Abstract: Trace elements in different silica gels are determined by neutron activation analysis. The presence of 20 elements in the ppm range and of 15 elements in the ppb range is established in all silica gels; even in spherical material probably obtained via an organosilicium starting material. Removal of these elements by acid treatment before and after derivatization to a reversed-phase is studied. This is only partially effective. The resulting HPLC phases are, however, much better in cases where trace elements are detrimental. Even octadecyl derivatized silicagel can withstand boiling in 12 N hydrochloric acid without loosing significant amounts of bonded organic material.

Abstract: We describe a chemical assay involving "high-pressure" liquid chromatography for the quantitative determination of three aminoglycosides: netilmicin, tobramycin, and gentamicin. The drugs are separated from serum by means of precipitation of the serum proteins with acetonitrile after dilution with a buffer. The aminoglycosides are quantitatively extracted into the supernate, which is further purified by a two-step partition procedure involving derivatization of the drugs with o-phthalaldehyde. The drug derivatives are separated by reversed-phase chromatography and detected by on-line fluorometry. Sensitivity is 1 mg/L for tobramycin and 0.5 mg/L for netilmicin and gentamicin. Intra- and interassay variation was below 8%. Analytical recovery of each of the three drugs was 92 to 100%. Correlation with microbiological and radioimmunological assay methods was good. The assay is rapid (about 30 min), precise, and specific, and seems suitable for use in a routine clinical laboratory.

Abstract: A liquid chromatography procedure is described for separating the amino acids in protein hydrolysates. The proteins are hydrolyzed with hydrochloric acid and an aliquot of the hydrolysate is derivatized with dansyl chloride reagent. The derivatization procedure takes only 2 minutes using a reaction temperature of 100°C. The dansylated amino acids are chromatographed using a reversed-phase C8 column and a multi-step, nonlinear gradient elution solvent program which is readily achieved using a microprocessor-controlled liquid chromatograph. Chromatography is complete in approximately 40 min. The procedure is useful for characterizing proteins and may also be used to analyse intact dansylated polypeptides. Chromatograms showing the amino acid profile of chymotrypsin, albumin and histone are given.

Abstract: An analytical method has been developed to measure Pt(II) in urine via derivatization and UV or HPLC analysis. A measured quantity of urine is heated briefly with diethyl ammonium diethyl-dithiocarbamate, and the resulting Pt(Et2NCS2)2 is extracted into a measured volume of chloroform. Concentrations of Pt(II) are determined by UV absorption at 346 nm or by reverse phase HPLC analysis. The detection limit for Pt(II) as its dithiocarbamate is ∼ 1 ng by HPLC; the concentration limit for HPLC analysis by direct extraction was ∼ 25 ng/ml. Chromatographic response was linearly related to Pt(II) concentration over the range 100-4, 000 ng/ml; dilution of more concentrated samples has extended this range to at least 30, 000 ng/ml. This method has been applied to the analysis of Pt(II) in the urine of patients who have received cis-dichlorodiamniineplatinum(II) (CDDP) chemotherapy.

Abstract: Gas chromatography mass spectrometry has been used to study the reaction between a range of aromatic, alicyclic and aliphatic sulphate esters and three perfluoroacylating reagents, viz. trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydride. Aromatic sulphates were found to react readily, when treated with a 1:1 mixture of a perfluoroacid anhydride and dry ethyl acetate, to form the perfluoroester derivative of the parent phenol in quantitative yield. Non-aromatic sulphates, on the other hand, gave a variety of products. A mechanism is proposed for the one-step derivatization of aromatic sulphates and the potential of the procedure for the analysis of sulphate conjugates by mass spectrometry is discussed.

Abstract: New derivatization of primary and secondary amines for electrochemical detection in liquid chromatography has been developed. The derivatization reagents were prepared from vanillic acid and homovanillic acid by condensation with N-hydroxysuccinimide. Of the two reagents the activated ester of homovanillic acid reacted more readily with amines, providing the amides which were highly responsible for an electrochemical detector in reversed phase chromatography. The detection and quantitation limits determined with ethyl phenylalaninate were 200 pg and 1 ng, respectively.

Abstract: High-pressure liquid chromatography was used to separate the fluorescent adduct formed from the reaction of histamine with o-phthalaldehyde (OPT) from other biogenic amines in tissue, cerebrospinal fluid (CSF), sweat and urine samples. Using off-column derivatization and isocratic elution techniques fluorescent OPT adducts can be detected in the low picogram range. Perchloric acid extracts of tissue samples from Aplysia california and urine specimens collected from healthy adult males, including internal standard, were derivatized with OPT buffer, pH 9.5 and extracted with ethylacetate to increase sensitivity and stabilization of the fluorescent adduct prior to chromatography. Sweat and CSF samples were reacted with OPT buffer and aliquots of this mixture injected directly onto the chromatographic column (μBondapak CN) with methanol/0.08 mol/liter acetic acid (52/48 by volume) as the mobile phase. Assay of pooled urine containing added histamine (1 μg/ml) gave a with-in run coefficient of variati...

Abstract: Polyglycerols and other polyols can be conveniently analyzed by partition HPLC on silica columns. Derivatization is not necessary. Compounds of this type are often found in the esterified form in food emulsifiers, and are set free upon saponification. They are also used as humectants and freezing point depressants, e. g. in soft ice cream. A chemical classification of food emulsifiers is given, and the separation and identification of their neutral polyols by HPLC is described. Lipid class HPLC of the intact esters is also briefly mentioned.