Rapid determination of histamine and its metabolites in mice hair by ultra-performance liquid chromatography with time-of-flight mass spectrometry

Photoluminescence-Electrochemiluminescence Dual-Mode Sensor Arrays for Histidine and Its Metabolite Discrimination and Disease Identification

Histidine (His) and its metabolite analysis is significant due to their vital roles in the diagnosis of diseases. In practical applications, simple and effective detection and discrimination of these metabolic species are still a great challenge due to their highly similar structures. Herein, photoluminescence (PL)-electrochemiluminescence (ECL) dual-mode sensor arrays consisting of a series of sensing elements were proposed for simultaneous quantitation and accurate discrimination of His and its four key metabolites (including histamine, imidazole-4-acetic acid, N-acetylhistamine, and imidazole propionate). The sensing elements of these sensor arrays were constructed by employing two solvent iridium(III) complexes ([Ir(pbz)2(DMSO)Cl] and [Ir(ppy)2(DMSO)Cl], pbz = 3-(2-pyridyl)benzoic acid, ppy = 2-phenylpyridine) with excellent PL and ECL performances as cross-responsive sensing units. Based on diverse coordination abilities of the two complexes with the imidazole group of the five targets, PL and ECL responses of each sensing unit can be enhanced to various degrees, which generate unique fingerprint patterns for the corresponding targets. Through principal component analysis, the multifarious patterns (two-, three-, and four-element sensor arrays) can be transformed into simple visualization modes, from which His and its four key metabolites can be effectively discriminated against each other. Moreover, the quantitation of an individual metabolic species at different concentrations and the recognition of the mixtures with different ratios were also accurately achieved. Notably, His and its four key metabolites in urine can also be successfully discriminated by the as-fabricated sensor arrays, and the patients with kidney diseases can be identified clearly, providing a promising way for disease diagnosis.

Development of Highly Sensitive Analysis Method for Histamine and Metabolites in Pregnant Women's Fingernail by UPLC-ESI-MS

In this study, a highly sensitive analysis method for the rapid detection of histamine (HA), imidazole-4-acetic acid (IAA) and 1-methylhistamine (MHA) in pregnant women's fingernails was developed using the ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS). HA and MHA were connected with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) as the derivation reagent for the first time. IAA was derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) successfully. The derivative mixtures were simultaneously separated within 8 min on an ACQUITY UPLC^TM BEH C18 column (1.7 μm, 100 × 2.1 mm i.d.) by isocratic elution using a mixture of 20 mM HCOONH₄ and CH₃CN (82:18) as the mobile phase, and sensitively detected by selected reaction monitoring (SRM). The quantitative analysis of HA, IAA, and MHA are performed by SRM using the fragmentation transitions of m/z 337.2 → 292.1, 420.6 → 375.1 and 351.2 → 306.0 under the positive ESI mode. The calibration curves for HA, IAA and MHA are presented herein, and their correlation coefficient were found to be above 0.9998, the measured detection limit for derivatized histamine and metabolites ranged from 0.06 to 0.15 fmol, and the relative standard derivation of intra-day and inter-day assays was 6.3%. Furthermore, the mean recoveries (%) of the standards added to human fingernails were in the range of 90.2 - 100.5%. The validated method was successfully applied to analyze human fingernail samples from three pregnant women and three healthy non-pregnant women. To the best of our knowledge, this report about the detection of histamine and metabolites in the fingernails of pregnant women's fingernails is the first published.

New approach for the diagnosis of histamine intolerance based on the determination of histamine and methylhistamine in urine

Histamine intolerance is a disorder in the homeostasis of histamine due to a reduced intestinal degradation of this amine, mainly caused by diamine oxidase (DAO) enzyme deficiency, which provokes its accumulation in plasma and the appearance of adverse health affects. A new approach for the diagnosis of this intolerance could be the determination of histamine and its metabolites in urine. The aim of this work was to develop and validate a rapid method to determine histamine and methylhistamine in human urine by Ultra High Performance Liquid Chromatography and Fluorimetric detection (UHPLC-FL). The proposed method is a consistent procedure to determine histamine and methylhistamine in less than 11min with adequate linearity and sensitivity. Relative standard deviation was always lower than 5.5%, ensuring method precision; and mean recovery was greater than 99% for both analytes. The structure of histamine and methylhistamine conjugated with OPA were confirmed by UHPLC-ITD-FTMS which enabled to unequivocally identify both analytes in standards and also in urine samples. The analysis of histamine and methylhistamine in urine samples could be a potential new approach for the routine diagnosis of histamine intolerance, more patient-friendly and with clear advantages in terms of equipment and personnel demand for sample collection in comparison with current plasmatic DAO activity determination.

