The power of LC-MS has been recognized by the global biomedical laboratory. 1,2 Current LC-MS instruments have been widely used from research to routine clinical laboratories and are effectively used in the following areas:
- Therapeutic drug monitoring - measuring drugs in plasma, blood or tissue (eg immunosuppressants)
- Drug abuse test - measure drugs in urine or saliva (eg marijuana, methadone, amphetamine, morphine, pethidine, etc.)
- Hormone test - measuring hormones in serum or plasma (eg steroids or thyroid hormones)
- Biogenic amine analysis - measurement of biogenic amines in plasma or urine (eg catecholamines)
- Newborn Screening - Detection of treatable diseases in infants by monitoring amino acid and acylcarnitine using LC-MS levels
LC-MS instruments are highly attractive over other analytical tools because they can simultaneously measure multiple complex analytes with very high sensitivity. In addition, speed and trust are key factors in patient care, while successful LC-MS biomedical analysis is highly sensitive, traceable and reliable. Therefore, the role of reagent water and its water in the LC-MS workflow for biomedical use in the successful analysis of LC-MS will be introduced in the following three aspects.
Sensitivity
Ultrapure water is widely used in all aspects of the LC-MS process (Figure 1), so it is the main source of pollution for experimental data such as ghost peaks, baseline noise and high MS background. Also causes the instrument or method sensitivity decreases, so that some low concentration of the analyte 3 becomes difficult. In order to avoid interference, ensure that the detected analyte is from the sample, not from the experimental water. 4 The experimental process requires the use of high-quality ultrapure water to avoid data deviation and re-contamination 5 .
Figure 1. The role of water in the LC-MS laboratory
Ultra-trace analysis is an application area in LC-MS biomedical analysis. In hormone detection, the amount of water used is very large compared to other experimental components. Milli-Q water (resistivity 18.2 MΩ·cm (25 ° C), TOC < 5 ppb) was therefore analyzed as an example of estradiol analysis in hormones. The results of this experiment are shown in Figure 2. The MRM chromatogram shows the absence of estradiol in Milli-Q ® water, ensuring a low detection limit for the analytical method. The estradiol concentration was determined to be 265.40 ng using the standard addition method. L.
The precursor ions were 273 m/z and the fragment ions were 255 m/z with multiple reaction monitoring (MRM) ESI+ conversion. HPLC and MS and LC-MS / MS instrument parameters and preparing Milli-Q ® water water source, shown in Figure 2.
Figure 2. MRM chromatogram (ESI+) of estradiol in a sample and in Milli-Q ® water.
Traceability
The online monitoring function of the water purification system allows scientists to determine if the water they use meets the requirements of LC-MS analysis. However, when the problem arises, it indicates that the pollution has occurred in the LC-MS analysis process. It is very important to find and eliminate the source. Because the source of the pollution hazard is very much, the data of the collected water quality parameters when using the LC-MS experiment can be Specific dates are linked to sources of pollution to facilitate water quality assessment and troubleshooting.
Moreover, in all clinical laboratories, traceability is an important requirement in the quality management system, enabling the laboratory to meet certification, for example, ISO 15189:2007 standard or CLSI ® C3-A4. Therefore, the method of electronically recording water quality parameters in this case is a solution to ensure high quality certification.
reliability
In order to meet the requirements of the LC-MS biomedical laboratory, the water source must be reliable. Therefore, the water purification system must not only produce high-quality experimental water, but the quality must be consistent. To ensure consistent water quality, online monitoring tools are used. The ion content in the water is evaluated by resistivity measurement, and water having a resistivity of 18.2 MΩ·cm (25 ° C) generally means that no ion impurities are contained.
To detect the extent of organic contaminants, oxidizable total organic carbon (TOC) can be used; water with a TOC of less than 5 ppb (or μg/L) is suitable for LC-MS experiments. Therefore, to monitor the stability of water quality requires continuous monitoring of the resistivity and TOC parameters of Milli-Q ® water quality. Figure 3 shows the online monitoring data for water quality stability provided by the Milli-Q ® system.
Figure 3. Levels of Resistivity (MOhm·cm) measured continuously and TOC (ppb) measured every 3 minutes as a function of volume produced by a Milli-Q ® water system. Different colors refer to data obtained for three different sets of consumables installed By turns.
in conclusion
Ultrapure water is suitable and meets the requirements of LC-MS biomedical analytical experiments, and good water quality is critical to the quality and stability of the experiment. LC-MS Experimental clinical laboratory use Milli-Q ® water purification system that can meet the LC-MS instrument also requires high sensitivity and reliable traceability of the analysis result.
References
1. K. SY. Leung, B. MW. Fong, LC–MS/MS in the routine clinical laboratory: has its time come? Analytical and Bioanalytical Chemistry, 406, 2289-2301 (2013).
2. M. Himmelsbach, 10 years of MS instrumental developments--impact on LC-MS/MS in clinical chemistry, J. Chromatogr. B, 883–884, 3–17 (2012).
3. A. Khvataeva-Domanov, S. Mabic, Four Ways to Better Water Quality in LC-MS, R&D Magazine, (2015); http:// Better-water-quality-lc-ms
4. CLSI® C62-A - Liquid-Chromatography-Mass Spectrometry methods; approved guideline, Johns Hopkins Medical Institutions, First Edition, 5.3.1, 34, (2014); http://shop.clsi.org/chemistry-documents /C62.html
5. Controlling Contamination in UltraPerformance LC?/MS and HPLC/MS Systems, Waters Corporation; http://
6. B. Keller, J. Sui, AB Young, RM Whittal, Interferences and contaminants encountered in modern mass spectrometry, Anal. Chim. Acta, 627, 71-81 (2008).
7. M. Vogeser, C. Seger, Pitfalls associated with the use of liquid chromatography-tandem mass spectrometry in the clinical laboratory, Clin. Chem. 56, 1234-1244 (2010).
8. Millitrack? e-Solutions, A unique set of data management and monitoring software solutions for water purification systems, MilliporeSigma;
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