Advances in Techniques for Copper Analysis in Aqueous Systems

Abstract

Copper is an essential micronutrient but can be toxic at elevated levels. Monitoring copper in aqueous systems is critical for characterizing pollution sources and mitigating human health risks. This chapter comprehensively evaluates recent advances in analytical methods for detecting copper, including atomic spectrometry, molecular spectrophotometry, electrochemical sensors, voltammetry, and chromatography. Each technique’s critical detection limits, selectivity, complexity, and advantages are outlined. Atomic absorption spectrometry, inductively coupled plasma-optical emission, and inductively coupled plasma-mass spectrometry provide the most sensitive copper quantification down to parts per trillion levels. Meanwhile, spectroscopic methods using novel reagents offer inexpensive and rapid copper screening. Electrochemical and optical sensors show promise for on-site and continuous monitoring. Chromatographic separation before detection improves selectivity in complex sample matrices. Critical evaluation of these complementary approaches can inform the selection of optimal copper quantification techniques for different environmental, industrial, and biological monitoring applications. Recent advances continue to expand the analytical toolkit for sensitive, selective, and cost-effective copper analysis across diverse aqueous systems.

1. Introduction

The lack of clean and safe drinking water is a severe issue threatening human health and quality of life worldwide. The rapid increase in population and industrialization have led to a higher demand for drinkable water, resulting in increased wastewater contaminated with pollutants. Wastewater discharge significantly contributes to drinking water, groundwater, and marine environment pollution, especially with heavy metals. Although some heavy metals are necessary for biological systems, excessive exposure can harm ecosystems. For instance, exposure to heavy metals can result in bioaccumulation in fish’s liver and muscle tissues, which can occur through different exposure pathways. These contaminants could severely affect marine life and human health if they enter the food chain. For instance, water pollution caused by heavy metals like lead, mercury, cadmium, chromium, copper, nickel, zinc, and arsenic poses a significant threat to our environment, leading to severe ecological and human health consequences. Heavy metals can enter water bodies through various pathways, including industrial wastewater discharges from mining, metal plating, electronics, and chemical manufacturing. Agricultural runoff, such as pesticides, fertilizers, and animal manure, can also contain heavy metals that may leach into water. Natural mineral deposits can erode and weather rocks and soil, releasing heavy metals. Corroded pipes and plumbing, particularly those made of lead and copper, can also leach into drinking water. Heavy metals released into the air from industries, incinerators, and so on can deposit via particulate matter into water. Leached heavy metals from landfills can enter surface and groundwater through rainfall percolating through the landfill. Untreated or partially treated sewage can introduce heavy metals into rivers, lakes, and oceans [1, 2, 3, 4, 5].

Copper is a typical heavy metal found in the environment. It is an essential micronutrient for many organisms but can also biomagnify the food chain. Human activities such as agriculture, mining, and manufacturing are significant sources of copper pollution. Copper-based fertilizers and pesticides used in agriculture; effluents from chemical, pharmaceutical, and paper manufacturing facilities; and corrosion of household plumbing can all contribute to copper pollution [4, 6, 7].

Due to the increasing global production of copper, the concentrations of bioavailable copper compounds have significantly risen in the environment. Soluble forms of copper are the most harmful to human health, and prolonged exposure to elevated levels of copper can lead to severe toxicity, anemia, diabetes, renal disorders, liver damage, and even death. Because of this, it is crucial to use sensitive analytical techniques to monitor copper levels in water resources and effluents to determine if concentrations exceed safe limits and mitigate risks to human populations. The World Health Organization (WHO) has established limits for the maximum acceptable concentration of copper in drinking water to safeguard human health. The World Health Organization (WHO) suggests that the maximum tolerable concentration of copper in drinking water should not exceed 2 mg/L (ppm) as a provisional guideline value. Copper can cause gastrointestinal issues in short-term exposures at levels above 2 ppm. For long-term exposure, the guideline value is set based on a level that does not cause liver damage in sensitive populations [5, 6, 8, 9, 10].

Various methods, such as spectrophotometry, voltammetry, sensors, and selective membranes, have been developed to detect copper in water samples. Therefore, this chapter aims to comprehensively assess these technologies for different water samples and evaluate their advantages and disadvantages. Figure 1 demonstrates a hierarchical graph of these methods.

Figure 1.