Pharmacokinetic properties and safety profile of histamine dihydrochloride injection in Chinese healthy volunteers: a phase I, single-center, open-label, randomized study

PURPOSE

Histamine dihydrochloride (HDC) injection has been approved in Europe for the treatment of adults with acute myeloid leukemia, used in combination therapy with the T-cell-derived cytokine interleukin-2. Despite years of clinical applications of HDC in Europe, no data are available on its tolerability and pharmacokinetic properties in Chinese patients. The objective of this study was to determine the safety profile and pharmacokinetic properties of HDC in Chinese healthy volunteers (HVs).

METHODS

In this Phase I, single-center, open-label, randomized study, 20 Chinese HVs were randomized to receive a single dose of 0.5 or 1.0 mg HDC via a 10-minute subcutaneous injection. Whole-blood and urine samples were collected at designated time points after dosing. Plasma and urine concentrations of histamine and metabolite N-methyl histamine were measured using a validated HPLC-MS/MS method. Pharmacokinetic parameters were estimated through noncompartmental procedures based on concentration-time data. Adverse events and evaluation of clinical laboratory tests were used to assess the safety profile. The pharmacokinetic profile for a single-dose of 1.0 mg HDC in Chinese HVs was compared with that in Western HVs.

FINDINGS

No severe adverse events occurred in this study, and the severity of all adverse events was grade I according to the Common Terminology Criteria for Adverse Events, version 4.0. For the pharmacokinetic parameters of histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.50 and 1.02 hours; Tmax was 0.15 and 0.14 hours; mean Cmax was 26.59 and 71.01 nmol/L; AUC0-t was 8.35 and 20.43 nmol/h/L; AUC0-∞ was 9.61 and 22.69 nmol/h/L; accumulated amount excreted in urine within 24 hours was 125.93 and 145.52 nmol; and maximum urine excretion rates were 21.85 and 38.94 nmol/h, respectively. For N-methyl histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.58 and 0.66 hours; Tmax was 0.28 and 0.26 hours; mean Cmax was 17.01 and 23.54 nmol/L; AUC0-t was 7.72 and 17.08 nmol/h/L; AUC0-∞ was 9.01 and 19.62 nmol/h/L; accumulated amount excreted in urine within 24 hours was 331.7 and 583.21 nmol; and maximum urine excretion rates were 53.29 and 133.53 nmol/h, respectively.

IMPLICATIONS

Both single-dose 0.5 mg and 1.0 mg HDC were well tolerated in Chinese HVs, and the pharmacokinetic profile of HDC in Chinese HVs was characterized in this study. A single dose of 1.0 mg HDC had a more rapid but similar extent of absorption, a wider distribution, and a little more rapid elimination in Chinese HVs compared with Western HVs. Findings from this study support additional clinical trials for HDC using in Chinese patients. Chinese Clinical Trial Registry identifier: ChiCTR-ONC-13003954.

Development of a UHPLC-MS/MS method for the determination of plasma histamine in various mammalian species

Histamine is an important mediator of anaphylactic reactions. Although several methods have been developed to measure histamine levels, each has its limitations. In this study, we developed and validated a convenient bioanalytical method for the qualitative and quantitative determination of histamine in plasma samples from humans, beagle dogs, Sprague-Dawley rats, and imprinting control region mice. A simple plasma protein precipitation method using acetonitrile was selected, and hydrophilic interaction liquid chromatography coupled with mass spectrometry was used for sample separation and detection. Histamine was subjected to gradient elution with acetonitrile, ammonium acetate buffer, and formic acid. A mass spectrometer equipped with an electrospray ionization source was operated in the positive-ion multiple reaction monitoring mode for the detection of histamine and the internal standard. The [M+H](+) transitions were m/z 112→95 for histamine and m/z 116→99 for d4-histamine, which was used as the internal standard. The lower limit of quantification was 0.2μg/L and the calibration range was 0.2-500μg/L. The overall recovery ranged from 93.6% to 102.8%. The intra- and inter-run precision and accuracy were <15% for plasma samples from all four species. The method was validated by measuring the plasma histamine concentrations in five healthy human volunteers. In conclusion, we have developed and validated a novel bioanalytical method for the quantification of histamine levels in plasma samples from various mammalian species.

