Biomedical subjects

F Rieders

Publications and source records attributed to F Rieders.

26 records · Page 2Linked to original sources

PubMedDate not supplied

Determination of lysergic acid diethylamide (LSD) in urine by instrumental high-performance thin-layer chromatography.

An instrumental high-performance thin-layer chromatographic (HPTLC) technique for the determination of lysergic acid diethylamide (LSD) in urine was developed. Before chromatographic separation, a single-step extraction with alkaline wash is performed. The procedure can detect less than 1 microgram LSD/L urine. Results of HPTLC determination are compared with those from a radioimmunoassay (RIA) procedure.

Chromatography, Thin Layer↗

PubMedDate not supplied

Direct automated EMIT d.a.u. analysis of N,N-dimethylformamide-modified serum, plasma, and postmortem blood for amphetamines, barbiturates, methadone, methaqualone, phencyclidine, and propoxyphene.

The addition of two volumes of N,N-dimethylformamide (DMF) to serum, plasma, and postmortem blood with subsequent centrifugation resulted in supernatant that could be directly analyzed by EMIT d.a.u. urine reagents on the Syva autocarousel. Application of this method to the drugs below gave cutoff concentrations in milligrams of immunochemically cross-reactive analyte equivalents/L as follows: 0.05 for amphetamine, 0.05 for secobarbital, 0.075 for methadone, 0.05 for methaqualone, 0.025 for phencyclidine, and 0.05 for propoxyphene. Quantitative "false" negative/positive noncongruence between total EMIT cross-reactants and free-drug analyses by gas chromatography/mass spectrometry were 3/4 (n = 50) for amphetamines, 2/0 (n = 60) for barbiturates, 0/0 (n = 47) for methadone, 0/0 (n = 48) for methaqualone, 1/0 (n = 44) for phencyclidine, and 1/2 for propoxyphene (n = 53). Within-day precision, as indicated by the coefficient of variation, of quantitative estimates using low and high controls ranged from 3.7 to 11% and 1.8 to 10.3%, respectively. Using the same control levels, between-day precision of quantitative estimates varied from 5.8 to 30.3% and 3.0 to 11.8%, respectively.

Amphetamines↗

PubMedDate not supplied

Report of a fluoxetine fatality.

Several fatalities due to fluoxetine combined with other drugs such as ethyl alcohol have been reported. We now report an apparent suicide in which fluoxetine was the only causative agent. Because this drug is widely described as having a wide safety margin, it is important to note concentrations in blood associated with overdose fatalities. The findings by GC/NPD and GC/MS in blood were as follows: fluoxetine 6,000 ng and demethylated metabolite 5,000 ng/mL. Parent compound and metabolite were 13,000 ng/mL each in bile. Details of the analytical method and data from 2,100 National Medical Services cases are also presented.

Chromatography, Gas↗

PubMedDate not supplied

Sensitive, selective detection and differentiation of salicylates and metabolites in urine by a simple HPTLC method.

We present a method for salicylates which is slightly more labor intensive than the usual manual Trinder's test, but is much more sensitive and able to identify individual drugs or metabolites. A 2-mL acidified urine aliquot is briefly extracted with 5 mL ether, and the residue from evaporating the ether under nitrogen is chromatographed on a 250-microns silica gel HPTLC plate using benzene-acetic acid-diethylether-methanol (60:9:30:5) as mobile phase and 5% aqueous ferric chloride as chromogen. The hardiness of the method is evidenced by the Rf values, which vary by no more than 3% over a four-month period. The Rf values are 0.70 for salicylic acid and diflunisal, 0.67 for aspirin and methyl salicylate, 0.60 for gentisic acid, 0.57 for p-aminosalicyclic acid, and 0.40 for salicyluric acid. Detection limits of 1 ppm or less for all the analytes compared favorably to limits of more than 20 ppm for Trinder's test. Separations and spot shapes are sufficiently good to make instrumental quantitation potentially applicable. Sensitivity is sufficient to give clearcut, positive test results 48 h after a single 80-mg dose of ASA by mouth or a 100-mg dose of methyl salicylate by skin injection with a muscle rub, and more than 96 h after a 660-mg oral aspirin dose. Thus, the test is useful for detection and a good degree of differentiation, even in patients using subtherapeutic doses of these salicylates or in those with trace residues from significantly remote full therapeutic or larger doses prior to specimen collections.

Chromatography, Thin Layer↗

PubMedDate not supplied

Cocaine and some of its products in hair by RIA and GC/MS.

