Mass spectrometry quality control samples

There are proficiency testing programs that are geared toward clinical sensitivity or specificity by seeking to determine whether a disease can be detected versus other types of controls that are use to test sensitivity, selectivity, and most importantly, reproducibility and precision. With mass spectrometry, the controls are and should be no different than those used for other assays, with one interesting exception. Quality assurance materials prepared for MS/MS may not be useful in other assays that are less selective. The example is newborn screening where quality assurance/control QA/QC materials have a mixture of compounds present in the blood specimens. However, in less selective immunoassays, the mixture creates interferences. In addition, material is used to spike a blood sample is key and one should ensure there is no enzyme activity. We have encountered such a problem with a d/1 mixture of metabolites where one form was degraded in the prepared blood. 

FIA and, in particular, computer-controlled derived techniques still have an important contribution to make to quality control aspects in food analysis. Future trends will accompany the changes observed in analytical laboratories, where mass spectrometry-based detectors are replacing molecular spectrophotometry (e.g., diode array detectors [DAD]). Hence, it is expected the hyphenation of flow injection techniques to mass spectrometry, particularly for sample treatment (extraction, sample matrix removal) using FIA. Other less exploited feature, designated as reversed FIA (Mansour and Danielson, 2012), may also have an important role in future years. In this case, sample is applied as carrier, which allows an enhancement of detection limits. The only constraints are possible sample scarcity or high cost and multiplication of artifacts due to interferences. The future application of FIA is left to the imagination and ingenuity of future food analysts. 

The analysis of tetramethylammonium hydroxide (TMAH) solutions manufactured by SACHEM Inc. of Cleburne, Texas, includes the determination of trace elements. These elements cause less-than-optimum performance of integrated circuit boards manufactured by SACHEM s customers that use these solutions in their processes. Alkali and alkaline earth metals (e.g., Li, Na, K, Mg, Ca, and Ba) can reduce the oxide breakdown voltage of the devices. In addition, transition and heavy metal elements (e.g., Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Au, and Pb) can produce higher dark current. Doping elements (e.g., B, Al, Si, P, As, and Sn) can alter the operating characteristics of the devices. In SACHEM s quality control laboratory, ICP coupled to mass spectrometry is used to simultaneously analyze multiple trace elements in one sample in just 1 to 4 min. This ICP-MS instrument is a state-of-the-art instrument that can provide high throughput and low detection Emits at the parts per thousand level. Trace elemental determination at the parts per thousand level must be performed in a clean room so that trace elemental contamination from airborne particles can be minimized. 

Boomer and Powell [242] have developed an analytical technique using inductively coupled plasma mass spectrometry to estimate the concentration of uranium in a variety of environmental samples including soil. The lower limit for quantitation is 0.1 ng/ml. Calibration is linear from the low limit to 100 ng/ml. Precision, accuracy and a quality control protocol were established. Results are compared with those obtained by the conventional fluorometric method. 

A selective, sensitive, and rapid hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry was developed for the determination of donepezil in human plasma [32], Donepezil was twice extracted from human plasma using methyl-ferf-butyl ether at basic pH. The analytes were separated on an Atlantis HILIC Silica column with the mobile phase of acetonitrile ammonium formate (50 mM, pH 4.0) (85 15, v/v) and detected by tandem mass spectrometry in the selective reaction monitoring mode. The calibration curve was linear (r = 0.9994) over the concentration range of 0.10-50.0 ng/ ml and the lower limit of quantification was 0.1 ng/ml using 200 /d plasma sample. The CV and relative error for intra- and inter-assay at four quality control levels were 2.7% to 10.5% and —10.0% to 0.0%, respectively. There was no matrix effect for donepezil and cisapride. The present method was successfully applied to the pharmacokinetic study of donepezil after oral dose of donepezil hydrochloride (10 mg tablet) to male healthy volunteers. 

Ketterer, M.E. (1992) Assessment of overall accuracy of lead isotope ratios determined by inductively coupled plasma mass spectrometry using batch quality control and the Youden two-sample method. J. Anal. Atomic Spectrom. 7, 1125-1129. 

CRM for road dust (BCR-723) containing 81.3 2.5 Jg/kg Pt, 6.1 1.9 ig/ kg Pd, and 12.8 1.3 Jg/kg Rh, was introduced [49, 228]. It is widely used for quality control of results obtained in the analysis of environmental materials (e.g., airborne particulate matters, dusts, soils, and sediments). Comparison of results obtained using different analytical procedures and interlaboratory studies are recommended when there is a lack of suitable CRM (e.g., in examination of clinical samples). The use of standards based on real matrices (e.g., saliva, plasma, ultrafiltrates, and lung fluids) instead of synthetic solutions is recommended in such analyses. Difficulties with the identification and quantification of different metal species in examined samples make the reliability of results of great importance. The use of various instrumental techniques for examination of particular samples can be helpful. The application of chromatography, mass spectrometry, and electrochemistry [199] HPLC ICP MS and HPLC MS/MS [156] ESI MS and MALDI [162] micellar electrokinetic chromatography, NMR, and MS [167] AAS, ESI MS, and CD spectroscopy [179] SEC IC ICP MS and EC ESI MS [180] and NMR and HPLC [229] are examples of such approaches. 

The emphasis of this work is on the analysis of plastic additives through gas chromatography/mass spectrometry (GC/MS). GC/MS systems are a common analytical tool in quality control and analytical service laboratories and electron impact (El) mass spectra are recognized as reliable data for the identification of organic compounds. Traditional methods have employed a flame ionization detector (FID) with identifications based solely on GC retention time data. These methods lack the specificity necessary to distinguish between components attributable to the sample matrix or the additive(s). 

When applied together with a LC-MS analysis, IR mapping allows a statistical investigation and thus a rapid quality control of the library synthesized by the split-and-combine method. The decisive advantage of this technique is that 1R analysis, in contrast to mass spectrometry, can be carried out without destruction of the sample, and with spatial resolution. 

Cole RB (1997) Electrospray ionization mass spectrometry - fundamentals, instrumentation applications. John Wiley Sons Inc, New York. CoRNELis R (1994) Quest for quality control in trace element analysis of clinical and biolo cal samples. How good are your data In Schramel P, Bratter P and Ribas B, eds. Trace element analytical chemistry in medicine and biology, Vol 6, pp. 73-90. Consejo Superior De Investigationes Cientificas, Madrid. 

The book offers the reader in its first part a general and as detailed as necessary introduction into the basic principles and methods, starting with sampling, sample storage and sample treatment. These steps are of utmost importance for each analytical procedure. This is followed by the description of the potential of a number of modern trace analytical methods, i.e. atomic absorption and emission spectrometry, voltammetry, neutron activation and isotope dilution mass spectrometry. The latter method is an important reference method within a general concept for quality control and the generation of reference materials which are an absolute must in this context. 

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