Liquid chromatographic determination of narasin in feed premixes

A liquid chromatographic (LC) method has been developed to determine narasin in feed premixes. Narasin is extracted from the premix with a methanol-water solvent, and the extracted solution is assayed by using LC. Recovery of narasin from a 12.5 g/lb premix is quantitative (100%), with a relative standard deviation of 1.44%. The results correlated well (coefficient 0.92) with a turbimetric bioassay method.

Liquid chromatographic determination of nicarbazin in feeds and premixes

A liquid chromatographic (LC) method has been developed for the determination of nicarbazin in premixes and poultry feed. Liquid chromatography of the 4,4'-dinitrocarbanilide (DNC) portion of nicarbazin is performed isocratically with a reverse phase octadecylsilica column and a UV detector set at 340 nm. The 2-hydroxy-4,6-dimethylpyrimidine (HDP) portion of nicarbazin is chromatographed isocratically with a reverse phase octylsilica column and a UV detector set at 305 nm. Nicarbazin concentration can be calculated by assaying both DNC and HDP, or by assaying DNC or HDP and assuming that nicarbazin is a 1:1 molar ratio of the two. Average recoveries of DNC and HDP added to poultry feed were 101% and 87%, respectively. This procedure provides an alternative to existing colorimetric procedures for determining nicarbazin in premixes and poultry feeds.

High pressure liquid chromatographic determination of Monensin in feed premixes

A high pressure liquid chromatographic (HPLC) method has been developed to determine monensin in feed premixes. The method is simple and rapid. Monensin is extracted with methanol-water and determined in the extracting solution by HPLC. Average recovery for monensin from a 13.2% premix sample was 103% (coefficient of variation (CV), 2.6%) by HPLC and compares with the value of 100% (CV, 3.4%) obtained by the turbidimetric bioassay method.

Determination of ethinyl estradiol in human urine by radiochemical GLC

A radiochemical GLC analysis was developed for 3H-labeled ethinyl estradiol in human urine. The technique was applied to the unconjugated and aglycone fractions of urine collected from women who were dosed orally with: (a) single capsules containing 2.0 mg of 3H-quinestrol (900 muCi) and 2.5 mg of unlabeled quingestanol acetate dissolved in sesame oil and (b) single tablets containing 100 microgram of 3H-quinestrol (86 muCi). Unconjugated ethinyl estradiol in Day 1 urine collections represented means of 0.02% of the high quinestrol dose and 0.12% of the low dose. Ethinyl estradiol glucuronide in the same collections represented means of 0.55% of the high drug dose and 1.35% of the low dose. The method could detect 1-ng quantities of 3H-ethinyl estradiol and 3H-quinestrol.

Radiochemical GLC assay for nortriptyline in human plasma

A novel method was developed for the assay of nortriptyline in plasma. After nortriptyline was extracted, it was acetylated with 3H-acetic anhydride; the quantity of 3H-acetylnortriptyline in the extract was determined by radiochemical GLC. The method is capable of assaying 5 ng of nortriptyline/ml of plasma. The instrumentation was assembled from commercially available components.

Assay of human plasma for nortriptyline by radioacetylation and thin-layer chromatography

A highly specific and sensitive thin-layer chromatographic method for determining nortriptyline levels in plasma is presented. The procedure involves extracting nortriptyline, acetylating it with radioactive acetic anhydride, resolving acetylnortriptyline by thin-layer chromatography, and measuring its radioactivity.

Surface predominance of trace elements in airborne particles

A number of minor and trace elements including Be, C, Ca, Cr, K, Li, Mn, Na, P, Pb, S, Tl, V, and Zn present in coal fly ash are found to be preferentially concentrated on the particle surfaces. Environmentally effective concentrations of these elements are thus much higher than indicated by conventional bulk analyses.