Determination of Caffeine in Serum and Urine

1969 ◽  
Vol 15 (8) ◽  
pp. 661-668 ◽  
Author(s):  
J I Routh ◽  
N A Shane ◽  
E G Arredondo ◽  
W D Paul
Keyword(s):  
Serum Levels ◽  
Compound A ◽  
Spectral Absorbance ◽  
Related Compounds ◽  
Absorbance Curve ◽  
Serum And Urine

Abstract The method of Axelrod and Reichenthal for the determination of caffeine in serum and urine was modified. The benzene used in the extraction of caffeine was shown to alter the spectral absorbance curve of this compound. A method based on the differential absorbance spectrums of caffeine and related compounds is described. Both methods exhibited satisfactory replication, recovery of added caffeine, and comparable serum levels of the drug.

Human Prothrombin Activation: Determination of Plasma and Serum Levels of Prothrombin Fragment 3 by Radioimmunoassay

1979 ◽  
Author(s):  
Daniel Walz ◽  
Thomas Brown
Keyword(s):  
Blood Clotting ◽  
Factor Xa ◽  
Heart Association ◽  
Serum Levels ◽  
Cross Reactivity ◽  
Assay Procedure ◽  
A Chain ◽  
Prothrombin Activation ◽  
Theoretical Amount

Human prothrombin activation is unique in that, in addition to the release of fragment 1.2 (FI.2) from the NH-terminus of prothrombin by factor Xa during the generation of thrombin, an additional 13 residue polypeptide, fragment 3 (F3), is autocatalytically removed from the amino-terminus of the thrombin A chain. We have developed a rapid radioimmunoassay for human F3 which incorporates short incubation times and the use of a preprecipitated second antibody; the assay can be performed in three hours. Specificity studies in buffer systems show prothrombin and prethrombin 1 cross-reacting at a level of 0.001; purified thrombin does not cross-react. In the presence of 5% BSA, prothrombin displays considerably less cross-reactivity. No immunoreactive material to F3 antibodies could be detected in 400 μL of plasma. Serum, obtained from whole blood clotting, contained measurable quantities of F3 (40-100 ng/mL). This amount in serum represents only 5-10% of the theoretical amount available should all of the fragment be hydrolytically cleaved during the conversion of prothrombin to thrombin. This assay procedure is currently being utilized to monitor the activation of purified human prothrombin in the absence and presence of selected plasma inhibitors. (Supported in part by NIH 05384-17 and the Michigan Heart Association).

Liquid Chromatographic Determination of Amiodarone Hydrochloride and Related Compounds in Raw Materials and Tablets

1994 ◽  
Vol 77 (6) ◽  
pp. 1447-1453 ◽  
Author(s):  
Pauline M Lacrok ◽  
Norman M Curran ◽  
Wing-Wah Sy ◽  
Dennis K J Goreck ◽  
Pierre Thibault ◽  
...  
Keyword(s):  
Raw Materials ◽  
Chromatographic Determination ◽  
Raw Material ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Amiodarone Hydrochloride ◽  
Related Compounds

Abstract A liquid chromatographic method for the determination of amiodarone hydrochloride and 10 related compounds in drug raw material and for assay of drug in tablets was developed. The method specifies a 3 jxm Hypersil nitrile column (150 × 4.6 mm), a mobile phase of 1 + 1 acetonitrile–ammonium acetate buffer (0.1 M adjusted to pH 6.0 with 0.1 M acetic acid), a flow rate of 1 mL/min, and detection at 240 nm. The lower limit of quantitation of the related compounds is 0.02% or less. Drug contents in 2 raw material samples were 100.1 and 99.9% and ranged from 98.2 to 99.4% in 3 tablet formulations. Impurity levels in 2 samples of raw material from different manufacturers were ca 0.4%. The presence of 3 of the known related compounds in these samples was confirmed by liquid chromatographymass spectrometry. The method applied to raw materials was evaluated by a second laboratory and found to be satisfactory.

