Molybdenum and Chromium Concentrations in Breast Milk from Japanese Women

Molybdenum (Mo) and chromium (Cr) in 79 Japanese breast milk samples were measured by inductively coupled plasma-mass spectrometry. For Mo, 51 samples (64.6%) showed less than 5 ng/ml and only 12 samples (15.2%) showed more than 10 ng/ml. The range and median were <0.1 to 25.91 and 3.18 ng/ml respectively. For Cr, 38 samples (48.1%) showed less than 1 ng/ml, 20 samples (25.3%) showed 1 to 2 ng/ml, and only six samples (7.6%) showed more than 5 ng/ml. The range and median were <0.1 to 18.67 and 1.00 ng/ml respectively.     

Serum molybdenum concentration in healthy Japanese adults determined by inductively coupled plasma-mass spectrometry

The serum molybdenum (Mo) concentrations in 70 Japanese adults (35 males and 35 females) not receiving any medical care or treatment were determined by inductively coupled plasma-mass spectrometry. Serum Mo concentration in the subjects ranged from <0.1 to 9.11 ng/mL. More than half (55.7%) of the subjects showed values of less than 1 ng/mL and only 6 (8.6%) subjects showed more than 2 ng/mL. The mean+/-SD, geometrical mean (GM), range of GM+/-geometrical SD (GSD) and median value were 1.21+/-1.34, 0.81, 0.30 to 2.16, and 0.90 ng/mL, respectively. Among age, body mass index and several serum biochemical values, activities of aspartate aminotransferase and alanine aminotransferase showed significant associations with serum Mo; 15 subjects suspected of having liver dysfunction showed significantly higher serum Mo than others. We propose a range of 0.10-4.73 ng/mL, estimated as a range of GM+/-2GSD of serum Mo in the remaining 55 subjects without liver dysfunction, as a reference range of serum Mo in Japanese healthy adults.     

Serum and urine chromium as indices of chromium status in tannery workers

Serum and urinary Cr levels of a selected group of men exposed to CrIII in four Southern Ontario tanneries were compared with those of men not exposed to Cr. Fasted blood samples were obtained from 72 tannery workers (TW; mean age +/- SD = 36 +/- 12 years) and from 52 controls (CS; mean age +/- SD = 41 +/- 13 years). Serum Cr levels as determined by graphite furnace atomic absorption spectrophotometry were significantly higher (P = 0.0001) for TW (median 0.49 ng/ml, range 0.37-0.81) than for CS (median 0.15 ng/ml, range 0.12-0.20). Urine samples were collected from 49 TW and 43 CS on a Friday pm and from 42 TW on a Monday am. Urinary creatine (Cre) was determined by the Jaffe reaction. For Friday samples, the median urinary Cr/Cre ratio was significantly higher (P = 0.0001) for TW (median 0.83 ng/mg, range 0.48-1.82) than for CS (median 0.18 ng/mg, range 0.13-0.26). For TW, Cr/Cre was correlated with serum Cr (r = 0.72, P = 0.0001). Neither urinary Cr/Cre nor serum Cr was correlated with length of employment in the tanning industry. There were significant differences in serum Cr levels and urinary Cr/Cre ratios among TW employed in different areas of the tanneries. For TW, the median urinary Cr/Cre ratio for Monday morning samples was significantly lower than for Friday afternoon samples (P = 0.03). These data indicate that CrIII is absorbed and that serum and urine Cr in tannery workers may be indices of Cr exposure and status.     