Techniques for copper analysis in aqueous systems.

2. Atomic spectrometric methods

Atomic spectrometric methods (ASMs) use specialized equipment to isolate and measure element-specific signals. These methods can be classified into two categories based on the type of spectral dispersion used: atomic absorption spectroscopy (AAS) and atomic emission spectroscopy (AES). In AAS, ground-state atoms of the analyte element absorb light at specific wavelengths, allowing electronic transitions in the atom’s electron orbitals. On the other hand, in AES, thermal energy excites atoms, which then generate emission signals as they return from high-energy states to lower-energy levels. While modern analytical instruments can measure multiple elemental species by inserting equipment set to excite these elements, one significant advantage of atomic emission is the ability to measure numerous elemental species simultaneously [11, 12].

ASM can be divided into two types based on the detection method: photo-spectroscopy and mass-spectroscopy. In photo-spectroscopy, the process is measured by detecting the emitted or absorbed photons. On the other hand, in mass-spectrometric methods, the atom is first ionized to obtain an electric charge and gain electrons. The analytes are then identified and quantified based on their mass-to-charge (m/z) ratio generated from the sample [13].

2.1 Atomic absorption spectroscopy

A widely used technique for analyzing heavy metals is atomic absorption spectrometry (AAS). This encompasses several methods in which free atoms in a gaseous state absorb specific optical radiation, determining the atomic composition. AAS is classified according to the atomization methods into graphite furnace atomic absorption spectrometry (GFAAS), flame atomic absorption spectrometry (FAAS), cold vapor atomic absorption spectrometry (CVAAS), and hydride atomic absorption spectrometry (HAAS). The absorption intensity can be used to evaluate the sample’s concentration levels of detected elements. AAS can detect over 70 elements in samples with different physical states, such as solid or solution phases [14, 15, 16]. Figure 2 illustrates the principle of instrumentation for atomic absorption spectrometry. The key features of various atomic absorption spectrometry techniques are presented in Table 1.

Figure 2.

The principle of instrumentation for atomic absorption spectrometry.

Technique	Principle	Temperature (°C)	Detection limit	Advantages	Disadvantages
Graphite furnace AAS (GFAAS)	Sample heated in graphite furnace	Up to 3000	Pg-ng/mL range	Very low detection limits, minimal sample volumes	Slow analysis, fewer elements detectable
Flame AAS (FAAS)	Sample aspirated into flame	2300 (air-acetylene) 3000 (N2O-acetylene)	Ppb-ppm range	Faster analysis, more elements detectable	Higher detection limits
Cold vapor AAS (CVAAS)	Used for volatile elements like Hg and As	Room temperature	Ppt range	High sensitivity for Hg and As	Only suitable for volatile elements
Hydride AAS (HAAS)	Generates volatile hydrides	Room temperature	Ppb range	Good sensitivity for elements forming hydrides	Only applicable for hydride-forming elements

Table 1.

Comparison of the critical features of various atomic absorption spectrometry techniques.

AAS, FAAS, and GFAAS are standard analytical equipment for detecting copper in liquid samples. Studies worked to improve detection limits, and Table 2 summarizes the studies conducted on detecting copper (Cu) in water samples using atomic absorption spectroscopy (AAS).

AAS equipment	Sample preparation	Sample type	Detection limit(s)	Reference
GFAAS	Direct determination	Seawater	0.3–0.4 μg/L (single injection) and 0.07 μg/L (multiple injections)	[17]
GFAAS	Dispersive liquid-liquid microextraction	Environmental water	0.01 ng/mL	[18]
FAAS	Direct determination	Wastewater	4 ppb	[19]
FAAS	Solid phase extraction	River water/sewage water	ng/mL	[9]
FAAS	Dispersive liquid-liquid microextraction	Water samples/food samples	0.60 μg/L	[20]
FAAS	Direct determination	Pure water spiked with Cu	21 μg/L	[21]
FAAS	Cloud-point preconcentration	Seawater/river water	1.5 μg/L	[22]
FAAS	Cloud-point preconcentration	Seawater/river water	0.04 μg/L	[23]
FAAS	Dispersive liquid-liquid microextraction-slotted quartz tube	Wastewater/tap water/seawater	0.67 μg/L	[24]
FAAS	Cloud-point extraction preconcentration	Water samples	1.5 μg/L	[25]
FAAS	Adsorption onto microcrystalline benzophenone	Water samples	6.9 ng/mL	[26]

Table 2.