Noncomminuted hair samplings (100 mg) from 132 individuals were analyzed for cocaine products by both RIA and GC/MS with D3 internal standards and selected ions for cocaine, benzoylecgonine, and methylecgonine. Ethanol and pH 7 buffer washing until the washes were negative by RIA or GC/MS were followed by overnight digestion in warm 0.1M HCI. A small portion of digest buffered to pH 7 was analyzed by RIA. The remainder, internally standardized, buffered extract was TMS derivatized and analyzed on a capillary OV-1 column by GC/MS. Of the 132 specimens, 10 were positive by RIA and positive by GC/MS for cocaine only, while another 20 specimens were positive for both cocaine and benzoylecgonine by GC/MS as well as positive by RIA. One specimen that was positive by RIA was positive for cocaine and methylecgonine by GC/MS; an additional one was positive for cocaine, methylecgonine, and benzoylecgonine and positive by RIA. The RIA used (100x more reactive to cocaine than to benzoylecgonine) gave positive test results for an additional 47 of the 132 hair samples. Cutoffs used for the RIA were equivalent to 2 micrograms benzoylecgonine or 0.04 micrograms cocaine/g hair, and for GC/MS, cutoffs per gram hair were 0.1 micrograms cocaine and 0.2 micrograms benzoylecgonine or methylecgonine. Relationships between RIA and GC/MS results and distribution of values found are discussed, as are factors that appear to affect recovery from the hair.

Cocaine↗

PubMedDate not supplied

Estimation of perimortal percent carboxy-heme in nonstandard postmortem specimens using analysis of carbon monoxide by GC/MS and iron by flame atomic absorption spectrophotometry.

In decomposed, formalin-fixed, embalmed, exhumed, and some fire-dried cases in which normal blood is unavailable, the usual methods for determination of carboxyhemoglobin saturation frequently fail. To address these specimens, a method utilizing both gas chromatography/mass spectrometric (GC/MS) determination of carbon monoxide (CO) and flame atomic absorption spectrophotometry (FAAS) determination of iron (Fe), in the same specimen, was developed. The method is reported here, along with its application to seven pertinent forsensic death investigations. The CO analytical methodology involves acid liberation of the gas from the specimen aliquot in a headspace vial. After heating and equilibrating, a sample of the headspace vapor is injected into the GC/MS system with a gastight syringe. Quantitation is achieved by standard addition comparison utilizing the ideal gas law equation. Iron is quantified by FAAS analysis of the same aliquot used for the CO determination, following nitric acid digestion. The concentration is determined by comparison to a standard curve. A formula for determining the minimum percent carboxy-heme saturation was derived by using the ratio of the amount of CO to the amount of Fe in the aliquot analyzed. Tissue types analyzed include spleen, liver, muscle, dried blood, and unspecified decomposed tissue.

Calibration↗

PubMedDate not supplied

Silicon analysis in biological specimens by direct current plasma-atomic emission spectroscopy.

A method for the determination of total elemental silicon concentrations in biological fluids by direct current plasma-atomic emission spectrometry (DCP-AES) is presented. The method is linear up to 30 micrograms/mL in blood, serum, plasma, and urine, with a detection limit of 0.2 microgram/mL. Population ranges of silicon concentration in blood, plasma, serum, and urine were found to be less than 0.3 to 33 micrograms/mL, less than 0.4 to 39 micrograms/mL, less than 0.2 to 68 micrograms/mL, and less than 0.3 to 180 micrograms/mL, respectively. Over 50% of all measured concentrations were less than 0.5 microgram/mL for blood, plasma, and serum. Estimates of "normal" population ranges are reported, and potential applicability of this procedure to silicone-related maladies is discussed.

Humans↗

PubMedDate not supplied

Bioavailability of glipizide and its effect on blood glucose and insulin levels in patients with non-insulin-dependent diabetes.

The bioavailability of glipizide, plasma glucose, and insulin levels were measured in seven patients with non-insulin-dependent diabetes mellitus. Glucose and insulin response to three standard meals was measured at 11 identical time points on the day of placebo administration and on the first and 15th day of glipizide administration (mean dose of 8.7 mg glipizide orally per day). The bioavailability profile of glipizide was highly consistent between day 1 and day 15 of administration. On both days, the drug peaked within 1.2-1.8 h and displayed a plasma half-life of between 2.5 and 3.2 h. While insulin levels were significantly (P less than 0.05) increased at 4 of 11 time points of day 1, significantly elevated insulin levels were found at one time point on day 15 of glipizide administration. Insulin levels were found to be increased only in the presence of plasma drug concentrations of 200 ng/ml or greater. The hypoglycemic effect of the drug was significantly greater on day 15 than on day 1 of administration, and a significant hypoglycemic effect was noted even when drug levels were undetectable in plasma.

Adult↗