Chromatographic and electrophoretic approaches in ink analysis

Inks are manufactured from a wide variety of substances that exhibit very different chemical behaviors. Inks designed for use in different writing instruments or printing methods have quite dissimilar components. Since the 1950s chromatographic and electrophoretic methods have played important roles in the analysis of inks, where compositional information may have bearing on the investigation of counterfeiting, fraud, forgery, and other crimes. Techniques such as paper chromatography and electrophoresis, thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gel electrophoresis, and the relatively new technique of capillary electrophoresis have all been explored as possible avenues for the separation of components of inks. This paper reviews the components of different types of inks and applications of the above separation methods are reviewed.     

Chromatographic separation of 2,3-benzodiazepines

A review of chromatographic methods for the determination of 2,3-benzodiazepines (2,3-BZs) is presented. The determinations are performed to investigate the presence of potential impurities in drug substances and to study their pharmacokinetic profile in biological samples, either in animals or in humans. Several methods dealt with a pretreatment of samples, i.e., liquid-liquid extraction by using a variety of solvents, solid-phase extraction, direct injection of specimens into the chromatographic apparatus. Different chromatographic techniques have been used. High-performance liquid chromatography allows optimal sensitivity and specificity by using ultraviolet or diode array detection methods. Gas chromatography-mass spectrometry and gas chromatography with nitrogen-phosphorous or electron-capture detectors have been also reported. Suitable methods for the separation of enantiomers of 2,3-BZs have been described. Thin-layer chromatography has been shown to be capable to isolate analytes from biological samples as urine or faeces. The reported chromatographic techniques are currently applied to define the metabolic pathways of 2,3-BZs in experimental and clinical studies.     

Chromatographic studies of uremic plasma.

In order to characterize the spectrum of possibly toxic retention compounds in uremia we have developed a simple reproducible method of separating fractions of uremic serum by Sephadex G-15 column chromatography. This technique, which requires no prior deproteinisation and is carried out at ambient temperatures, allowed the separation of uremic serum into several well defined fractions. Subsequent thin layer chromatography (TLC) showed that each peak represented a mixture of peptides, and that there were qualitative and quantitative differences between the plasma of normal and uremic patients as well as between patients with acute renal failure and chronic renal failure.     

Chromatographic and capillary electrophoretic methods for the analysis of nicotinic acid and its metabolites

Methods for the assay of nicotinic acid (NiAc) and its metabolites in biological fluids using high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are reviewed. Most of the references cited in this review concern HPLC methods. A few CE methods that have been recently reported are also included. As these compounds are relatively polar and have a wide range of physico-chemical properties, the sample pre-treatment or clean-up process prior to analysis is included. Most HPLC methods using an isocratic elution system allow determination of a single or few metabolites, but gradient HPLC methods enable simultaneous determination of five to eight compounds. Simultaneous determination of NiAc including many metabolites in a single run can be achieved by CE. We also discuss the pharmacokinetics of NiAc and some of its metabolites.     

Preparative electrophoretic separation of normal and neoplastic human bone marrow cells

Summary Bone marrow cells of patients with chronic myeloid leukemia, monocytic leukemia, myeloblast leukemia, chronic lymphatic leukemia, typical and atypical plasma cell myeloma and M. Waldenström were separated by free flow electrophoresis and their distribution profiles compared with profiles of normal bone marrow cells. Except for myeloma cells, the pathologic cells possess the same electrophoretic mobility as their normal counterparts. Atypical or typical myeloma cells show a much faster mobility than normal plasma cells. The importance of these results is discussed.

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Abbreviations EPM electrophoretic mobility.     

Chromatographic separation and 13C NMR characterization of aromatic diester-diacids isomers

Reverse phase high performance liquid chromatography (HPLC) was used to separate and quantify aromatic diester-diacids isomers which arise from the opening selectivity of anhydride rings towards methanol. ¹³C NMR spectroscopy was a supplementary tool to characterize the isomer structure. It was found that a meta-position attack is slightly preferred in pyromellitic dianhydride (PMDA), while the preferred position of an attack in bridged dianhydrides is determined by the chemical nature (donors or acceptors) of the bridged group. The stronger its electron-withdrawing abilities, the lower the probability of a meta-position attack.     

Multivariate analysis of data from two-dimensional electrophoretic separation of macromolecules

Recent work on two-dimensional electrophoretic separation of molecules has concentrated on technical aspects of molecule identification, leaving little in the way of time and resources to explore new, effective methods for analyzing the data thus produced. We present a method for coding electrophorograms that is capable of capturing sufficient information in order that subsequent analysis might be revealing. Along with this coding method, we describe a flexible approach to the analysis of electrophoretic data employing multivariate methods for summarization and comparison. In this we have found an effective vehicle for revealing some unexpected properties of the electrophorograms.     

Clinical assessment of the electrophoretic separation of alkaline phosphatase isoenzymes

Over a five-month period, using data from patients in whom alkaline phosphatase (ALP) isoenzyme studies were requested routinely, we compared actual clinical diagnoses with the predicted diagnoses based on the results of electrophoretic separation of ALP isoenzymes on cellulose acetate before and after heat treatment and on elevated enzymatic activity of gamma glutamyl transferase (GGT) and alanine aminotransferase (ALT) activity. ALP isoenzymes were interpreted on a qualitative basis (presence or absence of liver, bone, or other isoenzyme) by individual clinical pathologists. Overall, the consistency of agreement in 61 patients was 66% for GGT, 51% for ALP isoenzymes, and 21% for ALT. In 44 patients with definite diagnoses, the sensitivity and specificity, respectively, of each laboratory test for patients with liver disease were 88 +/- 5.7% and 64 +/- 14.5% (ALP isoenzymes); 88 +/- 5.7% and 91 +/- 8.6% (GGT); and 6 +/- 4.1% and 91 +/- 8.6% (ALT). In patients with bone disease, the sensitivity and specificity of ALP isoenzymes was 75 +/- 10.8% and 86 +/- 6.6%, respectively. The results indicate that isoenzymes as currently performed need to be improved through standardization of the interpretation of ALP isoenzyme patterns to establish uniformity of comments.