Summary of the studies conducted on detecting copper (Cu) in water samples using atomic absorption spectroscopy (AAS).

2.2 Atomic emission spectroscopy

Atomic emission spectroscopy encompasses several techniques that utilize plasma or electrical excitation to generate characteristic atomic emissions for analysis. Major atomic emission spectroscopy techniques include:

• Flame photometry: uses a flame to excite alkali and alkaline earth metals

• Inductively coupled plasma (ICP): uses radio frequency induction to create an argon plasma that excites/ionizes samples. Optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS). In ICP-OES, detection relies on emitted photons, whereas in ICP-MS, it depends on the mass-to-charge ratio (m/z). To benefit from the unique features of each detector, many researchers have investigated a combination of OES and MS.

• Microwave-induced plasma optical emission spectrometry (MIP-OES): uses microwave energy to generate a plasma for excitation

• Atmospheric pressure glow discharge (APGD): operates a plasma at atmospheric pressure and gas temperature to excite sample atoms

• Spark or arc atomic emission spectrometry: utilizes an electric spark or arc for atomic excitation

• X-ray fluorescence (XRF): though not a traditional AES technique, it analyzes characteristic X-ray emissions to detect heavy elements

• Laser-induced breakdown spectroscopy (LIBS): focuses a laser onto the sample to create a plasma and analyzes emitted light

There are two methods for detecting ICP: Optical Emission Spectrometry (ICP-OES) and Mass Spectrometry (ICP-MS). In ICP-OES, detection relies on emitted photons, whereas in ICP-MS, it depends on the mass-to-charge ratio (m/z). To benefit from the unique features of each detector, many researchers have investigated a combination of OES and MS. This results in more accurate analysis and a broader linear range of calibration curves [27, 28, 29, 30]. The principle of instrumentation for inductively coupled plasma is illustrated in Figure 3, and a comparison of different atomic emission spectroscopy techniques is detailed in Table 3.

Figure 3.

The principle of instrumentation for inductively coupled plasma.

Technique	Principle	Excitation source	Detection	Elements detected	Key features	Limitations	Reference
ICP-OES	Atomic emission spectrometry. Samples are converted to aerosols and introduced into argon plasma, causing excitation and emission of characteristic wavelengths.	Argon plasma torch - radio frequency inductive coil creates a magnetic field that ionizes argon gas into sustained plasma at 6000–10,000 K	Optical emission at characteristic wavelengths measured by spectrometer	Cu, Co, Ni, Mg, Zn	Rapid multi-element analysis; wide linear range; lower detection limits than FAAS	Matrix interferences; spectral interferences	[31]
			Optical emission at characteristic wavelengths measured by spectrometer	Wide range of metals	—	—	[32]
			Optical emission at characteristic wavelengths measured by spectrometer	Cu	Optimized operation conditions to enhance Cu detection limit	—	[33]
ICP-MS	Ionizes sample in plasma, then separates and detects ions based on mass/charge ratio (m/z).	Argon plasma torch - radio frequency inductive coil creates a magnetic field that ionizes argon gas into sustained plasma at 6000–10,000 K	Mass spectrometer separates and detects ions based on m/z	Cu, Cd, Mn, Zn, Pb and isotopes	Very low detection limits; simultaneous analysis of multiple elements; isotope ratio determination	Spectral interferences; sample matrix effects; risk of contamination	[34]
			Mass spectrometer separates and detects ions based on m/z	Heavy metals, including Cu	Preconcentration before analysis improves detection	—	[35]
Microwave-induced plasma optical emission spectrometry (MIP-OES)	Samples are ionized by microwave-induced argon plasma, emitting characteristic optical emissions	Microwave-induced argon plasma	Optical emission spectroscopy	Cd, Cu, Cr, Ni, Pb, Zn	Rapid multi-element analysis; lower detection limits than ICP-OES	Interference from easily ionized elements	[36]
Atmospheric pressure glow discharge (APGD)	Samples nebulized into aerosol droplets that are introduced into atmospheric pressure glow discharge plasma, causing excitation and characteristic atomic emission	Atmospheric pressure glow discharge argon plasma	Optical emission spectroscopy	Cu	In situ analysis; detection limit of 0.074 μg/L	Only Cu reported; interferences not discussed	[37]
X-ray fluorescence spectrometry	Samples are irradiated with X-rays, causing the emission of secondary fluorescent X-rays that are characteristic of specific elements	X-ray tube excitation source	Detection of emitted fluorescent X-rays	Cu	Rapid quantitative analysis of Cu in water samples	Only Cu reported; interferences not discussed	[38]
					Rapid analysis of Cu content in rocks/minerals; detection limit 0.51% Cu		[39]
X-ray fluorescence spectroscopy with graphene oxide probes	Samples interact with graphene oxide probes, which enhance characteristic X-ray fluorescence signal of elements	X-ray tube excitation source	Detection of emitted fluorescent X-rays	Cu	Sensitive, quantitative detection of trace Cu; detection limit of 9.8 μg/L	Only Cu was reported; matrix effects were not discussed	[40]
Laser-induced breakdown spectroscopy (LIBS) with chelating resin enrichment	Samples were enriched using chelating resin, then ablated with a laser pulse to form plasma and detect emitted light	Pulsed laser excitation	Optical emission spectroscopy of laser-induced plasma	Pb, Cd, Cu, Cr	Enrichment improves detection limits; detection limits 0.8–2.1 μg/L	Further interferences not discussed	[41]