A quantitative LC/MS method targeting urinary 1-methyl-4-imidazoleacetic acid for safety monitoring of the global histamine turnover in clinical studies

Anaphylaxis is a potentially life-threatening condition triggered mainly by the release of inflammatory mediators, notably histamine. In pharmaceutical research, drug discovery, and clinical evaluation, it may be necessary to accurately assess the potential of a compound, event, or disorder to promote the release of histamine. In contrast to the measurement of plasma histamine, determination of the stable metabolite 1-methyl-4-imidazoleacetic acid (tele-MIAA) in urine provides a noninvasive and more reliable methodology to monitor histamine release. This study presents a repeatable high-performance liquid chromatography coupled to electrospray mass spectrometry (LC-ESI-MS) method where tele-MIAA is baseline separated from its structural isomer 1-methyl-5-imidazoleacetic acid (pi-MIAA) and an unknown in human urine. The ion-pairing chromatography method, in reversed-phase mode, based on 0.5 mM tridecafluoroheptanoic acid demonstrated high repeatability and was applied in a clinical development program that comprised a large number of clinical samples from different cohorts. The inter- and intra-run precision of the method for tele-MIAA were 8.4 and 4.3%, respectively, at the mean urinary concentration level, while method accuracy was between -16.2 and 8.0% across the linear concentration range of 22-1,111 ng mL(-1). Overall, method precision was greater than that reported in previously published methods and enabled the identification of gender differences that were independent of age or demography. The median concentration measured in female subjects was 3.0 μmol mmol(-1) of creatinine, and for male subjects, it was 2.1 μmol mmol(-1) of creatinine. The results demonstrate that the method provides unprecedented accuracy, precision, and practicality for the measurement of tele-MIAA in large clinical settings.

High-throughput LC-MS/MS based simultaneous determination of polyamines including N-acetylated forms in human saliva and the diagnostic approach to breast cancer patients

The determination of polyamines and their N-acetylated forms was performed by ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The polyamines efficiently reacted with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) in 0.1 M borax (pH 9.3) at 60 °C for 30 min. The resulting derivatives were analyzed by electrospray ionization (ESI)-MS and sensitively detected by selected reaction monitoring (SRM). Furthermore, a rapid separation of the polyamine derivatives within 10 min was performed by UPLC using an antipressurized column packed with 1.7-μm octadecylsilyl (ODS) silica gel. The limits of detection (S/N = 3) on the SRM chromatograms were at the attomole level (9-43 amol). This procedure was used to successfully determine 11 polyamines, including their N-acetylated forms, in the saliva of patients with primary and relapsed breast cancer and healthy volunteers. The level of several polyamines (Ac-PUT, Ac-SPD, Ac-SPM, DAc-SPD, and DAc-SPM) increases in breast cancer patients. Furthermore, the levels of three polyamines (Ac-SPM, DAc-SPD, and DAc-SPM) were significantly higher only in the relapsed patients. The present method proved highly sensitive and is characterized by specificity and feasibility for sample analysis. Consequently, the proposed method is useful for the noninvasive salivary diagnosis of cancer patients and could be applied to determine polyamines in several specimens of biological nature.

Biomarker discovery in biological specimens (plasma, hair, liver and kidney) of diabetic mice based upon metabolite profiling using ultra-performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry

BACKGROUND

The number of diabetic patients has recently been increasing worldwide. Diabetes is a multifactorial disorder based on environmental factors and genetic background. In many cases, diabetes is asymptomatic for a long period and the patient is not aware of the disease. Therefore, the potential biomarker(s), leading to the early detection and/or prevention of diabetes mellitus, are strongly required. However, the diagnosis of the prediabetic state in humans is a very difficult issue, because the lifestyle is variable in each person. Although the development of a diagnosis method in humans is the goal of our research, the extraction and structural identification of biomarker candidates in several biological specimens (i.e., plasma, hair, liver and kidney) of ddY strain mice, which undergo naturally occurring diabetes along with aging, were carried out based upon a metabolite profiling study.

