Accurate measurement of free carnitine in dried blood spots by isotope-dilution electrospray tandem mass spectrometry without butylation

Schulze, Andreas; Schmidt, Christiane; Kohlmüller, Dirk; Hoffmann, Georg F.; Mayatepek, Ertan

doi:10.1016/s0009-8981(03)00292-4

Cited by 21 publications

(21 citation statements)

References 20 publications

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“…Excessive butanol-HCl was removed by evaporating at 40°C under nitrogen stream and carnitine ester derivatives were dissolved in 100 L acetonitrile:water (80:20 v:v%) eluent mixture. This procedure is known to result in conversion of a small quantity of C2-carnitine into free carnitine, which can lead to an artificial increase of its level (21).…”

Section: Methodsmentioning

confidence: 99%

Determination of Carnitine Ester Patterns During the Second Half of Pregnancy, at Delivery, and in Neonatal Cord Blood by Tandem Mass Spectrometry: Complex and Dynamic Involvement of Carnitine in the Intermediary Metabolism

et al. 2007

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ABSTRACT:We studied plasma concentrations of free carnitine and 30 carnitine esters by electron spray ionization (ESI) tandem mass spectrometry in 37 pregnant women at the 20th and 30th weeks of gestation and at delivery, and in their neonates at birth, and in 22 age-matched nonpregnant women. The plasma levels of acetylcarnitine and carnitine esters with more than five carbons were significantly higher, whereas the concentration of free carnitine was significantly lower at term than at the 20th week of pregnancy (16.75 Ϯ 0.89 versus 19.61 Ϯ 1.25). Almost all of C2-to C12-carnitine esters were significantly lower, whereas C16-and C18-carnitines with in-chain modifications were significantly higher in mothers at delivery compared with nonpregnant women. Plasma levels of free carnitine and C2-, C3-, C4-, C5-, C6-, and C16-carnitines were significantly lower, while concentrations of carnitine esters with 8, 10, 12 and 18 carbons in the acyl chain as well as C14:1-, C14:2-, and C16:1-OH-carnitines were significantly higher in mothers at term than in their neonates. The data of the present study clearly show dynamic features of plasma carnitine profile during pregnancy and indicate an extraordinarily active participation of the carnitine in the intermediary metabolism both in the pregnant woman and in the neonate. (Pediatr Res 62: 88-92, 2007) D uring the first two trimesters of pregnancy, the maternal metabolism continuously adapts, with accretion of fat stores deriving from aliments and then shifting to an accelerated catabolism of lipids in the late gestation (1). In human newborns, fat represents 15-16% of total body composition, and the accumulation of white adipose tissue occurs predominantly during the last trimester (2).Carnitine is a conditionally essential quaternary amino acid that plays a crucial role in beta-oxidation of long-chain fatty acids and in ketogenesis (3-5). The carnitine molecule can form esters with FFA of different chain length; the endogenous (4) or exogenous acyl groups (6 -8) are transferred from coenzyme-A to carnitine by different carnitine acyltransferases (9).Availability of carnitine has been reported to be essential for the developing fetus (10,11), and carnitine is stored in increasing amounts in fetal tissues, mainly in the liver and muscle, during the last period of gestation (12). Fetal carnitine is derived from the mother via transplacental transfer of carnitine (13). The Na ϩ -dependent high-affinity carnitine transporter OCTN2 (14,15) is expressed in human placenta (16), and placental OCTN2 is necessary for the accumulation of carnitine in placenta and fetus, and, consequently, for the oxidation of long-chain fatty acids in fetal-placental unit (17,18). Studies on OCTN2 -/-mice suggest that the placental carnitine synthesis might depend on the carnitine status of the fetus and/or the mother (13). On the basis of these observations, it is clear that further studies of maternal and neonatal carnitine status are needed, including the investigation of participation of carnitine ...