Table 3.

Comparison of different atomic emission spectroscopy techniques for copper detection in eques samples.

3. Molecular spectrophotometric methods

Quantifying copper via colored complex formation with organic reagents offers a simple, rapid, and sensitive detection method for routine analysis. Molecular spectrophotometric methods are widely used for copper detection by measuring the absorption of ultraviolet (UV), visible, or near-infrared (NIR) light by copper-reagent complexes known as chromophores. When copper ions react with specific reagents, characteristic-colored complexes are formed. These chromophores exhibit peak absorbance at specific wavelengths, with the absorbance proportional to the copper concentration as described by Beer’s law [12].

Sensitive and selective copper quantification in water samples has been made possible by developing various spectrophotometric reagents [42, 43, 44]. Alharthi Al-Saidi [45] synthesized a chromogenic reagent known as 4-amino-3-mercapto-6-[2-(2-thienyl)vinyl]-1,2,4-triazin-5(4H)-one (AMT), which quickly forms a colored complex with copper(II) ions. To prepare a Cu(II) stock solution, Cu(NO3)2 was dissolved in deionized water. Using a HACH DR-6000 spectrophotometer, absorbance spectra of AMT and the Cu-AMT complex were recorded. The AMT-copper(II) complex exhibited a distinct brown color within 10 seconds and was effective over a wide pH range. This method has a detection limit of 0.011 μg/mL, making it suitable for routine copper analysis.

Various spectrophotometric reagents have been studied for detecting copper(II) ions, including azo-Schiff base ligands [46], chloro(phenyl)glyoxime [47], cefixime [48], and 1-(2-pyridylazo)-2-naphthol [49]. These reagents create colored complexes with copper(II), making it possible to detect copper(II) ions at concentrations as low as 0.1 μg/mL. Notably, some of these techniques use non-toxic and environmentally friendly reagents like 5-(4-nitrophenylazo)salicylic acid (NPAS) [50] and polyethyleneimine (PEI) [51]. PEI reacts quickly and selectively with copper(II) ions and exhibits absorbance peaks at 275 and 630 nm. A detection limit of 566 nM has been demonstrated.

Advances in chromogenic reagents for copper analyses with improved selectivity are presented in Table 4.

Reagent used	Detection limit	Key features	References
4-amino-3-mercapto-6-[2-(2-thienyl) vinyl]-1,2,4-triazin-5(4H)-one (AMT)	0.011 μg/ml	Rapid color formation, wide pH range	[45]
Azo-Schiff base 1-((4-(1-(2-hydroxyphenyl imino)ethyl)-phenyl)diazenyl) naphthalene-2-ol (HPEDN)	1.7–5.4 μg/ml	Forms colored complex with copper	[46]
Chloro (phenyl) glyoxime	10 μg/L	High molar absorptivity, low detection limit	[47]
Cefixime in 1,4-dioxan-water	0.0319 μg/ml	Rapid analysis, minimal reagents	[48]
1-(2-pyridylazo)-2-naphthol	0.1–2.5 μg/ml	Forms colored chelate complex	[49]
5-(4-nitrophenylazo)salicylic acid and 2,2′-dipyridyl	0.63–5.04 μg/ml	Ternary complex formation	[50]
Polyethyleneimine	566 nM	Fast detection, high sensitivity	[51]

Table 4.

