Direct Determination of Urinary Creatinine by Reactive-Thermal Desorption-Extractive Electrospray-Ion Mobility-Tandem Mass Spectrometry.

Abstract

A direct, ambient ionization method has been developed for the determination of creatinine in urine that combines derivatization and thermal desorption with extractive electrospray ionization and ion mobility-mass spectrometry. The volatility of creatinine was enhanced by a rapid on-probe aqueous acylation reaction, using a custom-made thermal desorption probe, allowing thermal desorption and ionization of the monoacylated derivative. The monoacyl creatinine [M + H]+ ion (m/z 156) was subjected to mass-to-charge selection and collision induced dissociation to remove the acyl group, generating the protonated creatinine [M + H]+ product ion at m/z 114 before an ion mobility separation was applied to reduce chemical noise. Stable isotope dilution using creatinine-d3 as internal standard was used for quantitative measurements. The direct on-probe derivatization allows high sample throughput with a typical cycle time of 1 min per sample. The method shows good linearity (R2 = 0.986) and repeatability (%RSD 8–10%) in the range of 0.25–2.0 mg/mL. The creatinine concentrations in diluted urine samples from a healthy individual were determined to contain a mean concentration of 1.44 mg/mL creatinine with a precision (%RSD) of 9.9%. The reactive ambient ionization approach demonstrated here has potential for the determination of involatile analytes in urine and other biofluids.

Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry

“…In this paper, we focus on the application of one such approach to organic aerosol analysis, namely extractive electrospray ionisation (EESI) MS. The EESI process predominantly forms molecular ions ([M + H] + and [M − H] − ) and is able to efficiently ionise organic analytes even in complex sample matrices such as urine (Devenport et al, 2014), beer (Zhu et al, 2010) and olive oil . Doezema et al (2012) demonstrated an initial application of EESI-MS to organic aerosols, identifying a number of products formed from α-pinene ozonolysis in positive ion mode.…”

Fast vaporization solid phase microextraction and ion mobility spectrometry: A new approach for determination of creatinine in biological fluids

“…Modified acetylation of creatinine [9] was carried out in an aqueous media at a temperature more than 100 °C. The boiling point of the derivatized product is less than 100 °C [9], so almost all of the sample vaporized immediately and after extraction with PPy/GO fiber, IMS analysis was performed.…”

“…The boiling point of the derivatized product is less than 100 °C [9], so almost all of the sample vaporized immediately and after extraction with PPy/GO fiber, IMS analysis was performed.…”

“…Table 1 The traditional method applied for the determination of creatinine in urine and plasma samples is colorimetric Jaffé method which suffers from a poor selectivity [6]. Therefore, several methods for urinary creatinine determination such as matrix assisted laser desorption ionization time of flight mass spectrometry [7], LC-MS [8] and ion mobility spectrometry (IMS) [9], have been developed. Some methods have been also proposed for the analysis of creatinine in plasma such as amperometry [10] and chronoamperometry [11].…”

“…Besides, the mentioned methods are time consuming, applicable just for one kind of sample (urine or plasma), performed in a nonaqueous environment and/or demanding large dilution factors (100-1000). Recently, Devenport et al [9] suggested a rapid and aqueous derivatization procedure followed by electrospray-ion mobility-tandem MS (EI-IMS-MS) for creatinine analysis. They used acetic anhydride as a derivatization agent to produce low boiling point monoacylated creatinine (this method was proposed only for urine samples with 100 folds dilution).…”