A simple, direct radioimmunoassay for plasma cortisol, featuring a 125I radioligand and a solid-phase separation technique.

1979 ◽  
Vol 25 (5) ◽  
pp. 665-668 ◽  
Author(s):  
D Riad-Fahmy ◽  
G F Read ◽  
S J Gaskell ◽  
J Dyas ◽  
R Hindawi
Keyword(s):  
Solid Phase ◽  
Mass Spectrometric ◽  
High Mass ◽  
Selected Ion Monitoring ◽  
Mass Spectrometric Technique ◽  
Validation Criteria ◽  
Bovine Serum Albumin Conjugate ◽  
Ph Buffer ◽  
Very High ◽  
Chromatographic Mass

Abstract A simple, direct radioimmunoassay for cortisol in human serum and plasma is described. An antiserum, raised in sheep to a cortisol-3-(O-carboxymethyl)oxime/bovine serum albumin conjugate, is coupled to microcellulose. No extraction is required because plasma samples and standards are incubated with the antiserum and an 125I radioligand in a low-pH buffer, which denatures cortisol-binding globulins. The assay satisfies accepted validation criteria. In addition, results from the radioimmunoassay compare well with those obtained by a gas chromatographic-mass spectrometric technique (r = 0.968; FRIA = 0.97 FGCMS + 2.0 nmol/L). The latter procedure features the very high intrinsic specificity obtained by selected ion monitoring at high mass-spectrometric resolution (M/deltaM = 8500) with a Varian MAT-731 instrument. The simplicity of the radioimmunoassay procedure, with use of reagents prepared "in house," makes this a very practical and economical assay for use in the medium or large endocrine laboratory.

Gas Chromatographic/Mass Spectrometric Confirmation of Leucomalachite Green in Catfish (Ictalurus punctatus) Tissue

1995 ◽  
Vol 78 (4) ◽  
pp. 971-977 ◽  
Author(s):  
Sherri B Turnipseed ◽  
José E Roybal ◽  
Jeffrey A Hurlbut ◽  
Austin R Long
Keyword(s):  
Solid Phase Extraction ◽  
Ictalurus Punctatus ◽  
Solid Phase ◽  
Mass Spectrometric ◽  
Phase Extraction ◽  
Neutral Alumina ◽  
Ms Analysis ◽  
Solid Phase Extraction Cartridge ◽  
Leucomalachite Green ◽  
Chromatographic Mass

Abstract A gas chromatographic/mass spectrometric (GC/MS) method was developed to confirm the presence of leucomalachite green (LMG), a metabolite of the triphenylmethane dye malachite green (MG), in catfish tissue. Residues were isolated according to a previously described liquid chromatographic (LC)A/IS spectrometric analysis of MG and LMG in fish. In our isolation procedure, analytes are extracted from tissue with acetonitrile–buffer, partitioned into CH2CI2, and applied to neutral alumina and propylsulfonic acid solid-phase extraction cartridges. Before GC/MS analysis, extracts prepared for the LC determinative method are eluted from a cyano solid-phase extraction cartridge, extracted into organic solvent, and concentrated for GC/MS analysis. Selected ion monitoring was performed by using 5 diagnostic ions (m/z 330,329,253,210, and 165) of LMG. The method was validated by confirming LMG in tissue fortified with mixtures of MG and LMG (5 and 10 ng/g each) and in tissue from fish that had been exposed to low levels of MG.

scholarly journals Gas chromatographic-mass spectrometric study of metabolites of C21 and C19 steroids in neonatal porcine testicular microsomes

1985 ◽  
Vol 227 (3) ◽  
pp. 909-916 ◽  
Author(s):  
T K Kwan ◽  
N F Taylor ◽  
D Watson ◽  
D B Gower
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Selected Ion Monitoring ◽  
17 Hydroxyprogesterone ◽  
Porcine Testis ◽  
Steroid Pathway ◽  
Chromatographic Mass

