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N. Krishnan, P. Raman and V. Mariappanadar, Eur. J. Mass Spectrom. 21, 481–486 (2015)
Received: 21 April 2015 n Revised: 14 May 2015 n Accepted: 14 May 2015 n Publication: 9 June 2015
EUROPEAN
JOURNAL
OF
MASS
SPECTROMETRY
Special Issue Celebrating the 20th Anniversary of EJMS—European Journal of Mass Spectrometry
Simple mass spectrometric method for the
estimation of boron and aluminum in water
at the parts per billion level
Nagasathiya Krishnan, Pachaiappan Raman and Vairamani Mariappanadar*
School of Bio Engineering, SRM University, Kattankulathur, Tamil Nadu 603203, India. E-mail: [email protected]
The coordinating nature of the hydroxy carboxylic acids, such as tartaric and citric acids, has been utilized for the in-situ formation of anions representing the trivalent elements boron and aluminum and two dianions of the hydroxy acid selected under negative electrospray
ionization mass spectral conditions. The abundance of these ions could be used for the quantification of boron and aluminum in water at
concentrations ranging from 4.0 ppb to 535.0 ppb. For a period of six months, the validity of this method was tested with citric acid as the
coordinating agent. Thus, the developed method offers a simple means for the quantification of boron and aluminum in water by negative
electrospray ionization mass spectrometry with a single quadrupole mass spectrometer.
Keywords: boron, aluminum, citric acid, tartaric acid, ESIMS
Introduction
It is well known that liquids such as water, methanol, and
tri­fluoroacetic acid become contaminated with boron
compounds when they are stored in borosilicate glass
containers.1–5 We recently reported that the boron compounds
leach into methanol from borosilicate glass bottles, and interfere with the electrospray ionization mass spectral analysis of
hydroxy acids such as malic acid, lactic acid, citric acid, tartaric
acid, serine, threonine, and salicylic acid.6 These compounds
give borate anions consisting of two divalent anions and one
boron atom for example, ion a in the case of tartaric acid.
formation­of borate anions a. Hence, we wondered whether
the formation of such an anion under electrospray ionization
mass spectrometry (ESI-MS) can be developed as a method for
the determination of boron in water samples. Atomic absorption spectroscopy, inductively coupled plasma (ICP) optical
emission spectroscopy, and ICP mass spectrometry are widely
used for the determination of most of the elements present in
water and other matrices.7,8 Irrespective of the nature of the
matrices, the sample preparation methods invariably bring
the elements in the form of a water-soluble salt solution and
the solution is directly analyzed by any of the above methods.
Colorimetric methods, which are cheap compared to the other
methods, usually make use of the complex-forming abilities
of various elements with chromophores that give color in the
visible region of light. For example, boron has been analyzed
as its curcumin complex by a colorimetric method since 1958,9
based on the reaction of boric acid with curcumin reported in
During the study it was observed that some water samples when tested also showed the ions During the study it was observed that some of the water 1866.10 Later, many other colorimetric methods were developed
corresponding to the formation of borate anion (a). Hence, we wondered whether the formation of such samples tested also showed ions corresponding to the
and used regularly for the determination of boron in water and
anion under ESI‐MS can be developed as a method for the determination of boron in water samples. Atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectroscopy (ICP‐
ISSN: 1469-0667 OES), and ICP mass spectrometry are widely used for the determination of most of the elements present doi: 10.1255/ejms.1349 in water and other matrices.7, 8 Irrespective of the nature of matrices, the sample preparation methods invariably bring the elements in the form of water soluble salt solution and the solution is directly analyzed by any of the above said methods. Colorimetric methods which are cheap compared to the © IM Publications LLP 2015
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