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Section: Methodsmentioning

confidence: 99%

Determination of Carnitine Ester Patterns During the Second Half of Pregnancy, at Delivery, and in Neonatal Cord Blood by Tandem Mass Spectrometry: Complex and Dynamic Involvement of Carnitine in the Intermediary Metabolism

et al. 2007

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“…However, one should be aware that derivatization might be a source of assay error due to unwanted reactions, e.g. hydrolysis (Schulze et al, 2003).…”

Section: Dbs Sample Extractionmentioning

confidence: 99%

Dried blood spot sampling in combination with LC‐MS/MS for quantitative analysis of small molecules

Li¹,

Tse²

2009

Biomedical Chromatography

542

428

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The collection of whole blood samples on paper, known as dried blood spot (DBS), dates back to the early 1960s in newborn screening for inherited metabolic disorders. DBS off ers a number of advantages over conventional blood collection. As a less invasive sampling method, DBS off ers simpler sample collection and storage and easier transfer, with reduced infection risk of various pathogens, and requires a smaller blood volume. To date, DBS-LC-MS/MS has emerged as an important method for quantitative analysis of small molecules. Despite the increasing popularity of DBS-LC-MS/MS, the method has its limitations in assay sensitivity due to the small sample size. Sample quality is often a concern. Systematic assessment on the potential impact of various blood sample properties on accurate quantifi cation of analyte of interest is necessary. Whereas most analytes may be stable on DBS, unstable compounds present another challenge for DBS as enzyme inhibitors cannot be conveniently mixed during sample collection. Improvements on the chemistry of DBS card are desirable. In addition to capturing many representative DBS-LS-MS/MS applications, this review highlights some important aspects of developing and validating a rugged DBS-LC-MS/MS method for quantitative analysis of small molecules along with DBS sample collection, processing and storage.

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“…The LODs were , 0.1 mmol/L with linear ranges up to 10 mmol/L for acylcarnitines and 100 mmol/L for free carnitine. Errors inherent in butyl esterification of carnitines in dried blood and plasma samples was evaluated by Schulze et al [47]. These authors compared the carnitine profiles of standards solutions, dried blood spots and plasma as measured by FIA-ESI-MS/MS with and without butylation and compared it to the spectrometric Cobas method [58].…”

Section: Carnitinesmentioning

confidence: 99%

A critical evaluation of high performance liquid chromatography‐electrospray ionisation‐mass spectrometry and capillary electrophoresis‐ electrospray‐mass spectrometry for the detection and determination of small molecules of significance in clinical and forensic science

Smyth¹,

Brooks

2004

Electrophoresis

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A critical review of applications for the period 2000-2003, taken from the Web of Knowledge database, of the techniques high performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS) and capillary electrophoresis-electrospray ionisation-mass spectrometry (CE-ESI-MS) to the detection and determination of small molecules of significance in clinical and forensic science is presented. The molecules of mass less than 500 Da are chosen according to selected structural classes in which they give ESI signals primarily as [M+H](+) ions although other ions such as [M-H](-), [M+Na](+) and [M+NH(4)](+) are also reported. The structural classes are drugs with amine-containing side chains, drugs with N-containing saturated ring structures, 1,4-benzodiazepines, carbohydrates, benzimidazoles, other heterocycles, sulphonylureas, anthracyclines, sulphonamides, penicillins, cephalosporins, tetracyclines, nitrocatechols, steroids, flavonoids, oxazaphosphorines, cannabinols, and miscellaneous molecules. Details are given on the fragmentations, where available, that these ionic species exhibit in-source and in ion-trap, triple quadrupole and time-of-flight mass spectrometers. The review then gives a critical evaluation of these recent HPLC-ESI-MS and CE-ESI-MS analytical methods for the detection and determination of small molecules of clinical and forensic significance. Analytical information on, for example, sample concentration techniques, HPLC and CE separation conditions, recoveries from biological media and limits of detection (LODs) are provided.

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Accurate measurement of free carnitine in dried blood spots by isotope-dilution electrospray tandem mass spectrometry without butylation

Cited by 21 publications

References 20 publications

Determination of Carnitine Ester Patterns During the Second Half of Pregnancy, at Delivery, and in Neonatal Cord Blood by Tandem Mass Spectrometry: Complex and Dynamic Involvement of Carnitine in the Intermediary Metabolism

Determination of Carnitine Ester Patterns During the Second Half of Pregnancy, at Delivery, and in Neonatal Cord Blood by Tandem Mass Spectrometry: Complex and Dynamic Involvement of Carnitine in the Intermediary Metabolism

Dried blood spot sampling in combination with LC‐MS/MS for quantitative analysis of small molecules

A critical evaluation of high performance liquid chromatography‐electrospray ionisation‐mass spectrometry and capillary electrophoresis‐ electrospray‐mass spectrometry for the detection and determination of small molecules of significance in clinical and forensic science

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