Microsomal fractions obtained from testes of 3-week-old piglets have been incubated, separately, with progesterone, 17-hydroxyprogesterone, 5-pregnene-3 beta,20 beta-diol, 16 alpha-hydroxypregnenolone, 5-androstene-3 beta,17 alpha-diol and dehydro-epiandrosterone. The metabolites, after derivatization, have been separated by capillary gas chromatography and identified by mass spectrometry. Quantification was by selected ion monitoring. Progesterone was shown to be 17-hydroxylated and also converted into 4,16-androstadien-3-one (androstadienone). The major metabolite of 17-hydroxyprogesterone was 4-androstene-3,17-dione (4-androstenedione), but little, if any, androstadienone was formed, indicating that this particular biosynthesis did not require 17-hydroxylation. The metabolites of 5-pregnene-3 beta, 20 beta-diol were found to be 17-hydroxypregnenolone, 3 beta-hydroxy-5,16-pregnadien-20-one (16-dehydropregnenolone) and 5,16-androstadien-3 beta-ol. Dehydroepiandrosterone and 5-androstene-3 beta,17 alpha-diol were interconvertible but neither steroid acted as a substrate for 16-androstene formation. However, dehydroepiandrosterone was metabolized to a small quantity of 4-androstenedione. Under the conditions used, no metabolites of 16 alpha-hydroxypregnenolone could be detected. The present results, together with those obtained earlier, indicate that the neonatal porcine testis has the capacity to synthesize weak androgens, mainly by the 4-en-3-oxo steroid pathway. Although 16-androstenes cannot be formed from C19 steroids, progesterone served as a substrate and may be converted directly to androstadienone, without being 17-hydroxylated first. The pathway to 5,16-androstadien-3 beta-ol, however, involves 17-hydroxypregnenolone and 16-dehydropregnenolone as intermediates.

Quantitation and Confirmation of Sulfamethazine Residues in Swine Muscle and Liver by LC and GC/MS

1991 ◽  
Vol 74 (3) ◽  
pp. 479-482 ◽  
Author(s):  
Germain Carignan ◽  
Karen Carrier
Keyword(s):  
Muscle Tissue ◽  
Liver Tissue ◽  
Internal Standard ◽  
Mass Spectrometric ◽  
Selected Ion Monitoring ◽  
Tissue Extracts ◽  
Coefficients Of Variation ◽  
Swine Tissue ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract The present paper describes a liquid chromatographic (LC) method for purification of crude swine tissue extracts before gas chromatographic/mass spectrometric (GC/MS) quantitation and confirmation of sulfamethazine at low ppb levels. Fractions corresponding to sulfamethazine were collected, evaporated to dryness, ^methylated with diazomethane, concentrated, and analyzed by GC/MS. A mass spectrometer was set to selected ion monitoring (SIM) mode. Ions 233, 227, 228, and 92 m/z were detected. Ratio 227/233 m/z (sulfamethazine/internal standard, [pheny| 13C6] sulfamethazine) was used for quantitation, while ratios 228/227 and 92/ 227 m/z, respectively, were used for confirmation. Quantitation in spiked blank muscle tissue was tested from 100 to 1 ppb and found acceptable at all concentrations studied; coefficients of variation ranged from 4.9 to 14.4%. Similar results were obtained for liver tissue from 5 to 20 ppb; coefficients of variation ranged from 1.2 to 9.1 %.

Gas Chromatographic/Mass Spectrometric Determination of α-Methylstyrene in Styrene-Based Polymers and Food Simulants

1991 ◽  
Vol 74 (5) ◽  
pp. 815-818
Author(s):  
Shigeru Tan ◽  
Takashi Tatsuno ◽  
Taro Okada
Keyword(s):  
Mass Spectrometry ◽  
Direct Injection ◽  
Mass Spectrometric ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Monitoring Method ◽  
Food Simulants ◽  
Multiple Ion Monitoring ◽  
Chromatographic Mass

Abstract A selected ion monitoring method is described for the analysis of styrene (St)-based polymers for a-methylstyrene (α- MSt) and for determining the level of α-MSt migration from St-based sheets Into 4 food simulants. The polymers are dissolved in dlchloromethane; α-MSt Is determined by direct Injection of the polymer solutions. α-MSt migration from St-based sheet to water, 4% acetic acid, 20% ethanol, and n-heptane was measured by gas chromatography/mass spectrometry, using multiple ion monitoring of Ions at mix 118,78, and 91. α-MSt can be quantltated at levels as low as 10 μ/g in the polymer and 0.01 μ/g In the food simulants. Recoveries were 83-113% from St-based sheets and 90-99% from food simulants, respectively.

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