Summary of molecular spectrophotometric methods for the detection of Cu²⁺ in aqueous samples by UV–Vis spectrophotometer.

4. Sensors

Recent advances in electrochemical, colorimetric, and optical sensor technologies have enabled rapid and sensitive detection of copper in water systems. Electrochemical sensors utilizing square wave anodic stripping voltammetry with electrodes modified by grapefruit peel bio-templates can detect copper at 0.99 μg/L levels in drinking water [52]. Colorimetric sensors employing nanoparticles or organic dyes have achieved detection limits approaching 0.01–6.4 μg/L in aqueous copper solutions and tap water by measuring color changes with UV–vis spectroscopy [53, 54, 55]. Optical sensors such as fluorescent Schiff base probes can selectively detect copper at 0.055 μg/L in aqueous samples through fluorescence enhancement upon copper binding [56]. Additionally, surface plasmon resonance biosensors functionalized with chelating agents have reached detection limits around 0.02 μg/L in drinking water [4]. The principles, detection methods, and applications of these sensors provide versatile techniques for sensitive copper quantification in the μg/L range for water quality monitoring. Sensors show immense promise for copper detection across environmental, industrial, and biological systems by combining sensitivity, selectivity, and ease of use. Advances in sensors for copper analyses with improved selectivity are presented in Table 5.

Sensor type	Principle	Detection method	Sample type	Detection limit	References
Electrochemical sensor using carbon paste electrode prepared from bio-template (grapefruit peels)	Adsorption of copper ions onto carboxyl-functionalized carbon paste electrode	Square wave anodic stripping voltammetry	Drinking water samples	0.99 μg/L	[52]
Colorimetric sensor using silver/dopamine nanoparticles	Color change of silver/dopamine nanoparticles in presence of copper ions	UV–vis absorption spectroscopy	Tap water samples	0.1 μM (equivalent to around 6.4 μg/L)	[53]
Colorimetric probe using gold nanoparticles	Color change caused by aggregation of gold nanoparticles in presence of dopamine	UV–vis spectroscopy	Dopamine solutions	0.5 μM (equivalent to around 0.1 μg/mL)	[54]
Colorimetric sensor using diamine-functionalized SBA-15	Color change caused by coordination of copper ions to diamine groups on SBA-15	UV–vis spectroscopy	Aqueous copper solutions	0.2 μM (equivalent to around 0.01 mg/L)	[55]
Optical sensor using fluorescent Schiff base	Fluorescence enhancement of Schiff base probes upon binding Cu^2+ and Al^3+	Fluorescence spectroscopy	Aqueous solutions	8.7 × 10^−9 M for Cu^2+ (equivalent to 0.055 μg/L)	[56]

Table 5.

Summary of sensors used for the detection of Cu²⁺ in aqueous samples.

5. Electrochemical methods

Electrochemical or (voltammetry) is a reliable method for detecting copper ions in water and wastewater samples. This technique involves applying a time-dependent potential to an electrochemical cell and measuring the resulting current to gain insights into the oxidation or reduction reactions of the subject ions [57].

Recent research has shown that a carbon paste electrode modified with biochar can effectively preconcentrate copper ions on the electrode surface, resulting in a low detection limit, high sensitivity, and stability. This cost-effective approach provides an excellent option for analyzing copper ions [58]. In addition, differential pulse anodic stripping voltammetry and fast Fourier transformation continuous stripping cycle voltammetry are two effective techniques for detecting copper in liquid samples. Differential pulse voltammetry utilizes a gold microelectrode and 0.01 M HNO₃ electrolyte to detect sensitive and fast copper at 1 μM concentrations [59]. The gold microelectrode facilitates the anodic stripping process, where copper is first reduced and deposited on the electrode surface, then oxidized to produce a measurable current peak [60]. In contrast, fast Fourier transform voltammetry employs a carbon paste electrode without an electrolyte. Instead, it uses 2-amino-N-(2-pyridyl methyl)-benzamide as an organic ligand to complex copper ions and transfers them across a supported liquid membrane [61]. The carbon paste electrode enables continuous cyclic stripping measurements for complex copper. While anodic stripping offers very low detection limits, ligand-assisted continuous stripping allows for constant monitoring and speciation of complex copper [62]. Both techniques provide complementary capabilities for sensitive trace copper quantification and dynamic concentration profiling in water quality monitoring applications. Advances in voltammetric methods for copper analyses with improved selectivity are presented in Table 6.

