In this chapter, a wide variety of derivatization reactions used for the GC analysis of amines has been surveyed. Some potential problems with derivatization procedures include the formation of unwanted derivatives, the presence of unchanged derivatization reagents, and the requirement for non-aqueous reaction conditions. Amines in environmental and biological samples are usually found in aqueous solutions except for air samples, and are often at trace levels among complex matrices containing a number of coexisting substances. It is therefore desirable that these amines be derivatized in aqueous solutions and be sensitively detected. Of the derivatization reactions presented in this chapter, silylation and acylation usually require anhydrous reaction conditions because their respective reagents are very sensitive to moisture and hydrolyze. In contrast, alkylation, halogenation and the formation of Schiff base, carbamates, sulfonamide and phosphonamide derivatives can be generally performed in aqueous solutions. GC detectors must be not only sensitive to the minute amounts of analytes, but selective enough to discriminate among coexisting substances. The nitrogen selective detector NPD and GC-MS have been used to obtain results with high sensitivity and selectivity. In addition, the conversions of amines into fluorinated derivatives to introduce ECD responses and into sulfur- and phosphorus-derivatives to introduce FPD responses have been devised for these purposes. The GC methods with selective detectors, described in this chapter, have advantages and disadvantages and to date there is no all-powerful analytical methods. The choice of an analytical method depends on the presence of amines at low parts per billion or less and the variety and complexity of the sample. To achieve the efficient isolation and preconcentration of amines in environmental and biological samples, several methods of sample preparation have been developed using a number of different purification techniques. Among these, SPME is simple and rapid, and may be applied directly to the sample in combination with derivatization. Finally, it is the author's hope that this review will serve as a guide for choosing the most effective techniques for the GC analysis of amines. Derivatization for the protection of amino groups is widely employed to increase volatility, to form diastereomers, and to improve the chromatographic and, if possible, the mass spectral properties of derivatives. In this chapter, we summarize derivatization methods for the determination of amines by gas chromatography (GC), especially with regard to the reactivity, selectivity and sensitivity of these reactions. Among the derivatives used for GC analysis are the silyl, acyl, alkyl, carbamate, sulfonamide, phosphonamide, Shiff base and thiourea derivatives of amines. Some derivatives can be selectively and sensitively detected using a variety of methods, including thermionic, flame photometric, electron capture and mass selective detectors. The recent applications of these derivatization methods to the analysis of individual aliphatic and aromatic amines in food, environmental, clinical chemistry and other areas are also described.
Summary Pre-column derivatization of amino acids with 5-dimethylaminonaphthalene-1-sulfonyl chloride (dansyl chloride) or 4-dimethylaminoazobenzene-4′-sulfonyl chloride (dabsyl chloride) is described. These pre-column derivatization methods enable a sensitive HPLC analysis of amino acids. Dansyl derivatization has originally been applied to the sequential analysis of peptides and proteins. It finds another use in biochemistry for the fluorogenic labeling of proteins and enzymes. Dansyl chloride is the most widely used for the derivatization of amino acids. Dansyl chloride readily reacts with primary and secondary amino groups of amino acids. The reaction medium is usually an aqueous-organic mixture (e.g., 1:1 acetone-water) adjusted to a pH of 9.5-10. Dansylation reaction is usually carried out at elevated temperatures. Various dansylation reaction conditions are reported, involving 60 °C for 60 min or at 38 °C for 90-120 min. Dansyl amino acids absorb light in the UV region. For example, absorption maxima are observed at 214, 246 and 325 nm for dansyl glycine, and the absorption at 214 nm is the strongest. Dansyl group is also fluorescent and dansyl amino acids can therefore be detected by a fluorimetric detector. The excitation and emission wavelengths for dansyl glycine are 324 and 559 nm, respectively. Dansyl amino acids are mostly separated in the reversed-phase mode on a C8 or C18 column with a linear gradient. Dabsyl chloride has a number of advantages over other derivatization methods, including a simple derivatization procedure, very good stability, good reproducibility and a good limit of detection for the method, complete HPLC separation of all the amino acids, and specific detection at a wavelength in the visible region. Dabsyl chloride also reacts with primary and secondary amino groups of amino acids as does dansyl chloride. Dabsylation reagent solution can be prepared by dissolving dabsyl chloride in acetone or in acetonitrile, followed by mixing with buffer (e.g., carbonate, pH 8.5-9.5). Derivatization of amino acid with dabsyl chloride is also carried out at elevated temperatures as for dansylation. For example, samples were incubated at 70 °C for 15-30 min. There have been a number of literatures dealing with application of dansylation to the determination of amino acids contained in various sample sources, involving biological fluids, tissues, foods, peptide or protein hydrolyzates, etc. Dabsylation also covers nearly the same application areas as for dansylation. Enantiomeric separation of dansyl and dabsyl amino acids can be carried out by ligand-exchange chromatography. The use of native, and derivatized β- and γ-cyclodextrin stationary phases as well as the use of γ-cyclodextrin mobile phase additive are other options for the chiral separation of these derivatized amino acids.