Social suppression of ovarian cyclicity in captive and wild colonies of naked mole-rats, Heterocephalus glaber

To investigate the endocrine cause of reproductive suppression in nonbreeding female naked mole-rats, animals from 35 colonies were studied in captivity. Urinary and plasma progesterone concentrations were elevated in pregnant females (urine: 10.0-148.4 ng/mg Cr, 27 samples from 8 females; plasma: 3.6-30.0 ng/ml, 5 samples from 5 females; Days 21-40 of pregnancy) and cyclic breeding females (urine: 0.5-97.8 ng/mg Cr, 146 samples from 7 females; plasma: less than 1.0-35.4 ng/ml, 25 samples from 7 females). The latter group showed cyclic patterns of urinary progesterone, indicating a mean ovarian cycle length of 34.4 +/- 1.6 days (mean +/- s.e.m.) with a follicular phase of 6.0 +/- 0.6 days and a luteal phase of 27.5 +/- 1.3 days (19 cycles from 9 breeding females). In non-breeding females urinary and plasma progesterone values were undetectable (urine: less than 0.5 ng/mg Cr, 232 samples from 64 females; plasma: less than 1.0 ng/ml, 7 samples from 6 females). Breeding females had higher (P less than 0.001) plasma LH concentrations (3.0 +/- 0.2 mi.u./ml, 73 samples from 24 females) than did non-breeding females (1.6 +/- 0.1 mi.u./ml, 57 samples from 44 females). Urinary and plasma progesterone concentrations in non-breeding females from wild colonies situated near Mtito Andei, Kenya, were either below the assay sensitivity limit (urine: less than 0.5 ng/mg Cr, 11 females from 2 colonies; plasma: less than 1.0 ng/ml, 25 females from 4 colonies), or very low (plasma: 1.6 +/- 0.6 ng/ml, 15 females from 4 colonies). In captivity, non-breeding females removed from their colonies (i.e. the dominant breeding female) and either paired directly with a non-breeding male (N = 2), or removed and housed singly for 6 weeks before pairing with a non-breeding male (N = 5) may develop a perforate vagina for the first time in as little as 7 days. Urinary progesterone concentrations rose above 2.0 ng/mg Cr (indicative of a luteal phase) for the first time 8.0 +/- 1.9 days after being separated. These results suggest that ovulation is suppressed in subordinate non-breeding female naked mole-rats in captive and wild colonies, and show that plasma LH concentrations are significantly lower in these non-breeding females. This reproductive block in non-breeding females is readily reversible if the social factors suppressing reproduction are removed.     

High-performance liquid chromatographic determination of (−)-β-d-2,6-diaminopurine dioxolane and its metabolite,dioxolane guanosine,using ultraviolet and on-line radiochemical detection

(−)-β-d-2,6-Diaminopurine dioxolane (DAPD) and its metabolite dioxolane guanosine (DXG) have potent activity against hepatitis B virus and HIV, in vitro. A reversed-phase HPLC analytical method using UV and on-line radiochemical detection for the determination of DAPD and DXG in monkey serum and urine is described in this report. Retention times for DXG, DAPD and internal standard (2′,3′-didehydro-2′ deoxythymidine, D4T) were 5.0, 6.0 and 13.0 min, respectively. The extraction recovery was greater than 97% for DAPD and 94% for DXG. The limit of quantitation for UV detection was 100 ng/ml and 125 ng/ml for DXG and DAPD in monkey serum. The standard curves were linear from 0.1 μg/ml to 5 μg/ml for DXG and 0.125 μg/ml to 5 μg/ml for DAPD. For radiochemical detection, calibration curves of standard solutions of DAPD and DXG were linear in the range of 3500 Bq to 32 000 Bq and 7500 Bq to 60 000 Bq. The intra- and inter-day relative standard deviations were less than 7.2% using UV and less than 8.6% using on-line radiochemical detection. The HPLC method was applied to serum and urine samples collected from a male rhesus monkey that was administered 33.3 mg/kg DAPD with 200 μgCi of [³H]DAPD intravenously.     