Technique	Working electrode	Backing electrolyte/ligand	Stripping	Detection range	Advantages	Limitations	References
Square wave anodic stripping voltammetry	Carbon paste electrode modified with biochar	0.1 mol/L acetate buffer (pH 4.5)	Anodic	0.3–100 μg/L	Low cost, simple preparation, wide linear range	Single use electrode; only tested for Cu	[58]
Differential pulse anodic stripping voltammetry	Gold microelectrode	0.01 M HNO3	Anodic	1 μM Cu(II)	Sensitive, fast response	Interference from other metals	[59, 60]
Fast Fourier transformation continuous stripping cycle voltammetry	Carbon paste electrode	2-Amino-N-(2-Pyridyl Methyl)-Benzamide	Continuous cyclic	—	Can detect complexed Cu, continuous monitoring	Slower than anodic stripping	[61, 62]

Table 6.

Summary of electrochemical methods for copper analyses with improved selectivity.

6. Chromatography

Liquid chromatographic (LC) techniques such as high-performance liquid chromatography (HPLC), reverse phase high-pressure liquid chromatography (RP-HPLC), and ion chromatography (IC) can provide sensitive and selective quantitation of copper at trace levels. Figure 4 illustrates the operational principle of LC.

Figure 4.

Operational principle of LC.

HPLC with UV detection allows copper detection down to low parts per billion levels [63]. Reverse phase high-pressure liquid chromatography (RP-HPLC) can reach trace detection limits by preconcentrating samples with a tetra (m-aminophenyl) porphyrin (Tm-App) ligand before injection [64, 65, 66, 67]. In contrast, ion chromatography uses a mixed mode cation/anion exchange column and ammonium formate/KOH eluent, which retains both hydrated and complex Cu²⁺ species [64, 68]. These chromatographic methods’ sensitivity, accuracy, and precision make them ideal for monitoring copper concentrations in environmental waters, evaluating treatment efficiency, and assessing regulatory compliance. When analyzing complex water samples, careful optimization of operating parameters and sample preparation steps are needed to mitigate matrix effects and interferences. Chromatographic techniques are indispensable for reliable copper quantification at environmentally relevant levels in diverse aqueous matrices. Advances in chromatographic techniques for copper analyses with improved selectivity are presented in Table 7.

Technique	High-performance liquid chromatography (HPLC)	Reverse phase high-pressure liquid chromatography (RP-HPLC)	Ion chromatography (IC)
Stationary phase	C18 reverse-phase column [63]	Nonpolar C18 column [67]	Mixed mode cation/anion exchange column (Ionpac CS5A) [68]
Mobile phase	Buffer with ion pairing agent [63]	Methanol/acetone buffer [67]	Ammonium formate/KOH eluent [68]
Detection	UV–VIS spectrophotometry [63]	Spectrophotometer at 435 nm [67]	Absorbance at 530 nm after post-column PAR complexation [68]
Preconcentration	Solid phase extraction[63]	Solid phase extraction with Tm-App ligand [66, 67]	—
Copper species	Free copper ions [63]	Hydrated Cu^2+ [64]	Hydrated and complexed Cu^2+ [68]
Sensitivity	Low ppb range [63]	Trace levels [64]	~mg/L range [69]
Advantages	High sensitivity, ability to speciate copper [63]	Very sensitive speciation capabilities [64]	Detects complexed copper [70]
Limitations	Matrix effects, interferences [63]	Only detects free hydrated Cu^2+ [65]	Less sensitive than HPLC [70]

Table 7.

Summary of chromatographic techniques for copper analyses with improved selectivity.

7. Advantages and drawbacks of different detection methods

Various analytical techniques are available for quantitatively detecting copper, each with inherent advantages and limitations. Table 8 summarizes the advantages and drawbacks of different detection methods for copper analyses.