Summary The recent advances in evaporative light scattering (ELS), chemiluminescent nitrogen (CLN) and mass spectrometry (MS) techniques provide new opportunities in native amino acid determination. Seven chromatographic detectors (low-wavelength UV, refractive index, conductivity detector, nuclear magnetic resonance, ELSD, CLND, MS/MS) are compatible with a direct detection of amino acids. The triple quadrupole ESI-MS/MS was found to be the most promising detector due to its high sensitivity. However, in spite of its high specificity, a high number of amino acids have to be separated due to the intrinsic limitations of MS when the simultaneous analysis of closely related chemical structures is required. By using perfluorinated carboxylic acids of longer n-alkyl chain than trifluoroacetic acid, as ion-pairing reagents in the mobile phase, high amino acid selectivities can be obtained on C8, C18 silica or porous graphitic carbon. They are efficient reagents for the separation of underivatized amino acids and are volatile enough for their use in MS/MS. LC coupled with MS has been shown to be a viable alternative to traditional detection techniques for the separation of underivatized amino acids and their determination in biological extracts without any further treatment. The use of stable isotopically labeled internal standards ensured the accuracy of quantification and eliminated matrix effects. Quantification limits for each molecule were found compatible with their measurement in plasma and urine.
Taking to heart the meaning of the proverb “Simple is best”, we have been aiming to develop a method for the determinations of biogenic amines that is so simple that almost anyone could perform it. The present platform, oncolumn derivatization CEC, has the following advantages: 1) No additional apparatus or devices are needed. 2) Biogenic amines can be separated and detected, regardless of the presence of other substances in the sample, such as amino acids. This selectivity makes unnecessary the need for any sort of pre-treatment of the sample to remove unwanted components, thereby resulting in a streamlining of the analytical procedure. 3) A high-sensitivity detection can be easily obtained with an on-line preconcentration technique. 4) Downsizing the format onto a μ-chip is possible. Although oncolumn derivatization CEC still has some problems requiring solution or improvement, I believe this will be one of the best platforms for the high-throughput determinations of biogenic amines in food or biological sample in the near future
This chapter summarizes the advances in the enantioseparation of Dns-DL-AAs by CE and CEC. The basic principle of chiral recognition with the different chiral selectors is discussed by combining the typical examples for resolving the Dns-AAs. Cu(II) complexes with Lamino acids, L-amino acylamides or other complex-forming agents, CDs or CD derivatives, chiral surfactants and other chiral selectors have been well used as the chiral selectors added in the CE background electrolytes for chirally resolving Dns-DL-AAs. With the introduction of micellar phase of anionic surfactants in the CE electrolytes, two separation modes, LE-MEKC and CD-MEKC, have been developed for improving the separation selectivity. In addition, the combination of different chiral selectors, the addition of organic modifiers, and the adjustment of separation conditions like pH, ionic strength, buffer composition were also used to manipulate the selectivity. In CEC, with the advent of monolithic column technology, chiral stationary phases have been immobilized on the monolithic matrix by in situ co-polymerization and/or post-modifications or grafting of chiral selectors. Monolithic column technology makes CEC a very powerful technique for chiral separation with high separation selectivity and efficiency. New chiral selectors and column technology are expected to develop for the chiral separation of Dns-AAs in the future
Summary The chloroformate chemistry of AAs is reviewed taking different aspects into account such as reactivity, method constructions, automation, sensitivity, detector arrangements, sample matrix problems. The exceptional vigourous derivatization reaction is sensitive to pH and buffer capacities. These influence the formation of FMOC-derivatives with tyrosine and sometimes histidine. During stronger basic conditions coupling as well as deblocking of AAs occurs. The FMOC-Cl, a classical reagent within peptide synthesis, is proved to yield derivatives without racemization. The analogues (+)- and (−)- FLEC chiral reagents are useful for trace analysis of enantiomeric AAs. The optical purity problems in ascertaining accuracy in the enantiomer determinations with chiral chloroformate reagents are discussed. Anthracene is proposed as a chromogenic label instead of fluorine since the sensitivity is considerably raised. For instance as a consequence of the attained sensitivities the matrix problems in complex constituted samples can be solved just by dilution. High resolution separation systems with capillary columns and laser induced fluorescence detection are exemplified.
