination of urinary 3-hydroxybenzo[a]pyrene by automated column-switching high-performance liquid chromatography

3-Hydroxybenzo[a]pyrene (3-OHB[a]P), one of the metabolites of benzo[a]pyrene (B[a]P), has been determined in human urine using an automated column-switching procedure. The hydrolysed biological sample is centrifuged just prior to being injected into a reusable precolumn loop, which is packed with a preparative phase and coupled on-line to a liquid chromatographic (LC) system. A rapid pre-treatment of the hydrolysed sample, consisting of a concentration and a crude clean-up, is performed on the precolumn. The analytes are then non-selectively desorbed with the LC eluent and the sample is cleaned again in three successive purification columns using the direct transfer or “heart-cut” technique. The pre-treatment does not exceed 3 min. and the entire analytical purification and separation procedure takes less than 30 min. Average 3-OHB[a]P recovery reaches 95% in the 1–50 ng/l range of urine, and the detection limit is 0.1 ng/l urine for a 3 ml injection of hydrolysed urine. The developed method was compared with a more time-consuming off-line method to analyse urines of B[a]P gavaged rats; the statistical treatment indicates that both methods are in agreement. The method was applied to purify and concentrate the urine samples of workers exposed and apparently unexposed to polycyclic aromatic hydrocarbons (PAHs).     

Investigation of the effect of freezing on protease-catalyzed peptide synthesis using cryoprotectants and frozen organic solvent

In order to investigate the effect of freezing on aqueous protease-catalyzed peptide synthesis systems, the influence of polyethylene glycols as cryoprotecting substances on alpha-chymotrypsin-catalyzed coupling of a N-protected acyl donor ester and various nucleophilic amino components was studied. Changes in S'-specificity of alpha-chymotrypsin in frozen aqueous systems were suppressed by polyethylene glycols even at concentrations below 1% (w/v). Furthermore, the influence of freeze-concentration in organic solvents on protease-catalyzed peptide synthesis was investigated for the first time. In frozen tert-butanol, alpha-chymotrypsin-catalyzed peptide synthesis took advantage from freeze-concentration, but in contrast to frozen aqueous systems, no changes in S'-specificity of the biocatalyst were observed. The results suggest that freeze-concentration is not the only cause of freezing-induced yield improvement in aqueous peptide synthesis systems, but interactions between enzyme and ice structures strongly contribute to the observed effects.     

Combination of MS Protein Identification and Bioassay of Chromatographic Fractions to Identify Biologically Active Substances from Complex Protein Sources

Purification of biologically active proteins from complex biological sources is a difficult task, usually requiring large amounts of sample and many separation steps. We found an active substance in a serum response element-dependent luciferase reporter gene bioassay in interstitial cystitis urine that we attempted to purify with column chromatography and the bioassay. With anion-exchange Mono Q and C₄ reversed-phase columns, apparently sharp active peaks were obtained. However, more than 20 kinds of proteins were identified from the active fractions with MS, indicating that the purification was not complete. As further purification was difficult, we chose a candidate molecule by means of studying the correlation between MS protein identification scores and bioassay responses of chromatographic fractions near the active peaks. As a result, epidermal growth factor (EGF) was nominated as a candidate molecule among the identified proteins because the elution profile of EGF was consistent with that of the bioassay, and the correlation coefficient of EGF between MS protein identification scores and bioassay responses was the highest among all the identified proteins. With recombinant EGF and anti-EGF and anti-EGF receptor antibodies, EGF was confirmed to be the desired substance in interstitial cystitis urine. This approach required only 20 ml of urine sample and two column chromatographic steps. The combination of MS protein identification and bioassay of chromatographic fractions may be useful for identifying biologically active substances from complex protein sources.Purification and identification of biologically active proteins existing in minute amounts from biological sources such as urine is still a difficult task (1). It requires a large volume of the sample and many separation steps for purification (2, 3). Nevertheless the recent progress of MS has dramatically changed protein analysis (4). With MS, smaller protein samples can be used than with classical protein identification methods such as N-terminal peptide sequencing.Interstitial cystitis (IC)¹ is a chronic inflammatory disease characterized by frequency and urgency and/or severe pelvic pain (5). The International Continence Society also selected the term “painful bladder syndrome” for IC (6). The quality of life of IC patients is extremely low because of their severe symptoms. The pathogenesis of IC is unclear, and effective treatments have not been established. To elucidate the mechanism of IC pathogenesis, we attempted to find characteristic proteins in IC urine using proteomics techniques and have already reported active neutrophil elastase as an IC urinary marker (7). We had also performed gene expression analysis of IC bladder tissues using GeneChip technology and found that mRNA expression of GPR18, a member of the G-protein-coupled receptors, was higher in IC bladder than in the control.² We tried to confirm whether GPR18 endogenous ligand existed in IC urine by using a bioassay with GPR18 transfectant cells.In the present study, the existence of an active substance in IC urine was suggested in the bioassay using the serum response element (SRE)-dependent luciferase reporter gene with the stable recombinant HEK293 cell line expressing GPR18. We thought that the response was derived from GPR18 and tried to purify the active substance from a small volume of IC urine using chromatographic techniques. Among the many proteins identified from partially purified samples, we clearly nominated epidermal growth factor (EGF) as a candidate molecule judging from the correlation between MS protein identification and the bioassay of chromatographic fractions. With recombinant EGF and anti-EGF antibody, EGF was confirmed to be the desired substance found in IC urine. The complete inhibition of the bioassay response by anti-EGF receptor antibody also indicated that the response was based on the EGF receptor, not GPR18, suggesting that GPR18 overexpression enhanced the EGF signal via the endogenous EGF receptor of the HEK293 cell line.     