METHODS

The low-molecular-mass compounds including metabolites in the biological specimens of diabetic mice (ddY-H) and normal mice (ddY-L) were globally separated by ultra-performance liquid chromatography (UPLC) using different reversed-phase columns (i.e., T3-C18 and HS-F5) and detected by electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). The biomarker candidates related to diabetes mellitus were extracted from a multivariate statistical analysis, such as an orthogonal partial least-squares-discriminant analysis (OPLS-DA), followed by a database search, such as ChemSpider, KEGG and HMDB.

RESULTS

Many metabolites and unknown compounds in each biological specimen were detected as the biomarker candidates related to diabetic mellitus. Among them, the elucidation of the chemical structures of several possible metabolites, including more than two biological specimens, was carried out along with the comparison of the tandem MS/MS analyses using authentic compounds. One metabolite was clearly identified as N-acetyl-L-leucine based upon the MS/MS spectra and the retention time on the chromatograms.

CONCLUSIONS

N-acetyl-L-leucine is an endogenous compound included in all biological specimens (plasma, hair, liver and kidney). Therefore, this metabolite appears to be a potential biomarker candidate related to diabetes. Although the structures of other biomarker candidates have still not yet determined, the present approach based upon a metabolite profiling study using UPLC-ESI-TOF-MS could be helpful for understanding the abnormal state of various diseases.

Fast separation and determination of sterols in vegetable oils by ultraperformance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection

A method for the determination of sterols in vegetable oils by ultraperformance liquid chromatography (UPLC) with atmospheric pressure chemical ionization mass spectrometry detection has been developed. The separation of sterols was optimized in terms of mobile phase composition, column temperature and flow rate. The optimal conditions were achieved using an Acquity UPLC BEH C18 column (50 x 2.1 mm, 1.7 microm) with a mobile phase consistent of acetonitrile/water (0.01% acetic acid) using a linear gradient, at a flow rate of 0.8 mL min(-1) and column temperature of 10 degrees C, giving a total analysis time below 5 min. The determination was performed in selective ion recording mode. The limits of detection were in all cases below 0.07 microg mL(-1), with relative standard deviation values of retention times and peak areas below 0.4 and 5%, respectively. The content of main sterols present in several vegetable oils with different botanical origins was also established.

Systematic screening and characterization of tertiary and quaternary alkaloids from corydalis yanhusuo W.T. Wang using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry

Ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) is an effective technique for analysis of complex samples with offering rapid, efficient separation in combination with accurate mass measurement and tandem mass spectrometry (MS/MS). This paper exploits this technique to identify the alkaloids in corydalis yanhusuo, an important antalgic Traditional Chinese Medicine (TCM). The mass spectral fragmentation behavior of one tertiary alkaloid and two quaternary alkaloids was studied in detail. Low-abundance product ions of tertiary and quaternary alkaloids were investigated and compared between each other. Sixteen alkaloids were screened out by using a systematic screening method developed in our laboratory; structures of eight therein were identified by characteristic UV absorption spectrum and positive ion mode of Q-TOF-MS/MS; and two of them were discovered for the first time in corydalis yanhusuo to our knowledge. This research demonstrates the potential of UPLC-Q-TOF-MS in structural characterization and identification of components in traditional Chinese herbal medicines.

Rapid, sensitive and simultaneous determination of fluorescence-labeled polyamines in human hair by high-pressure liquid chromatography coupled with electrospray-ionization time-of-flight mass spectrometry