This chapter reviews the most recent developments in polyamine analysis. A substantial part is devoted to the most important biogenic polyamines (putrescine, cadaverine, spermidine and spermine); some attention is also given to synthetic polyamine polymers. The chapter is subdivided into non-derivatization and derivatization methods. Besides an overview of older derivatization techniques, also recently described highly interesting procedures (e.g. PBC (4-(1-pyrene)butanoyl chloride) for selective detection of diamines beside monoamines are discussed. Special attention is given to sample preparation, recovery, repeatability and detection limit of the method. Sample preparation of different sample matrices is discussed throughout this review. The feasibility of applying comprehensive two-dimensional gas chromatography, coupled with time of flight mass spectrometry is demonstrated. Different selective approaches have been discussed. Derivatization approaches, including sample preparation of different samples were reviewed. Selective approaches, like Ni- inhibition of monoamines and pyrene labeling for selective polyamine determination are described. Ideas are discussed from synthetic polyamines (non aqueous derivatization, critical chromatography, high pH mobile phase), which could be applied to the separation for biogenic polyamines. It was demonstrated that polyamines can be highly selectively determined in urine by means of GC*GC-TOF MS.
Some of the general problems encountered in the analysis of amino acids derivatized with various isothiocyanates, determined both as phenylthiocarbamoyl (PTC) and as phenylthiohydantoin (PTH) derivatives, are presented. Based on our own experience and the literature associated with sample preparation, stability, optimum chromatographic and quantitation conditions are discussed. Twenty-seven PTC-AAs have been separated on seven columns, with the same gradient program, applying various temperatures and eluent flow rates, within 40 min, including equilibration time. Response values and spectral characteristics of the 27 AAs proved to be independent of the chromatographic conditions performed. Particular attention was paid to the issue of sensitive amino acids under hydrolysis (cystine/cysteine, methionine, tryptophan), and derivatization (cystine/cysteine) conditions as well. The special behavior of the PTC-cystine/cysteine has been examined by LC/API/MS measurements showing that, irrespective of the initial compound to be derivatized, the same stereoisomer pairs are formed at m/z = 255, PTC-cysteines (∼80 % of the total) and their oxidized version at m/z = 287 (∼20 % of the total). Whether there is an advantage of the microwave irradiation procedure is still not decided: however the hydrolysis time of lysozyme has been shortened considerably, but optimum hydrolysis conditions were not uniformly found for all essential amino acids.
An overview is presented of chromatographic methods currently in use to determine AAs and As (i) simultaneously in a single run, (ii) in the presence of each others by separate methods, or (iii) amines alone subsequently to their isolation from AAs. Separation, derivatization and chromatographic conditions are summarized. The advantages and drawbacks of all three possibilities were characterized on the basis of recovery, reproducibility values, time and cost phenomena of methods, (i) From the point of view of the analytical chemist the simultaneous quantitation of AAs and As seems to be the best choice: however to find optimum conditions, with the time not being considered, for AAs and As simultaneously occurring in a matrix, is an unambiguous challenge. In order to solve the problem quickly it helps to have practice in the derivatization and chromatographic conditions of the two groups (AAs, As), separately. (ii) In cases when knowledge of the A content of the sample only is needed, the best choice could be the fast chromatographic elution of AAs without separation: prior to the slow, well-resolved separation of As, such as putrescine, cadaverine, spermine and spermidine, etc. Certainly, As of low molecular weight, inserted into the AA derivatives and are eluting together with them. (iii) On the basis of the unfortunately low recoveries of As, (determined subsequently to their isolation/extraction from AAs), this possibility can be regarded as the worst solution of the task.