Sensitive isocratic liquid chromatographic assay for the determination of 5, 10, 15, 20-tetra(m-hydroxyphenyl)chlorin in plasma and tissue with electrochemical detection

A simple extraction procedure and a sensitive high-performance liquid chromatographic (HPLC) method are described for the determination of the photodynamic therapeutic agent 5, 10, 15, 20-tetra(m-hydroxyphenyl)chlorin (mTHPC) in plasma and tumour tissue. Reversed-phase high-performance liquid chromatography was performed on a C₁₈ column (70×4.6 mm I.D.) with a mobile phase of 0.01 M potassium dihydrogenphosphate buffer, pH 2.5-acetonitrile (55:45, v/v) and a coulometric detection (+0.80 V). The mean recoveries of mTHPC in the concentration ranges (5–2000 and 10–1000 ng/ml) were 90 and 89% for plasma and tumour samples, respectively. The procedure for plasma and tissue preparation involved solvent precipitation using methanol combined with ammonia solution and dimethyl sulphoxide (4, 0.2, 0.1, v/v/v) and (2, 0.1, 0.1, v/v/v) for plasma and tissue, respectively. For mTHPC at concentrations ranging from 5 to 2000 ng/ml, the within-day relative standard deviations, based on triplicate determinations were less than 8% and the between-day relative standard deviations calculated by performing extraction procedure of plasma samples on three different days ranged from 3 to 18%. This highly sensitive method, 5 and 10 ng/ml for plasma and tissue respectively, was applied successfully to the determination of mTHPC in mouse tumours for pharmacokinetic studies.     

Stereoselective determination of methadone and the primary metabolite EDDP in human plasma by automated on-line extraction and liquid chromatography mass spectrometry

A sensitive stereoselective bioanalytical liquid chromatographic assay with mass spectrometric detection (LC-MS) was developed and validated for the on-line extraction and quantification of R- and S-methadone and the primary metabolite R- and S-2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) from human plasma. Deproteinized plasma was injected directly onto a small C8 column, washed and then back-flushed using a column switching valve and a second pump onto an alpha1-acid glycoprotein analytical column, and enantioselective separation achieved using a mobile phase gradient of methanol and ammonium formate. Analytes were validated over a range of 0.1-25 ng/ml R- and S-EDDP and 0.1-100ng/ml R- and S-methadone, respectively. Unweighted standard curves were linear over this concentration range (regression coefficients > 0.999). Quality control samples were evaluated at 1, 5, 12.5 ng/ml R- and S-EDDP and 1, 10, 50 ng/ml R- and S-methadone. Intra- and inter-day accuracy was >95%, and intra- and inter-day coefficients of variation were less than 10% for all analytes and concentrations. This assay represents the only method currently available which combines on-line extraction and achieves chiral separation of both methadone and EDDP from plasma, and offers improvements in sensitivity over existing methods.     

Epidermal growth factor-like proteins in breast fluid and human milk

Epidermal growth factor (EGF), and the transforming growth factor-alpha (TGF-alpha) family of proteins, which also bind to the EGF receptor, have been associated with human breast cancer. The total EGF-like proteins were determined by a radioreceptor assay, and TGF-alpha by radioimmunoassay, in human milk and breast fluid samples. The breast fluids were collected by nipple aspiration from healthy premenopausal women. Both the 24 milks and 18 breast fluids assayed contained EGF-like proteins, at concentrations ranging from 32-600 ng/ml (median, 140 ng/ml), and 62-654 ng/ml (median, 205 ng/ml) respectively. Immunoreactive TGF-alpha proteins were detected at higher levels in 21 breast fluids (range, 0-50.0; median 5.1 ng/ml) than in 24 milk samples (range, 0-8.4; median, 0.8 ng/ml).     

