U.S. flag

An official website of the United States government, Department of Justice.

Quantitative Analysis of Liquids from Aerosols and Microdrops using Laser Induced Breakdown Spectroscopy

NCJ Number
Analytical Chemistry Dated: 2012
Date Published
0 pages

Findings and methodology are reported for a study that found laser induced breakdown spectroscopy (LIBS) is capable of low-volume (90 pL) quantitative elemental analysis of picogram amounts of dissolved metals in solutions.


Single-pulse and collinear double-pulse LIBS were investigated using a 532 nm dual head laser coupled to a spectrometer with an intensified charge coupled device (CCD) detector. Aerosols were produced using a micronebulizer, conditioned inside a concentric spray chamber, and released through an injector tube with a diameter of 1 mm such that a LIBS plasma could be formed 2 mm from the exit of the tube. The emissions from both the aerosols and a single microdrop were then collected with a broadband high-resolution spectrometer. Multielement calibration solutions were prepared, and continuing calibration verification (CCV) standards were analyzed for both aerosol and microdrop systems to calculate the precision, accuracy, and limits of detection for each system. The calibration curves produced correlation coefficients with R2 values > 0.99 for both systems. The precision, accuracy, and limit of detection (LOD) determined for aerosol LIBS were averaged and determined for the emission lines of Sr II (421.55 nm), Mg II (279.80 nm), Ba II (493.41 nm), and Ca II (396.84 nm) to be 3.8 percent RSD, 3.1 percent bias, 0.7 μg/mL, respectively. A microdrop dispenser was used to deliver single drops containing 90 pL into the space where a LIBS plasma was generated with a focused laser pulse. In the single drop microdrop LIBS experiment, the analysis of a single drop containing a total mass of 45 pg, resulted in a precision of 13 percent RSD and a bias of 1 percent for the Al I (394.40 nm) emission line. The absolute limits of detection of single drop microdrop LIBS for the emission lines Al I (394.40 nm) and Sr II (421.5 nm) were approximately 1 pg, and Ba II (493.41 nm) produced an absolute detection limit of approximately 3 pg. Overall, the precision, accuracy, and absolute LOD determined for single microdrop LIBS resulted in a typical performance of 14 percent RSD, 6 percent bias, and 1 pg for the elements Sr II (421.55 nm), Al I(394.40 nm), Mg II (279.80), and Ba II(493.41 nm). (publisher abstract modified)

Date Published: January 1, 2012