Quantitative determination of total L-carnitine in infant formula, follow-up formula, and raw materials by liquid chromatography with tandem mass spectrometry

Simultaneous determination of semi-essential nutrients taurine, l-carnitine and choline in infant formulas and adult/pediatric nutritional formulas by hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry

BACKGROUND

The nutritional intake of formula-fed newborns is often limited to a single source, so it must be supplemented with essential nutrients for the growth and proper development of infants. Taurine, l-carnitine, and choline are considered conditionally essential nutrients especially in newborns and infants.

RESULTS

In this work, a simple routine hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry (HILIC-ESI-MS/MS) method was developed and validated for the simultaneous determination of these semi-essential nutrients in infant and adult/pediatric milk formulas. The extraction recoveries were between 90% and 114%. Precision of the method offered relative standard deviation below 5% and 7% for intra-day and inter-day precision, respectively. The proposed method was successfully applied to quantification of taurine, l-carnitine, and choline in milk formula. The contents found were in good agreement with those provided on the product label for almost all samples.

CONCLUSION

In view of these results, it can be concluded that the developed method can be a useful approach for the simultaneous determination of taurine, l-carnitine and choline in powdered milk samples, so it can be useful in the routine quality control of this kind of samples. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Associations of Region and Lactation Stage with Odd-Chain Fatty Acid Profile in Triglycerides of Breast Milk in China

Odd-chain fatty acids (OCFAs), with potential value for growing infants, have been reported in breast milk. The association of location and lactation stage with the profile and content of OCFAs in breast milk was studied. We analyzed 1487 breast milk samples collected from 12 areas in China, and 102 infant formulas from different brands were purchased from the local supermarket. The content of sn-2 C15:0 significantly decreased from the colostrum to the mature stage, while that of C17:0 was not significantly increased by the lactation stage (p > 0.05). The content of C15:0 and C17:0 significantly decreased dramatically after the colostrum period, while the content of C13:0 was highest in the mature stage. The level of C15:0 and C17:0 in human milk from Gansu and Xinjiang was significantly higher than that from other areas. Similar trends were observed on the level of sn-2 C15:0 and C17:0, whereas the content of sn-2 C11:0 and C13:0 was significantly higher in breast milk from Shandong. Based on the PDS-LA analysis, the difference among infant formulas, each stage of human milk and human milk from different locations were different. Research is needed to determine if there are health benefits associated with OCFAs.

Comparison of LC-MS/MS and Enzymatic Methods for the Determination of Total Choline and Total Carnitine in Infant Formula and Milk Products

BACKGROUND

Choline and l-carnitine are classified as pseudo-vitamins because of their conditionally essential status. As they are involved in multiple physiological metabolic pathways in the human body, they are routinely fortified in infant and adult nutritional formulas.

OBJECTIVE

The performance of an LC-MS/MS method for the analysis of choline and carnitine, compared with enzymatic methods in routine use for the analysis of total carnitine and total choline, is described.

METHOD

Powder samples were reconstituted, with release of carnitine and choline facilitated by both acid and alkaline hydrolysis and the extract analyzed by LC-MS/MS. Quantitation was by internal standard technique using deuterium-labeled carnitine and deuterium-labeled choline.

RESULTS

Method range, specificity, sensitivity, precision, recovery, accuracy, and ruggedness were assessed for milk powders, infant formulas, and soy- and milk-based nutritional products. Spike recoveries of 94.0-108.4% were obtained for both total carnitine and choline, and no statistical bias (α = 0.05) between measured results and certified values (choline: P = 0.36; free carnitine: P = 0.67) was found for NIST 1849a certified reference material (NIST1849a). Precision, as repeatability relative standard deviation (RSD), was 2.0% RSDr for total carnitine and 1.7% RSDr for total choline. Equivalent results for total choline and total carnitine were obtained by LC-MS/MS and enzymatic methods (n = 30).

CONCLUSIONS

The described LC-MS/MS method is fit for purpose for routine product compliance release testing environments. This validation study has confirmed that alternative enzymatic assays can be used with confidence in laboratories in which LC-MS/MS platforms are unavailable.

HIGHLIGHTS

An LC-MS/MS method was evaluated and found to be fit-for-purpose for routine product compliance release testing of infant formula. The LC-MS/MS method was compared with enzymatic methods for the analysis of total carnitine and total choline. Alternative enzymatic assays can be used with confidence in laboratories in which LC-MS/MS platforms are unavailable.

A rapid ion chromatography column-switching method for online sample pretreatment and determination ofl-carnitine, choline and mineral ions in milk and powdered infant formula

A simple and rapid column-switching ion chromatography with non-suppressed conductivity detection method was developed for simultaneous determination ofl-carnitine, choline and mineral ions in milk and powdered infant formula samples.

The great importance of normalization of LC-MS data for highly-accurate non-targeted metabolomics

The non-targeted metabolomics analysis of biological samples is very important to understand biological functions and diseases. LC combined with electrospray ionization-based MS has been a powerful tool and widely used for metabolomic analyses. However, the ionization efficiency of electrospray ionization fluctuates for various unexpected reasons such as matrix effects and intraday variations of the instrument performances. To remove these fluctuations, normalization methods have been developed. Such techniques include increasing the sensitivity, separating co-eluting components and normalizing the ionization efficiencies. Normalization techniques allow simultaneously correcting of the ionization efficiencies of the detected metabolite peaks and achieving quantitative non-targeted metabolomics. In this review paper, we focused on these normalization methods for non-targeted metabolomics by LC-MS.

Identification of candidate diagnostic biomarkers for adolescent idiopathic scoliosis using UPLC/QTOF-MS analysis: a first report of lipid metabolism profiles

Adolescent idiopathic scoliosis (AIS) is a complex spine deformity, affecting approximately 1–3% adolescents. Earlier diagnosis could increase the likelihood of successful conservative treatment and hence reduce the need for surgical intervention. We conducted a serum metabonomic study to explore the potential biomarkers of AIS for early diagnosis. Serum metabolic profiles were firstly explored between 30 AIS patients and 31 healthy controls by ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Then, the candidate metabolites were validated in an independent cohort including 31 AIS patients and 44 controls. The results showed that metabolic profiles of AIS patients generally deviated from healthy controls in both the discovery set and replication set. Seven differential metabolites were identified as candidate diagnostic biomarkers, including PC(20:4), 2-hexenoylcarnitine, beta-D-glucopyranuronicacid, DG(38:9), MG(20:3), LysoPC(18:2) and LysoPC(16:0). These candidate metabolites indicated disrupted lipid metabolism in AIS, including glycerophospholipid, glycerolipid and fatty acid metabolism. Elevated expressions of adipose triglyceride lipase and hormone sensitive lipase in adipose tissue further corroborated our findings of increased lipid metabolism in AIS. Our findings suggest that differential metabolites discovered in AIS could be used as potential diagnostic biomarkers and that lipid metabolism plays a role in the pathogenesis of AIS.