Analytical method	Advantages	Disadvantages	References
Atomic absorption spectrometry (AAS)	High selectivity Accurate and reliable quantitation Fast and simple	Expensive equipment Requires skilled staff Standards needed for calibration Cannot determine oxidation state or isotope	[14]
Inductively coupled plasma-optical emission spectrometry (ICP-OES)	Simultaneous multi-element analysis Fast and simple Low sample volume	Expensive equipment Requires skilled staff Standards needed for calibration Cannot determine oxidation state or isotope	[71, 72]
Inductively coupled plasma-mass spectrometry (ICP-MS)	Very low detection limits High-resolution capabilities Simultaneous multi-element analysis Low sample volume	Expensive equipment Requires skilled staff Standards needed for calibration Spectral interferences need control	[28, 71, 73]
Microwave-induced plasma optical emission spectrometry (MIP-OES)	Sensitive detection Fast analysis Multi-element capability	Expensive equipment Requires skilled personnel Standards needed for calibration	[36]
Atmospheric pressure glow discharge (APGD)	Cost-effective Simple operation Low power requirements	Limited sensitivity Difficulty in quantification May need complementary methods for precise analysis	[37]
X-ray fluorescence spectrometry (XRF)	Non-destructive Multi-element analysis No sample preparation required	Surface analysis primarily Limited sensitivity for some elements Expensive equipment	[38, 39]
X-ray fluorescence spectroscopy with graphene oxide probes	Enhanced sensitivity Selective detection Possibility of real-time analysis	Requires probe preparation Limited to surface analysis Requires skilled personnel	[40]
Laser-induced breakdown spectroscopy (LIBS) with chelating resin enrichment	Fast, almost real-time analysis Minimal sample preparation Multi-element capability Portable systems available	Requires skilled personnel Equipment can be expensive Standards needed for calibration Sample enrichment step may add complexity	[41]
Spectrophotometric	Simple and inexpensive Precise and sensitive with proper reagents	Time consuming Uses large solvent volumes	[45, 46]
Sensors	Fast real-time analysis High sensitivity and selectivity Potential for continuous monitoring	Sensor lifetime issues Special calibration solutions Qualified operators needed	[74]
Voltammetric	Inexpensive equipment Easy sensor fabrication Rapid copper quantitation	Variability with environmental conditions Hazardous waste generated Requires indicator reagents	[59]
Chromatography	Small sample volumes High selectivity for complex samples Environmentally friendly	Expensive equipment Requires skilled staff Standards needed for calibration Long analysis times High pressures	[68, 75, 76]

Table 8.

Summary of advantages and drawbacks of different detection methods for copper analyses.

Spectrophotometric and voltammetric methods offer inexpensive and rapid copper analysis but can suffer from interferences and environmental variability. Meanwhile, sophisticated instrumentation like atomic absorption spectrometry (AAS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and inductively coupled plasma-mass spectrometry (ICP-MS) provide sensitive and reliable quantitation, although at substantially higher costs. ICP-MS, in particular, enables isotope ratio analysis and limits detection down to parts per trillion levels. Electrochemical sensors present a promising on-site or continuous monitoring approach given their real-time measurement capabilities. However, widespread implementation still needs to address sensor robustness and operator expertise. Where sample complexity is high, chromatographic separation before element-specific detection can improve selectivity and sensitivity without extensive sample pretreatment. Critical parameters such as target detection limits, available resources, and sample matrix effects are needed to select the optimal copper detection methodology for a given application.

Abbreviations

AAS	atomic absorption spectroscopy
AES	atomic emission spectroscopy
FAAS	flame atomic absorption spectrometry
GFAAS	graphite furnace atomic absorption spectrometry
CVAAS	cold vapor atomic absorption spectrometry
HAAS	hydride atomic absorption spectrometry
ICP-OES	inductively coupled plasma-optical emission spectrometry
ICP-MS	inductively coupled plasma-mass spectrometry
MIP-OES	microwave-induced plasma optical emission spectrometry
APGD	atmospheric pressure glow discharge
XRF	X-ray fluorescence spectroscopy
LIBS	laser-induced breakdown spectroscopy
UV-Vis	ultraviolet-visible spectroscopy
HPLC	high-performance liquid chromatography
RP-HPLC	reverse phase high-pressure liquid chromatography
IC	ion chromatography