A selective protein sensor for heparin detection

No clinical assays for the direct detection of heparin in blood exist. To create a heparin sensor, the hyaluronan (HA)-binding domain (HABD) of a protein that binds heparin and HA was engineered. GST fusion proteins containing one to three HABD modules were cloned, expressed, and purified. The affinities of each construct for heparin and for HA were determined by a competitive enzyme-linked immunosorbent assay using immobilized HA or heparin. Each of the constructs showed modest affinity for immobilized HA. However, heparin was 100-fold more potent than HA as a competing ligand. With immobilized heparin, affinity increased as the HABD copy number increased. The three-copy construct, GST-HB3, detected unfractionated free heparin (UFH) as low as 39ng/ml (equivalent to approximately 0.1U/ml) with a signal-to-noise ratio of 5.6. GST-HB3 also showed 100-fold selectivity for heparin in preference to other glycosaminoglycans. The plot of logKd vs log [Na+] showed 2.5 ionic interactions per heparin-HB3 interaction. GST-HB3 showed a linear detection of both UFH (15kDa) and low-molecular-weight heparin (LMWH; 6kDa) added to human plasma. For UFH, the range examined was 78 to over 2000ng/ml (equivalent to 0.2 to 5.0U/ml). For LMWH, the useful range was 312 to over 2000ng/ml. The coefficient of variance for the assay was < 9% for six serial heparin dilutions and <12% for three plasma samples. In clinical use, GST-HB3 could accurately measure therapeutic heparin levels in plasma (0.2 to 2U/ml).     

Determination of L-756 423, a novel HIV protease inhibitor, in human plasma and urine using high-performance liquid chromatography with fluorescence detection

A method for the determination of L-756 423, a novel HIV protease inhibitor, in human plasma and urine is described. Plasma and urine samples were extracted using 3M Empore extraction disk cartridges in the C₁₈ and MPC (mixed-phase cation-exchange) formats, respectively. The extract was analyzed using HPLC with fluorescence detection (ex 248 nm, em 300 nm), and included a column switching procedure to reduce run-time. The assay was linear in the concentration range 5 to 1000 ng/ml when 1-ml aliquots of plasma and urine were extracted. Recoveries of L-756 423 were greater than 84% over the calibration curve range using the described sample preparation procedures. Intra-day precision and accuracy for this assay was less than 9% RSD and within 7%, respectively. Inter-day variabilities for the plasma (n=17) and urine (n=10) were less than 5% and 3% for low (15 ng/ml) and high (750 ng/ml) quality control samples. Bovine serum albumin (0.5%) was used as an additive to urine to prevent precipitation of L-756 423 during the storage of clinical samples. The assay was used in support of human clinical trials.     

Ochratoxin A in porcine blood and in consumed feed samples

The aim of the study was to estimate occurrence of ochratoxin A (OA) in feeds and the metabolite residues in porcine blood serum in Poland. Samples were collected in the period from February to May, 1999, in the southern Wielkopolska region. Altogether 40 and 45 samples of feed and porcine blood serum, respectively, were analyzed for OA. Percentage of samples contaminated with OA, both in case of feeds and blood, collected in the winter season was considerably higher than that for the spring season. The percentages for feeds were as follows: 47.6 and 26.3 %, while for porcine serum: 66.7 and 50.0 %, respectively winter and spring. In 25 % of cases ochratoxin A was present in both types of investigated material (feed, blood), whereas in 27.5 % of samples this metabolite was detected in blood only, or in 7.5 % only in the feed. The presence of OA was found neither in the feed nor in the serum in 40 % of all cases. In subgroups (feed, blood) the concentration in the whole collective of positive samples were in the range 0.3–13.5 ng/g and 0.3–69.5 ng/ml, respectively, while median values were 2.3 ng/g and 6.0 ng/ml. Only one feed and three porcine serum samples, were found to be contaminated at concentration levels higher than 10 ng/g or 10 ng/ml.     

