It is shown that both electrospray and fast atom bombardment mass spectrometry provide excellent negative-ion mass spectra of the anionic esters of boric, boronic and borinic acids. For electrospray, contact of the esters with water causes some hydrolysis but, in most cases, spectra of the intact molecular anions are readily obtained. For fast atom bombardment, solvents that chelate with the boron esters must be avoided. Tetraethylene glycol diethyl ether, pentaethylene glycol dimethyl ether or hexaethylene glycol dimethyl ether are suitable solvents. Negative-ion electrospray mass spectra showed few, if any, fragment ions, whereas fast atom bombardment generally produced abundant M-ions and several fragment ions of low abundance. It is shown that a simple reaction with dibenzeneborinic acid converts diols such as monoglycerides and monoalkyl glyceryl ethers into anionic borinate esters as a pre-ionization procedure for analysis by electrospray or fast atom bombardment mass spectrometry.

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In humans, acylcarnitines (1) are important metabolites for the diagnosis of several genetic disorders, including defects in the b-oxidation of fatty acids and in the metabolism of branched-chain amino acids. This diagnostic role of acylcarnitines stems form their biological function in the transport of long-chain fatty acids across the mitochondria1 membrane for p-oxidation and in the removal from mitochondria of potentially toxic excesses of acyl groups.'.'Several methods are available for detection of acylcarnitines.3 The most successful approaches involve mass spectrometry, especially the fast atom bombardment (FAB) method developed by Millington et al.'-' To date, the combination of continuous-flow FAB and tandem mass spectrometry (MS/MS) offers the most successful screening for acylcarnitines. Other approaches are based on derivatization of acylcarnitines to acyloxylact~nes~~~ or to N-demethylated esters" followed by capillary-column gas chromatography/ mass spectrometry. This letter reports our preliminary application of positive-ion electrospray mass spectrometry' to underivatized medium-and long-chain acylcarnitines.In acidic solution, the zwitterionic acylcarnitines exist as cations ( a ) (protonated molecules). Not having a strong basic site within their structure, these protonated species might be expected to yield single peaks for the singly charged cations. To ensure that the zwitterions exist in the cationic form a for electrospray mass spectrometry, formic acid (1%) was added to the water/acetonitrile carrier solution. The anions present are thus formate and chloride (the standard acylcarnitines are used in the form of their HCI salts). Under these conditions, each of the homologues that we examined exhibited [M + H]+ ions (a) as the only significant peak in their positive-ion electrospray mass spectra. Examples are shown in Fig. 1. Octanoylcarnitine is a key urinary metabolite for the diagnosis of medium-chain acyl-CoA dehydrogenase deficiency (MCADD). Its electrospray spectrum consists of [M + HI' ions at m/z 288 along with background ions only. 0030-493X/92/080924-03 $06.50 0 1992 by John Wiley & Sons, Ltd.4-Phenylbutanoylcarnitine is not a natural product. We use it as an internal standard in gas chromatography/mass spectrometry It too provides a clear peak for the protonated molecule, at m/z 308. Figure 1 also shows the largest acylcarnitine that we examined, hexadecanoylcarnitine (palmitoylcarnitine). Its protonated molecule at m/z 400 is accompanied by smaller peaks that are not considered to be background ions (m/z 415, 439, 221 and 204). These are thought to be due to impurities in the commercial sample. The peak at m/z 204 corresponds to the protonated molecule of acetylcarnitine which is thought to be an impurity rather than a fragment ion from [M + HI' ions of hexadecanoylcarnitine.In conclusion, medium-and long-chain acylcarnitines are readily and directly compatible with electrospray mass spectrometry. To all intents and purposes, the mass spectra obtained comprise only protonated mo...

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Any doubt that ICP-MS is now a full-blooded laboratory workhorse is dispelled by the breadth of applications of the technique. Analysts in the environmental, mining, nuclear, metallurgical and electronic industries will find this volume a useful source of information. The application of ICP-MS to the analysis of electronic chemicals, automotive exhaust gases, radioactive liquid samples, and to the measurement of 'This volume is a useful addition to the growing literature in this area, but it is difficult to recommend it to the specialist'.skin absorption of lead demonstrates the versatility of the technique. However, there is little new on offer to the researcher who is conversant with the literature in their area of expertise. The three non-application papers on glow discharge, measurement of isotope ratios and ion kinetic energies in ICP-MS, respectively, are useful reviews of the subject areas. Also thrown in for good measure is a paper by Gray, one of the pioneers of ICP-MS, on how he sees the technique evolving. Although a number of authors have made the effort to bring their contributions to refereed journal standards, a few have fallen short of this criterion.This volume is a useful addition to the growing literature in this area, but it is difficult to recommend it to the specialist.