scholarly journals Circulating bioactive sclerostin levels in an Austrian population-based cohort

2021 ◽  
Author(s):  
Katharina Kerschan-Schindl ◽  
Ursula Föger-Samwald ◽  
Andreas Gleiss ◽  
Stefan Kudlacek ◽  
Jacqueline Wallwitz ◽  
...  
Keyword(s):  
Serum Levels ◽  
Population Based ◽  
Negative Regulator ◽  
Total Serum ◽  
Mineral Density ◽  
Cross Sectional ◽  
Robust Parameter ◽  
Austrian Population ◽  
Different Levels

Summary Background Circulating serum sclerostin levels are supposed to give a good estimation of the levels of this negative regulator of bone mass within bone. Most studies evaluating total serum sclerostin found different levels in males compared to females and in older compared to younger subjects. Besides an ELISA detecting total sclerostin an ELISA determining bioactive sclerostin has been developed. The aim of this study was to investigate serum levels of bioactive sclerostin in an Austrian population-based cohort. Methods We conducted a cross-sectional observational study in 235 healthy subjects. Using the bioactive ELISA assay (Biomedica) bioactive sclerostin levels were evaluated. Results Serum levels of bioactive sclerostin were higher in men than in women (24%). The levels correlated positively with age (r = 0.47). A positive correlation could also be detected with body mass index and bone mineral density. Conclusion Using the ELISA detecting bioactive sclerostin our results are consistent with data in the literature obtained by different sclerostin assays. The determination of sclerostin concentrations in peripheral blood thus appears to be a robust parameter of bone metabolism.

Urinary gonadotropin measurements by enhanced luminometric assays (LIA) for the evaluation of pubertal development

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
And Demir ◽  
Adem Aydın ◽  
Atilla Büyükgebiz ◽  
Ulf-Håkan Stenman ◽  
Matti Hero
Keyword(s):  
Healthy Subjects ◽  
Reliable Method ◽  
Pubertal Development ◽  
High Sensitivity ◽  
Tanner Stage ◽  
Time Resolved ◽  
Stage 1 ◽  
Sensitive Detection Technique ◽  
Serum And Urine

Abstract Objectives Determination of LH in urine has proved to be a reliable method for evaluation of pubertal development. The human LH assay based on time-resolved immunofluorometric (IFMA) technology (AutoDELFIA, PerkinElmer, Wallac) has been found to be suitable for this purpose thanks to its high sensitivity but other assays have not been evaluated. We have analyzed our data obtained by another potentially sensitive detection technique, enhanced luminometric assay (LIA) with the objective of finding a viable alternative to IFMA since these may not be available in the future. Methods LIA was used to measure LH and FSH in serum and urine samples from 100 healthy subjects of each Tanner stage and both genders, whose pubertal development has been determined. Results Urinary gonodotropin concentrations measured by LIA correlated well with Tanner stage [(r=0.93 for girls, r=0.81 for boys; p<0.01 for LH) and (r=0.81 for girls, r=0.73 for boys; p<0.01 for FSH)]. LIA determinations revealed the increase in U-LH concentrations during the transition from Tanner stage 1–2 in both girls and boys (p<0.001), whereas U-FSH and S-LH were able to detect the increase from Tanner stage 1–2 only in boys or girls, respectively (both p<0.001). Conclusions Measurement of urinary gonadotropin concentrations by LIA may be useful for the evaluation of overall pubertal development and also in the detection of transition from prepuberty to puberty.

scholarly journals A CHEMICAL METHOD FOR THE DETERMINATION OF PTEROYLGLUTAMIC ACID AND RELATED COMPOUNDS

1947 ◽  
Vol 168 (2) ◽  
pp. 705-710
Author(s):  
B.L. Hutchings ◽  
E.L.R. Stokstad ◽  
J.H. Boothe ◽  
J.H. Mowat ◽  
C.W. Waller ◽  
...  
Keyword(s):  
Chemical Method ◽  
Pteroylglutamic Acid ◽  
Related Compounds
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