Microbore high-performance liquid chromatographic determination of cisapride in rat serum samples using column switching

For the determination of cisapride from serum samples, an automated microbore high-performance liquid chromatographic method with column switching has been developed. After serum samples (100 μl) were directly injected onto a Capcell Pak MF Ph-1 pre-column (10×4 mm I.D.), the deproteinization and concentration were carried out by acetonitrile–phosphate buffer (20 mM, pH 7.0) (2:8, v/v) at valve position A. At 2.6 min, the valve was switched to position B and the concentrated analytes were transferred from MF Ph-1 pre-column to a C₁₈ intermediate column (35×2 mm I.D.) using washing solvent. By valve switching to position A at 4.3 min, the analytes were separated on a Capcell Pak C₁₈ UG 120 column (250×1.5 mm I.D.) with acetonitrile–phosphate buffer (20 mM, pH 7.0) (5:5, v/v) at a flow-rate of 0.1 ml/min. Total analysis time per sample was 18 min. The linearity of response was good (r=0.999) over the concentration range of 5–200 ng/ml. The within-day and day-to-day precision (CV) and inaccuracy were less than 3.7% and 3.8%, respectively. The mean recovery was 96.5±2.4% with the detection limit of 2 ng/ml.     

Simultaneous determination of thienorphine and its active metabolite thienorphine glucuronide in rat plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies

A simple, sensitive and reliable method was developed to determine simultaneously the concentrations of thienorphine and its metabolite thienorphine glucuronide conjugate in rat plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolite was identified by MS: thienorphine glucuronide conjugate. Sample preparation involved protein precipitation with methanol. Analytes were separated on Finnigan BetaBasic-18 column (150 mm x 2.1mm i.d., 5 microm) using methanol: water: formic acid (56:44:0.1, v/v/v) as mobile phase at a flow rate of 0.2 ml/min. The method had a linear calibration curve over the concentration range of 0.1-50 ng/ml for thienorphine and 2-1000 ng/ml for thienorphine glucuronide conjugate, respectively. LOQ of thienorphine and thienorphine glucuronide conjugate was 0.1 and 2 ng/ml, respectively. The intra- and inter-batch precisions were less than 12% and their recoveries were greater than 80%. Pharmacokinetic data of thienorphine and its metabolite thienorphine glucuronide conjugate obtained with this method following a single oral dose of 3mg/kg thienorphine to rats were also reported for the first time.     

Development and comparison of high-performance liquid chromatographic methods with tandem mass spectrometric and ultraviolet absorbance detection for the determination of cyclobenzaprine in human plasma and urine

Sensitive assays for the determination of cyclobenzaprine (I) in human plasma and urine were developed utilizing high-performance liquid chromatography (HPLC) with tandem mass spectrometric (MS-MS) and ultraviolet (UV) absorbance detections. These two analytical techniques were evaluated for reliability and sensitivity, and applied to support pharmacokinetic studies. Both methods employed a liquid-liquid extraction of the compound from basified biological sample. The organic extract was evaporated to dryness ,the residue was reconstituted in the mobile phase and injected onto the HPLC system. The HPLC assay with MS-MS detection was performed on a PE Sciex API III tandem mass spectrometer using the heated nebulizer interface. Multiple reaction monitoring using the parent → daughter ion combinations of m/z 276 → 215 and 296 → 208 was used to quantitate I and internal standard (II), respectively. The HPLC-MS-MS and HPLC-UV assays were validated in human plasma in the concentration range 0.1–50 ng/ml and 0.5–50 ng/ml, respectively. In urine, both methods were validatedin the concentration range 10–1000 ng/ml. The precision of the assays, as expressed as coefficients of variation (C.V.) was less than 10% over the entire concentration range, with adequate assay specificity and accuracy. In addition to better sensitivity, the HPLC-MS-MS assay was more efficient and allowed analysis of more biological fluid samples in a single working day than the HPLC-UV method.     