Electroseparation methods are perfectly applicable for the analysis of relatively polar compounds such as underivatized amines. These systems provide a series of advantages over the commonly employed chromatographic methods such as the more straightforward possibility of miniaturization and integration and low cost of analysis. If the analysis of amines is performed without a precedent derivatization step additional benefits like the avoidance of all types of pitfalls related to this procedure can be achieved. Unfortunately the analysis of amines in their underivatized form also generates some new problems such as the necessity to separate compounds with often quite similar structures and the need to find detection systems providing sufficient sensitivity for these compounds. The capillary electroseparation method most commonly employed for underivatized amines still is capillary zone electrophoresis and up to now a substantial number of reports exist, describing the application of this technique for a variety of amines in different of matrices ranging from biological fluids to environmental samples. Detection is mostly performed using spectrophotometric detectors (mainly because of their presence in most commercially available instruments) in particular UV-vis detectors either in the indirect mode for simple amines or in the direct mode for heterocyclic or aromatic amines. Some work describing the use of electrochemical detection (mostly conductivity detection) also exists. Optimum choice for the detection of underivatized amines, especially due to their easy ptonizability, is the use of a mass spectrometric detector. This can also be seen from the increasing number of publications dealing with this issue.
The potential of dansyl chloride as labelling reagent for the derivatization of amines prior their determination by high performance liquid chromatography is overviewed. Different approaches for carrying out the dansylation reaction, such as bath derivatization, the use of solid supports and automated on-line procedures are discussed. Dansylation, separation and detection of low-molecular-mass aliphatic amines, biogenic amines including polyamines and aromatic amines of clinical significance are summarized. From a critical study, the most favourable conditions for the determination of these amine compounds in real samples such as waters, foods, beverages and clinical samples are reported.
A method for the analysis of free amino acids in beverage samples by capillary electrophoresis and direct UV detection at 185 nm is presented. Separations were performed in a strongly acidic carrier electrolyte containing an alkanesulfonic acid and varying amounts of acetonitrile. The organic modifier permitted a manipulation of the separation selectivity for a number of analytes investigated in this study, thereby allowing design of appropriate carrier electrolyte compositions for a given analytical problem. Orange juices as well as beer samples could be analyzed with respect to their content of free amino acids. In this way, different types of beer could be distinguished by their amino acid patterns.
6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC), a recently discovered derivatizing reagent for amines, is presented to analyze biogenic amines, in particular polyamines using reversed-phase high performance liquid chromatography (HPLC). Adducts of AQC and polyamines were characterized regarding their spectroscopic properties and their suitability for fluorescence detection. Conditions for a derivatization of amines with AQC are discussed in detail and possible fluorescent by-products within the derivatization process are described. Further, extraction procedures for amines and polyamines from various tissues and matrices prior to AQC derivatization are presented and stability of N-acetylated polyamines within acidic precipitation was investigated. An overview of HPLC methods for the analysis of polyamines and other amines is given with their respective data of validation. Additional, recovery study of polyamines from various tissues is discussed and further, potential interferences of adducts of AQC with commonly used inhibitors of polyamine metabolism were presented. AQC is a powerful derivatization reagent for amines forming stable and highly fluorescent derivatives. The reagent reacts with primary as well as secondary amines under mild alkaline conditions within a broad pH range. The presented HPLC methods for a chromatographic separation of AQC adducts with polyamines demonstrated high accuracy as well as reproducibility and is suitable for analysis of unconjugated and acetylated polyamines without interference of fluorescent byproduct.
HPLC quantitation of amines as OPA derivatives has been evaluated and discussed. Stability and characteristics of the C1-C8 aliphatic monoamines, several diamines, including biogenic amines, derivatized with various SH-additives containing OPA reagents of different compositions have been studied from an analytical and theoretical point of view, equally. Stoichiometric studies have been followed as a function of the reaction time by using different SH-additives, varying the molar ratios of OPA/SH-additive from 1/0.5 to 1/50. The composition of derivatives was determined by on-line HPL/MS(ESI) measurements. As a result of an exhaustive derivatization program, performed under strictly the same practical conditions, we obtained comparable results and new knowledge: (i) in the case of the C1-C5 aliphatic amines it has been shown that the use of the OPA/MPA and/or the OPA/NAC=1/50 reagent resulted in two benefits: in an increased stability of the derivatives and in a lower number of species formed, consequently these reagents proved to be proper for their quantitation purposes, (ii) Derivatization studies performed with hexyl, heptyl and octyl amines revealed that applying the OPA/SH-additive=1/50 reagents, in order to inhibit the formation of the two OPA derivative-containing product, resulted in an additional, transformed OPA derivative: detected and determined by HPLC for the first time, (on the basis of on line HPLC/MS(ESI measurements), these proved to be the two SH-additive-containing OPA derivatives. The proportion of the transformed derivatives can be unambiguously influenced by the quality of SH-additive, by the composition of the OPA reagent, i.e., by the molar ratio of the OPA to the SH-additive and by the pH of derivatizations. In terms of side reaction free derivatization the OPA/ET reagents proved to be superb compared to the OPA/MPA one. (iii) In order to improve stability and to increase responses of spermidine and spermine a new principle, the two step derivatization of biogenic amines, has been introduced, applying the OPA/ET/FMOC reagent.