The rapid, sensitive and simultaneous determination of six polyamines, i.e., ornithine (ORN), 1,3-diaminopropane (DAP), putrescine (PUT), cadaverine (CAD), spermidine (SPD) and spermine (SPM), in human hairs was performed by ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS). The primary (-NH(2)) and secondary (-NH) amines in the polyamine structures were first labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) at 60 degrees C for 30 min in the mixture of 0.1M borax (pH 9.3) and acetonitrile (CH(3)CN). The resulting derivatives were perfectly separated using an ACQUITY UPLC BEH C(18) column (1.7 microm, 100 mm x 2.1mm i.d.) by a gradient elution with a mixture of water-acetonitrile containing 0.1% formic acid (HCOOH). The separated polyamine derivatives were sensitively detected with both FL and TOF-MS. The detection limits in FL and TOF-MS were 11-86 and 2-5 fmol, respectively. However, the determination of several polyamines by FL detection was interfered with by endogenous substances in the hair. Therefore, the simultaneous determination in hair was carried out by the combination of UPLC separation and the ESI-TOF-MS detection. The structures of the polyamines were identified from the protonated-molecular ions [M+H](+) obtained from the TOF-MS measurement. A good linearity was achieved from the calibration curves, that was obtained by plotting the peak area ratios of the analytes relative to the internal standard (IS), i.e., 1,6-diaminohexane (DAH), against the injected amounts of each polyamine (0.05-50 pmol, r(2)>0.999). The proposed method was applied to the determination in the hairs of healthy volunteers. The mean concentrations of ORN, DAP, PUT, CAD, SPD and SPM in 1mg of human hairs (n=20) were 1.46, 0.18, 1.18, 0.11, 1.97 and 0.98 pmol, respectively. Because the proposed method provides a good mass accuracy and the trace detection of the polyamines in hair, this analytical technique seems to be applicable for the determination of various biological compounds in hair.

Metabolic profiling of rat hair and screening biomarkers using ultra performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry

An exhaustive analysis of metabolites in hair samples has been performed for the first time using ultra performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry (UPLC-ESI-TOF-MS). The hair samples were collected from spontaneously hypertensive model rats (SHR/Izm), stroke-prone SHR (SHRSP/Izm) and Wistar Kyoto (WKY/Izm) rats, and were analyzed by UPLC-ESI-TOF-MS; a multivariate statistical analysis method, such as the principal component analysis (PCA), was then used for screening the biomarkers. From the samples derived from the group of SHRSP/Izm at weeks 10, 18, 26 and 34, we successfully detected a potential biomarker of stroke, which existed at much higher concentrations as compared with that in the other groups. However, a significant difference could not be found at weeks less than 7 before the rats were subjected to stroke and hypertension. In addition, the present method was applicable to screening not only the disease markers, but also the markers related to aging. The method utilizing hair samples is expected to be quite useful for screening biomarkers of many other diseases, and not limited to stroke and hypertension.

Fundamental and practical aspects of ultrahigh pressure liquid chromatography for fast separations

The ongoing development of HPLC has been focused on increasing the speed and efficiency of separations over the past decade. The advances in separation speed have been primarily related to the development of column technology and instrumentation. Relatively short columns packed with sub-2 microm particles provide high-speed separations while maintaining or increasing resolution. Ultrahigh pressure pump systems have been developed to overcome the high-pressure drop generated by such sub-2 microm packings. In this review, fundamental and practical aspects of ultrahigh pressure or ultrahigh performance liquid chromatography (U-HPLC) are discussed. Applications of fast U-HPLC separations are also presented.

Evaluation and comparison of very high pressure liquid chromatography systems for the separation and validation of pharmaceutical compounds

Chromatography using sub-2 microm particles is becoming increasingly popular due to the potential for increased speed, resolution, sensitivity, and peak capacity. To meet the demand, various vendors have re-engineered traditional LC systems to operate at pressures of up to 15000 psi to accommodate the elevated backpressures associated with using sub-2 microm particles. This report investigates and compares the performance of three very high pressure LC (VHPLC) systems: Waters Acquity, Agilent 1200 SL, and Thermo Accela. Specifications for the pump, autosampler, column compartment, detector, and software for each instrument are presented. To assess the chromatographic performance of the three instruments, method development and validation were performed for three pharmaceutical compounds and the results are compared and discussed. The material presented herein serves to highlight the different features of the VHPLC instruments, and assess their suitability for the analysis of pharmaceutical compounds.