Validated gas chromatographic–mass spectrometric assay for determination of the antifreezes ethylene glycol and diethylene glycol in human plasma after microwave-assisted pivalylation

A gas chromatographic–mass spectrometric assay is described for identification and quantification of the antifreezes ethylene glycol (EG) and diethylene glycol (DEG) in plasma for early diagnosis of a glycol intoxication. After addition of 1,3-propanediol as internal standard, the plasma sample was deproteinized by acetone and an aliquot of the supernatant was evaporated followed by microwave-assisted pivalylation. After gas chromatographic separation, the glycols were first identified by comparison of the full mass spectra with reference spectra and then quantified. The quantification has been validated according to the criteria established by the Journal of Chromatography B. The assay was found to be selective. The calibration curves for EG and DEG were linear from 0.1 g/l to 1.0 g/l. The limit of detection for EG and DEG was 0.01 g/l and the limit of quantification for both was 0.1 g/l. The absolute recoveries were 50 and 65% for the low quality control samples and 51 and 73% for the high quality control samples of EG and DEG, respectively. Intra- and inter-day accuracy and precision were inside the required limits. The glycols in frozen plasma samples were stable for more than 6 months. The method was successfully applied to several authentic plasma samples from patients intoxicated with glycols. It has also been suitable for analysis of EG and DEG in urine.     

Bacterial Utilization of Ether Glycols

A soil bacterium capable of using oligo- and polyethylene glycols and ether alcohols as sole sources of carbon for aerobic growth was isolated. The effects of substituent groups added to the ether bonds on the acceptability of the compounds as substrates were studied. Mechanisms for the incorporation of two-carbon compounds were demonstrated by the observation that acetate, glyoxylate, ethylene glycol, and a number of the tricarboxylic acid cycle intermediates served as growth substrates in minimal media. The rate of oxidation of the short-chained ethylene glycols by adapted resting cells varied directly with increasing numbers of two-carbon units in the chains from one to four. The amount of oxygen consumed per carbon atom of oligo- and polyethylene glycols was 100% of theoretical, but only 67% of theoretical for ethylene glycol. Resting cells oxidized oligo- and polyethylene glycols with 2 to 600 two-carbon units in the chains. Longer chained polyethylene glycols (up to 6,000) were oxidized at a very slow rate by these cells. Dehydrogenation of triethylene glycol by adapted cells was observed, coupling the reaction with methylene blue reduction.     

Rapid analysis of furosemide in human urine by capillary electrophoresis with laser-induced fluorescence and electrospray ionization-ion trap mass spectrometric detection

Furosemide, a drug that promotes urine excretion, is used in the pharmacotherapy of various diseases and is considered as a doping agent in sports. Using alkaline electrolytes, analysis of furosemide by dodecyl sulfate based micellar electrokinetic capillary chromatography (MECC) and capillary zone electrophoresis (CZE) with laser-induced fluorescence detection (LIF, analyte excitation with the 325 nm line of a HeCd laser) is described. Data produced by injection of plain or diluted patient urines are confirmed with those obtained via analysis of urinary solid-phase extracts. CZE-LIF and MECC-LIF are thereby shown to permit unambiguous recognition of furosemide in urines collected after ingestion of therapeutic doses of this drug. This is in contrast to solute detection via UV absorbance for which the extraction of furosemide is required. MECC based electropherograms are somewhat more complex compared to those obtained by CZE-LIF, this suggesting that the latter approach is more suitable for rapid screening of urines with direct sample injection and LIF detection. Alternatively, capillary electrophoresis with negative electrospray ionization-ion-trap tandem mass spectrometry (CE-MS2) is shown to permit the direct confirmation of furosemide in human urine. This approach is based upon the monitoring of the m/z 329.3-->4m/z 285.2 precursor-product ion transition. CZE-LIF and CE-MS2 with injection of plain or diluted urine represent simple, rapid and attractive urinary screening and confirmation assays for furosemide in patient urines.     

Determination of uric acid in biological fluids by high-pressure liquid chromatography

A high-pressure liquid chromatographic assay for uric acid in biological fluids has been developed. Blood uric acid can be analyzed in as little as 20 μl of plasma. The mean and range of plasma uric acid concentrations in healthy adults determined by high-pressure liquid chromatography were similar to these obtained by enzymatic analysis. One of the advantages of the present method is that naturally occurring metabolites in biological fluids or drugs do not interfere with the analysis. Data are presented for blood and urine specimens obtained from mice fed a known uricase inhibitor, potassium oxonate. Comparisons are made between the present method and methods previously employed for uric acid determination.     

Stimulants,narcotics and β-blockers: 25 years of development in analytical techniques for doping control

More than 25 years of developing doping control methods have led to comprehensive screening and confirmation procedures for stimulants, narcotics and β-blockers. Much of this work has been initiated and/or improved by the late Prof. Dr. Manfred Donike. The methodological approach covered in this overview was applied to doping control procedures during the XXV Summer Olympics in Barcelona, Spain, in 1992 and the XVII Winter Olympics in Lillehammer, Norway, in 1994. Urine samples are screened through a combination of two analytical methods that are complementary: (a) gas chromatographic analysis of the parent compound and unconjugated metabolites, following single-step sample extraction and detection by a nitrogen-specific detector based on a retention index identification system and (b) gas chromatographic analysis including also conjugated drugs and metabolites after hydrolysis, solid-phase extraction, derivatisation and mass spectrometric detection. Confirmation and identification is always performed by gas chromatographic separation and full scan mass spectrometric detection. These methods facilitate the rapid screening and confirmation of more than 100 stimulants, narcotic analgesics and β-blockers in urine for at least 24 h after the intake of a pharmaceutical dose. Application of the methods ensures high quality standards for the unequivocal identification of doping agents as well as a rapid turnaround time for sample analyses.