The GC analysis of amino acids such as the N -trifluoroacetyl ( N -TFA) n -butyl esters—the established method developed principally in our laboratories—provides an effective and reliable means of amino acid determination that is applicable to a very wide range of analytical needs. My research group, graduate students, and colleagues during the period from 1960 to 1975, established the fundamentals of quantitative derivatization, conditions of chromatographic separation, and defined the interactions of the amino acid derivatives with the stationary and support phases. Our studies and continued refinements since 1974 have resulted in a precise and accurate, reliable, straightforward method for amino acid measurement [1–4]. We conducted an extensive array of the applications of GC of amino acid analysis on a wide range of sample matrices, from pine needle extracts to erythrocytes. The Experimental section developed (Volume 1, Chapter 1) [2] provides a thorough description of our quantitative analytical procedures, including preparation of ethylene glycol adipate (EGA) and silicone-mixed phase chromatographic columns. The EGA column which is used to separate and quantitate all the protein amino acids, except histidine, arginine, and cystine is composed of 0.65 w/w% stabilized grade EGA on 80/100 mesh acid-washed Chromosorb ® W, 1.5 m×4 mm ID glass. For quantitation of histidine, arginine, and cystine, the silicone-mixed phase of 1.0 w/w% OV-7 and 0.75 w/w% SP-2401 on 100/120 mesh Gas-Chrom® Q (1.5 m×4 mm I.D. glass) performs extremely well. We also describe the preparation and use of ion-exchange resins for sample cleanup, and complete sample derivatization to the N-TFA n -butyl esters. The amino acids are esterified by reaction with n -butanol · 3 N HCl for 15 min at 100°C and the excess n -butanol · 3 N HCl is removed under vacuum at 60°C any remaining moisture is removed azeotropically with dichloromethane; then the amino acid esters are trifluoroacylated by reaction with trifluoroacetic anhydride (TFAA) at 150°C—5 min in the presence of dichloromethane as solvent. Immediately following the Experimental section are valuable comments on various parts of the method [3], which provide guidance to the use of the entire technique, from sample preparation to chromatography to quantitation. Of particular value is a comparison of GLC and IEC results of hydrolysates of diverse matrices. This extensive comparison of an array of sample types showed that the values obtained by the two techniques were generally in close agreement. The analysis of amino acids as the N -TFA n -butyl esters is an established technique that offers much to scientists concerned with the determination of amino acids. The method offers excellent precision, accuracy, selectivity, and is an economical complementary technique to the elegant Stein-Moore ion-exchange method. We also provide both a detailed account and historical perspective on development of GC amino acid analysis and describe the solution of problems encountered as the methods evolved [2]. The N -TFA n -butyl ester and trimethylsilyl (TMS) derivatives are discussed, including reaction conditions, chromatographic separations, mass spectrometric (MS) identification of both classes of derivatives, interactions of the arginine, histidine, and cystine derivatives with the liquid phase and support materials, and application of the methods in (Volume 1, Chapter 3) [2]. The acylation of arginine posed a problem in early studies; the successful solution of this problem paved the way to a high-temperature acylation procedure, which is now widely used with numerous acylating reagents [5, 6]. Likewise, esterification of the amino acids was investigated in detail, resulting in a direct esterification procedure which quickly and reproducibly converts the amino acids to n -butyl esters. This approach has also been widely used to form various amino acid esters [3]. The early development of GLC analysis of iodine- and sulfur-containing amino acids as the TMS derivatives is described, with the finding that bis (trimethylsilyl)-trifluoroacetamide (BSTFA), a silylating reagent which we invented and patented, is an effective silylating reagent to form amino acid derivatives (Volume 1, Chapter 3) [2, 6]. Our studies on the derivatization of the protein amino acids with our silylation reagent, BSTFA, led the conversion of the amino acids to volatile derivatives in a single reaction step. Although certain amino acids tend to form multiple derivatives which contain varying numbers of TMS groups, high-temperature, long reaction time derivatization permits quantitative analysis