Separation and determination of diversiform phytosterols in food materials using supercritical carbon dioxide extraction and ultraperformance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

This paper presents at first time that the ultra-performance liquid chromatographic atmospheric pressure chemical ionization mass spectrometer (UPLC-APCI-MS) was used as an efficient method for the identification and quantification of diversiform phytosterols in food materials. The sample preparation consisted of extraction by supercritical carbon dioxide fluid extraction (SCE) and saponification by refluxing with ethanolic KOH, and then the non-saponificable fraction was extracted with petroleum ether. This fraction was subjected to solid phase extraction (SPE) on silica gel cartridge and then the sterols were eluted with hexane-ethyl acetate. Sterols were separated on an Acquity UPLC BEH C18 column (100 mm x 1.0 mm, 1.7 microm particle size) with a gradient of methanol/water (1% acetonitrile) at a flow of 0.1 mL min(-1). The determination was performed in selective ion monitoring mode. The quality parameter of the developed method was established using 6-ketocholestanol as internal standard. Limits of quantification (LOQ) were 0.1754, 0.0341, 0.0500, 0.0205, 0.0225, 0.3674, 0.0241, 0.0272, 0.0076 microg L(-1) and 0.1525 microg mL(-1) for 6-ketocholestanol, desmosterol, ergosterol, cholesterol, lanosterol, cholestanol, campesterol, stigmasterol, beta-sitosterol, and stigmastanol, respectively. The intra- and inter-day determination precision for the 10 phytosterols were less than 5 and 6% in relative standard deviations, and their recoveries were located in the range of 94-107%. The developed approach has been applied successfully for efficient determination of diversiform phytosterols in food materials, including corn, sesame, oat and peanut.

Hair analysis of histamine and several metabolites in C3H/HeNCrj mice by ultra performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry (UPLC-ESI-TOF-MS): Influence of hair cycle and age

BACKGROUND

According to a previous study, the concentration of HA in the hair of SD rats was similar in each rat and the variation in HA concentration was not so great. However, the concentration in human hair was fairly different in each person. As possible reasons for the higher variation in human hair, the differences in hair cycles and age in each person may be considerable. Based on this idea, the studies using C3H/HeNCrj mice who can synchronize their hair cycle were performed for resolution of the influence of hair cycle and age.

METHODS

The effects of hair cycle and age on the concentration of histamine (HA) and several metabolites, i.e., 1-methylhistamine (MHA), imidazole-4-acetic acid (IAA), and 1-methyl-4-imidazole-acetic acid (MIAA), in C3H/HeNCrj mice hair were investigated by ultra-performance liquid chromatography (UPLC) with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). HA and the metabolites were labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) and 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ). The resulting derivatives were separated by UPLC and determined with ESI-TOF-MS.

RESULTS

A good linearity was achieved from the calibration curves, obtained by plotting the peak area ratios of the analytes relative to the internal standard (IS), i.e., histamine-alpha,alpha,beta,beta-d4 (HA-d4) or 4-imidazolecarboxylic acid (ICA), against the injected amounts of each compound. The detection limits of HA, MHA, IAA, and MIAA on mass chromatograms were 0.21, 1.0, 0.17, and 0.11 pmol, respectively. The concentrations of HA and the metabolites in the hair shafts and hair root of C3H/HeNCrj mice were determined by this method. The concentration of HA in the hair shaft was relatively higher in the telogen phase. In contrast, the HA content in the anagen phase was increased only in the hair root of old mice.

CONCLUSION

HA appears to possess some effect on hair growth, although the exact reason was not obvious. The HA metabolites, i.e., MHA, MIAA and IAA, were also determined the same as HA; however, the difference in the metabolite concentrations between the hair cycle and age was not clear in both hair shaft and hair root. Such studies of the effect of hair cycle and age on these concentrations are the first report. This analytical technique may be applicable to the determination of various biological compounds in hair.

Quantitative liquid chromatography/time-of-flight mass spectrometry

Over the last decade, time-of-flight (TOF) instruments have increasingly been used as quantitation tools. In addition, because of their high resolving power, they can be used for verification of empirical formulas. Historically, TOF instruments have had limited quantitation capabilities because of their narrow dynamic range. However, recent advances have improved these limitations. This review covers the rationale for using TOF for LC detection, and describes the many methods currently in the literature for the quantitation of pharmaceuticals, environmental pollutants, explosives and many phytochemicals.