Measurement of bumetanide in plasma and urine by high-performance liquid chromatography and application to bumetanide disposition

A high-performance liquid chromatographic method for the measurement of bumetamide in plasma and urine is described. Following precipitation of proteins with acetonitrile, bumetanide was extracted from plasma or urine on a 1-ml bonded-phase C₁₈ column and eluted with acetonitrile. Piretanide dissolved in methanol was used as the internal standard. A C₁₈ Radial Pak column and fluorescence detection (excitation wavelength 228 nm; emission wavelength 418 nm) were used. The mobile phase consisted of methanol—water—glacial acetic acid (66:34:1, v/v) delivered isocratically at a flow-rate of 1.2 ml/min. The lower limit of detection for this method was 5 ng/ml using 0.2 ml of plasma or urine. Nafcillin, but not other semi-synthetic penicillins, was the only commonly used drug that interfered with this assay. No interference from endogenous compounds was detected. For plasma, the inter-assay coefficients of variation of the method were 7.6 and 4.4% for samples containing 10 and 250 ng/ml bumetanide, respectively. The inter-assay coefficients of variation for urine samples containing 10 and 2000 ng/ml were 8.1 and 5.7%, respectively. The calibration curve was linear over the range 5–2000 ng/ml.     

Determination of cabergoline and L-dopa in human plasma using liquid chromatography-tandem mass spectrometry

We determined cabergoline and L-dopa in human plasma using liquid chromatography-mass spectrometry with tandem mass spectrometry (LC-MS-MS). The deproteinized plasma samples with organic solvent or acid were analyzed directly by reversed-phase liquid chromatography. Using multiple reaction monitoring (MRM, product ions m/z 381 of m/z 452 for cabergoline and m/z 152 of m/z 198 for L-dopa) on LC-MS-MS with electrospray ionization (ESI), cabergoline and L-dopa in human plasma were determined. Calibration curves of the method showed a good linearity in the range 5-250 pg/ml for cabergoline and 1-200 ng/ml for L-dopa, respectively. The limit of determination was estimated to be approximately 2 pg/ml for cabergoline and approximately 0.1 ng/ml for L-dopa, respectively. The method was applied to the analysis of cabergoline and L-dopa in plasma samples from patients treated with these drugs. The precision of analysis showed coefficients of variation ranging from 3.8% to 10.5% at cabergoline concentration of 13.8-26.2 pg/ml and from 2.9% to 8.9% at an L-dopa concentration of 302.5-522.1 ng/ml in patient plasma. As a result, the procedure proved to be very suitable for routine analysis.     

Determination of amiodarone and desethylamiodarone in horse plasma and urine by high-performance liquid chromatography combined with UV detection and electrospray ionization mass spectrometry

A rapid method for the quantification of amiodarone and desethylamiodarone in animal plasma using high-performance liquid chromatography combined with UV detection (HPLC-UV) is presented. The sample preparation includes a simple deproteinisation step with acetonitrile. In addition, a sensitive method for the quantification of amiodarone and desethylamiodarone in horse plasma and urine using high-performance liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is described. The sample preparation includes a solid-phase extraction (SPE) with a SCX column. Tamoxifen is used as an internal standard for both chromatographic methods. Chromatographic separation is achieved on an ODS Hypersil column using isocratic elution with 0.01% diethylamine and acetonitrile as mobile phase for the HPLC-UV method and with 0.1% formic acid and acetonitrile as mobile phase for the LC-MS/MS method. For the HPLC-UV method, good linearity was observed in the range 0-5 microg ml(-1), and in the range 0-1 microg ml(-1) for the LC-MS/MS method. The limit of quantification (LOQ) was set at 50 and 5 ng ml(-1) for the HPLC-UV method and the LC-MS/MS method, respectively. For the UV method, the limit of detection (LOD) was 15 and 10 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs of the LC-MS/MS method in plasma were much lower, i.e. 0.10 and 0.04 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs obtained for the urine samples were 0.16 and 0.09 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The methods were shown to be of use in horses. The rapid HPLC-UV method was used for therapeutic drug monitoring after amiodarone treatment, while the LC-MS/MS method showed its applicability for single dose pharmacokinetic studies.     