of the amino acids as the TMS derivatives. Our studies on the GLC of the TMS amino acids resulted in the development of a 6 m column of 10% OV-11 on Supelcoport® for separation of the TMS derivatives. The development of a chromatographic column system for the N -TFA n -butyl esters came about from the realization that the derivatives of arginine, histidine, and cystine were not reproducibly eluted from columns with polyester liquid phases although this type of column was excellent for analysis of the other protein amino acids. We developed a siloxane mixed phase column specifically for these three amino acids, with the final system being an ethylene glycol adipate (EGA) column for 17 amino acids and the mixed phase column for the remaining 3 [5, 6]. Our summary points out, that the foundation of a successful amino acid analysis by GC is composed of two elements: (a) reproducible and quantitative conversion of amino acids to suitable derivatives, and (b) separation and quantitative elution of the derivatives by the chromatographic column. A literature review is presented for the period of 1984 to 2005 on topics ranging from N-acyl O-esters of amino acid derivatives to: Enantiomeric composition, racemization, gas chromatographic enantiomer separation, formation of volatile derivatives, mass spectrometric analysis of cyclosporine metabolites, GC of 1- and 3-methyl histidine in biological fluids, rapid analyses, resolution of sulfur-containing amino acids on chiral columns, simultaneous derivatization of functional groups with one-step ethyl chloroformate derivatization, derivatization of chiral amino acids in supercritical CO 2 , separation of diasteromeric esters of α-alkyl-α-amino acids, and capillary GC plus numerous other subjects on GC of amino acids (see titles and authors as follows).
9-fluorenylmethyloxycarbonyl chloride, also known as 9-fIuorenylmethyl chloroformate (FMOC-C1), reacts with primary and secondary amines and yields highly fluorescent and stable derivatives. It has been used for the derivatization and analysis of various types of amines including biogenic amines and polyamines; short-chain aliphatic amines; neurotransmitters, including catecholamines, and metanephrines. FMOC-C1 can also react with the amino groups of a number of drugs to yield the highly fluorescent derivatives for HPLC analysis. This approach is particularly useful to the analytes without chromophore or fluorophore for detection. This chapter reviews the experimental procedures on pre-column derivatization of these amines with FMOC-C1 for fluorescence detection after reversed phase separation. The increase in sensitivity by FMOC derivatization can be more than 3 orders of magnitude, when compared to the usual detection by UV absorbance. Table 1 summarizes the HPLC conditions for the detection of these amines. Despite the high sensitivity of these FMOC derivatives for HPLC analysis, there are some disadvantages associated with this approach, especially in the analysis of biological samples. One of the disadvantages is that many endogenous components in the biological matrix are also reactive towards the derivatizing reagents. Thus, extensive sample clean-up is usually required. Very often, solid phase extraction is employed to extract the analytes from the matrix, followed by derivatization, and in many instances, re-extraction of the derivatized analytes to remove the un-reacted reagent and concentration of the derivatives. As a result, the sample preparation can be very tedious and time-consuming. The second disadvantage of the approach is the interference to the analytes during chromatography from the un-reacted FMOC-C1 and also its hydrolysis product, FMOC-OH. To overcome this problem, an excess of glycine can be added to the reacting mixture, after derivatization of the analytes is complete. By doing this, the excess FMOC-C1 is converted to the relatively hydrophilic glycine derivative that elutes early in the chromatogram, not interfering detection of the much smaller peak of the analyte derivatives. With the advance in column technology, the problem of interference from the derivatizing agent may be further minimized by using the new generation of columns with higher resolution power.
Part 1. Amino Acids 1.1. Gas Chromatography 1.2. High Performance Liquid Chromatography 1.3. Capillary Electrophoresis/Capillary Electrochromatography Part 2. Amines 2.1. Gas Chromatography 2.2. High Performance Liquid Chromatography 2.3. Capillary Electrophoresis/Capillary Electrochromatography 3. Quantitation of Amino Acids and Amines, Simultaneously 4. Quantitation of Polyamines by Chromatography