Determination of a cyclooxygenase II inhibitor in human plasma by capillary gas chromatography with mass spectrometric detection

Sensitive methods based on capillary gas chromatography (GC) with mass spectrometric (MS) detection in a selected-ion monitoring mode (SIM) for the determination of a cyclooxygenase II (COX-II) inhibitor (3-isopropoxy-4-(4-methanesulfonylphenyl)-5,5'-dimethyl-5H-furan-2-one, I) in human plasma, in two concentration ranges of 0.1-20 and 5-1000 ng/ml, are described. Following liquid-liquid extraction, the residue, after evaporation of the organic phase to dryness, was reconstituted in acetonitrile (20 l) and part of the extract (1 l) was analyzed by GC/MS/SIM. The drug (I) and internal standard (II) were separated on a 25 mx0.2 mm capillary column with HP Ultra 1 (100% dimethylpolysiloxane, 0.33 m) phase and analyzed by MS/SIM monitoring ions at m/z 237 and 282 for I and II, respectively. The standard curve was linear within the lower concentration range of 0.1-20 ng/ml and the lower limit of quantification (LLOQ) in plasma was 0.1 ng/ml. Intraday coefficients of variation (CV, n=5) were 8.9, 4.2, 5.7, 3.1, 1.9, 1.9, and 4.4% at 0.1, 0.2, 0.5, 1.0, 5.0, 10, and 20 ng/ml, respectively. The standard curve was also linear within the higher concentration range of 5-1000 ng/ml and the LLOQ in plasma was 5 ng/ml. Intraday coefficients of variation (CV, n=5) were all below 9% at all concentrations within the standard curve range. The accuracy for I in human plasma was 91-112% and the recovery of I and II was greater than 70% at all concentrations within both standard curve ranges. The details of the assay methodology are presented.     

Effect of heavy metals on samples and model population of rotifers <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> muller at different salinity

Effect of Cu²⁺ and Cr⁶⁺ on samples and on model populations of rotifers Brachionus plicatilis Muller in chronic conditions at different salinity was investigated. The LC₅₀ (48 h) at salinities 10, 20, and 30‰ were 53.9, 0.25, and 0.1 mg Cr/l, respectively. The concentrations of 0.3 mg Cu/l and more led to the death of 100% of rotifers in 48 h in salinities 10 and 20‰, but at 30‰ the concentration 0.1 mg Cu/l was lethal. LC₅₀ (48 h) at salinities 10, 20, and 30‰ were 7.06, 0.07, and 0.01 mg Cu/l, respectively. The toxicity of Cr and Cu for samples became higher with increasing salinity. For the model populations, the salinity influenced toxicity only at high concentrations of Cr (20 mg/l). The effect of Cr was higher on samples than on model populations.     

Simultaneous determination of selegiline and desmethylselegiline in human body fluids by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A method for the simultaneous determination of selegiline and its metabolite, desmethylselegiline, in human whole blood and urine is presented. The method, which combines a fiber-based headspace solid-phase microextraction (SPME) technique with gas chromatography-mass spectrometry (GC-MS), required optimization of various parameters (e.g., salt additives, extraction temperatures, extraction times and the extraction properties of the SPME fiber coatings). Pargyline was used as the internal standard. Extraction efficiencies for both selegiline and desmethylselegiline were 2.0-3.4% for whole blood, and 8.0-13.2% for urine. The regression equations for selegiline and desmethylselegiline extracted from whole blood were linear (r(2)=0.996 and 0.995) within the concentration ranges 0.1-10 and 0.2-20 ng/ml, respectively. For urine, the regression equations for selegiline and desmethylselegiline were linear (r(2)=0.999 and 0.998) within the concentration ranges 0.05-5.0 and 0.1-10 ng/ml, respectively. The limit of detection for selegiline and desmethylselegiline was 0.01-0.05 ng/ml for both samples. The lower and upper limits of quantification for each compound were 0.05-0.2 and 5-20 ng/ml, respectively. Intra- and inter-day coefficients of variation for selegiline and desmethylselegiline in both samples were not greater than 8.7 and 11.7%, respectively. The determination of selegiline and desmethylselegiline concentrations in Parkinson's disease patients undergoing continuous selegiline treatment is presented and is shown to validate the present methodology.